Initial submission for validation service

Change-Id: I9372430f1ae347373d5a9a0c7a427d7bd393d61e
Issue-ID: LOG-427
Signed-off-by: Prudence Au (prudence.au@amdocs.com)
Signed-off-by: Geora Barsky <georab@amdocs.com>
Signed-off-by: Pierre Rioux <pierre.rioux@amdocs.com>

72 files changed, 9741 insertions, 0 deletions

diff --git a/src/main/java/org/onap/aai/auth/AAIAuthException.java b/src/main/java/org/onap/aai/auth/AAIAuthException.java
new file mode 100644
index 0000000..5bbfc11
--- /dev/null
+++ b/src/main/java/org/onap/aai/auth/AAIAuthException.java
@@ -0,0 +1,34 @@
+/*
+ * ============LICENSE_START===================================================
+ * Copyright (c) 2018 Amdocs
+ * ============================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=====================================================
+ */
+package org.onap.aai.auth;
+
+public class AAIAuthException extends Exception {
+	/**
+	 * 
+	 */
+	private static final long serialVersionUID = 1L;
+
+	public AAIAuthException(String string) {
+		super(string);
+	}
+	
+	public AAIAuthException(String string, Exception e) {
+		super(string, e);
+	}
+
+}
diff --git a/src/main/java/org/onap/aai/auth/AAIMicroServiceAuth.java b/src/main/java/org/onap/aai/auth/AAIMicroServiceAuth.java
new file mode 100644
index 0000000..fc40e0b
--- /dev/null
+++ b/src/main/java/org/onap/aai/auth/AAIMicroServiceAuth.java
@@ -0,0 +1,103 @@
+/*
+ * ============LICENSE_START===================================================
+ * Copyright (c) 2018 Amdocs
+ * ============================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=====================================================
+ */
+package org.onap.aai.auth;
+
+import java.security.cert.X509Certificate;
+import javax.inject.Inject;
+import javax.security.auth.x500.X500Principal;
+import javax.servlet.http.HttpServletRequest;
+import javax.ws.rs.core.Cookie;
+import org.onap.aai.validation.config.ValidationServiceAuthConfig;
+import org.onap.aai.validation.logging.LogHelper;
+
+public class AAIMicroServiceAuth {
+
+    private static LogHelper applicationLogger = LogHelper.INSTANCE;
+
+    private ValidationServiceAuthConfig validationServiceAuthConfig;
+
+    @Inject
+    public AAIMicroServiceAuth(final ValidationServiceAuthConfig validationServiceAuthConfig) throws AAIAuthException {
+        this.validationServiceAuthConfig = validationServiceAuthConfig;
+        if (!validationServiceAuthConfig.isAuthenticationDisable()) {
+            AAIMicroServiceAuthCore.init(validationServiceAuthConfig.getAuthPolicyFile());
+        }
+    }
+
+    public boolean authBasic(String username, String authFunction) throws AAIAuthException {
+        return AAIMicroServiceAuthCore.authorize(username, authFunction);
+    }
+
+    public String authUser(String authUser, String authFunction) throws AAIAuthException {
+        StringBuilder username = new StringBuilder();
+
+        username.append(authUser);
+        if (!authBasic(username.toString(), authFunction)) {
+            return "AAI_9101";
+
+        }
+        return "OK";
+    }
+
+    public boolean authCookie(Cookie cookie, String authFunction, StringBuilder username) throws AAIAuthException {
+        if (cookie == null) {
+            return false;
+        }
+        applicationLogger.debug("Got one:" + cookie);
+
+        return AAIMicroServiceAuthCore.authorize(username.toString(), authFunction);
+    }
+
+    public boolean validateRequest(HttpServletRequest req, String action, String apiPath) throws AAIAuthException {
+
+        applicationLogger.debug("validateRequest: " + apiPath);
+        applicationLogger.debug("validationServiceConfig.isAuthenticationDisable(): "
+                + validationServiceAuthConfig.isAuthenticationDisable());
+
+        if (validationServiceAuthConfig.isAuthenticationDisable()) {
+            return true;
+        }
+        String[] ps = apiPath.split("/");
+        String authPolicyFunctionName = ps[0];
+        if (ps.length > 1) {
+            if (ps[0].matches("v\\d+")) {
+                authPolicyFunctionName = ps[1];
+            } else {
+                authPolicyFunctionName = ps[0];
+            }
+        }
+
+        String cipherSuite = (String) req.getAttribute("javax.servlet.request.cipher_suite");
+        String authUser = null;
+        if (cipherSuite != null) {
+            X509Certificate[] certChain = (X509Certificate[]) req.getAttribute("javax.servlet.request.X509Certificate");
+            if (certChain != null) {
+                X509Certificate clientCert = certChain[0];
+                X500Principal subjectDN = clientCert.getSubjectX500Principal();
+                authUser = subjectDN.toString();
+            }
+        }
+
+        if (authUser == null) {
+            return false;
+        }
+
+        String status = authUser(authUser.toLowerCase(), action + ":" + authPolicyFunctionName);
+        return "OK".equals(status);
+    }
+}
diff --git a/src/main/java/org/onap/aai/auth/AAIMicroServiceAuthCore.java b/src/main/java/org/onap/aai/auth/AAIMicroServiceAuthCore.java
new file mode 100644
index 0000000..25273fc
--- /dev/null
+++ b/src/main/java/org/onap/aai/auth/AAIMicroServiceAuthCore.java
@@ -0,0 +1,269 @@
+/*
+ * ============LICENSE_START===================================================
+ * Copyright (c) 2018 Amdocs
+ * ============================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=====================================================
+ */
+package org.onap.aai.auth;
+
+import com.fasterxml.jackson.core.JsonProcessingException;
+import com.fasterxml.jackson.databind.JsonNode;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import java.io.File;
+import java.io.FileNotFoundException;
+import java.io.IOException;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.util.ArrayList;
+import java.util.Date;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map.Entry;
+import java.util.Timer;
+import java.util.TimerTask;
+import java.util.concurrent.TimeUnit;
+import org.onap.aai.validation.logging.ApplicationMsgs;
+import org.onap.aai.validation.logging.LogHelper;
+
+/**
+ * Authentication and authorization by user and role.
+ */
+public class AAIMicroServiceAuthCore {
+
+    private static LogHelper applicationLogger = LogHelper.INSTANCE;
+
+    public static final String APPCONFIG_DIR = (System.getProperty("CONFIG_HOME") == null)
+            ? Paths.get(System.getProperty("APP_HOME"), "appconfig").toString() : System.getProperty("CONFIG_HOME");
+
+    private static Path appConfigAuthDir = Paths.get(APPCONFIG_DIR, "auth");
+    private static Path defaultAuthFileName = appConfigAuthDir.resolve("auth_policy.json");
+
+    private static boolean usersInitialized = false;
+    private static HashMap<String, AAIAuthUser> users;
+    private static boolean timerSet = false;
+    private static String policyAuthFileName;
+
+    public enum HTTP_METHODS {
+        GET,
+        PUT,
+        DELETE,
+        HEAD,
+        POST
+    }
+
+    // Don't instantiate
+    private AAIMicroServiceAuthCore() {}
+
+    public static String getDefaultAuthFileName() {
+        return defaultAuthFileName.toString();
+    }
+
+    public static void setDefaultAuthFileName(String defaultAuthFileName) {
+        AAIMicroServiceAuthCore.defaultAuthFileName = Paths.get(defaultAuthFileName);
+    }
+
+    public static synchronized void init(String authPolicyFile) throws AAIAuthException {
+
+        try {
+            policyAuthFileName = AAIMicroServiceAuthCore.getConfigFile(authPolicyFile);
+        } catch (IOException e) {
+            applicationLogger.debug("Exception while retrieving policy file.");
+            applicationLogger.error(ApplicationMsgs.PROCESS_REQUEST_ERROR, e);
+            throw new AAIAuthException(e.getMessage());
+        }
+        if (policyAuthFileName == null) {
+            throw new AAIAuthException("Auth policy file could not be found");
+        }
+        AAIMicroServiceAuthCore.reloadUsers();
+
+        TimerTask task = new FileWatcher(new File(policyAuthFileName)) {
+            @Override
+            protected void onChange(File file) {
+                // here we implement the onChange
+                applicationLogger.debug("File " + file.getName() + " has been changed!");
+                try {
+                    AAIMicroServiceAuthCore.reloadUsers();
+                } catch (AAIAuthException e) {
+                    applicationLogger.error(ApplicationMsgs.PROCESS_REQUEST_ERROR, e);
+                }
+                applicationLogger.debug("File " + file.getName() + " has been reloaded!");
+            }
+        };
+
+        if (!timerSet) {
+            timerSet = true;
+            Timer timer = new Timer();
+            long period = TimeUnit.SECONDS.toMillis(1);
+            timer.schedule(task, new Date(), period);
+            applicationLogger.debug("Config Watcher Interval = " + period);
+        }
+    }
+
+    public static String getConfigFile(String authPolicyFile) throws IOException {
+        File authFile = new File(authPolicyFile);
+        if (authFile.exists()) {
+            return authFile.getCanonicalPath();
+        }
+        authFile = appConfigAuthDir.resolve(authPolicyFile).toFile();
+        if (authFile.exists()) {
+            return authFile.getCanonicalPath();
+        }
+        if (getDefaultAuthFileName() != null) {
+            authFile = new File(getDefaultAuthFileName());
+            if (authFile.exists()) {
+                return getDefaultAuthFileName();
+            }
+        }
+        return null;
+    }
+
+    /**
+     * @throws AAIAuthException
+     */
+    public static synchronized void reloadUsers() throws AAIAuthException {
+        users = new HashMap<>();
+        ObjectMapper mapper = new ObjectMapper();
+
+        try {
+            applicationLogger.debug("Reading from " + policyAuthFileName);
+            JsonNode rootNode = mapper.readTree(new File(policyAuthFileName));
+            JsonNode rolesNode = rootNode.path("roles");
+
+            for (JsonNode roleNode : rolesNode) {
+                String roleName = roleNode.path("name").asText();
+                AAIAuthRole r = new AAIAuthRole();
+                JsonNode usersNode = roleNode.path("users");
+                JsonNode functionsNode = roleNode.path("functions");
+                for (JsonNode functionNode : functionsNode) {
+                    addFunctionToRole(r, roleName, functionNode);
+                }
+                for (JsonNode userNode : usersNode) {
+                    String name = userNode.path("username").asText().toLowerCase();
+                    AAIAuthUser user;
+                    if (users.containsKey(name)) {
+                        user = users.get(name);
+                    } else {
+                        user = new AAIAuthUser();
+                    }
+
+                    applicationLogger.debug("Assigning " + roleName + " to user " + name);
+                    user.addRole(roleName, r);
+                    users.put(name, user);
+                }
+            }
+        } catch (FileNotFoundException e) {
+            throw new AAIAuthException("Auth policy file could not be found", e);
+        } catch (JsonProcessingException e) {
+            throw new AAIAuthException("Error processing Auth policy file ", e);
+        } catch (IOException e) {
+            throw new AAIAuthException("Error reading Auth policy file", e);
+        }
+
+        usersInitialized = true;
+    }
+
+    /**
+     * @param role
+     * @param roleName
+     * @param functionNode
+     */
+    private static void addFunctionToRole(AAIAuthRole role, String roleName, JsonNode functionNode) {
+        String functionName = functionNode.path("name").asText();
+        JsonNode methodsNode = functionNode.path("methods");
+
+        if (methodsNode.size() == 0) {
+            for (HTTP_METHODS method : HTTP_METHODS.values()) {
+                String fullFunctionName = method.toString() + ":" + functionName;
+                applicationLogger.debug("Installing (all methods) " + fullFunctionName + " on role " + roleName);
+                role.addAllowedFunction(fullFunctionName);
+            }
+        } else {
+            for (JsonNode methodNode : methodsNode) {
+                String methodName = methodNode.path("name").asText();
+                String fullFunctionName = methodName + ":" + functionName;
+                applicationLogger.debug("Installing function " + fullFunctionName + " on role " + roleName);
+                role.addAllowedFunction(fullFunctionName);
+            }
+        }
+    }
+
+    public static class AAIAuthUser {
+        private HashMap<String, AAIAuthRole> roles;
+
+        public AAIAuthUser() {
+            this.roles = new HashMap<>();
+        }
+
+        public void addRole(String roleName, AAIAuthRole r) {
+            this.roles.put(roleName, r);
+        }
+
+        public boolean checkAllowed(String checkFunc) {
+            for (Entry<String, AAIAuthRole> role_entry : roles.entrySet()) {
+                AAIAuthRole role = role_entry.getValue();
+                if (role.hasAllowedFunction(checkFunc)) {
+                    return true;
+                }
+            }
+            return false;
+        }
+
+    }
+
+    public static class AAIAuthRole {
+        private List<String> allowedFunctions;
+
+        public AAIAuthRole() {
+            this.allowedFunctions = new ArrayList<>();
+        }
+
+        public void addAllowedFunction(String func) {
+            this.allowedFunctions.add(func);
+        }
+
+        public void delAllowedFunction(String delFunc) {
+            if (this.allowedFunctions.contains(delFunc)) {
+                this.allowedFunctions.remove(delFunc);
+            }
+        }
+
+        public boolean hasAllowedFunction(String functionName) {
+            return allowedFunctions.contains(functionName) ? true : false;
+        }
+    }
+
+    public static boolean authorize(String username, String authFunction) throws AAIAuthException {
+        if (!usersInitialized || users == null) {
+            throw new AAIAuthException("Auth module not initialized");
+        }
+
+        if (users.containsKey(username)) {
+            if (users.get(username).checkAllowed(authFunction)) {
+                logAuthenticationResult(username, authFunction, "AUTH ACCEPTED");
+                return true;
+            } else {
+                logAuthenticationResult(username, authFunction, "AUTH FAILED");
+                return false;
+            }
+        } else {
+            logAuthenticationResult(username, authFunction, "User not found");
+            return false;
+        }
+    }
+
+    private static void logAuthenticationResult(String username, String authFunction, String result) {
+        applicationLogger.debug(result + ": " + username + " on function " + authFunction);
+    }
+
+}
diff --git a/src/main/java/org/onap/aai/auth/FileWatcher.java b/src/main/java/org/onap/aai/auth/FileWatcher.java
new file mode 100644
index 0000000..edc8bfe
--- /dev/null
+++ b/src/main/java/org/onap/aai/auth/FileWatcher.java
@@ -0,0 +1,58 @@
+/*
+ * ============LICENSE_START===================================================
+ * Copyright (c) 2018 Amdocs
+ * ============================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=====================================================
+ */
+package org.onap.aai.auth;
+
+import java.io.File;
+import java.util.TimerTask;
+
+public abstract class FileWatcher extends TimerTask {
+    private long timeStamp;
+    private File file;
+
+    /**
+     * Instantiates a new file watcher.
+     *
+     * @param file the file
+     */
+    public FileWatcher(File file) {
+        this.file = file;
+        this.timeStamp = file.lastModified();
+    }
+
+    /**
+     * runs a timer task
+     * 
+     * @see java.util.TimerTask.run
+     */
+    @Override
+    public final void run() {
+        long newTimeStamp = file.lastModified();
+
+        if ((newTimeStamp - this.timeStamp) > 500) {
+            this.timeStamp = newTimeStamp;
+            onChange(file);
+        }
+    }
+
+    /**
+     * On change.
+     *
+     * @param file the file
+     */
+    protected abstract void onChange(File file);
+}
diff --git a/src/main/java/org/onap/aai/validation/ValidationServiceApplication.java b/src/main/java/org/onap/aai/validation/ValidationServiceApplication.java
new file mode 100644
index 0000000..8bf7a44
--- /dev/null
+++ b/src/main/java/org/onap/aai/validation/ValidationServiceApplication.java
@@ -0,0 +1,57 @@
+/*
+ * ============LICENSE_START===================================================
+ * Copyright (c) 2018 Amdocs
+ * ============================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=====================================================
+ */
+package org.onap.aai.validation;
+
+import org.eclipse.jetty.util.security.Password;
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+import org.springframework.boot.builder.SpringApplicationBuilder;
+import org.springframework.boot.web.support.SpringBootServletInitializer;
+import org.springframework.context.annotation.ComponentScan;
+import org.springframework.context.annotation.ImportResource;
+
+import java.util.HashMap;
+
+
+/**
+ * Validation Service Spring Boot Application.
+ */
+
+@SpringBootApplication
+@ComponentScan(basePackages = "org.onap.aai.validation")
+@ImportResource("classpath:validation-service-beans.xml")
+public class ValidationServiceApplication extends SpringBootServletInitializer {
+
+   // public static void main(String[] args) {
+   //     SpringApplication.run(ValidationServiceApplication.class, args);
+   // }
+
+
+    public static void main(String[] args) {
+        HashMap<String, Object> props = new HashMap<>();
+        String keyStorePassword = System.getProperty("KEY_STORE_PASSWORD");
+        if (keyStorePassword != null && !keyStorePassword.isEmpty()) {
+            props.put("server.ssl.key-store-password", Password.deobfuscate(keyStorePassword));
+        }
+        new ValidationServiceApplication()
+                .configure(new SpringApplicationBuilder(ValidationServiceApplication.class).properties(props))
+                .run(args);
+    }
+
+
+}
diff --git a/src/main/java/org/onap/aai/validation/Validator.java b/src/main/java/org/onap/aai/validation/Validator.java
new file mode 100644
index 0000000..c3ecc2a
--- /dev/null
+++ b/src/main/java/org/onap/aai/validation/Validator.java
@@ -0,0 +1,45 @@
+/*
+ * ============LICENSE_START===================================================
+ * Copyright (c) 2018 Amdocs
+ * ============================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=====================================================
+ */
+package org.onap.aai.validation;
+
+import java.util.List;
+import org.onap.aai.validation.exception.ValidationServiceException;
+import org.onap.aai.validation.result.ValidationResult;
+
+/**
+ * Validator (e.g. model-driven or rule-based)
+ *
+ */
+public interface Validator {
+
+    /**
+     * This method should be called (once) before validate() to ensure that all configuration is correctly loaded.
+     * 
+     * @throws ValidationServiceException
+     */
+    public void initialise() throws ValidationServiceException;
+
+    /**
+     * Validate the entity or entities found in the event.
+     *
+     * @param event JSON containing the entity or entities to validate
+     * @return a list of validation results
+     * @throws ValidationServiceException
+     */
+    public List<ValidationResult> validate(String event) throws ValidationServiceException;
+}
diff --git a/src/main/java/org/onap/aai/validation/config/EventReaderConfig.java b/src/main/java/org/onap/aai/validation/config/EventReaderConfig.java
new file mode 100644
index 0000000..c819351
--- /dev/null
+++ b/src/main/java/org/onap/aai/validation/config/EventReaderConfig.java
@@ -0,0 +1,163 @@
+/*
+ * ============LICENSE_START===================================================
+ * Copyright (c) 2018 Amdocs
+ * ============================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=====================================================
+ */
+package org.onap.aai.validation.config;
+
+import org.springframework.beans.factory.annotation.Value;
+
+/**
+ * Loaded via Spring from src/main/resources/event-reader.properties.
+ */
+public class EventReaderConfig extends PropertiesConfig {
+
+	@Value("${event.domain.path}")
+	private String eventDomainPath;
+
+    @Value("${event.action.path}")
+	private String eventActionPath;
+
+	@Value("${event.type.path}")
+	private String eventTypePath;
+
+	@Value("${event.entity.type.path}")
+	private String entityTypePath;
+
+	@Value("${event.entity.type.top.path}")
+	private String topEntityTypePath;
+
+	@Value("${event.entity.link.path}")
+	private String entityLinkPath;
+
+	@Value("${event.entity.link.delimiter}")
+	private String entityLinkDelimiter;
+
+	@Value("${event.entity.path}")
+	private String entityPath;
+
+	@Value("${event.entity.nested.path}")
+	private String nestedEntityPath;
+
+	/** Entity relative path. Use when the entity has been extracted from the event. */
+	@Value("${entity.id.path}")
+	private String entityIdPath;
+
+	/** Entity relative path. Use when the entity has been extracted from the event. */
+	@Value("${entity.resource.version.path}")
+	private String entityResourceVersionPath;
+
+	public String getEventDomainPath() {
+		return eventDomainPath;
+	}
+
+	public void setEventDomainPath(String eventDomainPath) {
+		this.eventDomainPath = eventDomainPath;
+	}
+
+	public String getEventActionPath() {
+		return eventActionPath;
+	}
+
+	public void setEventActionPath(String eventActionPath) {
+		this.eventActionPath = eventActionPath;
+	}
+
+	public String getEventTypePath() {
+		return eventTypePath;
+	}
+
+	public void setEventTypePath(String eventTypePath) {
+		this.eventTypePath = eventTypePath;
+	}
+
+	public String getTopEntityTypePath() {
+		return topEntityTypePath;
+	}
+
+	public void setTopEntityTypePath(String topEntityTypePath) {
+		this.topEntityTypePath = topEntityTypePath;
+	}
+
+	public String getEntityLinkPath() {
+		return entityLinkPath;
+	}
+
+	public void setEntityLinkPath(String entityLinkPath) {
+		this.entityLinkPath = entityLinkPath;
+	}
+
+	public String getEntityLinkDelimiter() {
+		return entityLinkDelimiter;
+	}
+
+	public void setEntityLinkDelimiter(String entityLinkDelimiter) {
+		this.entityLinkDelimiter = entityLinkDelimiter;
+	}
+
+	public String getEntityTypePath() {
+		return entityTypePath;
+	}
+
+	public void setEntityTypePath(String entityTypePath) {
+		this.entityTypePath = entityTypePath;
+	}
+
+	public String getEntityPath() {
+		return entityPath;
+	}
+
+	public void setEntityPath(String entityPath) {
+		this.entityPath = entityPath;
+	}
+
+	/**
+	 * Formats the nested entity path using the entity type provided.
+	 *
+	 * @param entityType
+	 *            an entity type
+	 * @return the formatted nested entity path
+	 */
+	public String getNestedEntityPath(String entityType) {
+		return formatter(nestedEntityPath, entityType);
+	}
+
+	public void setNestedEntityPath(String nestedEntityPath) {
+		this.nestedEntityPath = nestedEntityPath;
+	}
+
+	/**
+	 * Formats the entity ID path using the entity type provided.
+	 *
+	 * @param entityType
+	 *            an entity type
+	 * @return the formatted entity ID path
+	 */
+	public String getEntityIdPath(String entityType) {
+		return formatter(entityIdPath, entityType);
+	}
+
+	public void setEntityIdPath(String entityIdPath) {
+		this.entityIdPath = entityIdPath;
+	}
+
+	public String getEntityResourceVersionPath() {
+		return entityResourceVersionPath;
+	}
+
+	public void setEntityResourceVersionPath(String entityResourceVersionPath) {
+		this.entityResourceVersionPath = entityResourceVersionPath;
+	}
+}
\ No newline at end of file
diff --git a/src/main/java/org/onap/aai/validation/config/ModelConfig.java b/src/main/java/org/onap/aai/validation/config/ModelConfig.java
new file mode 100644
index 0000000..02e14bc
--- /dev/null
+++ b/src/main/java/org/onap/aai/validation/config/ModelConfig.java
@@ -0,0 +1,39 @@
+/*
+ * ============LICENSE_START===================================================
+ * Copyright (c) 2018 Amdocs
+ * ============================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=====================================================
+ */
+package org.onap.aai.validation.config;
+
+import org.springframework.beans.factory.annotation.Value;
+
+/**
+ * Model Configuration Bean
+ *
+ */
+public class ModelConfig {
+
+	@Value("${model.cache.expirySeconds}")
+	private Long modelCacheExpirySeconds;
+
+	public Long getModelCacheExpirySeconds() {
+		return modelCacheExpirySeconds;
+	}
+
+	public void setModelCacheExpirySeconds(Long modelCacheExpirySeconds) {
+		this.modelCacheExpirySeconds = modelCacheExpirySeconds;
+	}
+
+}
\ No newline at end of file
diff --git a/src/main/java/org/onap/aai/validation/config/PropertiesConfig.java b/src/main/java/org/onap/aai/validation/config/PropertiesConfig.java
new file mode 100644
index 0000000..cf4bcb2
--- /dev/null
+++ b/src/main/java/org/onap/aai/validation/config/PropertiesConfig.java
@@ -0,0 +1,41 @@
+/*
+ * ============LICENSE_START===================================================
+ * Copyright (c) 2018 Amdocs
+ * ============================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=====================================================
+ */
+package org.onap.aai.validation.config;
+
+import java.text.MessageFormat;
+
+/**
+ * Base properties configuration class.
+ */
+public class PropertiesConfig {
+
+	/**
+	 * Replaces place-holders in property values.
+	 *
+	 * @param s
+	 *            a string with place-holders in the form {n}
+	 * @param args
+	 *            values for place-holders
+	 * @return a formated String with replaced place-holders.
+	 */
+	public String formatter(String s, Object... args) {
+		MessageFormat formatter = new MessageFormat("");
+		formatter.applyPattern(s);
+		return formatter.format(args);
+	}
+}
diff --git a/src/main/java/org/onap/aai/validation/config/RestConfig.java b/src/main/java/org/onap/aai/validation/config/RestConfig.java
new file mode 100644
index 0000000..e99d6c2
--- /dev/null
+++ b/src/main/java/org/onap/aai/validation/config/RestConfig.java
@@ -0,0 +1,225 @@
+/*
+ * ============LICENSE_START===================================================
+ * Copyright (c) 2018 Amdocs
+ * ============================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=====================================================
+ */
+package org.onap.aai.validation.config;
+
+import java.util.Objects;
+import org.apache.commons.lang3.builder.EqualsBuilder;
+import org.springframework.beans.factory.annotation.Value;
+
+/**
+ * Configuration required to establish REST client requests with an application.
+ */
+public class RestConfig {
+
+    @Value("${host}")
+    private String host;
+
+    @Value("${port}")
+    private Integer port;
+
+    @Value("${httpProtocol}")
+    private String protocol;
+
+    @Value("${baseModelURI}")
+    private String baseModelURI;
+
+    @Value("${trustStorePath}")
+    private String trustStorePath;
+
+    @Value("${trustStorePassword.x}")
+    private String trustStorePassword;
+
+    @Value("${keyStorePath}")
+    private String keyStorePath;
+
+    @Value("${keyStorePassword.x}")
+    private String keyStorePassword;
+
+    @Value("${keyManagerFactoryAlgorithm}")
+    private String keyManagerFactoryAlgorithm;
+
+    @Value("${keyStoreType}")
+    private String keyStoreType;
+
+    @Value("${securityProtocol}")
+    private String securityProtocol;
+
+    @Value("${connectionTimeout}")
+    private Integer connectionTimeout;
+
+    @Value("${readTimeout}")
+    private Integer readTimeout;
+
+    public String getHost() {
+        return host;
+    }
+
+    public void setHost(String host) {
+        this.host = host;
+    }
+
+    public Integer getPort() {
+        return port;
+    }
+
+    public void setPort(Integer port) {
+        this.port = port;
+    }
+
+    public String getProtocol() {
+        return protocol;
+    }
+
+    public void setProtocol(String protocol) {
+        this.protocol = protocol;
+    }
+
+    public String getBaseModelURI() {
+        return baseModelURI;
+    }
+
+    public void setBaseModelURI(String baseModelURI) {
+        this.baseModelURI = baseModelURI;
+    }
+
+    public String getTrustStorePath() {
+        return trustStorePath;
+    }
+
+    public void setTrustStorePath(String trustStorePath) {
+        this.trustStorePath = trustStorePath;
+    }
+
+    /**
+     * Assumes the password is encrypted.
+     *
+     * @return the decrypted password
+     */
+    public String getTrustStorePassword() {
+    	return trustStorePassword;
+    }
+
+    public void setTrustStorePassword(String trustStorePassword) {
+        this.trustStorePassword = trustStorePassword;
+    }
+
+    public String getKeyStorePath() {
+        return keyStorePath;
+    }
+
+    public void setKeyStorePath(String keyStorePath) {
+        this.keyStorePath = keyStorePath;
+    }
+
+    /**
+     * Assumes the password is encrypted.
+     *
+     * @return the decrypted password
+     */
+    public String getKeyStorePassword() {
+    	return keyStorePassword;
+    }
+
+    public void setKeyStorePassword(String keyStorePassword) {
+        this.keyStorePassword = keyStorePassword;
+    }
+
+    public String getKeyManagerFactoryAlgorithm() {
+        return keyManagerFactoryAlgorithm;
+    }
+
+    public void setKeyManagerFactoryAlgorithm(String keyManagerFactoryAlgorithm) {
+        this.keyManagerFactoryAlgorithm = keyManagerFactoryAlgorithm;
+    }
+
+    public String getKeyStoreType() {
+        return keyStoreType;
+    }
+
+    public void setKeyStoreType(String keyStoreType) {
+        this.keyStoreType = keyStoreType;
+    }
+
+    public String getSecurityProtocol() {
+        return securityProtocol;
+    }
+
+    public void setSecurityProtocol(String securityProtocol) {
+        this.securityProtocol = securityProtocol;
+    }
+
+    public Integer getConnectionTimeout() {
+        return connectionTimeout;
+    }
+
+    public void setConnectionTimeout(Integer connectionTimeout) {
+        this.connectionTimeout = connectionTimeout;
+    }
+
+    public Integer getReadTimeout() {
+        return readTimeout;
+    }
+
+    public void setReadTimeout(Integer readTimeout) {
+        this.readTimeout = readTimeout;
+    }
+
+    @Override
+    public String toString() {
+        return "RestConfig [host=" + host + ", port=" + port + ", protocol=" + protocol + ", baseModelURI="
+                + baseModelURI + ", trustStorePath=" + trustStorePath + ", trustStorePassword=" + trustStorePassword
+                + ", keyStorePath=" + keyStorePath + ", keyStorePassword=" + keyStorePassword
+                + ", keyManagerFactoryAlgorithm=" + keyManagerFactoryAlgorithm + ", keyStoreType=" + keyStoreType
+                + ", securityProtocol=" + securityProtocol + ", connectionTimeout=" + connectionTimeout
+                + ", readTimeout=" + readTimeout + "]";
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(this.baseModelURI, this.connectionTimeout, this.host, this.keyManagerFactoryAlgorithm,
+                this.keyStorePassword, this.keyStorePath, this.keyStoreType, this.port, this.protocol, this.readTimeout,
+                this.securityProtocol, this.trustStorePassword, this.trustStorePath);
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (!(obj instanceof RestConfig)) {
+            return false;
+        } else if (obj == this) {
+            return true;
+        }
+        RestConfig rhs = (RestConfig) obj;
+     // @formatter:off
+     return new EqualsBuilder()
+                  .append(baseModelURI, rhs.baseModelURI)
+                  .append(connectionTimeout, rhs.connectionTimeout)
+                  .append(host, rhs.host)
+                  .append(keyManagerFactoryAlgorithm, rhs.keyManagerFactoryAlgorithm)
+                  .append(keyStorePassword, rhs.keyStorePassword)
+                  .append(keyStorePath, rhs.keyStorePath)
+                  .append(keyStoreType, rhs.keyStoreType)
+                  .append(port, rhs.port)
+                  .append(protocol, rhs.protocol)
+                  .append(readTimeout, rhs.readTimeout)
+                  .append(securityProtocol, rhs.securityProtocol)
+                  .append(trustStorePassword, rhs.trustStorePassword)
+                  .append(trustStorePath, rhs.trustStorePath)
+                  .isEquals();
+     // @formatter:on
+    }
+}
diff --git a/src/main/java/org/onap/aai/validation/config/RuleIndexingConfig.java b/src/main/java/org/onap/aai/validation/config/RuleIndexingConfig.java
new file mode 100644
index 0000000..1d27705
--- /dev/null
+++ b/src/main/java/org/onap/aai/validation/config/RuleIndexingConfig.java
@@ -0,0 +1,73 @@
+/*
+ * ============LICENSE_START===================================================
+ * Copyright (c) 2018 Amdocs
+ * ============================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=====================================================
+ */
+package org.onap.aai.validation.config;
+
+import java.util.List;
+
+/**
+ * Loads the properties needed by the controller using spring.
+ */
+public class RuleIndexingConfig extends PropertiesConfig {
+
+    private List<String> indexedEvents;
+
+    private List<String> excludedOxmValidationEvents;
+
+    private List<String> indexAttributes;
+
+    private String defaultIndexKey;
+
+    public List<String> getIndexedEvents() {
+        return indexedEvents;
+    }
+
+    public void setIndexedEvents(List<String> indexedEvents) {
+        this.indexedEvents = indexedEvents;
+    }
+
+    public List<String> getExcludedOxmValidationEvents() {
+        return excludedOxmValidationEvents;
+    }
+
+    public void setExcludedOxmValidationEvents(List<String> excludedOxmValidationEvents) {
+        this.excludedOxmValidationEvents = excludedOxmValidationEvents;
+    }
+
+    public List<String> getIndexAttributes() {
+        return indexAttributes;
+    }
+
+    public void setIndexAttributes(List<String> indexAttributes) {
+        this.indexAttributes = indexAttributes;
+    }
+
+    public String getDefaultIndexKey() {
+        return defaultIndexKey;
+    }
+
+    public void setDefaultIndexKey(String defaultIndexKey) {
+        this.defaultIndexKey = defaultIndexKey;
+    }
+
+    public boolean skipOxmValidation(String event) {
+        if(excludedOxmValidationEvents == null) {
+            return false;
+        }
+        return excludedOxmValidationEvents.contains(event);
+    }
+}
diff --git a/src/main/java/org/onap/aai/validation/config/TopicAdminConfig.java b/src/main/java/org/onap/aai/validation/config/TopicAdminConfig.java
new file mode 100644
index 0000000..22fbe97
--- /dev/null
+++ b/src/main/java/org/onap/aai/validation/config/TopicAdminConfig.java
@@ -0,0 +1,103 @@
+/*
+ * ============LICENSE_START===================================================
+ * Copyright (c) 2018 Amdocs
+ * ============================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=====================================================
+ */
+package org.onap.aai.validation.config;
+
+import java.util.Objects;
+import org.apache.commons.lang3.builder.EqualsBuilder;
+import org.springframework.beans.factory.annotation.Value;
+
+/**
+ * Configuration bean with topic administration properties that are loaded via Spring configuration.
+ */
+public class TopicAdminConfig {
+
+    @Value("${topic.publish.enable}")
+    private boolean publishEnable;
+
+    @Value("${topic.publish.retries}")
+    private Long publishRetries;
+
+    @Value("${topic.consume.enable}")
+    private boolean consumeEnable;
+
+    @Value("${topic.consume.polling.interval.seconds}")
+    private Long consumePollingIntervalSeconds;
+
+    public boolean isPublishEnable() {
+        return publishEnable;
+    }
+
+    public void setPublishEnable(boolean publishEnable) {
+        this.publishEnable = publishEnable;
+    }
+
+    public Long getPublishRetries() {
+        return publishRetries;
+    }
+
+    public void setPublishRetries(Long publishRetries) {
+        this.publishRetries = publishRetries;
+    }
+
+    public boolean isConsumeEnable() {
+        return consumeEnable;
+    }
+
+    public void setConsumeEnable(boolean consumeEnable) {
+        this.consumeEnable = consumeEnable;
+    }
+
+    public Long getConsumePollingIntervalSeconds() {
+        return consumePollingIntervalSeconds;
+    }
+
+    public void setConsumePollingIntervalSeconds(Long consumePollingIntervalSeconds) {
+        this.consumePollingIntervalSeconds = consumePollingIntervalSeconds;
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(this.consumeEnable, this.consumePollingIntervalSeconds, this.publishEnable,
+                this.publishRetries);
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (!(obj instanceof TopicAdminConfig)) {
+            return false;
+        } else if (obj == this) {
+            return true;
+        }
+        TopicAdminConfig rhs = (TopicAdminConfig) obj;
+     // @formatter:off
+     return new EqualsBuilder()
+                  .append(consumeEnable, rhs.consumeEnable)
+                  .append(consumePollingIntervalSeconds, rhs.consumePollingIntervalSeconds)
+                  .append(publishEnable, rhs.publishEnable)
+                  .append(publishRetries, rhs.publishRetries)
+                  .isEquals();
+     // @formatter:on
+    }
+
+    @Override
+    public String toString() {
+        return "TopicAdminConfig [publishEnable=" + publishEnable + ", publishRetries=" + publishRetries
+                + ", consumeEnable=" + consumeEnable + ", consumePollingIntervalSeconds="
+                + consumePollingIntervalSeconds + "]";
+    }
+}
diff --git a/src/main/java/org/onap/aai/validation/config/TopicConfig.java b/src/main/java/org/onap/aai/validation/config/TopicConfig.java
new file mode 100644
index 0000000..99742ac
--- /dev/null
+++ b/src/main/java/org/onap/aai/validation/config/TopicConfig.java
@@ -0,0 +1,243 @@
+/*
+ * ============LICENSE_START===================================================
+ * Copyright (c) 2018 Amdocs
+ * ============================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=====================================================
+ */
+package org.onap.aai.validation.config;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+import java.util.Objects;
+import java.util.Properties;
+import javax.annotation.Resource;
+import org.apache.commons.lang3.builder.EqualsBuilder;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.beans.factory.annotation.Value;
+import org.springframework.stereotype.Component;
+
+/**
+ * Gets the configuration of the topics. The topics are configured using Spring in topic-config-beans.xml.
+ */
+
+@Component("TopicConfig")
+public class TopicConfig {
+
+    private List<String> consumerTopicNames;
+
+    private List<String> publisherTopicNames;
+
+    @Resource(name = "topicProperties")
+    private Properties topicProperties;
+
+    List<Topic> consumerTopics = new ArrayList<>();
+    List<Topic> publisherTopics = new ArrayList<>();
+
+    @Autowired
+    public TopicConfig (@Value("${consumer.topic.names}") final String consumerNames, @Value("${publisher.topic.names}") final String publisherNames){
+
+        consumerTopicNames = Arrays.asList(consumerNames.split(","));;
+        publisherTopicNames = Arrays.asList(publisherNames.split(","));;
+
+
+    }
+    /**
+     * Gets the configuration of topics for consumption.
+     *
+     * @return a list of topic configurations.
+     */
+    public List<Topic> getConsumerTopics()
+    {
+        return populateTopics(consumerTopics, consumerTopicNames);
+    }
+
+
+    /**
+     * Gets the configuration of topics for publishing.
+     *
+     * @return a list of topic configurations.
+     */
+    public List<Topic> getPublisherTopics() {
+        return populateTopics(publisherTopics, publisherTopicNames);
+    }
+
+    /**
+	 * Populates the topics list with topic objects created from each item in the topicNames list.
+	 *
+	 * @param topics
+	 *            The topic list to populate.
+	 * @param topicNames
+	 *            The list of topic names to populate the topic list with.
+	 * @return The populated topic list.
+	 */
+	private List<Topic> populateTopics(List<Topic> topics, List<String> topicNames) {
+		if (topics.isEmpty()) {
+			for (String topicName : topicNames) {
+				Topic topicConfig = new Topic();
+				topicConfig.setName(getTopicProperties().getProperty(topicName + ".name"));
+				topicConfig.setHost(getTopicProperties().getProperty(topicName + ".host"));
+				topicConfig.setUsername(getTopicProperties().getProperty(topicName + ".username"));
+				topicConfig.setPassword(getTopicProperties().getProperty(topicName + ".password"));
+				topicConfig.setPartition(getTopicProperties().getProperty(topicName + ".publisher.partition"));
+				topicConfig.setConsumerGroup(getTopicProperties().getProperty(topicName + ".consumer.group"));
+				topicConfig.setConsumerId(getTopicProperties().getProperty(topicName + ".consumer.id"));
+				topicConfig.setTransportType(getTopicProperties().getProperty(topicName + ".transport.type"));
+				topics.add(topicConfig);
+			}
+		}
+		return topics;
+	}
+
+    public List<String> getConsumerTopicNames() {
+        return consumerTopicNames;
+    }
+
+    public void setConsumerTopicNames(List<String> consumerTopicNames) {
+        this.consumerTopicNames = consumerTopicNames;
+    }
+
+    public List<String> getPublisherTopicNames() {
+        return publisherTopicNames;
+    }
+
+    public void setPublisherTopicNames(List<String> publisherTopicNames) {
+        this.publisherTopicNames = publisherTopicNames;
+    }
+
+    public Properties getTopicProperties() {
+        return topicProperties;
+    }
+
+    public void setTopicProperties(Properties topicProperties) {
+        this.topicProperties = topicProperties;
+    }
+
+    /**
+     * Defines the properties of a single topic for consumption.
+     */
+    public class Topic {
+        private String name;
+        private String host;
+        private String username;
+        private String password;
+        private String partition;
+        private String consumerGroup;
+        private String consumerId;
+        private String transportType;
+
+        public String getName() {
+            return name;
+        }
+
+        public void setName(String name) {
+            this.name = name;
+        }
+
+        public String getHost() {
+            return host;
+        }
+
+        public void setHost(String host) {
+            this.host = host;
+        }
+
+        public String getUsername() {
+            return username;
+        }
+
+        public void setUsername(String username) {
+            this.username = username;
+        }
+
+        public String getPassword() {
+        	return password;
+        }
+
+        public void setPassword(String password) {
+            this.password = password;
+        }
+
+        public String getPartition() {
+            return partition;
+        }
+
+        public void setPartition(String partition) {
+            this.partition = partition;
+        }
+
+        public String getConsumerGroup() {
+            return consumerGroup;
+        }
+
+        public void setConsumerGroup(String consumerGroup) {
+            this.consumerGroup = consumerGroup;
+        }
+
+        public String getConsumerId() {
+            return consumerId;
+        }
+
+        public void setConsumerId(String consumerId) {
+            this.consumerId = consumerId;
+        }
+
+        public List<String> getHosts() {
+            return Arrays.asList(host.split(","));
+        }
+
+        public String getTransportType() {
+            return transportType;
+        }
+
+        public void setTransportType(String transportType) {
+            this.transportType = transportType;
+        }
+
+        @Override
+        public int hashCode() {
+            return Objects.hash(this.consumerGroup, this.consumerId, this.host, this.username, this.name, this.partition,
+                    this.password, this.transportType);
+        }
+
+        @Override
+        public boolean equals(Object obj) {
+            if (!(obj instanceof Topic)) {
+                return false;
+            } else if (obj == this) {
+                return true;
+            }
+            Topic rhs = (Topic) obj;
+         // @formatter:off
+	     return new EqualsBuilder()
+	                  .append(consumerGroup, rhs.consumerGroup)
+	                  .append(consumerId, rhs.consumerId)
+	                  .append(host, rhs.host)
+	                  .append(username, rhs.username)
+	                  .append(name, rhs.name)
+	                  .append(partition, rhs.partition)
+	                  .append(password, rhs.password)
+	                  .append(transportType, rhs.transportType)
+	                  .isEquals();
+	     // @formatter:on
+        }
+
+        @Override
+        public String toString() {
+            return "Topic [name=" + name + ", host=" + host + ", username=" + username + ", password=" + password + ", partition="
+                    + partition + ", consumerGroup=" + consumerGroup + ", consumerId=" + consumerId
+                    + ", transportType =" + transportType + "]";
+        }
+    }
+}
diff --git a/src/main/java/org/onap/aai/validation/config/TopicPropertiesConfig.java b/src/main/java/org/onap/aai/validation/config/TopicPropertiesConfig.java
new file mode 100644
index 0000000..4742cef
--- /dev/null
+++ b/src/main/java/org/onap/aai/validation/config/TopicPropertiesConfig.java
@@ -0,0 +1,75 @@
+/*
+ * ============LICENSE_START===================================================
+ * Copyright (c) 2018 Amdocs
+ * ============================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=====================================================
+ */
+package org.onap.aai.validation.config;
+
+import org.onap.aai.validation.logging.LogHelper;
+import org.springframework.beans.factory.annotation.Value;
+import org.springframework.beans.factory.config.PropertiesFactoryBean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.context.annotation.Bean;
+import org.springframework.core.io.Resource;
+import org.springframework.core.io.support.PathMatchingResourcePatternResolver;
+
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Properties;
+
+@Configuration
+public class TopicPropertiesConfig {
+
+    private static LogHelper applicationLogger = LogHelper.INSTANCE;
+
+    @Value("${topics.properties.location}")
+    private String topicsPropertiesLocation;
+
+    private static final String[] TOPICS_PROPERTIES_LOCATION_TPL = { "file:./%s/*.properties", "classpath:/%s/*.properties" };
+
+    @Bean(name="topicProperties")
+    public Properties topicProperties() throws IOException {
+        PropertiesFactoryBean config = new PropertiesFactoryBean();
+        PathMatchingResourcePatternResolver resolver = new PathMatchingResourcePatternResolver();
+        List<Resource> resouceList = new ArrayList<Resource>();
+        try {
+            for (String p : bldrsPropLoc2Path(topicsPropertiesLocation)) {
+                Resource[] resources = resolver.getResources(p);
+                if (resources != null && resources.length > 0) {
+                    for (Resource resource : resources) {
+                        resouceList.add(resource);
+                    }
+                    break;
+                }
+            }
+        } catch (Exception e) {
+            applicationLogger.logAuditError(e);
+        }
+        config.setLocations(resouceList.toArray(new Resource[]{}));
+        config.afterPropertiesSet();
+        return config.getObject();
+    }
+
+    private static String[] bldrsPropLoc2Path(String topicsPropertiesLocation) {
+        String[] res = new String[TOPICS_PROPERTIES_LOCATION_TPL.length];
+        int indx = 0;
+        for (String tmpl : TOPICS_PROPERTIES_LOCATION_TPL) {
+            res[indx++] = String.format(tmpl, topicsPropertiesLocation).replace("//", "/");
+        }
+        return res;
+    }
+
+}
diff --git a/src/main/java/org/onap/aai/validation/config/ValidationControllerConfig.java b/src/main/java/org/onap/aai/validation/config/ValidationControllerConfig.java
new file mode 100644
index 0000000..4110175
--- /dev/null
+++ b/src/main/java/org/onap/aai/validation/config/ValidationControllerConfig.java
@@ -0,0 +1,82 @@
+/*
+ * ============LICENSE_START===================================================
+ * Copyright (c) 2018 Amdocs
+ * ============================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=====================================================
+ */
+package org.onap.aai.validation.config;
+
+import java.util.List;
+import org.springframework.beans.factory.annotation.Value;
+
+/**
+ * Loads the properties needed by the controller using spring.
+ */
+public class ValidationControllerConfig extends PropertiesConfig {
+
+	@Value("${event.domain}")
+	private String eventDomain;
+
+	@Value("#{'${event.action.exclude}'.split(',')}")
+	private List<String> excludedEventActions;
+
+	@Value("#{'${event.type.rule}'.split(',')}")
+	private List<String> eventTypeRule;
+
+	@Value("#{'${event.type.model}'.split(',')}")
+	private List<String> eventTypeModel;
+
+	@Value("${event.type.end:END-EVENT}")
+    private String eventTypeEnd;
+
+	public String getEventDomain() {
+		return eventDomain;
+	}
+
+	public void setEventDomain(String eventDomain) {
+		this.eventDomain = eventDomain;
+	}
+
+	public List<String> getExcludedEventActions() {
+		return excludedEventActions;
+	}
+
+	public void setExcludedEventActions(List<String> excludedEventActions) {
+		this.excludedEventActions = excludedEventActions;
+	}
+
+	public List<String> getEventTypeRule() {
+		return eventTypeRule;
+	}
+
+	public void setEventTypeRule(List<String> eventTypeRule) {
+		this.eventTypeRule = eventTypeRule;
+	}
+
+	public List<String> getEventTypeModel() {
+		return eventTypeModel;
+	}
+
+	public void setEventTypeModel(List<String> eventTypeModel) {
+		this.eventTypeModel = eventTypeModel;
+	}
+
+    public String getEventTypeEnd() {
+        return eventTypeEnd;
+    }
+
+    public void setEventTypeEnd(String eventTypeEnd) {
+        this.eventTypeEnd = eventTypeEnd;
+    }
+}
diff --git a/src/main/java/org/onap/aai/validation/config/ValidationServiceAuthConfig.java b/src/main/java/org/onap/aai/validation/config/ValidationServiceAuthConfig.java
new file mode 100644
index 0000000..62280fa
--- /dev/null
+++ b/src/main/java/org/onap/aai/validation/config/ValidationServiceAuthConfig.java
@@ -0,0 +1,46 @@
+/*
+ * ============LICENSE_START===================================================
+ * Copyright (c) 2018 Amdocs
+ * ============================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=====================================================
+ */
+package org.onap.aai.validation.config;
+
+import org.springframework.beans.factory.annotation.Value;
+
+public class ValidationServiceAuthConfig {
+
+	@Value("${auth.authentication.disable}")
+	private boolean authenticationDisable;
+
+	@Value("${auth.policy.file}")
+	private String authPolicyFile;
+
+	public boolean isAuthenticationDisable() {
+		return authenticationDisable;
+	}
+
+	public void setAuthenticationDisable(boolean authenticationDisable) {
+		this.authenticationDisable = authenticationDisable;
+	}
+
+	public String getAuthPolicyFile() {
+		return authPolicyFile;
+	}
+
+	public void setAuthPolicyFile(String authPolicyFile) {
+		this.authPolicyFile = authPolicyFile;
+	}
+
+}
diff --git a/src/main/java/org/onap/aai/validation/controller/ValidationController.java b/src/main/java/org/onap/aai/validation/controller/ValidationController.java
new file mode 100644
index 0000000..60d1c1c
--- /dev/null
+++ b/src/main/java/org/onap/aai/validation/controller/ValidationController.java
@@ -0,0 +1,380 @@
+/*
+ * ============LICENSE_START===================================================
+ * Copyright (c) 2018 Amdocs
+ * ============================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=====================================================
+ */
+package org.onap.aai.validation.controller;
+
+import java.io.PrintWriter;
+import java.io.StringWriter;
+import java.time.LocalDateTime;
+import java.time.LocalTime;
+import java.time.format.DateTimeFormatter;
+import java.time.temporal.ChronoUnit;
+import java.time.temporal.Temporal;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Optional;
+import java.util.SortedMap;
+import java.util.TreeMap;
+import javax.inject.Inject;
+import org.onap.aai.validation.Validator;
+import org.onap.aai.validation.config.ValidationControllerConfig;
+import org.onap.aai.validation.exception.ValidationServiceException;
+import org.onap.aai.validation.logging.ApplicationMsgs;
+import org.onap.aai.validation.logging.LogHelper;
+import org.onap.aai.validation.publisher.MessagePublisher;
+import org.onap.aai.validation.reader.EventReader;
+import org.onap.aai.validation.reader.data.Entity;
+import org.onap.aai.validation.result.ValidationResult;
+import org.onap.aai.validation.result.Violation;
+import org.onap.aai.validation.util.JsonUtil;
+
+/**
+ * Controls the execution (of validation of an event) for the various validation service components.
+ */
+public class ValidationController {
+
+    private static LogHelper applicationLogger = LogHelper.INSTANCE;
+
+    public static final String VALIDATION_ERROR_SEVERITY = "CRITICAL";
+
+    private static final String VALIDATION_ERROR_CATEGORY = "CANNOT_VALIDATE";
+    private static final String VALIDATION_ERROR_VIOLATIONTYPE = "NONE";
+
+    /**
+     * Result of the Controller executing validation of a single event. Either there is a set of ValidationResults or
+     * instead an exception was handled.
+     */
+    public class Result {
+        /**
+         * A successful validation will produce a set of results.
+         */
+        Optional<List<ValidationResult>> validationResults = Optional.empty();
+
+        /**
+         * For an unsuccessful validation, we will record the error details.
+         */
+        private String errorText;
+
+        /**
+         * @return whether or not we have a set of validation results
+         */
+        public boolean validationSuccessful() {
+            return validationResults.isPresent();
+        }
+
+        public List<ValidationResult> getValidationResults() {
+            return validationResults.orElse(Collections.emptyList());
+        }
+
+        /**
+         * @return a JSON string representing the first ValidationResult, or an empty string when there are no results
+         */
+        public String getValidationResultAsJson() {
+            List<ValidationResult> resultsList = getValidationResults();
+            if (resultsList.isEmpty()) {
+                return "";
+            } else {
+                // Only one Validation Result is returned (as only one is expected)
+                return JsonUtil.toJson(resultsList.get(0));
+            }
+        }
+
+        public Optional<String> getErrorText() {
+            return Optional.ofNullable(errorText);
+        }
+
+        private void handleException(String event, Exception rootException) {
+            try {
+                Entity entity = eventReader.getEntity(event);
+                if (!entity.getIds().isEmpty() && eventReader.getEntityType(event).isPresent()
+                        && entity.getResourceVersion().isPresent()) {
+                    ValidationResult validationResult = new ValidationResult(entity);
+                    // @formatter:off
+					validationResult.addViolation(new Violation.Builder(entity)
+						.category(VALIDATION_ERROR_CATEGORY)
+						.severity(VALIDATION_ERROR_SEVERITY)
+						.violationType(VALIDATION_ERROR_VIOLATIONTYPE)
+						.errorMessage(rootException.getMessage())
+						.build());
+					// @formatter:on
+
+                    validationResults = Optional.of(Collections.singletonList(validationResult));
+                    publishValidationResults(validationResults);
+                }
+            } catch (Exception e) {
+                errorText = e.getMessage();
+                applicationLogger.error(ApplicationMsgs.CANNOT_VALIDATE_HANDLE_EXCEPTION_ERROR, e, event);
+            }
+        }
+    }
+
+    /**
+     * Status Report for the Controller
+     *
+     */
+    public class StatusReport {
+
+        private Temporal reportTime = LocalDateTime.now();
+        private long upTime = ChronoUnit.SECONDS.between(startTime, reportTime);
+        private long upTimeDays = ChronoUnit.DAYS.between(startTime, reportTime);
+
+        @Override
+        public String toString() {
+            StringBuilder sb = new StringBuilder("Started at ");
+            sb.append(startTime).append('\n').append("Up time ");
+            if (upTimeDays > 0) {
+                sb.append(upTimeDays).append(" days ");
+            }
+            sb.append(LocalTime.MIDNIGHT.plusSeconds(upTime).format(DateTimeFormatter.ofPattern("HH:mm:ss")));
+            sb.append('\n').append(formatStats(stats));
+            return sb.toString();
+        }
+
+        /**
+         * @return formatted statistics
+         */
+        private String formatStats(Statistics stats) {
+            StringBuilder sb = new StringBuilder();
+            formatStats(stats, "info", sb, "Info Service");
+            formatStats(stats, "http", sb, "Validation REST API");
+            formatStats(stats, "topic", sb, "Events Consumed");
+            if (stats.reportedThrowable != null) {
+                StringWriter sw = new StringWriter();
+                stats.reportedThrowable.printStackTrace(new PrintWriter(sw));
+                sb.append("Exception reported: ").append(sw.toString());
+            }
+            return sb.toString();
+        }
+
+        private void formatStats(Statistics stats, String eventSource, StringBuilder sb, String heading) {
+            sb.append("\n").append(heading).append("\n");
+            if (stats.keyValues(eventSource).isEmpty()) {
+                sb.append("total=0\n");
+            } else {
+                for (String key : stats.keyValues(eventSource)) {
+                    sb.append(key).append("=").append(stats.messageCount(eventSource, key)).append("\n");
+                }
+            }
+        }
+    }
+
+    private ValidationControllerConfig validationControllerConfig;
+    private EventReader eventReader;
+    private Validator ruleDrivenValidator;
+    private Validator modelDrivenValidator;
+    private MessagePublisher messagePublisher;
+    private LocalDateTime startTime;
+    private Statistics stats;
+
+    /**
+     * Record of actions taken by the Controller
+     *
+     */
+    private class Statistics {
+
+        private Map<String, SortedMap<String, Integer>> sourceMap = new HashMap<>();
+        private Throwable reportedThrowable;
+
+        /**
+         * Increment the message count for the composite key <eventSource, key>
+         *
+         * @param eventSource the source of the event - used for statistics reporting purposes
+         * @param key the statistic to increment by one
+         */
+        private void incrementEventCount(String eventSource, String key) {
+            Map<String, Integer> messagesConsumed = getMessageCountsMap(eventSource);
+            int count = messagesConsumed.getOrDefault(key, 0);
+            messagesConsumed.put(key, count + 1);
+        }
+
+        private Map<String, Integer> getMessageCountsMap(String eventSource) {
+            return sourceMap.computeIfAbsent(eventSource, k -> new TreeMap<>());
+        }
+
+        /**
+         * @param eventSource the source of the event
+         * @return List<String> the keys for the specified eventSource
+         */
+        private List<String> keyValues(String eventSource) {
+            Map<String, Integer> messagesConsumed = getMessageCountsMap(eventSource);
+            return new ArrayList<>(messagesConsumed.keySet());
+        }
+
+        /*
+         * return the count for the supplied event source and statistic key
+         */
+        private int messageCount(String eventSource, String key) {
+            Map<String, Integer> messagesConsumed = getMessageCountsMap(eventSource);
+            return messagesConsumed.getOrDefault(key, 0);
+        }
+
+    }
+
+    /**
+     * Constructs a new validation controller with the injected parameters.
+     *
+     * @param validationControllerConfig the configuration parameters for validation controllers
+     * @param eventReader an object that can read events
+     * @param ruleDrivenValidator a validator for validating rules
+     * @param modelDrivenValidator a validator for validating model
+     * @param messagePublisher an instance of a publisher for messages
+     */
+    @Inject
+    public ValidationController(ValidationControllerConfig validationControllerConfig, EventReader eventReader,
+            Validator ruleDrivenValidator, Validator modelDrivenValidator, MessagePublisher messagePublisher) {
+        this.startTime = LocalDateTime.now();
+        this.validationControllerConfig = validationControllerConfig;
+        this.eventReader = eventReader;
+        this.ruleDrivenValidator = ruleDrivenValidator;
+        this.modelDrivenValidator = modelDrivenValidator;
+        this.messagePublisher = messagePublisher;
+        this.stats = new Statistics();
+    }
+
+    /**
+     * @throws ValidationServiceException if an error occurs initialising the controller
+     */
+    public void initialise() throws ValidationServiceException {
+        ruleDrivenValidator.initialise();
+        modelDrivenValidator.initialise();
+    }
+
+    /**
+     * Validates the event and publishes the results of the validation onto the topic configured in the message
+     * publisher.
+     *
+     * @param event the event to be validated
+     * @param eventSource the source of the event
+     * @return Result a result containing either the set of ValidationResults or an error message
+     */
+    public Result execute(String event, String eventSource) {
+        Result result = new Result();
+        try {
+            stats.incrementEventCount(eventSource, "total");
+            if (isEndEvent(event)) {
+                applicationLogger.debug("Event has not been processed. End event type was detected. Event :" + event);
+                stats.incrementEventCount(eventSource, "end");
+            } else if (isValidationCandidate(event)) {
+                result.validationResults = dispatchEvent(event, eventSource);
+                publishValidationResults(result.validationResults);
+            } else {
+                stats.incrementEventCount(eventSource, "filtered");
+            }
+        } catch (Exception e) {
+            applicationLogger.error(ApplicationMsgs.CANNOT_VALIDATE_ERROR, e, event);
+            stats.incrementEventCount(eventSource, "errored");
+            result.handleException(event, e);
+        }
+        return result;
+    }
+
+    private void publishValidationResults(Optional<List<ValidationResult>> validationResults) {
+        if (validationResults.isPresent()) {
+            for (ValidationResult validationResult : validationResults.get()) {
+                try {
+                    messagePublisher.publishMessage(validationResult.toJson());
+                } catch (ValidationServiceException e) {
+                    applicationLogger.error(ApplicationMsgs.MESSAGE_PUBLISH_ERROR, e, validationResult.toString());
+                }
+            }
+        }
+    }
+
+    private Optional<List<ValidationResult>> dispatchEvent(String event, String eventSource)
+            throws ValidationServiceException {
+        List<ValidationResult> validationResults = null;
+        Optional<String> eventType = eventReader.getEventType(event);
+
+        applicationLogger.debug("Event consumed: " + event);
+
+        if (eventType.isPresent()) {
+            if (isRuleDriven(eventType.get())) {
+                validationResults = ruleDrivenValidator.validate(event);
+                stats.incrementEventCount(eventSource, "rule");
+            } else if (isModelDriven(eventType.get())) {
+                validationResults = modelDrivenValidator.validate(event);
+                stats.incrementEventCount(eventSource, "model");
+            } else {
+                applicationLogger.debug("Event has not been validated. Invalid event type. Event :" + event);
+                stats.incrementEventCount(eventSource, "invalid");
+            }
+        } else {
+            stats.incrementEventCount(eventSource, "missing event type");
+        }
+
+        return Optional.ofNullable(validationResults);
+    }
+
+    private Boolean isRuleDriven(String eventType) {
+        return validationControllerConfig.getEventTypeRule().contains(eventType);
+    }
+
+    private Boolean isModelDriven(String eventType) {
+        return validationControllerConfig.getEventTypeModel().contains(eventType);
+    }
+
+    private boolean isEndEvent(String event) throws ValidationServiceException {
+        Optional<String> eventType = eventReader.getEventType(event);
+
+        return eventType.isPresent() && "END-EVENT".equalsIgnoreCase(eventType.get());
+    }
+
+    private Boolean isDomainValid(String event) throws ValidationServiceException {
+        Optional<String> eventDomain = eventReader.getEventDomain(event);
+
+        // Domain is optional in Event Header
+        return !eventDomain.isPresent()
+                || validationControllerConfig.getEventDomain().equalsIgnoreCase(eventDomain.get());
+    }
+
+    private Boolean isNotExcludedAction(String event) throws ValidationServiceException {
+        Optional<String> eventAction = eventReader.getEventAction(event);
+
+        // Action is optional in Event Header
+        return !eventAction.isPresent()
+                || !validationControllerConfig.getExcludedEventActions().contains(eventAction.get());
+    }
+
+
+    private Boolean isValidationCandidate(String event) throws ValidationServiceException {
+        return isDomainValid(event) && isNotExcludedAction(event);
+    }
+
+    /**
+     * @return a formatted string containing status information
+     */
+    public StatusReport statusReport() {
+        return new StatusReport();
+    }
+
+    /**
+     * Record a Throwable which will then be added to the status reporting text.
+     *
+     * @param t a Throwable to be reported (on demand)
+     */
+    public void recordThrowable(Throwable t) {
+        stats.reportedThrowable = t;
+    }
+
+    public void incrementInfoCount() {
+        stats.incrementEventCount("info", "total");
+    }
+
+}
diff --git a/src/main/java/org/onap/aai/validation/data/client/RestClient.java b/src/main/java/org/onap/aai/validation/data/client/RestClient.java
new file mode 100644
index 0000000..d2d1196
--- /dev/null
+++ b/src/main/java/org/onap/aai/validation/data/client/RestClient.java
@@ -0,0 +1,121 @@
+/*
+ * ============LICENSE_START===================================================
+ * Copyright (c) 2018 Amdocs
+ * ============================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=====================================================
+ */
+package org.onap.aai.validation.data.client;
+    
+import com.sun.jersey.core.util.MultivaluedMapImpl;
+import java.util.Arrays;
+import java.util.UUID;
+import javax.inject.Inject;
+import javax.ws.rs.core.MediaType;
+import javax.ws.rs.core.MultivaluedMap;
+import org.onap.aai.restclient.client.OperationResult;
+import org.onap.aai.validation.config.RestConfig;
+import org.onap.aai.validation.exception.ValidationServiceError;
+import org.onap.aai.validation.exception.ValidationServiceException;
+
+/**
+ * REST client capable of establishing secured requests.
+ */
+public class RestClient {
+    private RestConfig restConfig;
+    private org.onap.aai.restclient.client.RestClient aaiRestClient;
+    private MultivaluedMap<String, String> headers;
+
+    private static final String ACCEPT = "application/json";
+    private static final String HEADER_X_FROM_APP_ID = "validation-service";
+    private static final String APP_CONFIG_HOME = System.getProperty("CONFIG_HOME");
+
+    /**
+     * Constructs a new rest client with the injected parameters.
+     *
+     * @param restConfig
+     */
+    @Inject
+    public RestClient(RestConfig restConfig) {
+        this.restConfig = restConfig;
+        initialiseRestClient();
+    }
+
+    /**
+     * Initialises the REST client
+     *
+     */
+    private void initialiseRestClient() {
+        // @formatter:off
+		aaiRestClient = new org.onap.aai.restclient.client.RestClient()
+		    .validateServerHostname(false)
+		    .validateServerCertChain(true)
+		    .clientCertFile(APP_CONFIG_HOME + restConfig.getKeyStorePath())
+		    .clientCertPassword(restConfig.getKeyStorePassword())
+		    .trustStore(APP_CONFIG_HOME + restConfig.getTrustStorePath())
+		    .connectTimeoutMs(restConfig.getConnectionTimeout())
+		    .readTimeoutMs(restConfig.getReadTimeout());
+		// @formatter:on
+
+        headers = new MultivaluedMapImpl();
+        headers.put("Accept", Arrays.asList(ACCEPT));
+        headers.put("X-FromAppId", Arrays.asList(HEADER_X_FROM_APP_ID));
+        headers.put("X-TransactionId", Arrays.asList(UUID.randomUUID().toString()));
+    }
+
+    /**
+     * Invokes the REST URL and returns the payload string.
+     *
+     * @param uriPath
+     * @param mediaType
+     * @return The payload of the REST URL call as a string.
+     * @throws ValidationServiceException
+     */
+    public String get(String uriPath, String mediaType) throws ValidationServiceException {
+        // Construct URI
+        String uri = restConfig.getProtocol() + "://" + restConfig.getHost() + ":" + restConfig.getPort() + uriPath;
+
+        OperationResult result = aaiRestClient.get(uri, headers, MediaType.valueOf(mediaType));
+
+        if (result.getResultCode() == 200) {
+            return result.getResult();
+        } else if (result.getResultCode() == 404) {
+            throw new ValidationServiceException(ValidationServiceError.REST_CLIENT_RESPONSE_NOT_FOUND,
+                    result.getResultCode(), result.getFailureCause());
+        } else {
+            throw new ValidationServiceException(ValidationServiceError.REST_CLIENT_RESPONSE_ERROR,
+                    result.getResultCode(), result.getFailureCause());
+        }
+    }
+
+    /**
+     * POSTs a request.
+     *
+     * @param url
+     * @param payload
+     *
+     * @return The payload of the REST URL call as a string.
+     * @throws GapServiceException
+     */
+    public String post(String url, String payload) throws ValidationServiceException {
+        OperationResult result = aaiRestClient.post(url, payload, headers, MediaType.APPLICATION_JSON_TYPE,
+                MediaType.APPLICATION_JSON_TYPE);
+        if (result.getResultCode() == 200) {
+            return result.getResult();
+        } else {
+            throw new ValidationServiceException(ValidationServiceError.REST_CLIENT_RESPONSE_ERROR,
+                    result.getResultCode(), result.getFailureCause());
+        }
+
+    }
+}
diff --git a/src/main/java/org/onap/aai/validation/exception/BaseValidationServiceException.java b/src/main/java/org/onap/aai/validation/exception/BaseValidationServiceException.java
new file mode 100644
index 0000000..59fdb72
--- /dev/null
+++ b/src/main/java/org/onap/aai/validation/exception/BaseValidationServiceException.java
@@ -0,0 +1,66 @@
+/*
+ * ============LICENSE_START===================================================
+ * Copyright (c) 2018 Amdocs
+ * ============================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=====================================================
+ */
+package org.onap.aai.validation.exception;
+
+import java.util.Locale;
+
+/**
+ * Validation service exception base class
+ *
+ */
+public class BaseValidationServiceException extends Exception {
+
+	private static final long serialVersionUID = -6663403070792969748L;
+
+	public static final Locale LOCALE = Locale.US;
+
+	private final String id;
+
+	/**
+	 * Default constructor.
+	 *
+	 * @param id
+	 */
+	public BaseValidationServiceException(String id) {
+		super();
+		this.id = id;
+	}
+
+	/**
+	 * @param id
+	 * @param message
+	 */
+	public BaseValidationServiceException(String id, String message) {
+		super(message);
+		this.id = id;
+	}
+
+	/**
+	 * @param id
+	 * @param message
+	 * @param cause
+	 */
+	public BaseValidationServiceException(String id, String message, Throwable cause) {
+		super(message, cause);
+		this.id = id;
+	}
+
+	public String getId() {
+		return this.id;
+	}
+}
diff --git a/src/main/java/org/onap/aai/validation/exception/ValidationServiceError.java b/src/main/java/org/onap/aai/validation/exception/ValidationServiceError.java
new file mode 100644
index 0000000..45d79d4
--- /dev/null
+++ b/src/main/java/org/onap/aai/validation/exception/ValidationServiceError.java
@@ -0,0 +1,103 @@
+/*
+ * ============LICENSE_START===================================================
+ * Copyright (c) 2018 Amdocs
+ * ============================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=====================================================
+ */
+package org.onap.aai.validation.exception;
+
+import java.text.MessageFormat;
+
+/**
+ * Error text formatting
+ *
+ */
+public enum ValidationServiceError {
+
+	//@formatter:off
+
+	// Rule Configuration exceptions. Range 100..199
+	RULES_FILE_ERROR("VS-100", "Error reading rules configuration file(s) {0}"),
+	RULE_UNEXPECTED_TOKEN("VS-101", "Token {0} unexpected in rules configuration file."),
+    RULES_NOT_DEFINED("VS-102", "Event type {0} has no rule definitions."),
+
+	// Rule exceptions. Range 200..299
+	RULE_EXECUTION_ERROR("VS-201", "Error executing rule {0} with arguments {1}"),
+
+	// Validation service processing exceptions. Range 300..399
+	OMX_LOAD_ERROR("VS-300", "Validation service failed to load the OXM file."),
+	OXM_MISSING_KEY("VS-301", "Validation service failed to retrieve primary key for object of type {0}."),
+	MESSAGE_DIGEST_ERROR("VS-302", "Java platform security error. Failed to create Message Digest hashing object {0}."),
+	MODEL_RETRIEVAL_ERROR("VS-303", "Validator failed to get the model from external system."),
+	MODEL_CACHE_ERROR("VS-304", "Validator failed to retrieve the model from the cache. {0}"),
+	MODEL_NOT_FOUND("VS-305", "Model with UUID {0} not found."),
+
+	// Event publishing exceptions. Range 400..499
+	EVENT_CLIENT_PUBLISHER_INIT_ERROR("VS-400", "Error while initialising the Event Publisher Client."),
+	EVENT_CLIENT_SEND_ERROR("VS-401", "Error while sending a message to the event bus."),
+	EVENT_CLIENT_INCORRECT_NUMBER_OF_MESSAGES_SENT("VS-402", "Publisher client returned a result of {0} messages sent."),
+	EVENT_CLIENT_CLOSE_ERROR("VS-403", "Error while closing the Event Publisher Client."),
+	EVENT_CLIENT_CLOSE_UNSENT_MESSAGE("VS-404", "Failed to publish message. Error while closing the Event Publisher Client. " +
+	                                            "The following message is unsent: {0}. Please check the logs for more information."),
+	EVENT_CLIENT_CONSUMER_INIT_ERROR("VS-405", "Error while initialising the Event Consumer Client."),
+
+	// Reader exceptions. Range 500..599
+	JSON_READER_PARSE_ERROR("VS-500", "JSON could not be parsed."),
+	EVENT_READER_MISSING_PROPERTY("VS-501", "Missing property: {0}"),
+	EVENT_READER_TOO_MANY_ENTITIES("VS-502", "Unexpected number or entities."),
+	INSTANCE_READER_NO_INSTANCE("VS-503", "Failed to extract instance under path: {0}. JSON payload: {1}"),
+	EVENT_READER_PROPERTY_READ_ERROR("VS-504", "Failed to read entity link property. Check event reader configuration properties."),
+
+	// Model-instance mapping exceptions. Range 600..649
+	MODEL_INSTANCE_MAPPING_RETRIEVAL_ERROR("VS-600", "Error retrieving model-instance mappings."),
+	MODEL_INSTANCE_MAPPING_FILE_IO_ERROR("VS-601", "IO error when reading from the model-instance mapping file {0}."),
+	MODEL_PARSE_ERROR("VS-602", "Validator failed to parse the model provided. Source:\n{0}"),
+	MODEL_VALUE_ERROR("VS-603", "Validator failed to access the model value {0} in {1}"),
+	INSTANCE_MAPPING_ROOT_ERROR("VS-604", "Missing 'root' property in instance mapping."),
+
+	// REST client exceptions. Range 650..699
+	REST_CLIENT_RESPONSE_ERROR("VS-650", "REST client response error: Response Code: {0}, Failure Cause: {1}."),
+	REST_CLIENT_RESPONSE_NOT_FOUND("VS-651", "REST client response error: Response Code: {0}, Failure Cause: {1}."),
+
+	// Validation Service configuration exceptions. Range 700..799
+	VS_PROPERTIES_LOAD_ERROR("VS-700", "Failed to read property {0} in the validation service properties file."),
+
+	// Miscellaneous exceptions. Range 800..849
+	STRING_UTILS_INVALID_REGEX("VS-800", "Invalid regular expression: {0}");
+
+	//@formatter:on
+
+	private String id;
+	private String message;
+
+	private ValidationServiceError(String id, String message) {
+		this.id = id;
+		this.message = message;
+	}
+
+	public String getId() {
+		return this.id;
+	}
+
+	/**
+	 * @param args
+	 *            to be formatted
+	 * @return the formatted error message
+	 */
+	public String getMessage(Object... args) {
+		MessageFormat formatter = new MessageFormat("");
+		formatter.applyPattern(this.message);
+		return formatter.format(args);
+	}
+}
diff --git a/src/main/java/org/onap/aai/validation/exception/ValidationServiceException.java b/src/main/java/org/onap/aai/validation/exception/ValidationServiceException.java
new file mode 100644
index 0000000..2606ce9
--- /dev/null
+++ b/src/main/java/org/onap/aai/validation/exception/ValidationServiceException.java
@@ -0,0 +1,78 @@
+/*
+ * ============LICENSE_START===================================================
+ * Copyright (c) 2018 Amdocs
+ * ============================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=====================================================
+ */
+package org.onap.aai.validation.exception;
+
+/**
+ * Validation service exception
+ *
+ */
+public class ValidationServiceException extends BaseValidationServiceException { // NOSONAR
+
+	private static final long serialVersionUID = 883498159309797607L;
+
+	/**
+	 * Constructs an exception defined by the Error.
+	 *
+	 * @param error
+	 *            {@link ValidationServiceError} with the error id.
+	 */
+	public ValidationServiceException(ValidationServiceError error) {
+		super(error.getId(), error.getId() + ", " + error.getMessage());
+	}
+
+	/**
+	 * Constructs an exception defined by the Error. The message is parameterised with the arguments.
+	 *
+	 * @param error
+	 *            {@link ValidationServiceError} with the error id.
+	 * @param args
+	 *            Arguments for the exception message.
+	 */
+	public ValidationServiceException(ValidationServiceError error, Object... args) {
+		super(error.getId(), error.getId() + ", " + error.getMessage(args));
+	}
+
+	/**
+	 * Constructs an exception defined by the Error and the underlying Exception. The message is parameterised with the
+	 * arguments and enhanced with the underlying Exception message.
+	 *
+	 * @param error
+	 *            {@link ValidationServiceError} with the error id.
+	 * @param exception
+	 *            Exception thrown by an underlying API.
+	 * @param args
+	 *            Arguments for the exception message.
+	 */
+	public ValidationServiceException(ValidationServiceError error, Exception exception, Object... args) {
+		super(error.getId(), error.getId() + ", " + error.getMessage(args) + "; Caused by: " + exception.getMessage(), exception);
+	}
+
+	/**
+	 * Constructs an exception defined by the Error and the underlying Exception. The message is enhanced with the
+	 * underlying Exception message.
+	 *
+	 * @param error
+	 *            {@link ValidationServiceError} with the error id.
+	 * @param exception
+	 *            Exception thrown by an underlying API.
+	 */
+	public ValidationServiceException(ValidationServiceError error, Exception exception) {
+		super(error.getId(), error.getId() + ", " + error.getMessage() + "; Caused by: " + exception.getMessage(), exception);
+	}
+
+}
diff --git a/src/main/java/org/onap/aai/validation/factory/DMaaPEventPublisherFactory.java b/src/main/java/org/onap/aai/validation/factory/DMaaPEventPublisherFactory.java
new file mode 100644
index 0000000..fa4af74
--- /dev/null
+++ b/src/main/java/org/onap/aai/validation/factory/DMaaPEventPublisherFactory.java
@@ -0,0 +1,34 @@
+/*
+ * ============LICENSE_START===================================================
+ * Copyright (c) 2018 Amdocs
+ * ============================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=====================================================
+ */
+package org.onap.aai.validation.factory;
+
+import org.onap.aai.event.client.DMaaPEventPublisher;
+
+public class DMaaPEventPublisherFactory {  
+
+
+    public DMaaPEventPublisher createEventPublisher(String topicHost, String topicName, String topicUsername,
+            String topicPassword, String topicTransportType) {
+        int defaultBatchSize = DMaaPEventPublisher.DEFAULT_BATCH_SIZE;
+        long defaultBatchAge = DMaaPEventPublisher.DEFAULT_BATCH_AGE;
+        int defaultBatchDelay = DMaaPEventPublisher.DEFAULT_BATCH_DELAY;
+        return new DMaaPEventPublisher(topicHost, topicName, topicUsername, topicPassword, defaultBatchSize,
+                defaultBatchAge, defaultBatchDelay, topicTransportType);
+    }
+
+}
diff --git a/src/main/java/org/onap/aai/validation/logging/ApplicationMsgs.java b/src/main/java/org/onap/aai/validation/logging/ApplicationMsgs.java
new file mode 100644
index 0000000..6066a20
--- /dev/null
+++ b/src/main/java/org/onap/aai/validation/logging/ApplicationMsgs.java
@@ -0,0 +1,74 @@
+/*
+ * ============LICENSE_START===================================================
+ * Copyright (c) 2018 Amdocs
+ * ============================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=====================================================
+ */
+package org.onap.aai.validation.logging;
+
+import com.att.eelf.i18n.EELFResourceManager;
+import org.onap.aai.cl.eelf.LogMessageEnum;
+
+/**
+ * Application messages
+ */
+public enum ApplicationMsgs implements LogMessageEnum {
+
+    /**
+     * Add message keys here.
+     */
+    // @formatter:off
+	MESSAGE_VALIDATION_REQUEST,
+    MESSAGE_AUDIT,
+    MESSAGE_METRIC,
+   	MESSAGE_PUBLISH_ERROR,
+	OXM_LOAD_ERROR,
+	OXM_MISSING_KEY_ERROR,
+    MISSING_REQUEST_ID,
+	CANNOT_VALIDATE_ERROR,
+	CANNOT_VALIDATE_HANDLE_EXCEPTION_ERROR,
+	POLL_EVENTS,
+	NUMBER_OF_MESSAGES_CONSUMED,
+	INVOKE_EVENT_CONSUMER_ERROR,
+	READ_FILE_ERROR,
+	STARTUP_SERVLET_INIT,
+	POLLING_INTERVAL_CONFIG_NOT_PRESENT,
+	POLLING_FOR_EVENTS,
+	POLLING_DISABLED,
+	STARTUP_SERVLET_INIT_SUCCESS,
+	UNSENT_MESSAGE_WARN,
+	UNSENT_MESSAGE_ERROR,
+	EVENT_CLIENT_CLOSE_UNSENT_MESSAGE,
+	SEND_MESSAGE_ABORT_WARN,
+	SEND_MESSAGE_RETRY_WARN,
+	FILE_ARG_NULL_ERROR,
+	LOAD_PROPERTIES,
+	FILE_LOAD_INTO_MAP,
+	FILE_LOAD_INTO_MAP_ERROR,
+	CREATE_PROPERTY_MAP_ERROR,
+	FILE_MONITOR_BLOCK_ERROR,
+	READ_FILE_STREAM_ERROR,
+	STRING_UTILS_INVALID_REGEX,
+	MALFORMED_REQUEST_ERROR,
+	PROCESS_REQUEST_ERROR;
+	// @formatter:on
+
+    /**
+     * Static initializer to ensure the resource bundles for this class are loaded... Here this application loads
+     * messages from three bundles
+     */
+    static {
+        EELFResourceManager.loadMessageBundle("validation-service-logging-resources");
+    }
+}
diff --git a/src/main/java/org/onap/aai/validation/logging/LogHelper.java b/src/main/java/org/onap/aai/validation/logging/LogHelper.java
new file mode 100644
index 0000000..4abf5fd
--- /dev/null
+++ b/src/main/java/org/onap/aai/validation/logging/LogHelper.java
@@ -0,0 +1,548 @@
+/*
+ * ============LICENSE_START===================================================
+ * Copyright (c) 2018 Amdocs
+ * ============================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=====================================================
+ */
+package org.onap.aai.validation.logging;
+
+import static com.att.eelf.configuration.Configuration.MDC_SERVICE_NAME;
+
+import ch.qos.logback.classic.AsyncAppender;
+import ch.qos.logback.core.FileAppender;
+import com.att.eelf.configuration.EELFLogger;
+import com.att.eelf.configuration.EELFManager;
+import com.att.eelf.i18n.EELFResolvableErrorEnum;
+import java.io.File;
+import java.text.DateFormat;
+import java.text.SimpleDateFormat;
+import java.util.Date;
+import java.util.function.BiConsumer;
+import java.util.function.Consumer;
+import javax.servlet.ServletRequest;
+import javax.ws.rs.core.Response.Status;
+import org.apache.commons.lang.time.StopWatch;
+import org.onap.aai.cl.api.LogFields;
+import org.onap.aai.cl.api.Logger;
+import org.onap.aai.cl.mdc.MdcContext;
+import org.onap.aai.cl.mdc.MdcOverride;
+import org.onap.aai.restclient.client.Headers;
+import org.onap.aai.validation.services.RequestHeaders;
+import org.slf4j.MDC;
+import org.springframework.http.HttpHeaders;
+
+/*-
+ * This Log Helper mimics the interface of a Common Logging Logger 
+ * but adds helper methods for audit and metrics logging requirements.
+ * 
+ * Messages are logged to the appropriate EELF functional logger as described below.
+ * 
+ * Error Log: INFO/WARN/ERROR/FATAL 
+ * Debug Log: DEBUG/TRACE 
+ * Audit Log: summary view of transaction processing
+ * Metrics Log: detailed timings of transaction processing interactions
+ * 
+ * Audit and Metrics log messages record the following fields:
+ * 
+ * RequestID   - an RFC4122 UUID for the transaction request
+ * ServiceName - the API provided by this service
+ * PartnerName - invoker of the API
+ * ClassName   - name of the class creating the log record
+ * 
+ * The above list is not exhaustive.
+ */
+public enum LogHelper implements Logger {
+    INSTANCE; // Joshua Bloch's singleton pattern
+
+    @FunctionalInterface
+    public interface TriConsumer<T, U, V> {
+        public void accept(T t, U u, V v);
+    }
+
+    /**
+     * Audit log message status code values. See {@code MdcParameter.STATUS_CODE}
+     */
+    public enum StatusCode {
+        COMPLETE,
+        ERROR;
+    }
+
+    /**
+     * Mapped Diagnostic Context parameter names.
+     * 
+     * Note that MdcContext.MDC_START_TIME is used for audit messages, and indicates the start of a transaction.
+     * Messages in the metrics log record sub-operations of a transaction and thus use different timestamps.
+     */
+    public enum MdcParameter {
+        REQUEST_ID(MdcContext.MDC_REQUEST_ID),
+        CLASS_NAME("ClassName"),
+        BEGIN_TIMESTAMP("BeginTimestamp"),
+        END_TIMESTAMP("EndTimestamp"),
+        ELAPSED_TIME("ElapsedTime"),
+        STATUS_CODE("StatusCode"),
+        RESPONSE_CODE("ResponseCode"),
+        RESPONSE_DESCRIPTION("ResponseDescription"),
+        TARGET_ENTITY("TargetEntity"),
+        TARGET_SERVICE_NAME("TargetServiceName"),
+        USER("User");
+
+        private final String parameterName;
+
+        MdcParameter(String parameterName) {
+            this.parameterName = parameterName;
+        }
+
+        /**
+         * Get the MDC logging context parameter name as referenced by the logback configuration
+         * 
+         * @return the MDC parameter name
+         */
+        public String value() {
+            return parameterName;
+        }
+    }
+
+    /**
+     * Our externally advertised service API
+     */
+    private static final String SERVICE_NAME_VALUE = "AAI-VS";
+
+    private static final EELFLogger errorLogger = EELFManager.getInstance().getErrorLogger();
+    private static final EELFLogger debugLogger = EELFManager.getInstance().getDebugLogger();
+    private static final EELFLogger auditLogger = EELFManager.getInstance().getAuditLogger();
+    private static final EELFLogger metricsLogger = EELFManager.getInstance().getMetricsLogger();
+
+    /**
+     * Formatting for timestamps logged as Strings (from the MDC)
+     */
+    private DateFormat timestampFormat = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss.SSSXXX");
+
+    // Records the elapsed time (since the start of servicing a request) for audit logging
+    private StopWatch auditStopwatch;
+
+    /**
+     * Initialises the MDC (logging context) with default values, to support any logging of messages BEFORE the
+     * startAudit() method is invoked.
+     */
+    private LogHelper() {
+        setContextValue(MDC_SERVICE_NAME, SERVICE_NAME_VALUE);
+        // This value is not expected to be used in the default logging configuration
+        setContextValue(MdcContext.MDC_START_TIME, timestampFormat.format(new Date()));
+    }
+
+    /**
+     * Begin recording transaction information for a new request. This data is intended for logging purposes. This
+     * method does not actually write any messages to the log(s).
+     * 
+     * Initialise the MDC logging context for auditing and metrics, using the HTTP request headers. This information
+     * includes: the correlation ID, local application service name/ID, calling host details and authentication data.
+     * 
+     * The request object is used to find the client details (e.g. IP address)
+     * 
+     * @param headers raw HTTP headers
+     * @param servletRequest the request
+     */
+    public void startAudit(final HttpHeaders headers, ServletRequest servletRequest) {
+        auditStopwatch = new StopWatch();
+        auditStopwatch.start();
+
+        String requestId = null;
+        String serviceInstanceId = null;
+        String partnerName = "<UNKNOWN_PARTNER>";
+
+        if (headers != null) {
+            requestId = setRequestId(headers);
+            serviceInstanceId = headers.getFirst(RequestHeaders.HEADER_SERVICE_INSTANCE_ID);
+            partnerName = headers.getFirst(Headers.FROM_APP_ID);
+        }
+
+        String clientHost = null;
+        String clientIPAddress = null;
+        String user = "<UNKNOWN_USER>";
+
+        if (servletRequest != null) {
+            clientHost = servletRequest.getRemoteHost();
+            clientIPAddress = servletRequest.getRemoteAddr();
+
+            if (partnerName == null) {
+                partnerName = clientHost;
+            }
+        }
+
+        // Populate standard MDC keys - note that the initialize method calls MDC.clear()
+        MdcContext.initialize(requestId, SERVICE_NAME_VALUE, serviceInstanceId, partnerName, clientIPAddress);
+
+        setContextValue(MdcParameter.USER, user);
+        setContextValue(MdcContext.MDC_REMOTE_HOST, clientHost);
+    }
+
+    /**
+     * Store a value in the current thread's logging context.
+     * 
+     * @param key non-null parameter name
+     * @param value the value to store against the key
+     */
+    public void setContextValue(String key, String value) {
+        debug(key + "=" + value);
+        MDC.put(key, value);
+    }
+
+    /**
+     * Store a value in the current thread's logging context.
+     * 
+     * @param param identifier of the context parameter
+     * @param value the value to store for this parameter
+     */
+    public void setContextValue(MdcParameter param, String value) {
+        setContextValue(param.value(), value);
+    }
+
+    /**
+     * Set a value in the current thread's logging context, only if this is not already set.
+     * 
+     * @param key non-null parameter name
+     * @param value the value to store against the key (only if the current value is null)
+     */
+    public void setDefaultContextValue(String key, String value) {
+        if (MDC.get(key) == null) {
+            setContextValue(key, value);
+        }
+    }
+
+    /**
+     * Set a value in the current thread's logging context, only if this is not already set.
+     * 
+     * @param param identifier of the context parameter
+     * @param value the value to store for this parameter (only if the current value is null)
+     */
+    public void setDefaultContextValue(MdcParameter param, String value) {
+        setContextValue(param.value(), value);
+    }
+
+    /**
+     * Clear all logging context values. This should be called at start-up only.
+     */
+    public void clearContext() {
+        debug("Clearing MDC context");
+        MDC.clear();
+    }
+
+    /**
+     * Clear the specified logging context value.
+     */
+    public void clearContextValue(MdcParameter param) {
+        MDC.remove(param.value());
+    }
+
+    /**
+     * Log an audit message to the audit logger. This method is expected to be called when a response is returned to the
+     * caller and/or when the processing of the request completes.
+     *
+     * @param status status of the service request: COMPLETE/ERROR
+     * @param responseCode optional application error code
+     * @param responseDescription human-readable description of the response code
+     * @param args the argument(s) required to populate the Audit Message log content
+     */
+    public void logAudit(StatusCode status, String responseCode, String responseDescription, final String... args) {
+        if (auditStopwatch == null) {
+            debug("Unexpected program state: audit stopwatch not started");
+            auditStopwatch = new StopWatch();
+            auditStopwatch.start();
+        }
+
+        if (auditLogger.isInfoEnabled()) {
+            setMdcElapsedTime(auditStopwatch);
+            setContextValue(MdcParameter.STATUS_CODE, status.toString());
+            setContextValue(MdcParameter.RESPONSE_CODE, responseCode);
+            setContextValue(MdcParameter.RESPONSE_DESCRIPTION, responseDescription);
+            invokeLogger(auditLogger::info, ApplicationMsgs.MESSAGE_AUDIT, args);
+        }
+    }
+
+    /**
+     * Log an audit message to the audit logger representing a non-specific processing success message.
+     *
+     * @param msg
+     */
+    public void logAuditSuccess(String msg) {
+        Status status = Status.OK;
+        logAudit(StatusCode.COMPLETE, Integer.toString(status.getStatusCode()), status.getReasonPhrase(), msg);
+    }
+
+    /**
+     * Log an audit message to the audit logger representing an internal error (e.g. for an exception thrown by the
+     * implementation). This method is expected to be called when a generic error response is returned to the caller to
+     * indicate a processing failure.
+     *
+     * @param e Exception
+     */
+    public void logAuditError(Exception e) {
+        Status status = Status.INTERNAL_SERVER_ERROR;
+        logAudit(StatusCode.ERROR, Integer.toString(status.getStatusCode()), status.getReasonPhrase(), e.getMessage());
+    }
+
+    /**
+     * Log a message to the metrics log.
+     * 
+     * @param error the log code
+     * @param args the info messages
+     */
+    public void logMetrics(final String... args) {
+        if (metricsLogger.isInfoEnabled()) {
+            invokeLogger(metricsLogger::info, ApplicationMsgs.MESSAGE_METRIC, args);
+        }
+    }
+
+    /**
+     * @param stopwatch
+     * @param args
+     */
+    public void logMetrics(final StopWatch stopwatch, String... args) {
+        setMdcElapsedTime(stopwatch);
+        logMetrics(args);
+    }
+
+    @Override
+    public String formatMsg(@SuppressWarnings("rawtypes") Enum arg0, String... args) {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public boolean isDebugEnabled() {
+        return debugLogger != null && debugLogger.isDebugEnabled();
+    }
+
+    @Override
+    public boolean isErrorEnabled() {
+        return errorLogger.isErrorEnabled();
+    }
+
+    @Override
+    public boolean isInfoEnabled() {
+        return errorLogger.isInfoEnabled();
+    }
+
+    @Override
+    public boolean isTraceEnabled() {
+        return debugLogger.isTraceEnabled();
+    }
+
+    @Override
+    public boolean isWarnEnabled() {
+        return errorLogger.isWarnEnabled();
+    }
+
+    /**
+     * Log a DEBUG level message to the debug logger.
+     * 
+     * @param message the debug message
+     */
+    @Override
+    public void debug(String message) {
+        if (isDebugEnabled()) {
+            invokeLogger(debugLogger::debug, message);
+        }
+    }
+
+    @Override
+    public void debug(@SuppressWarnings("rawtypes") Enum errorCode, String... args) {
+        if (isDebugEnabled()) {
+            invokeErrorCodeLogger(debugLogger::debug, (EELFResolvableErrorEnum) errorCode, args);
+        }
+    }
+
+    @Override
+    public void debug(@SuppressWarnings("rawtypes") Enum errorCode, LogFields arg1, String... args) {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public void error(@SuppressWarnings("rawtypes") Enum errorCode, String... args) {
+        if (isErrorEnabled()) {
+            invokeErrorCodeLogger(errorLogger::error, (EELFResolvableErrorEnum) errorCode, args);
+        }
+    }
+
+    @Override
+    public void error(@SuppressWarnings("rawtypes") Enum errorCode, Throwable t, String... args) {
+        if (isErrorEnabled()) {
+            invokeErrorCodeLogger(errorLogger::error, (EELFResolvableErrorEnum) errorCode, t, args);
+        }
+    }
+
+    @Override
+    public void error(@SuppressWarnings("rawtypes") Enum errorCode, LogFields arg1, String... args) {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public void error(@SuppressWarnings("rawtypes") Enum errorCode, LogFields arg1, Throwable arg2, String... args) {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public void info(@SuppressWarnings("rawtypes") Enum errorCode, String... args) {
+        if (isInfoEnabled()) {
+            invokeErrorCodeLogger(errorLogger::info, (EELFResolvableErrorEnum) errorCode, args);
+        }
+    }
+
+    @Override
+    public void info(@SuppressWarnings("rawtypes") Enum arg0, LogFields arg1, String... args) {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public void info(@SuppressWarnings("rawtypes") Enum arg0, LogFields arg1, MdcOverride arg2, String... args) {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public void trace(@SuppressWarnings("rawtypes") Enum errorCode, String... args) {
+        if (isTraceEnabled()) {
+            invokeErrorCodeLogger(debugLogger::trace, (EELFResolvableErrorEnum) errorCode, args);
+        }
+    }
+
+    @Override
+    public void trace(@SuppressWarnings("rawtypes") Enum arg0, LogFields arg1, String... args) {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public void warn(@SuppressWarnings("rawtypes") Enum errorCode, String... args) {
+        if (isWarnEnabled()) {
+            invokeErrorCodeLogger(errorLogger::warn, (EELFResolvableErrorEnum) errorCode, args);
+        }
+    }
+
+    @Override
+    public void warn(@SuppressWarnings("rawtypes") Enum arg0, LogFields arg1, String... args) {
+        throw new UnsupportedOperationException();
+    }
+
+    /**
+     * Get the method name for a calling method (from the current stack trace)
+     * 
+     * @param level number of levels for the caller (not including this method)
+     * @return the class and name of the calling method in the form "class#method"
+     */
+    public static String getCallerMethodName(int level) {
+        StackTraceElement callingMethod = Thread.currentThread().getStackTrace()[level + 2];
+        return callingMethod.getClassName() + "#" + callingMethod.getMethodName();
+    }
+
+
+    /**
+     * Convenience method to be used only for testing purposes.
+     * 
+     * @return the directory storing the log files
+     */
+    public static String getLogDirectory() {
+        ch.qos.logback.classic.Logger logger =
+                (ch.qos.logback.classic.Logger) org.slf4j.LoggerFactory.getLogger("com.att.eelf");
+        AsyncAppender appender = (AsyncAppender) logger.getAppender("asyncEELF");
+        FileAppender<?> fileAppender = (FileAppender<?>) appender.getAppender("EELF");
+        return new File(fileAppender.getFile()).getParent();
+    }
+
+    /**
+     * @param headers
+     * @return the request ID from the HTTP headers
+     */
+    private String setRequestId(final HttpHeaders headers) {
+        String requestId = headers.getFirst(RequestHeaders.HEADER_REQUEST_ID);
+
+        // If the request ID is missing, set it from the transaction ID
+        if (requestId == null) {
+            requestId = headers.getFirst(Headers.TRANSACTION_ID);
+        }
+
+        // Normalize the incoming ID by removing any suffix
+        if (requestId != null && requestId.contains(":")) {
+            requestId = requestId.split(":")[0];
+        }
+
+        return requestId == null ? "missing-request-id" : requestId;
+    }
+
+    private void setMdcClassName() {
+        MDC.put(MdcParameter.CLASS_NAME.value(), getCallerMethodName(3));
+    }
+
+    private void unsetMdcClassName() {
+        MDC.put(MdcParameter.CLASS_NAME.value(), null);
+    }
+
+    /**
+     * Set the Begin, End, and Elapsed time values in the MDC context.
+     * 
+     * @param stopwatch
+     */
+    private void setMdcElapsedTime(final StopWatch stopwatch) {
+        long startTime = stopwatch.getStartTime();
+        long elapsedTime = stopwatch.getTime();
+
+        setContextValue(MdcParameter.BEGIN_TIMESTAMP, timestampFormat.format(startTime));
+        setContextValue(MdcParameter.END_TIMESTAMP, timestampFormat.format(startTime + elapsedTime));
+        setContextValue(MdcParameter.ELAPSED_TIME, Long.toString(elapsedTime)); // Milliseconds
+    }
+
+    /**
+     * @param logMethod the logger method to invoke
+     * @param message
+     */
+    private void invokeLogger(Consumer<String> logMethod, String message) {
+        setMdcClassName();
+        logMethod.accept(message);
+        unsetMdcClassName();
+    }
+
+    /**
+     * @param logMethod
+     * @param msg
+     * @param args
+     */
+    private void invokeLogger(BiConsumer<ApplicationMsgs, String[]> logMethod, ApplicationMsgs msg, String[] args) {
+        setMdcClassName();
+        logMethod.accept(msg, args);
+        unsetMdcClassName();
+    }
+
+    /**
+     * @param logMethod
+     * @param errorEnum
+     * @param args
+     */
+    private void invokeErrorCodeLogger(BiConsumer<EELFResolvableErrorEnum, String[]> logMethod,
+            EELFResolvableErrorEnum errorEnum, String[] args) {
+        setMdcClassName();
+        logMethod.accept(errorEnum, args);
+        unsetMdcClassName();
+    }
+
+    /**
+     * @param logMethod
+     * @param errorEnum
+     * @param t a Throwable
+     * @param args
+     */
+    private void invokeErrorCodeLogger(TriConsumer<EELFResolvableErrorEnum, Throwable, String[]> logMethod,
+            EELFResolvableErrorEnum errorEnum, Throwable t, String[] args) {
+        setMdcClassName();
+        logMethod.accept(errorEnum, t, args);
+        unsetMdcClassName();
+    }
+
+}
diff --git a/src/main/java/org/onap/aai/validation/modeldriven/ModelCacheManager.java b/src/main/java/org/onap/aai/validation/modeldriven/ModelCacheManager.java
new file mode 100644
index 0000000..5c741fb
--- /dev/null
+++ b/src/main/java/org/onap/aai/validation/modeldriven/ModelCacheManager.java
@@ -0,0 +1,182 @@
+/*
+ * ============LICENSE_START===================================================
+ * Copyright (c) 2018 Amdocs
+ * ============================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=====================================================
+ */
+package org.onap.aai.validation.modeldriven;
+
+import com.google.common.cache.CacheBuilder;
+import com.google.common.cache.CacheLoader;
+import com.google.common.cache.LoadingCache;
+import java.io.File;
+import java.net.URI;
+import java.net.URISyntaxException;
+import java.util.concurrent.ExecutionException;
+import java.util.concurrent.TimeUnit;
+import javax.inject.Inject;
+import javax.ws.rs.core.MediaType;
+import org.apache.http.client.utils.URIBuilder;
+import org.dom4j.Element;
+import org.onap.aai.validation.config.ModelConfig;
+import org.onap.aai.validation.config.RestConfig;
+import org.onap.aai.validation.data.client.RestClient;
+import org.onap.aai.validation.exception.ValidationServiceError;
+import org.onap.aai.validation.exception.ValidationServiceException;
+import org.onap.aai.validation.modeldriven.parser.XMLModelParser;
+
+/**
+ * A cache of model UUID against the parsed model Element, using Guava's CacheBuilder.
+ */
+public class ModelCacheManager {
+
+	public static final String FILE_MODEL_PROTOCOL = "file";
+
+	private LoadingCache<ModelId, Element> modelCache;
+	private RestConfig restConfig;
+
+	/**
+	 * Initialises the instance by loading validator properties from config.
+	 *
+	 * @param modelConfig
+	 * @param restConfig
+	 * @throws ValidationServiceException
+	 */
+	@Inject
+	public ModelCacheManager(ModelConfig modelConfig, RestConfig restConfig) {
+		this.restConfig = restConfig;
+
+		// Create an expiring cache with a load implementation which is executed when a key value is not cached.
+		modelCache = CacheBuilder.newBuilder().maximumSize(1000)
+				.expireAfterWrite(modelConfig.getModelCacheExpirySeconds(), TimeUnit.SECONDS)
+				.build(new CacheLoader<ModelId, Element>() {
+					@Override
+					public Element load(ModelId key) throws ValidationServiceException {
+						return retrieveModelElement(key);
+					}
+				});
+	}
+
+	/**
+	 * Gets the model with specified uuid from the model cache. If model is not cached, retrieve the model from the
+	 * external system.
+	 *
+	 * @param uuid
+	 *            The model UUID.
+	 * @return The DOM Element representing the model's root element.
+	 * @throws ValidationServiceException
+	 */
+	public Element get(ModelId uuid) throws ValidationServiceException {
+		if (uuid == null || uuid.isEmpty()) {
+			return null;
+		}
+
+		return getCachedModel(uuid);
+	}
+
+	private Element getCachedModel(ModelId uuid) throws ValidationServiceException {
+		Element element = null;
+		try {
+			element = modelCache.get(uuid);
+		} catch (ExecutionException e) {
+			// If the wrapped exception is a model validation error, return null.
+			Throwable cause = e.getCause();
+			if (cause != null && cause.getClass().equals(ValidationServiceException.class)
+					&& (((ValidationServiceException) cause).getId().equals(ValidationServiceError.MODEL_NOT_FOUND.getId())
+							|| ((ValidationServiceException) cause).getId().equals(ValidationServiceError.REST_CLIENT_RESPONSE_NOT_FOUND.getId()))) {
+				return null;
+			}
+			throw new ValidationServiceException(ValidationServiceError.MODEL_CACHE_ERROR, e, "");
+		}
+		return element;
+	}
+
+	/**
+	 * Puts an item into the model cache.
+	 *
+	 * @param uuid
+	 *            The key.
+	 * @param modelElement
+	 *            The value.
+	 */
+	public void put(ModelId uuid, Element modelElement) {
+		modelCache.put(uuid, modelElement);
+	}
+
+	/**
+	 * Constructs and invokes the configured REST URL. The XML payload is then parsed into a model Element.
+	 *
+	 * @param uuid
+	 *            The model UUID to retrieve.
+	 * @return The payload of the REST URL call as a model Element.
+	 * @throws ValidationServiceException
+	 *             if the payload is null
+	 */
+	private Element retrieveModelElement(ModelId uuid) throws ValidationServiceException {
+		String protocol = restConfig.getProtocol();
+		Element modelElement;
+		if (FILE_MODEL_PROTOCOL.equals(protocol)) {
+			File modelFile = new File(restConfig.getBaseModelURI());
+			modelElement = retrieveModelElementFromFile(modelFile, uuid);
+		} else {
+			modelElement = retrieveModelElementFromREST(restConfig, uuid);
+		}
+
+		// Do not store a null value in the CacheBuilder
+		if (modelElement != null) {
+			return modelElement;
+		} else {
+			throw new ValidationServiceException(ValidationServiceError.MODEL_NOT_FOUND, uuid);
+		}
+	}
+
+	/**
+	 * Constructs and invokes the configured REST URL to retrieve the model for the supplied UUID. The XML payload is
+	 * then parsed into a model Element.
+	 *
+	 * @param uuid
+	 *            The model UUID to retrieve.
+	 * @return The payload of the REST URL call as a model Element, or null of no model could be found.
+	 * @throws ValidationServiceException
+	 */
+	private Element retrieveModelElementFromREST(RestConfig restConfig, ModelId uuid)
+			throws ValidationServiceException {
+		try {
+			URI restURI = new URIBuilder(restConfig.getBaseModelURI())
+					.addParameter(uuid.getModelIdAttribute(), uuid.getModelId()).build();
+			String restPayload = new RestClient(restConfig).get(restURI.toString(), MediaType.APPLICATION_XML);
+			return XMLModelParser.parse(restPayload, true);
+		} catch (URISyntaxException e) {
+			throw new ValidationServiceException(ValidationServiceError.MODEL_RETRIEVAL_ERROR, e);
+		}
+	}
+
+	/**
+	 * Retrieves the model with supplied model UUID from the supplied model file. The XML payload is then parsed into a
+	 * model Element.
+	 *
+	 * @param uuid
+	 *            The model UUID to retrieve.
+	 * @return The model Element, or null if no model could be found.
+	 * @throws ValidationServiceException
+	 */
+	private Element retrieveModelElementFromFile(File modelFile, ModelId uuid) throws ValidationServiceException {
+		Element rootElement = XMLModelParser.parse(modelFile, false);
+		// Check that the root element of the model file is correct.
+		if (!XMLModelParser.MODELS_ROOT_ELEMENT.equals(rootElement.getName())) {
+			return null;
+		}
+		return XMLModelParser.getModelElementWithId(rootElement, uuid.getModelIdAttribute(), uuid.getModelId());
+	}
+}
\ No newline at end of file
diff --git a/src/main/java/org/onap/aai/validation/modeldriven/ModelId.java b/src/main/java/org/onap/aai/validation/modeldriven/ModelId.java
new file mode 100644
index 0000000..25fbc22
--- /dev/null
+++ b/src/main/java/org/onap/aai/validation/modeldriven/ModelId.java
@@ -0,0 +1,86 @@
+/*
+ * ============LICENSE_START===================================================
+ * Copyright (c) 2018 Amdocs
+ * ============================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=====================================================
+ */
+package org.onap.aai.validation.modeldriven;
+
+import java.util.Objects;
+import org.apache.commons.lang3.builder.EqualsBuilder;
+
+/**
+ * Bean representing a model ID.
+ *
+ * The modelIdAttribute field defines the attribute in the model that holds the modelId
+ */
+public class ModelId {
+
+    public static final String ATTR_MODEL_NAME_VERSION_ID = "model-name-version-id";
+    public static final String ATTR_MODEL_ID = "model-id";
+
+    private String modelIdAttribute;
+    private String id;
+
+    /**
+     * @param modelIdAttribute The name of the attribute that holds the model ID.
+     * @param modelId The model ID.
+     */
+    public ModelId(String modelIdAttribute, String modelId) {
+        super();
+        this.modelIdAttribute = modelIdAttribute;
+        this.id = modelId;
+    }
+
+    public String getModelIdAttribute() {
+        return modelIdAttribute;
+    }
+
+    public void setModelIdAttribute(String modelIdAttribute) {
+        this.modelIdAttribute = modelIdAttribute;
+    }
+
+    public String getModelId() {
+        return id;
+    }
+
+    public void setModelId(String modelId) {
+        this.id = modelId;
+    }
+
+    public boolean isEmpty() {
+        return modelIdAttribute == null || id == null || modelIdAttribute.isEmpty() || id.isEmpty();
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(this.id, this.modelIdAttribute);
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (!(obj instanceof ModelId)) {
+            return false;
+        } else if (obj == this) {
+            return true;
+        }
+        ModelId rhs = (ModelId) obj;
+        // @formatter:off
+        return new EqualsBuilder()
+                  .append(id, rhs.id)
+                  .append(modelIdAttribute, rhs.modelIdAttribute)
+                  .isEquals();
+        // @formatter:on
+    }
+}
diff --git a/src/main/java/org/onap/aai/validation/modeldriven/configuration/mapping/Filter.java b/src/main/java/org/onap/aai/validation/modeldriven/configuration/mapping/Filter.java
new file mode 100644
index 0000000..a251d54
--- /dev/null
+++ b/src/main/java/org/onap/aai/validation/modeldriven/configuration/mapping/Filter.java
@@ -0,0 +1,75 @@
+/*
+ * ============LICENSE_START===================================================
+ * Copyright (c) 2018 Amdocs
+ * ============================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=====================================================
+ */
+package org.onap.aai.validation.modeldriven.configuration.mapping;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Objects;
+import org.apache.commons.lang3.builder.EqualsBuilder;
+
+/**
+ * Defines a path and value that will be used to validate a particular model.
+ * @see ValueConfiguration and ModelInstanceMapper
+ */
+public class Filter {
+
+	private String path;
+	private List<String> valid = new ArrayList<>();
+
+	public String getPath() {
+		return path;
+	}
+
+	public void setPath(String path) {
+		this.path = path;
+	}
+
+	public List<String> getValid() {
+		return valid;
+	}
+
+	public void setValid(List<String> valid) {
+		this.valid = valid;
+	}
+
+	@Override
+	public int hashCode() {
+		return Objects.hash(path, valid);
+	}
+
+	@Override
+	public boolean equals(Object obj) {
+        if (!(obj instanceof Filter)) {
+            return false;
+     } else if (obj == this) {
+            return true;
+     }
+        Filter rhs = (Filter) obj;
+     // @formatter:off
+     return new EqualsBuilder()
+                  .append(path, rhs.path)
+                  .append(valid, rhs.valid)
+                  .isEquals();
+     // @formatter:on
+	}
+	
+	@Override
+	public String toString() {
+		return "Filter [path=" + path + ", valid=" + valid + "]";
+	}
+}
diff --git a/src/main/java/org/onap/aai/validation/modeldriven/configuration/mapping/ModelInstanceMapper.java b/src/main/java/org/onap/aai/validation/modeldriven/configuration/mapping/ModelInstanceMapper.java
new file mode 100644
index 0000000..9ebe03c
--- /dev/null
+++ b/src/main/java/org/onap/aai/validation/modeldriven/configuration/mapping/ModelInstanceMapper.java
@@ -0,0 +1,89 @@
+/*
+ * ============LICENSE_START===================================================
+ * Copyright (c) 2018 Amdocs
+ * ============================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=====================================================
+ */
+package org.onap.aai.validation.modeldriven.configuration.mapping;
+
+import java.util.Objects;
+import org.apache.commons.lang3.builder.EqualsBuilder;
+
+/**
+ * Maps the configuration of model and instance values to be compared.
+ */
+public class ModelInstanceMapper {
+
+	/**
+	 * Types of mappings.
+	 */
+	public enum MappingType {
+		RELATIONSHIP, ATTRIBUTE
+	}
+	
+	private MappingType mappingType;
+	private ValueConfiguration model;
+	private ValueConfiguration instance;
+
+	public MappingType getMappingType() {
+		return mappingType;
+	}
+
+	public void setMappingType(String mappingType) {
+		this.mappingType = MappingType.valueOf(mappingType);
+	}
+
+	public ValueConfiguration getModel() {
+		return model;
+	}
+
+	public void setModel(ValueConfiguration model) {
+		this.model = model;
+	}
+
+	public ValueConfiguration getInstance() {
+		return instance;
+	}
+
+	public void setInstance(ValueConfiguration instance) {
+		this.instance = instance;
+	}
+
+	@Override
+	public int hashCode() {
+		return Objects.hash(instance, mappingType, model);
+	}
+
+	@Override
+	public boolean equals(Object obj) {
+        if (!(obj instanceof ModelInstanceMapper)) {
+            return false;
+     } else if (obj == this) {
+            return true;
+     }
+        ModelInstanceMapper rhs = (ModelInstanceMapper) obj;
+     // @formatter:off
+     return new EqualsBuilder()
+                  .append(instance, rhs.instance)
+                  .append(mappingType, rhs.mappingType)
+                  .append(model, rhs.model)
+                  .isEquals();
+     // @formatter:on
+	}
+
+	@Override
+	public String toString() {
+		return "ModelInstanceMapper [mappingType=" + mappingType + ", model=" + model + ", instance=" + instance + "]";
+	}
+}
\ No newline at end of file
diff --git a/src/main/java/org/onap/aai/validation/modeldriven/configuration/mapping/ModelInstanceMappingReader.java b/src/main/java/org/onap/aai/validation/modeldriven/configuration/mapping/ModelInstanceMappingReader.java
new file mode 100644
index 0000000..7be2d76
--- /dev/null
+++ b/src/main/java/org/onap/aai/validation/modeldriven/configuration/mapping/ModelInstanceMappingReader.java
@@ -0,0 +1,69 @@
+/*
+ * ============LICENSE_START===================================================
+ * Copyright (c) 2018 Amdocs
+ * ============================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=====================================================
+ */
+package org.onap.aai.validation.modeldriven.configuration.mapping;
+
+import java.util.ArrayList;
+import java.util.List;
+import org.json.JSONArray;
+import org.json.JSONException;
+import org.json.JSONObject;
+import org.onap.aai.validation.exception.ValidationServiceError;
+import org.onap.aai.validation.exception.ValidationServiceException;
+import org.onap.aai.validation.util.JsonUtil;
+
+/**
+ * Read mapping files
+ */
+public class ModelInstanceMappingReader {
+
+	private String mappingFile;
+
+	/**
+	 * @param mappingFile
+	 */
+	public ModelInstanceMappingReader(String mappingFile) {
+		this.mappingFile = mappingFile;
+	}
+
+	/**
+	 * Returns a list of model and object instance paths that will be used for comparing the corresponding model and
+	 * instance elements. The mappings are defined in the configuration file model-instance-mapping.json_conf and follows the
+	 * JSON notation.
+	 *
+	 * @return a List of {@link ModelInstanceMapper} beans which represents all the mappings defined in the file
+	 *         model-instance-mapping.json_conf.
+	 * @throws ValidationServiceException
+	 */
+	public List<ModelInstanceMapper> getMappings() throws ValidationServiceException {
+		List<ModelInstanceMapper> mappings = new ArrayList<>();
+
+		try {
+			JSONArray mappingsArray = new JSONArray(mappingFile);
+
+			for (int i = 0; i < mappingsArray.length(); i++) {
+				JSONObject jsonObject = mappingsArray.getJSONObject(i);
+				ModelInstanceMapper mapping = JsonUtil.fromJson(jsonObject.toString(), ModelInstanceMapper.class);
+				mappings.add(mapping);
+			}
+		} catch (JSONException e) {
+			throw new ValidationServiceException(ValidationServiceError.MODEL_INSTANCE_MAPPING_RETRIEVAL_ERROR, e);
+		}
+
+		return mappings;
+	}
+}
\ No newline at end of file
diff --git a/src/main/java/org/onap/aai/validation/modeldriven/configuration/mapping/ValueConfiguration.java b/src/main/java/org/onap/aai/validation/modeldriven/configuration/mapping/ValueConfiguration.java
new file mode 100644
index 0000000..230bbd9
--- /dev/null
+++ b/src/main/java/org/onap/aai/validation/modeldriven/configuration/mapping/ValueConfiguration.java
@@ -0,0 +1,124 @@
+/*
+ * ============LICENSE_START===================================================
+ * Copyright (c) 2018 Amdocs
+ * ============================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=====================================================
+ */
+package org.onap.aai.validation.modeldriven.configuration.mapping;
+
+import java.util.Objects;
+import org.apache.commons.lang3.builder.EqualsBuilder;
+
+/**
+ * Describes a model or instance value that is used in model to instance comparison.
+ *
+ * @see ModelInstanceMapper
+ */
+public class ValueConfiguration {
+
+    /** Top level element. From which all navigation starts. */
+    private String origin;
+
+    /**
+     * Root element from which the value will be extracted. Can be used to recursively navigate the model/instance
+     * hierarchy.
+     */
+    private String root;
+
+    /**
+     * Provides validation on the model before the value is extracted. If the filter is not satisfied other root models
+     * will be searched.
+     */
+    private Filter filter;
+
+    /**
+     * Path to the model id
+     */
+    private String id;
+
+    /**
+     * Path to a model or instance value
+     */
+    private String value;
+
+    public String getOrigin() {
+        return origin;
+    }
+
+    public void setOrigin(String origin) {
+        this.origin = origin;
+    }
+
+    public String getRoot() {
+        return root;
+    }
+
+    public void setRoot(String root) {
+        this.root = root;
+    }
+
+    public Filter getFilter() {
+        return filter;
+    }
+
+    public void setFilter(Filter filter) {
+        this.filter = filter;
+    }
+
+    public String getId() {
+        return id;
+    }
+
+    public void setId(String id) {
+        this.id = id;
+    }
+
+    public String getValue() {
+        return value;
+    }
+
+    public void setValue(String value) {
+        this.value = value;
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(this.filter, this.origin, this.root, this.value, this.id);
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (!(obj instanceof ValueConfiguration)) {
+            return false;
+        } else if (obj == this) {
+            return true;
+        }
+        ValueConfiguration rhs = (ValueConfiguration) obj;
+     // @formatter:off
+     return new EqualsBuilder()
+                  .append(filter, rhs.filter)
+                  .append(origin, rhs.origin)
+                  .append(root, rhs.root)
+                  .append(value, rhs.value)
+                  .append(id, rhs.id)
+                  .isEquals();
+     // @formatter:on
+    }
+
+    @Override
+    public String toString() {
+        return "ValueConfiguration [origin=" + origin + ", root=" + root + ", id=" + id + ", filter=" + filter
+                + ", value=" + value + "]";
+    }
+}
diff --git a/src/main/java/org/onap/aai/validation/modeldriven/parser/XMLModelParser.java b/src/main/java/org/onap/aai/validation/modeldriven/parser/XMLModelParser.java
new file mode 100644
index 0000000..cf7aa38
--- /dev/null
+++ b/src/main/java/org/onap/aai/validation/modeldriven/parser/XMLModelParser.java
@@ -0,0 +1,152 @@
+/*
+ * ============LICENSE_START===================================================
+ * Copyright (c) 2018 Amdocs
+ * ============================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=====================================================
+ */
+package org.onap.aai.validation.modeldriven.parser;
+
+import java.io.File;
+import java.io.IOException;
+import java.nio.charset.Charset;
+import java.nio.file.Files;
+import java.util.List;
+import org.dom4j.DocumentException;
+import org.dom4j.DocumentHelper;
+import org.dom4j.Element;
+import org.dom4j.Node;
+import org.onap.aai.validation.exception.ValidationServiceError;
+import org.onap.aai.validation.exception.ValidationServiceException;
+
+/**
+ * Read models from XML file
+ *
+ */
+public class XMLModelParser {
+
+	public static final String MODEL_ROOT_ELEMENT = "model";
+	public static final String MODELS_ROOT_ELEMENT = "models";
+
+	private XMLModelParser() {
+		// Do nothing
+	}
+
+	/**
+	 * Parses an xml file and returns the root Element.
+	 *
+	 * @param modelFile
+	 *            The XML File.
+	 * @param validateModel
+	 *            If true the model will be validated.
+	 * @return The root Element of the document.
+	 * @throws DocumentException
+	 * @throws ValidationServiceException
+	 */
+	public static Element parse(File modelFile, boolean validateModel) throws ValidationServiceException {
+		try {
+			byte[] encoded = Files.readAllBytes(modelFile.toPath());
+			String modelString = new String(encoded, Charset.defaultCharset());
+
+			return parse(modelString, validateModel);
+		} catch (IOException e) {
+			throw new ValidationServiceException(ValidationServiceError.MODEL_PARSE_ERROR, e, modelFile.toString());
+		}
+	}
+
+	/**
+	 * Parses an xml String and returns the root Element.
+	 *
+	 * @param modelString
+	 *            The XML String.
+	 * @param validateModel
+	 *            If true the model will be validated.
+	 * @return The root Element of the document, or null if no valid model can be parsed.
+	 * @throws DocumentException
+	 */
+	public static Element parse(String modelString, boolean validateModel) throws ValidationServiceException {
+		// Strip namespace information first.
+		String model = removeXmlStringNamespaceAndPreamble(modelString);
+
+		try {
+			Element modelElement = DocumentHelper.parseText(model).getRootElement();
+			if (validateModel && (modelElement == null || !isValidModel(modelElement))) {
+				return null;
+			}
+			return modelElement;
+		} catch (DocumentException e) {
+			throw new ValidationServiceException(ValidationServiceError.MODEL_PARSE_ERROR, e, model);
+		}
+	}
+
+	/**
+	 * Returns the result of running the XPath expression on the DOM Node.
+	 *
+	 * @param currentNode
+	 *            The current Node being processed.
+	 * @param xPath
+	 *            The XPath expression to run on the Node.
+	 * @return A List of Nodes representing the result of the XPath expression.
+	 */
+	@SuppressWarnings("unchecked")
+	public static List<Node> getObjectsFromXPath(Node currentNode, String xPath) {
+		return currentNode.selectNodes(xPath);
+	}
+
+	/**
+	 * Returns the child model Element that corresponds to the provided root Element and model ID.
+	 *
+	 * @param rootElement
+	 *            The root Element to search.
+	 * @param attributeName
+	 *            The name of the attribute that holds the model ID.
+	 * @param modelId
+	 *            The model ID to search for.
+	 * @return The model Element that matches the model ID supplied.
+	 */
+	public static Element getModelElementWithId(Element rootElement, String attributeName, String modelId) {
+		Element modelElement = null;
+		List<Node> modelsList = getObjectsFromXPath(rootElement, MODEL_ROOT_ELEMENT + "/" + attributeName);
+		for (Node model : modelsList) {
+			if (model.getText().equals(modelId)) {
+				modelElement = model.getParent();
+			}
+		}
+		return modelElement;
+	}
+
+	/**
+	 * Determines the validity of the supplied model element by checking if the name of the root element is correct.
+	 *
+	 * @param modelElement
+	 *            The model element to check.
+	 * @return True if the root element matches the expected name.
+	 */
+	private static boolean isValidModel(Element modelElement) {
+		return MODEL_ROOT_ELEMENT.equals(modelElement.getName());
+	}
+
+	/**
+	 * Strips all namespace information from the model XML.
+	 *
+	 * @param modelXML
+	 *            The model XML as a String.
+	 * @return The model XML String minus the namespace information.
+	 */
+	private static String removeXmlStringNamespaceAndPreamble(String xmlString) {
+		return xmlString.replaceAll("(<\\?[^<]*\\?>)?", "") /* remove preamble */
+				.replaceAll("xmlns.*?(\"|\').*?(\"|\')", "") /* remove xmlns declaration */
+				.replaceAll("(<)(\\w+:)(.*?>)", "$1$3") /* remove opening tag prefix */
+				.replaceAll("(</)(\\w+:)(.*?>)", "$1$3"); /* remove closing tags prefix */
+	}
+}
diff --git a/src/main/java/org/onap/aai/validation/modeldriven/validator/InstanceReader.java b/src/main/java/org/onap/aai/validation/modeldriven/validator/InstanceReader.java
new file mode 100644
index 0000000..7832e51
--- /dev/null
+++ b/src/main/java/org/onap/aai/validation/modeldriven/validator/InstanceReader.java
@@ -0,0 +1,316 @@
+/*
+ * ============LICENSE_START===================================================
+ * Copyright (c) 2018 Amdocs
+ * ============================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=====================================================
+ */
+package org.onap.aai.validation.modeldriven.validator;
+
+import com.google.common.collect.HashMultimap;
+import com.google.common.collect.Multimap;
+import com.google.gson.JsonArray;
+import com.google.gson.JsonElement;
+import com.google.gson.JsonObject;
+import com.google.gson.JsonParser;
+import com.jayway.jsonpath.DocumentContext;
+import java.util.Arrays;
+import java.util.List;
+import java.util.Map.Entry;
+import java.util.Set;
+import javax.inject.Inject;
+import org.onap.aai.validation.exception.ValidationServiceError;
+import org.onap.aai.validation.exception.ValidationServiceException;
+import org.onap.aai.validation.modeldriven.configuration.mapping.ModelInstanceMapper;
+import org.onap.aai.validation.modeldriven.configuration.mapping.ModelInstanceMapper.MappingType;
+import org.onap.aai.validation.reader.JsonReader;
+import org.onap.aai.validation.reader.OxmReader;
+
+/**
+ * Reads values from an instance object.
+ */
+public class InstanceReader {
+
+	private static final String MODEL_NAME = "model-name";
+	private static final String[] INVALID_ENTRIES = { "inventory-response-items", "extra-properties", MODEL_NAME };
+	private static final String RESOURCE_VERSION = "resource-version";
+	private static final String JSON_PATH_MODEL_ID = "$.*.persona-model-id";
+
+	private JsonReader jsonReader;
+	private OxmReader oxmReader;
+	private JsonParser jsonParser = new JsonParser();
+
+	/**
+	 * @param jsonReader
+	 * @param oxmReader
+	 */
+	@Inject
+	public InstanceReader(JsonReader jsonReader, OxmReader oxmReader) {
+		this.jsonReader = jsonReader;
+		this.oxmReader = oxmReader;
+	}
+
+	public OxmReader getOxmReader() {
+		return oxmReader;
+	}
+
+	/**
+	 * Gets object instance values.
+	 *
+	 * @param json
+	 *            a Named Query JSON payload
+	 * @param mapping
+	 *            defines the paths that allow the extraction of values from the object instance. This includes:
+	 *            <ul>
+	 *            <li>origin: path that serves as the starting point for the instance search</li>
+	 *            <li>root: path to underlying instance objects that can be examined by recursively calling the
+	 *            getValues method</li>
+	 *            </ul>
+	 *
+	 * @return a {@link Multimap} of instances keyed by their model id.
+	 * @throws ValidationServiceException
+	 */
+	public Multimap<String, String> getValues(String json, ModelInstanceMapper mapping) throws ValidationServiceException {
+		Multimap<String, String> values = HashMultimap.create();
+
+		DocumentContext document = jsonReader.parse(json);
+
+		if (MappingType.RELATIONSHIP.equals(mapping.getMappingType())) {
+			String rootPath = mapping.getInstance().getRoot();
+			if (rootPath == null || rootPath.isEmpty()) {
+				throw new ValidationServiceException(ValidationServiceError.INSTANCE_MAPPING_ROOT_ERROR);
+			}
+
+			JsonElement jsonElement = jsonReader.getJsonElement(document, rootPath);
+
+			if (jsonElement instanceof JsonArray) {
+				JsonArray jsonArray = jsonElement.getAsJsonArray();
+
+				processRelatedObjects(values, jsonArray);
+			}
+		} else {
+			// We are dealing with attributes.
+			String valuePath = mapping.getInstance().getValue();
+			if (valuePath != null && !valuePath.isEmpty()) {
+				List<String> attributes = jsonReader.get(json, valuePath);
+				for (String attribute : attributes) {
+					values.put(attribute, null);
+				}
+			}
+		}
+
+		return values;
+	}
+
+	/**
+	 * Gets the instance type, e.g. connector, pserver, etc.
+	 *
+	 * @param json
+	 *            a Named Query JSON payload
+	 * @return the type of the entity
+	 */
+	public String getInstanceType(String json) {
+		return getNamedQueryEntity(json).getEntityType();
+	}
+
+	/**
+	 * Gets the id of the instance. Uses the {@link OxmReader} to identify the property holding the primary key.<br>
+	 *
+	 * WARNING: Some types of object appear to have more than one primary key. This method uses the first primary key.
+	 *
+	 * @param json
+	 *            a Named Query JSON payload
+	 * @return the identifier of the object instance
+	 * @throws ValidationServiceException
+	 */
+	public String getInstanceId(String json) throws ValidationServiceException {
+		String instanceId = null;
+
+		InstanceEntity entity = getNamedQueryEntity(json);
+
+		List<String> primaryKeys = oxmReader.getPrimaryKeys(entity.getEntityType());
+
+		if (primaryKeys != null && !primaryKeys.isEmpty()) {
+			JsonObject instance = entity.getObject().getAsJsonObject();
+			JsonElement primaryKey = instance.get(primaryKeys.get(0));
+			instanceId = primaryKey == null ? null : primaryKey.getAsString();
+		}
+
+		return instanceId;
+	}
+
+	/**
+	 * Strips the instance out of its payload wrapping.
+	 *
+	 * @param json
+	 *            a Named Query JSON payload
+	 * @param mappings
+	 *            the definition of the paths that allow the extraction of the instance from the JSON payload
+	 * @return
+	 * @throws ValidationServiceException
+	 */
+	public String getInstance(String json, List<ModelInstanceMapper> mappings) throws ValidationServiceException {
+		String origin = mappings.iterator().next().getInstance().getOrigin();
+		List<String> jsonList = jsonReader.get(json, origin);
+
+		if (!jsonList.isEmpty()) {
+			return jsonList.get(0);
+		} else {
+			throw new ValidationServiceException(ValidationServiceError.INSTANCE_READER_NO_INSTANCE, origin, json);
+		}
+	}
+
+	/**
+	 * Extracts the entity from a Named Query JSON payload.
+	 *
+	 * @param json
+	 *            a Named Query JSON payload
+	 * @return an {@link InstanceEntity} object
+	 */
+	public InstanceEntity getNamedQueryEntity(String json) {
+		return getNamedQueryEntity(jsonParser.parse(json).getAsJsonObject());
+	}
+
+	/**
+	 * Gets the model identifier of a given entity.
+	 *
+	 * @param entity
+	 *            a JSON entity
+	 * @return a model identifier attribute value if the attribute exists else a null is returned.
+	 * @throws ValidationServiceException
+	 */
+	public String getModelId(String entity) throws ValidationServiceException {
+		String modelId = null;
+		List<String> readResult = jsonReader.get(entity, JSON_PATH_MODEL_ID);
+		if (!readResult.isEmpty()) {
+			modelId = readResult.get(0);
+		}
+		return modelId;
+	}
+
+	/**
+	 * Gets the resource version of the instance.
+	 *
+	 * @param json
+	 *            a Named Query JSON payload
+	 * @return the resource version of the object instance
+	 */
+	public String getResourceVersion(String json) {
+		String resourceVersion = null;
+
+		InstanceEntity entity = getNamedQueryEntity(json);
+
+		if (entity != null && entity.getObject() != null && entity.getObject().getAsJsonObject().has(RESOURCE_VERSION)) {
+			resourceVersion = entity.getObject().getAsJsonObject().get(RESOURCE_VERSION).getAsString();
+		}
+		return resourceVersion;
+	}
+
+	/**
+	 * Gets the model name of the instance.
+	 *
+	 * @param jsonString
+	 *            a Named Query JSON payload
+	 * @return the model name of the object instance
+	 * @throws ValidationServiceException
+	 */
+	public String getModelName(String jsonString) {
+		JsonObject jsonObject = jsonParser.parse(jsonString).getAsJsonObject();
+		return getModelName(jsonObject);
+	}
+
+	/**
+	 * @param jsonObject
+	 * @return
+	 */
+	private String getModelName(JsonObject jsonObject) {
+		for (Entry<String, JsonElement> entry : jsonObject.entrySet()) {
+			if (MODEL_NAME.equals(entry.getKey())) {
+				return entry.getValue().getAsString();
+			}
+		}
+		return null;
+	}
+
+	private void processRelatedObjects(Multimap<String, String> values, JsonArray jsonArray) {
+		for (JsonElement relatedObject : jsonArray) {
+			JsonObject jsonObject = relatedObject.getAsJsonObject();
+
+			InstanceEntity entity = getNamedQueryEntity(jsonObject);
+			if (entity != null) {
+				values.put(entity.getModelName() == null ? entity.getEntityType() : entity.getModelName(), jsonObject.toString());
+			}
+		}
+	}
+
+	private InstanceEntity getNamedQueryEntity(JsonObject jsonObject) {
+		Set<Entry<String, JsonElement>> entrySet = jsonObject.entrySet();
+
+		String modelName = getModelName(jsonObject);
+
+		for (Entry<String, JsonElement> entry : entrySet) {
+			if (!Arrays.asList(INVALID_ENTRIES).contains(entry.getKey())) {
+				return new InstanceEntity(entry.getKey(), modelName, entry.getValue().getAsJsonObject(), jsonObject);
+			}
+		}
+
+		return null;
+	}
+
+	/**
+	 * An Entity bean for the InstanceReader
+	 *
+	 */
+	public class InstanceEntity {
+
+		private String entityType;
+		private String modelName;
+		private JsonObject object;
+		private JsonObject objectAndGraph;
+
+		/**
+		 * @param entityType
+		 * @param modelName
+		 * @param object
+		 * @param objectAndGraph
+		 */
+		public InstanceEntity(String entityType, String modelName, JsonObject object, JsonObject objectAndGraph) {
+			this.entityType = entityType;
+			this.modelName = modelName;
+			this.object = object;
+			this.objectAndGraph = objectAndGraph;
+		}
+
+		public String getEntityType() {
+			return entityType;
+		}
+
+		public String getModelName() {
+			return modelName;
+		}
+
+		public JsonObject getObject() {
+			return object;
+		}
+
+		public JsonObject getObjectAndGraph() {
+			return objectAndGraph;
+		}
+
+		@Override
+		public String toString() {
+			return "Entity [entityType=" + entityType + ", modelName=" + modelName + ", object=" + object.toString() + ", fullObject="
+					+ objectAndGraph.toString() + "]";
+		}
+	}
+}
\ No newline at end of file
diff --git a/src/main/java/org/onap/aai/validation/modeldriven/validator/ModelDrivenValidator.java b/src/main/java/org/onap/aai/validation/modeldriven/validator/ModelDrivenValidator.java
new file mode 100644
index 0000000..1b8ab00
--- /dev/null
+++ b/src/main/java/org/onap/aai/validation/modeldriven/validator/ModelDrivenValidator.java
@@ -0,0 +1,306 @@
+/*
+ * ============LICENSE_START===================================================
+ * Copyright (c) 2018 Amdocs
+ * ============================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=====================================================
+ */
+package org.onap.aai.validation.modeldriven.validator;
+
+import com.google.common.collect.HashMultimap;
+import com.google.common.collect.Multimap;
+import com.google.gson.JsonObject;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collection;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Map.Entry;
+import java.util.Set;
+import javax.inject.Inject;
+import org.apache.commons.collections.CollectionUtils;
+import org.dom4j.Node;
+import org.onap.aai.validation.Validator;
+import org.onap.aai.validation.exception.ValidationServiceException;
+import org.onap.aai.validation.modeldriven.ModelCacheManager;
+import org.onap.aai.validation.modeldriven.ModelId;
+import org.onap.aai.validation.modeldriven.configuration.mapping.ModelInstanceMapper;
+import org.onap.aai.validation.modeldriven.configuration.mapping.ModelInstanceMappingReader;
+import org.onap.aai.validation.modeldriven.configuration.mapping.ModelInstanceMapper.MappingType;
+import org.onap.aai.validation.reader.EntityReader;
+import org.onap.aai.validation.reader.EventReader;
+import org.onap.aai.validation.reader.InstanceEntityReader;
+import org.onap.aai.validation.reader.data.Entity;
+import org.onap.aai.validation.reader.data.EntityId;
+import org.onap.aai.validation.result.ValidationResult;
+import org.onap.aai.validation.result.Violation;
+import org.onap.aai.validation.result.Violation.Builder;
+import org.onap.aai.validation.result.Violation.ViolationType;
+
+/**
+ * Validates object instances against the ONAP model.
+ *
+ */
+public class ModelDrivenValidator implements Validator {
+
+	/**
+	 * Types of validation rules.
+	 */
+	public enum RuleType {
+		REL, ATTR
+	}
+
+	/**
+	 * Types of validation outcomes.
+	 */
+	public enum ValidationOutcomeType {
+		NO_MODEL, MISSING, UNEXPECTED;
+	}
+
+	private ModelCacheManager modelCacheManager;
+	private List<ModelInstanceMapper> mappings;
+	private InstanceReader instanceReader;
+	private EventReader eventReader;
+
+	/**
+	 * Constructor defining injected dependencies.
+	 *
+	 * @param modelCacheManager
+	 *            a cache manager for the models
+	 * @param modelInstanceMappingReader
+	 *            a configuration reader to provide model and instance mapping
+	 * @param instanceReader
+	 *            a reader of A&AI instances
+	 * @param eventReader
+	 * @throws ValidationServiceException
+	 */
+	@Inject
+	public ModelDrivenValidator(ModelCacheManager modelCacheManager, ModelInstanceMappingReader modelInstanceMappingReader, InstanceReader instanceReader,
+			EventReader eventReader) throws ValidationServiceException {
+		this.modelCacheManager = modelCacheManager;
+		this.mappings = modelInstanceMappingReader.getMappings();
+		this.instanceReader = instanceReader;
+		this.eventReader = eventReader;
+	}
+
+	@Override
+	public void initialise() throws ValidationServiceException {
+		// Deliberately empty
+	}
+
+	/**
+	 * Validates the given event instance against the ECOMP model.
+	 *
+	 * @param eventInstance
+	 *            the event instance to be validated
+	 * @return {@link Violation} with the results of the object validation
+	 * @throws ValidationServiceException
+	 */
+	@Override
+	public List<ValidationResult> validate(String eventInstance) throws ValidationServiceException {
+		// Read event json into Entity bean
+		Entity eventEntity = eventReader.getEntity(eventInstance);
+
+		EntityReader reader = new InstanceEntityReader(instanceReader);
+		String entityJson = instanceReader.getInstance(eventEntity.getJson(), mappings);
+		Entity instanceEntity = new Entity(entityJson, instanceReader.getInstanceType(entityJson), eventEntity.getEntityLink(), reader);
+
+		// Get model ID from object instance and retrieve corresponding model.
+		ModelId modelId = new ModelId(ModelId.ATTR_MODEL_ID, instanceReader.getModelId(instanceEntity.getJson()));
+		Node modelElement = modelCacheManager.get(modelId);
+
+		List<Violation> violations = new ArrayList<>();
+
+		if (modelElement == null) {
+			ViolationInfo info = ViolationInfo.valueOf(ModelDrivenValidator.ValidationOutcomeType.NO_MODEL.toString());
+			Map<String, Object> details = new HashMap<>();
+			details.put("No model ID", modelId.getModelId());
+			Violation.Builder builder = new Violation.Builder(instanceEntity).violationType(ViolationType.MODEL);
+			builder.category(info.getCategory()).severity(info.getSeverity()).violationDetails(details)
+					.errorMessage(info.getErrorMessage(modelId.getModelId()));
+			violations.add(builder.build());
+		} else {
+			// Validate model with instance according to mappings.
+			for (ModelInstanceMapper mapping : mappings) {
+				List<Violation> currentViolations = new ArrayList<>();
+
+				// If we are validating related objects, find the first valid child object to begin validating from.
+				Node validModelElement = modelElement;
+				if (MappingType.RELATIONSHIP.equals(mapping.getMappingType()) && !ModelReader.isValidModelType(modelElement, mapping)) {
+					Multimap<String, Node> models = HashMultimap.create();
+					ModelReader.getValuesAndModels(modelElement, mapping, modelCacheManager, models);
+					validModelElement = models.isEmpty() ? modelElement : models.values().iterator().next();
+				}
+
+				validateAllRecursive(validModelElement, instanceEntity, mapping, currentViolations, reader);
+				violations.addAll(currentViolations);
+			}
+		}
+
+		ValidationResult validationResult = new ValidationResult(instanceEntity);
+
+		// This is a shortcut to passing the parent model name all the way down.
+		populateViolationModelNames(violations, instanceEntity);
+
+		validationResult.addViolations(violations);
+
+		return Arrays.asList(validationResult);
+	}
+
+	/*
+	 * Recursively validates all child entities starting with the crown widget.
+	 */
+	private void validateAllRecursive(Node currentModelNode, Entity entity, ModelInstanceMapper mapping, List<Violation> validations, EntityReader reader)
+			throws ValidationServiceException {
+		String entityLink = null;
+		Multimap<String, Node> modelMap = ModelReader.getValues(currentModelNode, mapping, modelCacheManager);
+		Multimap<String, String> instanceMap = instanceReader.getValues(entity.getJson(), mapping);
+
+		// Validate model with instance according to mappings.
+		// Note: Currently the cardinality of instances are not validated.
+		List<Violation> currentViolations = validateModelInstanceValues(modelMap.keySet(), instanceMap.keySet(), entity, mapping);
+		validations.addAll(currentViolations);
+
+		// Remove erroring objects from the maps so that we don't validate their children.
+		for (Violation currentViolation : currentViolations) {
+			String entityType = (String) currentViolation.getViolationDetails().get(Violation.ENTITY_TYPE_PROPERTY);
+			if (entityType != null) {
+				modelMap.removeAll(entityType);
+				instanceMap.removeAll(entityType);
+			}
+		}
+
+		// Continue down the model hierarchy for objects that did not error in the current layer.
+		for (Entry<String, Node> modelEntry : modelMap.entries()) {
+			// Get the child model.
+			Node childModelNode = modelEntry.getValue();
+			if (childModelNode != null) {
+				// Validate all child instance objects with current child model.
+				Collection<String> childInstanceObjects = instanceMap.get(modelEntry.getKey());
+				for (String childInstanceObject : childInstanceObjects) {
+					Entity childEntity = new Entity(childInstanceObject, instanceReader.getInstanceType(childInstanceObject), entityLink, reader);
+					validateAllRecursive(childModelNode, childEntity, mapping, validations, reader);
+				}
+			}
+		}
+	}
+
+	/**
+	 * Compares the List of values found in the model with the values found in the Json and generates validation errors
+	 * based on the differences.
+	 *
+	 * @param modelValues
+	 *            the values found in the model
+	 * @param instanceValues
+	 *            the values found in the Json.
+	 * @param entity
+	 * @param modelInstanceMapper
+	 *            the mappings used to to find the model and instance values
+	 * @return List of Validation objects representing the errors found during validation.
+	 * @throws ValidationServiceException
+	 */
+	private List<Violation> validateModelInstanceValues(Set<String> modelValues, Set<String> instanceValues, Entity entity,
+			ModelInstanceMapper modelInstanceMapper) throws ValidationServiceException {
+		List<Violation> violations = new ArrayList<>();
+
+		Collection<?> missingValues = CollectionUtils.subtract(modelValues, instanceValues);
+		violations.addAll(setViolationDetails(ValidationOutcomeType.MISSING, missingValues, entity, modelInstanceMapper));
+
+		Collection<?> unexpectedValues = CollectionUtils.subtract(instanceValues, modelValues);
+		violations.addAll(setViolationDetails(ValidationOutcomeType.UNEXPECTED, unexpectedValues, entity, modelInstanceMapper));
+
+		return violations;
+	}
+
+	/*
+	 * Sets the list of {@link Violation} objects with all the violation details.
+	 *
+	 * @param outcome
+	 *
+	 * @param values the values that are causing the violation
+	 *
+	 * @param entity the entity being validated
+	 *
+	 * @param modelInstanceMapper the mappings used to to find the model and instance values
+	 *
+	 * @return list of {@link Violation} objects set by this method
+	 *
+	 * @throws ValidationServiceException
+	 */
+	private List<Violation> setViolationDetails(ValidationOutcomeType outcome, Collection<?> values, Entity entity, ModelInstanceMapper modelInstanceMapper)
+			throws ValidationServiceException {
+
+		List<Violation> violations = new ArrayList<>();
+		Builder builder = new Builder(entity).violationType("Model");
+
+		for (Object value : values) {
+			RuleType ruleType = modelInstanceMapper.getMappingType().equals(MappingType.RELATIONSHIP) ? RuleType.REL : RuleType.ATTR;
+			String category = outcome.toString() + "_" + ruleType;
+
+			ViolationInfo info = ViolationInfo.valueOf(category);
+			builder.category(info.getCategory());
+			builder.severity(info.getSeverity());
+
+			Map<String, Object> details = new HashMap<>();
+			details.put(outcome.toString() + " " + ruleType.toString(), value);
+
+			switch (ruleType) {
+			case ATTR:
+				builder.errorMessage(info.getErrorMessage(value));
+				break;
+			case REL:
+				buildEntityIdDetails(details, entity);
+				builder.errorMessage(info.getErrorMessage(entity.getIds().toString(), entity.getType(), value));
+				break;
+			default:
+				// Do nothing
+				break;
+			}
+			builder.violationDetails(details);
+			violations.add(builder.build());
+		}
+
+		return violations;
+	}
+
+	/*
+	 * Add entity IDs to the violation details
+	 *
+	 * @param details the violation details to populate
+	 *
+	 * @param entity
+	 *
+	 * @throws ValidationServiceException
+	 */
+	private void buildEntityIdDetails(Map<String, Object> details, Entity entity) throws ValidationServiceException {
+		JsonObject entityIdsObject = new JsonObject();
+		for (EntityId entityId : entity.getIds()) {
+			entityIdsObject.addProperty(entityId.getPrimaryKey(), entityId.getValue());
+		}
+		details.put(Violation.ENTITY_ID_PROPERTY, entityIdsObject);
+		details.put(Violation.ENTITY_TYPE_PROPERTY, entity.getType());
+		details.put(Violation.ENTITY_MODELNAME_PROPERTY, instanceReader.getModelName(entity.getJson()));
+	}
+
+	/*
+	 * Sets the model name attribute on all violations in the list. The model name is retrieved from the entity
+	 * provided.
+	 */
+	private void populateViolationModelNames(List<Violation> violations, Entity entity) {
+		String modelName = instanceReader.getModelName(entity.getJson());
+		for (Violation violation : violations) {
+			violation.setModelName(modelName);
+		}
+	}
+}
diff --git a/src/main/java/org/onap/aai/validation/modeldriven/validator/ModelReader.java b/src/main/java/org/onap/aai/validation/modeldriven/validator/ModelReader.java
new file mode 100644
index 0000000..04728a3
--- /dev/null
+++ b/src/main/java/org/onap/aai/validation/modeldriven/validator/ModelReader.java
@@ -0,0 +1,236 @@
+/*
+ * ============LICENSE_START===================================================
+ * Copyright (c) 2018 Amdocs
+ * ============================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=====================================================
+ */
+package org.onap.aai.validation.modeldriven.validator;
+
+import com.google.common.collect.HashMultimap;
+import com.google.common.collect.Multimap;
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.List;
+import org.dom4j.Node;
+import org.onap.aai.validation.exception.ValidationServiceError;
+import org.onap.aai.validation.exception.ValidationServiceException;
+import org.onap.aai.validation.modeldriven.ModelCacheManager;
+import org.onap.aai.validation.modeldriven.ModelId;
+import org.onap.aai.validation.modeldriven.configuration.mapping.Filter;
+import org.onap.aai.validation.modeldriven.configuration.mapping.ModelInstanceMapper;
+import org.onap.aai.validation.modeldriven.configuration.mapping.ModelInstanceMapper.MappingType;
+import org.onap.aai.validation.modeldriven.parser.XMLModelParser;
+
+/**
+ * Reads values from the model.
+ */
+public class ModelReader {
+
+	private static final String ATTRIBUTE_MODELTYPE = "model-type";
+
+	/**
+	 * Do not instantiate an object of this class
+	 */
+	private ModelReader() {
+		// Deliberately empty
+	}
+
+	/**
+	 * Gets the values of a model element as defined by the model-instance mapping configuration. When the mapping
+	 * type is "attribute", the multimap will be returned with a null value.
+	 *
+	 * @param modelElement
+	 *            the model element from which the values will be extracted
+	 * @param mapping
+	 *            the model-instance mapping object defining the path to the model values
+	 * @param modelCacheManager
+	 *            the model cache manager used to retrieve further models
+	 * @return a {@link Multimap} of model values.
+	 * @throws ValidationServiceException
+	 */
+	public static Multimap<String, Node> getValues(Node modelElement, ModelInstanceMapper mapping, ModelCacheManager modelCacheManager)
+			throws ValidationServiceException {
+		Multimap<String, Node> values = HashMultimap.create();
+		
+		if (MappingType.ATTRIBUTE.equals(mapping.getMappingType())) {
+			// Get attributes on current model element.
+			Multimap<String, Node> modelValues = getModelValues(modelElement, mapping, false);
+			if (modelValues.isEmpty()) {
+				throw new ValidationServiceException(ValidationServiceError.MODEL_VALUE_ERROR,
+						mapping.getModel().getValue(), modelElement.asXML());
+			}
+			values.putAll(modelValues);
+		} else {
+			// Get related objects.
+			getValuesAndModels(modelElement, mapping, modelCacheManager, values);
+		}
+
+
+		return values;
+	}
+
+	/**
+	 * Returns the model type property of the current model element.
+	 *
+	 * @param model
+	 *            The current model element.
+	 * @return the model type of the current element or null if not found.
+	 */
+	public static String getModelType(Node model) {
+		String modelType = null;
+		List<Node> modelTypeElements = XMLModelParser.getObjectsFromXPath(model, ATTRIBUTE_MODELTYPE);
+		if (!modelTypeElements.isEmpty()) {
+			modelType = modelTypeElements.iterator().next().getText();
+		}
+		return modelType;
+	}
+
+	/**
+	 * @param model
+	 * @param mapping
+	 * @return True if supplied model is of type widget.
+	 */
+	public static boolean isValidModelType(Node model, ModelInstanceMapper mapping) {
+		Collection<String> validTypes = mapping.getModel().getFilter().getValid();
+		return validTypes.isEmpty() ? false :validTypes.contains(getModelType(model));
+	}
+
+	/**
+	 * Populates a Multimap of models. If a root and filter are defined in the mapping it will navigate the model to find a
+	 * valid models according to the filter. If the root property is not defined a model is not returned.
+	 *
+	 * @param model
+	 *            the model to be inspected
+	 * @param mapping
+	 *            the model-instance mapping object defining the root model
+	 * @param modelCacheManager
+	 *            the model cache manager used to retrieve further models
+	 * @param models
+	 *            a Multimap of models that will be populated with further models
+	 * @throws ValidationServiceException
+	 */
+	public static void getValuesAndModels(Node model, ModelInstanceMapper mapping, ModelCacheManager modelCacheManager, Multimap<String, Node> models) throws ValidationServiceException {
+		String root = mapping.getModel().getRoot();
+
+		if (root == null) {
+			return;
+		}
+
+		List<Node> childModelElements = XMLModelParser.getObjectsFromXPath(model, root);
+		for (Node childModel : childModelElements) {
+			// If the child element is a leaf, this could either mean the end of the hierarchy, or that we have
+			// encountered a resource and need to retrieve a separate model to continue the model traversal.
+			List<String> modelNames = getModelValuesList(childModel, mapping);
+			if (!hasChildren(childModel, root) && !isValidModel(childModel, mapping) && mapping.getModel().getId() != null) {
+				childModel = getChildModelNode(modelCacheManager, childModel, mapping);
+			}
+
+			if (isValidModel(childModel, mapping)) {
+				for (String modelName : modelNames) {
+					models.put(modelName, childModel);
+				}
+			} else {
+				getValuesAndModels(childModel, mapping, modelCacheManager, models);
+			}
+		}
+	}
+
+	/**
+	 * Find the next child model given a specific node.
+	 *
+	 * @param modelCacheManager
+	 *            the model cache manager used to retrieve further models
+	 * @param node
+	 *            the top-level node under which child model nodes are searched
+	 * @param rootXPath
+	 *            the path expression to apply to the node to find child elements
+	 * @param modelIdPath
+	 *            the path expression to apply to the node to find the child model IDs
+	 * @return either or the {@code node} if there were no matches for {@code id}
+	 * @throws ValidationServiceException
+	 */
+	private static Node getChildModelNode(ModelCacheManager modelCacheManager, Node node, ModelInstanceMapper mapping) throws ValidationServiceException {
+		Node childModel = node;
+
+		// Get the model for the specified node to check its type.
+		// Only one model ID is expected, although the API returns a list.
+		List<Node> childModelIds = XMLModelParser.getObjectsFromXPath(node, mapping.getModel().getId());
+
+		if (!childModelIds.isEmpty()) {
+			// Found the child model ID, so retrieve the child model from cache.
+			ModelId modelId = new ModelId(ModelId.ATTR_MODEL_NAME_VERSION_ID, childModelIds.iterator().next().getText());
+			Node fullChildModel = modelCacheManager.get(modelId);
+
+			if (fullChildModel != null && !isValidModelType(fullChildModel, mapping)) {
+				// Child model is not a widget so replace current child model with the full child model
+				// retrieved from the cache.
+				List<Node> fullChildModelElements = XMLModelParser.getObjectsFromXPath(fullChildModel, mapping.getModel().getRoot());
+				// Only one crown widget is expected, although the API returns a list.
+				childModel = fullChildModelElements.isEmpty() ? node : fullChildModelElements.iterator().next();
+			}
+		}
+
+		return childModel;
+	}
+
+	private static Multimap<String, Node> getModelValues(Node model, ModelInstanceMapper mapping, boolean addModel) {
+		Multimap<String, Node> values = HashMultimap.create();
+		List<String> valueStrings = getModelValuesList(model, mapping);
+		for (String value : valueStrings) {
+			values.put(value, addModel ? model : null);
+		}
+		return values;
+	}
+
+	private static List<String> getModelValuesList(Node model, ModelInstanceMapper mapping) {
+		List<String> values = new ArrayList<>();
+		List<Node> valueElements = XMLModelParser.getObjectsFromXPath(model, mapping.getModel().getValue());
+		for (Node node : valueElements) {
+			values.add(node.getText());
+		}
+		return values;
+	}
+
+	private static boolean isValidModel(Node node, ModelInstanceMapper mapping) {
+		Filter filter = mapping.getModel().getFilter();
+		if (filter == null) {
+			return true;
+		}
+
+		List<String> valid = filter.getValid();
+		// If there are no valid values, return false.
+		if (valid.isEmpty()) {
+			return false;
+		}
+
+		String filterXPath = filter.getPath();
+		if (filterXPath == null) {
+			return false;
+		}
+
+		List<Node> filterNodes = XMLModelParser.getObjectsFromXPath(node, filterXPath);
+		for (Node filterNode : filterNodes) {
+			String text = filterNode.getText();
+			if (valid.contains(text)) {
+				return true;
+			}
+		}
+
+		return false;
+	}
+
+	private static boolean hasChildren(Node parent, String rootXPath) {
+		return !XMLModelParser.getObjectsFromXPath(parent, rootXPath).isEmpty();
+	}
+}
\ No newline at end of file
diff --git a/src/main/java/org/onap/aai/validation/modeldriven/validator/ViolationInfo.java b/src/main/java/org/onap/aai/validation/modeldriven/validator/ViolationInfo.java
new file mode 100644
index 0000000..e452d73
--- /dev/null
+++ b/src/main/java/org/onap/aai/validation/modeldriven/validator/ViolationInfo.java
@@ -0,0 +1,88 @@
+/*
+ * ============LICENSE_START===================================================
+ * Copyright (c) 2018 Amdocs
+ * ============================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=====================================================
+ */
+package org.onap.aai.validation.modeldriven.validator;
+
+import java.text.MessageFormat;
+import org.onap.aai.validation.controller.ValidationController;
+
+/**
+ * Defines and formats the violation information.
+ */
+public enum ViolationInfo {
+	//@formatter:off
+	NO_MODEL           ("NO_MODEL",        ValidationController.VALIDATION_ERROR_SEVERITY, "No model ID=[{0}]",                              "The model [{0}] could not be found"),
+	MISSING_ATTR       ("MISSING_ATTR",    ValidationController.VALIDATION_ERROR_SEVERITY, "{0} {1}=[{2}]",                                  "Attribute [{0}] is missing in the object instance"),
+	UNEXPECTED_ATTR    ("UNEXPECTED_ATTR", ValidationController.VALIDATION_ERROR_SEVERITY, "{0} {1}=[{2}]",                                  "Attribute [{0}] should not be present in the object instance"),
+	MISSING_REL        ("MISSING_REL",     ValidationController.VALIDATION_ERROR_SEVERITY, "entityId=[{0}] entityType=[{1}], {2} {3}=[{4}]", "Entity {0} of type [{1}] must be related to [{2}]"),
+	UNEXPECTED_REL     ("UNEXPECTED_REL",  ValidationController.VALIDATION_ERROR_SEVERITY, "entityId=[{0}] entityType=[{1}], {2} {3}=[{4}]", "Entity {0} of type [{1}] must not be related to [{2}]");
+	//@formatter:on
+
+	private String category;
+	private String severity;
+	private String violationDetails;
+	private String errorMessage;
+
+	/**
+	 * @param category
+	 * @param severity
+	 * @param violationDetails
+	 * @param errorMessage
+	 */
+	private ViolationInfo(String category, String severity, String violationDetails, String errorMessage) {
+		this.category = category;
+		this.severity = severity;
+		this.violationDetails = violationDetails;
+		this.errorMessage = errorMessage;
+	}
+
+	/**
+	 * @return
+	 */
+	public String getCategory() {
+		return this.category;
+	}
+
+	/**
+	 * @return
+	 */
+	public String getSeverity() {
+		return this.severity;
+	}
+
+	/**
+	 * @param args
+	 * @return
+	 */
+	public String getViolationDetails(Object... args) {
+		return formatter(this.violationDetails, args);
+	}
+
+	/**
+	 * @param args
+	 * @return
+	 */
+	public String getErrorMessage(Object... args) {
+		return formatter(this.errorMessage, args);
+	}
+
+	private String formatter(String violationInfo, Object... args) {
+		MessageFormat formatter = new MessageFormat("");
+		formatter.applyPattern(violationInfo);
+		return formatter.format(args);
+	}
+}
\ No newline at end of file
diff --git a/src/main/java/org/onap/aai/validation/publisher/MessagePublisher.java b/src/main/java/org/onap/aai/validation/publisher/MessagePublisher.java
new file mode 100644
index 0000000..94e1f29
--- /dev/null
+++ b/src/main/java/org/onap/aai/validation/publisher/MessagePublisher.java
@@ -0,0 +1,47 @@
+/*
+ * ============LICENSE_START===================================================
+ * Copyright (c) 2018 Amdocs
+ * ============================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=====================================================
+ */
+package org.onap.aai.validation.publisher;
+
+import java.util.Collection;
+import org.onap.aai.validation.exception.ValidationServiceException;
+
+/**
+ * A Publisher of messages.
+ *
+ */
+public interface MessagePublisher {
+
+	/**
+	 * Sends a message somewhere.
+	 *
+	 * @param message
+	 *            The String message to send.
+	 * @throws ValidationServiceException
+	 */
+	void publishMessage(String message) throws ValidationServiceException;
+	
+	/**
+	 * Sends a Collection of messages somewhere.
+	 *
+	 * @param messages
+	 *            The String messages to send.
+	 * @throws ValidationServiceException
+	 */
+	void publishMessages(Collection<String> messages) throws ValidationServiceException;
+
+}
\ No newline at end of file
diff --git a/src/main/java/org/onap/aai/validation/publisher/ValidationEventPublisher.java b/src/main/java/org/onap/aai/validation/publisher/ValidationEventPublisher.java
new file mode 100644
index 0000000..0cebbf9
--- /dev/null
+++ b/src/main/java/org/onap/aai/validation/publisher/ValidationEventPublisher.java
@@ -0,0 +1,164 @@
+/*
+ * ============LICENSE_START===================================================
+ * Copyright (c) 2018 Amdocs
+ * ============================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=====================================================
+ */
+package org.onap.aai.validation.publisher;
+
+import org.onap.aai.event.client.DMaaPEventPublisher;
+import org.onap.aai.validation.config.TopicAdminConfig;
+import org.onap.aai.validation.config.TopicConfig;
+import org.onap.aai.validation.config.TopicConfig.Topic;
+import org.onap.aai.validation.exception.ValidationServiceError;
+import org.onap.aai.validation.exception.ValidationServiceException;
+import org.onap.aai.validation.factory.DMaaPEventPublisherFactory;
+import org.onap.aai.validation.logging.ApplicationMsgs;
+import org.onap.aai.validation.logging.LogHelper;
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.List;
+import javax.inject.Inject;
+
+/**
+ * Event Publisher
+ *
+ */
+public class ValidationEventPublisher implements MessagePublisher {
+
+    private static LogHelper applicationLogger = LogHelper.INSTANCE;
+
+	private List<Topic> publisherTopics;
+
+	private boolean enablePublishing;
+
+	private long retries;
+
+	private long retriesRemaining;
+
+    private DMaaPEventPublisherFactory dMaapFactory;
+
+
+	/**
+	 * Instantiates an Event Publisher instance using properties from config file.
+	 *
+	 * @param topicConfig
+	 * @param topicAdminConfig
+	 */
+	@Inject
+    public ValidationEventPublisher(TopicConfig topicConfig, TopicAdminConfig topicAdminConfig) {
+		enablePublishing = topicAdminConfig.isPublishEnable();
+		if (enablePublishing) {
+			publisherTopics = topicConfig.getPublisherTopics();
+			retries = topicAdminConfig.getPublishRetries();
+		}
+        dMaapFactory = new DMaaPEventPublisherFactory();
+	}
+
+	/**
+	 * Connect to the event publisher, add the message, and then publish it by closing the publisher.
+	 */
+	@Override
+	public void publishMessage(String message) throws ValidationServiceException {
+		Collection<String> messages = new ArrayList<>();
+		messages.add(message);
+		publishMessages(messages);
+	}
+
+	/**
+	 * Connect to the event publisher, adds the messages, and then publish them by closing the publisher.
+	 */
+	@Override
+	public void publishMessages(Collection<String> messages) throws ValidationServiceException {
+		if (!enablePublishing) {
+			return;
+		} else {
+            applicationLogger.debug("Publishing messages: " + messages);
+			for (Topic topic : publisherTopics) {
+				retriesRemaining = retries;
+				publishMessages(messages, topic);
+			}
+		}
+	}
+
+	private void publishMessages(Collection<String> messages, Topic topic) throws ValidationServiceException {
+
+	    DMaaPEventPublisher dMaapEventPublisher = dMaapFactory.createEventPublisher(topic.getHost(), topic.getName(), topic.getUsername(),
+                topic.getPassword(), topic.getTransportType());
+
+		try {
+			// Add our message to the publisher's queue/bus
+            int result = dMaapEventPublisher.sendSync(topic.getPartition(), messages);
+			if (result != messages.size()) {
+				applicationLogger.warn(ApplicationMsgs.UNSENT_MESSAGE_WARN);
+                closeEventPublisher(dMaapEventPublisher);
+                retryOrThrow(messages, topic, new ValidationServiceException(
+                        ValidationServiceError.EVENT_CLIENT_INCORRECT_NUMBER_OF_MESSAGES_SENT, result));
+			}
+        } catch (Exception e) {
+			applicationLogger.error(ApplicationMsgs.UNSENT_MESSAGE_ERROR);
+            closeEventPublisher(dMaapEventPublisher);
+            retryOrThrow(messages, topic,
+                    new ValidationServiceException(ValidationServiceError.EVENT_CLIENT_SEND_ERROR, e));
+		}
+
+        completeMessageSending(dMaapEventPublisher, topic);
+	}
+
+	/**
+	 * Publish the queued messages by closing the publisher.
+	 *
+     * @param eventPublisher the publisher to close
+	 * @throws AuditException
+	 */
+    private void completeMessageSending(DMaaPEventPublisher eventPublisher, Topic topic)
+            throws ValidationServiceException {
+        List<String> unsentMsgs = closeEventPublisher(eventPublisher);
+
+		if (unsentMsgs != null && !unsentMsgs.isEmpty()) {
+			// Log the error, as the exception will not be propagated due to the fact that the Cambria Client throws
+			// an exception first in a separate thread.
+			applicationLogger.error(ApplicationMsgs.EVENT_CLIENT_CLOSE_UNSENT_MESSAGE,
+                    ValidationServiceError.EVENT_CLIENT_CLOSE_UNSENT_MESSAGE.getMessage(unsentMsgs));
+
+            retryOrThrow(unsentMsgs, topic, new ValidationServiceException(
+                    ValidationServiceError.EVENT_CLIENT_CLOSE_UNSENT_MESSAGE, unsentMsgs));
+		}
+	}
+
+    private void retryOrThrow(Collection<String> messages, Topic topic, ValidationServiceException exceptionToThrow)
+            throws ValidationServiceException {
+		if (retriesRemaining <= 0) {
+			applicationLogger.warn(ApplicationMsgs.SEND_MESSAGE_ABORT_WARN);
+			throw exceptionToThrow;
+		} else {
+			applicationLogger.warn(ApplicationMsgs.SEND_MESSAGE_RETRY_WARN);
+			retriesRemaining--;
+			publishMessages(messages, topic);
+		}
+	}
+
+    private List<String> closeEventPublisher(DMaaPEventPublisher eventPublisher) throws ValidationServiceException {
+		try {
+            return eventPublisher.closeWithUnsent();
+		} catch (Exception e) {
+			throw new ValidationServiceException(ValidationServiceError.EVENT_CLIENT_CLOSE_ERROR, e);
+		}
+	}
+
+    public void setEventPublisherFactory(DMaaPEventPublisherFactory dMaapFactory) {
+        this.dMaapFactory = dMaapFactory;
+    }
+
+}
\ No newline at end of file
diff --git a/src/main/java/org/onap/aai/validation/reader/EntityReader.java b/src/main/java/org/onap/aai/validation/reader/EntityReader.java
new file mode 100644
index 0000000..f55af2f
--- /dev/null
+++ b/src/main/java/org/onap/aai/validation/reader/EntityReader.java
@@ -0,0 +1,61 @@
+/*
+ * ============LICENSE_START===================================================
+ * Copyright (c) 2018 Amdocs
+ * ============================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=====================================================
+ */
+package org.onap.aai.validation.reader;
+
+import java.util.List;
+import java.util.Optional;
+import org.onap.aai.validation.exception.ValidationServiceException;
+import org.onap.aai.validation.reader.data.EntityId;
+
+/**
+ * Interface for extracting values from an entity (in JSON format).
+ *
+ */
+public interface EntityReader {
+
+	/**
+	 * Return the value found at the supplied path.
+	 *
+	 * @param json
+	 *            the JSON representation of the entity
+	 * @param path
+	 *            specifier of the path to the value within the JSON entity
+	 * @return either a primitive object (e.g. String, Integer) or a JSON element
+	 * @throws ValidationServiceException
+	 */
+	Object getObject(String json, String path) throws ValidationServiceException;
+
+	/**
+	 * @param json
+	 *            the JSON representation of the entity
+	 * @param type
+	 *            the type of the entity
+	 * @return the key value(s) identifying the entity
+	 * @throws ValidationServiceException
+	 */
+	List<EntityId> getIds(String json, String type) throws ValidationServiceException;
+
+	/**
+	 * @param json
+	 *            the JSON representation of the entity
+	 * @return the resource version of the entity (if present)
+	 * @throws ValidationServiceException
+	 */
+	Optional<String> getResourceVersion(String json) throws ValidationServiceException;
+
+}
diff --git a/src/main/java/org/onap/aai/validation/reader/EventEntityReader.java b/src/main/java/org/onap/aai/validation/reader/EventEntityReader.java
new file mode 100644
index 0000000..7f285f8
--- /dev/null
+++ b/src/main/java/org/onap/aai/validation/reader/EventEntityReader.java
@@ -0,0 +1,118 @@
+/*
+ * ============LICENSE_START===================================================
+ * Copyright (c) 2018 Amdocs
+ * ============================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=====================================================
+ */
+package org.onap.aai.validation.reader;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Optional;
+import org.onap.aai.validation.config.EventReaderConfig;
+import org.onap.aai.validation.exception.ValidationServiceError;
+import org.onap.aai.validation.exception.ValidationServiceException;
+import org.onap.aai.validation.reader.data.EntityId;
+
+/**
+ * An entity reader for reading A&AI events. This implementation is used by the EventReader
+ *
+ */
+public class EventEntityReader implements EntityReader {
+
+    private JsonReader jsonReader;
+    private OxmReader oxmReader;
+
+    private EventReaderConfig config;
+
+    /**
+     * @param eventReaderConfig
+     * @param jsonReader
+     * @param oxmReader
+     */
+    public EventEntityReader(final EventReaderConfig eventReaderConfig, final JsonReader jsonReader,
+            final OxmReader oxmReader) {
+        this.jsonReader = jsonReader;
+        this.oxmReader = oxmReader;
+        this.config = eventReaderConfig;
+    }
+
+    /**
+     * Parse the supplied json and return the content (values) specified by the supplied path
+     *
+     * @param json
+     * @param path
+     * @return either a String or an Array of objects
+     * @throws ValidationServiceException
+     */
+    @Override
+    public Object getObject(String json, String path) throws ValidationServiceException {
+        return jsonReader.getObject(jsonReader.parse(json), path);
+    }
+
+    public String getEntityResourceVersionPath() {
+        return config.getEntityResourceVersionPath();
+    }
+
+    @Override
+    public List<EntityId> getIds(String json, String type) throws ValidationServiceException {
+        List<EntityId> ids = new ArrayList<>();
+        for (String pk : oxmReader.getPrimaryKeys(type)) {
+            String pkPaths = config.getEntityIdPath(pk);
+            String pkValue = getPropertyForMultiplePaths(json, pkPaths).orElseThrow(
+                    () -> new ValidationServiceException(ValidationServiceError.EVENT_READER_MISSING_PROPERTY,
+                            pkPaths));
+            ids.add(new EntityId(pk, pkValue));
+        }
+        return ids;
+    }
+
+    /**
+     * Get an entity property from an entity in JSON format.
+     *
+     * @param json the entity
+     * @param path the JSON path to the property
+     * @return an optional property value
+     * @throws ValidationServiceException
+     */
+    public Optional<String> getProperty(String json, String path) throws ValidationServiceException {
+        return jsonReader.get(json, path).stream().findFirst();
+    }
+
+    @Override
+    public Optional<String> getResourceVersion(String json) throws ValidationServiceException {
+        return getPropertyForMultiplePaths(json, getEntityResourceVersionPath());
+    }
+
+    /**
+     * Takes a comma separated list of jsonpaths and applies each one in turn until a value is found.
+     * 
+     * @param json The json to search
+     * @param multiplePaths Comma separated list of jsonpath strings
+     * @return The value of the first jsonpath string that returns a value
+     * @throws ValidationServiceException
+     */
+    private Optional<String> getPropertyForMultiplePaths(String json, String multiplePaths)
+            throws ValidationServiceException {
+        Optional<String> propertyValue = Optional.empty();
+        for (String path : multiplePaths.split(",")) {
+            propertyValue = getProperty(json, path);
+            if (propertyValue.isPresent()) {
+                break;
+            }
+        }
+        return propertyValue;
+    }
+
+}
diff --git a/src/main/java/org/onap/aai/validation/reader/EventReader.java b/src/main/java/org/onap/aai/validation/reader/EventReader.java
new file mode 100644
index 0000000..614ccbf
--- /dev/null
+++ b/src/main/java/org/onap/aai/validation/reader/EventReader.java
@@ -0,0 +1,215 @@
+/*
+ * ============LICENSE_START===================================================
+ * Copyright (c) 2018 Amdocs
+ * ============================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=====================================================
+ */
+package org.onap.aai.validation.reader;
+
+import com.jayway.jsonpath.DocumentContext;
+import java.util.List;
+import java.util.Optional;
+import org.onap.aai.validation.config.EventReaderConfig;
+import org.onap.aai.validation.exception.ValidationServiceError;
+import org.onap.aai.validation.exception.ValidationServiceException;
+import org.onap.aai.validation.reader.data.Entity;
+import org.onap.aai.validation.util.StringUtils;
+
+/**
+ * Reads event objects.
+ *
+ */
+public class EventReader {
+
+    private EventReaderConfig eventReaderConfig;
+
+    private JsonReader jsonReader;
+
+    private EntityReader entityReader;
+
+    /**
+     *
+     * @param eventReaderConfig the event reader configuration including paths to event properties
+     * @param jsonReader a JSON reader
+     * @param oxmReader an OXM reader to retrieve the primary key names for the entity
+     */
+    public EventReader(final EventReaderConfig eventReaderConfig, final JsonReader jsonReader,
+            final OxmReader oxmReader) {
+        this.eventReaderConfig = eventReaderConfig;
+        this.jsonReader = jsonReader;
+        this.entityReader = new EventEntityReader(eventReaderConfig, jsonReader, oxmReader);
+    }
+
+    ///////////////////////////////////////////////////////////////////////////
+    // PUBLIC METHODS
+    ///////////////////////////////////////////////////////////////////////////
+
+    /**
+     * Get the domain of the event.
+     *
+     * @param event a JSON String with the event contents
+     * @return the domain of the event
+     * @throws ValidationServiceException
+     */
+    public Optional<String> getEventDomain(String event) throws ValidationServiceException {
+        List<String> readerResult = jsonReader.get(event, eventReaderConfig.getEventDomainPath());
+        return getFirst(readerResult);
+    }
+
+    /**
+     * Get the action of the event.
+     *
+     * @param event a JSON String with the event contents
+     * @return the action of the event
+     * @throws ValidationServiceException
+     */
+    public Optional<String> getEventAction(String event) throws ValidationServiceException {
+        List<String> readerResult = jsonReader.get(event, eventReaderConfig.getEventActionPath());
+        return getFirst(readerResult);
+    }
+
+    /**
+     * Get the type of the event.
+     *
+     * @param event a JSON String with the event contents
+     * @return the type of the event
+     * @throws ValidationServiceException
+     */
+    public Optional<String> getEventType(String event) throws ValidationServiceException {
+        List<String> readerResult = jsonReader.get(event, eventReaderConfig.getEventTypePath());
+        return getFirst(readerResult);
+    }
+
+    /**
+     * Get the entity type of the entity in the event.
+     *
+     * @param event a JSON String with the event contents
+     * @return the type of the entity
+     * @throws ValidationServiceException
+     */
+    public Optional<String> getEntityType(String event) throws ValidationServiceException {
+        List<String> readerResult = jsonReader.get(event, eventReaderConfig.getEntityTypePath());
+        return getFirst(readerResult);
+    }
+
+    /**
+     * Get the entity contained in the event.
+     *
+     * @param event a JSON String with the event contents
+     * @return the entity
+     */
+    public Entity getEntity(String event) throws ValidationServiceException {
+        DocumentContext document = jsonReader.parse(event);
+
+        String entityType = getValue(document, eventReaderConfig.getEntityTypePath())
+                .orElseThrow(() -> new ValidationServiceException(ValidationServiceError.EVENT_READER_MISSING_PROPERTY,
+                        eventReaderConfig.getEntityTypePath()));
+        String topEntityType = getValue(document, eventReaderConfig.getTopEntityTypePath()).orElse(entityType);
+        String entityLink = getEntityLink(document);
+        String json = findEntity(event, topEntityType, entityType);
+
+        return new Entity(json, entityType, entityLink, entityReader);
+    }
+
+    /**
+     * Get the value of the JSON property defined by the path.
+     *
+     * @param json a JSON string
+     * @param path the path to a property
+     * @return the value
+     * @throws ValidationServiceException if the value is not present
+     */
+    public String getValue(final String json, final String path) throws ValidationServiceException {
+        return getFirst(jsonReader.get(json, path)).orElseThrow(
+                () -> new ValidationServiceException(ValidationServiceError.EVENT_READER_MISSING_PROPERTY, path));
+    }
+
+    ///////////////////////////////////////////////////////////////////////////
+    // PRIVATE METHODS
+    ///////////////////////////////////////////////////////////////////////////
+
+    private String findEntity(String event, String topEntityType, String entityType) throws ValidationServiceException {
+        String json;
+        if (entityType.equals(topEntityType)) {
+            json = getValue(event, eventReaderConfig.getEntityPath());
+        } else {
+            json = findNestedEntity(event, eventReaderConfig.getNestedEntityPath(entityType));
+        }
+        return json;
+    }
+
+    /**
+     * @param event
+     * @param path
+     * @return
+     * @throws ValidationServiceException
+     */
+    private String findNestedEntity(String event, String path) throws ValidationServiceException {
+        List<String> entities = jsonReader.get(event, path);
+        if (entities.isEmpty()) {
+            throw new ValidationServiceException(ValidationServiceError.EVENT_READER_MISSING_PROPERTY, path);
+        } else if (entities.size() > 1) {
+            throw new ValidationServiceException(ValidationServiceError.EVENT_READER_TOO_MANY_ENTITIES);
+        }
+        return entities.get(0);
+    }
+
+    private Optional<String> getFirst(List<String> l) {
+        return l.stream().findFirst();
+    }
+
+    private Optional<String> getValue(final DocumentContext document, final String path) {
+        return getFirst(jsonReader.getAsList(document, path));
+    }
+
+    /**
+     * Gets the entity link from the event but altered by stripping a prefix identified by a delimiter configured in the
+     * event reader properties configuration.
+     *
+     * @param document the parsed JSON event
+     * @return the entity link
+     * @throws ValidationServiceException
+     */
+    private String getEntityLink(DocumentContext document) throws ValidationServiceException {
+        String entityLink = getValue(document, eventReaderConfig.getEntityLinkPath()).orElse("");
+        String strippedEntityLink = null;
+        try {
+            strippedEntityLink = StringUtils.stripPrefixRegex(entityLink, eventReaderConfig.getEntityLinkDelimiter());
+        } catch (ValidationServiceException e) {
+            throw new ValidationServiceException(ValidationServiceError.EVENT_READER_PROPERTY_READ_ERROR, e);
+        }
+        return strippedEntityLink;
+    }
+
+    ///////////////////////////////////////////////////////////////////////////
+    // GETTERS AND SETTERS
+    ///////////////////////////////////////////////////////////////////////////
+
+    /**
+     *
+     * @return event configuration
+     */
+    public EventReaderConfig getEventReaderConfig() {
+        return eventReaderConfig;
+    }
+
+    /**
+     *
+     * @param eventReaderConfig event configuration
+     */
+    public void setEventReaderConfig(EventReaderConfig eventReaderConfig) {
+        this.eventReaderConfig = eventReaderConfig;
+    }
+
+}
diff --git a/src/main/java/org/onap/aai/validation/reader/InstanceEntityReader.java b/src/main/java/org/onap/aai/validation/reader/InstanceEntityReader.java
new file mode 100644
index 0000000..0b9fbed
--- /dev/null
+++ b/src/main/java/org/onap/aai/validation/reader/InstanceEntityReader.java
@@ -0,0 +1,75 @@
+/*
+ * ============LICENSE_START===================================================
+ * Copyright (c) 2018 Amdocs
+ * ============================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=====================================================
+ */
+package org.onap.aai.validation.reader;
+
+import com.google.gson.JsonElement;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Optional;
+import org.onap.aai.validation.exception.ValidationServiceError;
+import org.onap.aai.validation.exception.ValidationServiceException;
+import org.onap.aai.validation.modeldriven.validator.InstanceReader;
+import org.onap.aai.validation.modeldriven.validator.InstanceReader.InstanceEntity;
+import org.onap.aai.validation.reader.data.EntityId;
+
+/**
+ * Entity reader implemented using the model-driven instance reader.
+ *
+ */
+public class InstanceEntityReader implements EntityReader {
+
+	private InstanceReader reader;
+
+	/**
+	 * @param instanceReader
+	 */
+	public InstanceEntityReader(InstanceReader instanceReader) {
+		this.reader = instanceReader;
+	}
+
+	@Override
+	public Object getObject(String json, String attribute) throws ValidationServiceException {
+		throw new ValidationServiceException(ValidationServiceError.INSTANCE_READER_NO_INSTANCE, "Not implemented");
+	}
+
+	@Override
+	public List<EntityId> getIds(String json, String type) throws ValidationServiceException {
+		List<EntityId> ids = new ArrayList<>();
+
+		InstanceEntity entity = reader.getNamedQueryEntity(json);
+
+		List<String> primaryKeys = reader.getOxmReader().getPrimaryKeys(entity.getEntityType());
+
+		if (primaryKeys != null && !primaryKeys.isEmpty()) {
+			for (String pk : primaryKeys) {
+				JsonElement jsonValue = entity.getObject().getAsJsonObject().get(pk);
+				if (jsonValue != null) {
+					ids.add(new EntityId(pk, jsonValue.getAsString()));
+				}
+			}
+		}
+
+		return ids;
+	}
+
+	@Override
+	public Optional<String> getResourceVersion(String json) throws ValidationServiceException {
+		return Optional.of(reader.getResourceVersion(json));
+	}
+
+}
\ No newline at end of file
diff --git a/src/main/java/org/onap/aai/validation/reader/JsonReader.java b/src/main/java/org/onap/aai/validation/reader/JsonReader.java
new file mode 100644
index 0000000..9d349ac
--- /dev/null
+++ b/src/main/java/org/onap/aai/validation/reader/JsonReader.java
@@ -0,0 +1,186 @@
+/*
+ * ============LICENSE_START===================================================
+ * Copyright (c) 2018 Amdocs
+ * ============================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=====================================================
+ */
+package org.onap.aai.validation.reader;
+
+import com.google.gson.JsonArray;
+import com.google.gson.JsonElement;
+import com.jayway.jsonpath.Configuration;
+import com.jayway.jsonpath.DocumentContext;
+import com.jayway.jsonpath.JsonPath;
+import com.jayway.jsonpath.Option;
+import com.jayway.jsonpath.ReadContext;
+import com.jayway.jsonpath.spi.json.GsonJsonProvider;
+import com.jayway.jsonpath.spi.json.JsonProvider;
+import com.jayway.jsonpath.spi.mapper.GsonMappingProvider;
+import com.jayway.jsonpath.spi.mapper.MappingProvider;
+import java.util.ArrayList;
+import java.util.EnumSet;
+import java.util.List;
+import java.util.Set;
+import org.onap.aai.validation.exception.ValidationServiceError;
+import org.onap.aai.validation.exception.ValidationServiceException;
+
+/**
+ * Reads JSON objects. Supported by the JayWay JsonPath library.
+ */
+public class JsonReader {
+
+	private Configuration jsonPathConfig;
+
+	/**
+	 * Initialise the JSON reader.
+	 */
+	public JsonReader() {
+		setJsonProvider();
+		this.jsonPathConfig = Configuration.builder().options(Option.SUPPRESS_EXCEPTIONS).build();
+	}
+
+	/**
+	 * Parse the JSON.
+	 *
+	 * @param json
+	 *            the JSON object
+	 * @return a {@link ReadContext} the parsed JSON.
+	 * @throws ValidationServiceException
+	 */
+	public DocumentContext parse(String json) throws ValidationServiceException {
+		DocumentContext document = null;
+		try {
+			document = JsonPath.using(jsonPathConfig).parse(json);
+		} catch (Exception e) {
+			throw new ValidationServiceException(ValidationServiceError.JSON_READER_PARSE_ERROR, e);
+		}
+		return document;
+	}
+
+	/**
+	 * Gets values from JSON objects.
+	 *
+	 * @param json
+	 *            the JSON object
+	 * @param path
+	 *            the path to property values. The format must comply with the JayWay JsonPath definition.
+	 * @return a List of values found by evaluating the path.
+	 * @throws ValidationServiceException
+	 */
+	public List<String> get(String json, String path) throws ValidationServiceException {
+		return getAsList(parse(json), path);
+	}
+
+	/**
+	 * Gets values from JSON objects. Used in combination with {@link JsonReader#parse(String)} it reduces the number of
+	 * times the JSON document is parsed.
+	 *
+	 * @param document
+	 *            a {@link DocumentContext} object with the parsed JSON
+	 * @param path
+	 *            the path to property values. The format must comply with the JayWay JsonPath definition.
+	 * @return a List of values found by evaluating the path, or an empty list if no values were found
+	 */
+	public List<String> getAsList(DocumentContext document, String path) {
+		List<String> result = new ArrayList<>();
+		JsonElement jsonElement = document.read(path);
+		if (jsonElement != null) {
+			if (jsonElement.isJsonPrimitive()) {
+				result.add(jsonElement.getAsString());
+			} else if (jsonElement.isJsonObject()) {
+				result.add(jsonElement.getAsJsonObject().toString());
+			} else if (jsonElement.isJsonArray()) {
+				for (JsonElement obj : jsonElement.getAsJsonArray()) {
+					Object object = jsonElementToObject(obj);
+					result.add(object == null ? null : object.toString());
+				}
+			}
+		}
+		return result;
+	}
+
+	/**
+	 * Get the value(s) from the specified JSON document
+	 *
+	 * @param document
+	 *            a {@link DocumentContext} object with the parsed JSON
+	 * @param path
+	 *            the path to property value(s). The format must comply with the JayWay JsonPath definition.
+	 * @return either all the values found by evaluating the path (e.g. as an array), or a String object (only) where
+	 *         the path evaluates to a single primitive value
+	 */
+	public Object getObject(DocumentContext document, String path) {
+		return jsonElementToObject(document.read(path));
+	}
+
+	/**
+	 * Convert the JSON element to a String or Array where possible, otherwise return the JSON object.
+	 *
+	 * @param jsonElement
+	 * @return the jsonElement converted to a Java Object
+	 */
+	private Object jsonElementToObject(JsonElement jsonElement) {
+		if (jsonElement == null) {
+			return null;
+		} else if (jsonElement.isJsonPrimitive()) {
+			return jsonElement.getAsString();
+		} else if (jsonElement.isJsonObject()) {
+			return jsonElement.getAsJsonObject();
+		} else if (jsonElement.isJsonArray()) {
+			// Convert to a List for simplified handling within rules
+			return jsonArrayToList(jsonElement.getAsJsonArray());
+		} else {
+			return jsonElement;
+		}
+	}
+
+	private List<Object> jsonArrayToList(JsonArray jsonArray) {
+		List<Object> result = new ArrayList<>();
+		for (JsonElement obj : jsonArray) {
+			result.add(jsonElementToObject(obj));
+		}
+		return result;
+	}
+
+	/**
+	 * @param document
+	 * @param path
+	 * @return a JsonElement from the document
+	 */
+	public JsonElement getJsonElement(DocumentContext document, String path) {
+		return document.read(path);
+	}
+
+	private void setJsonProvider() {
+		Configuration.setDefaults(new Configuration.Defaults() {
+			private final JsonProvider jsonProvider = new GsonJsonProvider();
+			private final MappingProvider mappingProvider = new GsonMappingProvider();
+
+			@Override
+			public JsonProvider jsonProvider() {
+				return jsonProvider;
+			}
+
+			@Override
+			public MappingProvider mappingProvider() {
+				return mappingProvider;
+			}
+
+			@Override
+			public Set<Option> options() {
+				return EnumSet.noneOf(Option.class);
+			}
+		});
+	}
+}
diff --git a/src/main/java/org/onap/aai/validation/reader/OxmConfigTranslator.java b/src/main/java/org/onap/aai/validation/reader/OxmConfigTranslator.java
new file mode 100644
index 0000000..53be6dd
--- /dev/null
+++ b/src/main/java/org/onap/aai/validation/reader/OxmConfigTranslator.java
@@ -0,0 +1,100 @@
+/*
+ * ============LICENSE_START===================================================
+ * Copyright (c) 2018 Amdocs
+ * ============================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=====================================================
+ */
+package org.onap.aai.validation.reader;
+
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.PathMatcher;
+import java.nio.file.Paths;
+import java.util.List;
+import java.util.Map;
+import java.util.ServiceConfigurationError;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+import org.onap.aai.setup.ConfigTranslator;
+import org.onap.aai.setup.SchemaLocationsBean;
+import org.onap.aai.setup.Version;
+
+/**
+ * Determine which OXM and edge rules files to return based on the latest Version
+ *
+ */
+public class OxmConfigTranslator extends ConfigTranslator {
+
+    public OxmConfigTranslator(SchemaLocationsBean bean) {
+        super(bean);
+    }
+
+    @Override
+    public Map<Version, List<String>> getNodeFiles() {
+        String nodeDirectory = bean.getNodeDirectory();
+        if (nodeDirectory == null) {
+            throw new ServiceConfigurationError(
+                    "Node(s) directory is empty in the schema location bean (" + bean.getSchemaConfigLocation() + ")");
+        }
+        try {
+            return getVersionMap(Paths.get(nodeDirectory), "*_v*.xml");
+        } catch (IOException e) {
+            throw new ServiceConfigurationError("Failed to read node(s) directory " + getPath(nodeDirectory), e);
+        }
+    } 
+
+    @Override
+    public Map<Version, List<String>> getEdgeFiles() {
+        String edgeDirectory = bean.getEdgeDirectory();
+        if (edgeDirectory == null) {
+            throw new ServiceConfigurationError(
+                    "Edge(s) directory is empty in the schema location bean (" + bean.getSchemaConfigLocation() + ")");
+        }
+        try {
+            return getVersionMap(Paths.get(edgeDirectory), "*_v*.json");
+        } catch (IOException e) {
+            throw new ServiceConfigurationError("Failed to read edge(s) directory " + getPath(edgeDirectory), e);
+        }
+    }
+
+    private String getPath(String nodeDirectory) {
+        return Paths.get(nodeDirectory).toAbsolutePath().toString();
+    }
+
+    /**
+     * Creates a map containing each OXM Version and the matching OXM file path(s)
+     *
+     * @param folderPath the folder/directory containing the OXM files
+     * @param fileSuffix
+     * @return a new Map object (may be empty)
+     * @throws IOException if there is a problem reading the specified directory path
+     */
+    private Map<Version, List<String>> getVersionMap(Path folderPath, String globPattern) throws IOException {
+        final PathMatcher filter = folderPath.getFileSystem().getPathMatcher("glob:**/" + globPattern);
+        try (final Stream<Path> stream = Files.list(folderPath)) {
+            return stream.filter(filter::matches).map(Path::toString).filter(p -> getVersionFromPath(p) != null)
+                    .collect(Collectors.groupingBy(this::getVersionFromPath));
+        }
+    }
+
+    private Version getVersionFromPath(String pathName) {
+        String version = "V" + pathName.replaceAll("\\D+", "");
+        try {
+            return Version.valueOf(version);
+        } catch (IllegalArgumentException e) {
+            return null;
+        }
+    }
+}
diff --git a/src/main/java/org/onap/aai/validation/reader/OxmReader.java b/src/main/java/org/onap/aai/validation/reader/OxmReader.java
new file mode 100644
index 0000000..b8343f1
--- /dev/null
+++ b/src/main/java/org/onap/aai/validation/reader/OxmReader.java
@@ -0,0 +1,99 @@
+/*
+ * ============LICENSE_START===================================================
+ * Copyright (c) 2018 Amdocs
+ * ============================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=====================================================
+ */
+package org.onap.aai.validation.reader;
+
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.ServiceConfigurationError;
+import org.eclipse.persistence.internal.oxm.mappings.Descriptor;
+import org.eclipse.persistence.jaxb.dynamic.DynamicJAXBContext;
+import org.onap.aai.nodes.NodeIngestor;
+import org.onap.aai.setup.Version;
+import org.onap.aai.validation.exception.ValidationServiceError;
+import org.onap.aai.validation.exception.ValidationServiceException;
+import org.onap.aai.validation.util.StringUtils;
+
+/**
+ * Reads the primary keys of a specific OXM resource (identified by version).
+ */
+public class OxmReader {
+
+    private NodeIngestor nodeIngestor;
+    private Version version;
+    private Map<String, List<String>> primaryKeysMap = new HashMap<>();
+
+    public OxmReader(NodeIngestor nodeIngestor, Version version) {
+        this.nodeIngestor = nodeIngestor;
+        this.version = version;
+    }
+
+    public OxmReader(NodeIngestor nodeIngestor) {
+        this(nodeIngestor, Version.getLatest());
+    }
+
+    /**
+     * Get the primary keys for a given entity type.
+     *
+     * @param entityType the name of the entity type
+     * @return the primary keys for the entity type
+     * @throws ValidationServiceException
+     */
+    public List<String> getPrimaryKeys(String entityType) throws ValidationServiceException {
+        if (primaryKeysMap.isEmpty()) {
+            throw new ValidationServiceException(ValidationServiceError.OXM_MISSING_KEY, entityType);
+        }
+
+        List<String> primaryKeys = primaryKeysMap.get(entityType);
+        return primaryKeys != null ? primaryKeys : Collections.emptyList();
+    }
+
+    /**
+     * Populate a Map of primary keys for the entity types defined in the OXM.<br>
+     * The primary keys are keyed by the Default Root Element.
+     */
+    public void init() {
+        for (Descriptor<?, ?, ?, ?, ?, ?, ?, ?, ?, ?> descriptor : getObjectDescriptors()) {
+            if (!descriptor.getPrimaryKeyFieldNames().isEmpty()) {
+                primaryKeysMap.put(descriptor.getDefaultRootElement(),
+                        StringUtils.stripSuffix(descriptor.getPrimaryKeyFieldNames(), "/text()"));
+            }
+        }
+    }
+
+    /**
+     * Gets a list of descriptors from the OXM. These descriptor objects contain property information about each entity
+     * type.
+     *
+     * @return list of descriptors
+     */
+    @SuppressWarnings("rawtypes")
+    private List<Descriptor> getObjectDescriptors() {
+        DynamicJAXBContext dynamicJaxbContext = nodeIngestor.getContextForVersion(version);
+        if (dynamicJaxbContext == null) {
+            throw new ServiceConfigurationError("OXM Version " + version + " was not ingested.");
+        }
+        return dynamicJaxbContext.getXMLContext().getDescriptors();
+    }
+
+    public Map<String, List<String>> getPrimaryKeysMap() {
+        return primaryKeysMap;
+    }
+
+}
diff --git a/src/main/java/org/onap/aai/validation/reader/data/AttributeValues.java b/src/main/java/org/onap/aai/validation/reader/data/AttributeValues.java
new file mode 100644
index 0000000..78665ef
--- /dev/null
+++ b/src/main/java/org/onap/aai/validation/reader/data/AttributeValues.java
@@ -0,0 +1,139 @@
+/*
+ * ============LICENSE_START===================================================
+ * Copyright (c) 2018 Amdocs
+ * ============================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=====================================================
+ */
+package org.onap.aai.validation.reader.data;
+
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+/**
+ * Stores a collection of attribute values (retrievable by name).
+ */
+public class AttributeValues {
+
+	private Map<String, Object> map;
+
+	/**
+	 * Instantiates a new empty set of attribute values.
+	 */
+	public AttributeValues() {
+		this.map = new HashMap<>();
+	}
+
+	/**
+	 * Instantiates a new set of attribute values using the provided properties map.
+	 *
+	 * @param map
+	 *            the attribute name/value pairs
+	 */
+	public AttributeValues(Map<String, Object> map) {
+		this.map = map;
+	}
+
+	/**
+	 * Instantiates a new set of attribute values comprising one name/value pair.
+	 *
+	 * @param key
+	 *            the attribute name
+	 * @param value
+	 *            the attribute value
+	 */
+	public AttributeValues(String key, String value) {
+		this();
+		this.map.put(key, value);
+	}
+
+	@Override
+	public String toString() {
+		return map.toString();
+	}
+
+	/**
+	 *
+	 * @return the number of attributes stored
+	 */
+	public int size() {
+		return this.map.size();
+	}
+
+	/**
+	 * Add an attribute name/value pair.
+	 *
+	 * @param key
+	 *            the attribute name
+	 * @param value
+	 *            the attribute value
+	 */
+	public void put(String key, Object value) {
+		this.map.put(key, value);
+	}
+
+	/**
+	 * Add an attribute name with a collection of values.
+	 *
+	 * @param key
+	 *            the attribute name
+	 * @param valueList
+	 *            the collection of attribute values
+	 */
+	public void put(String key, List<String> valueList) {
+		this.map.put(key, valueList);
+	}
+
+	/**
+	 * Removes the attribute
+	 *
+	 * @param key
+	 *            the attribute name
+	 */
+	public void remove(String key) {
+		this.map.remove(key);
+
+	}
+
+	/**
+	 * Overwrites the attribute values, replacing them with the specified attribute to attribute values mappings
+	 *
+	 * @param map
+	 *            the name/values to store
+	 */
+	public void setMap(Map<String, Object> map) {
+		this.map = map;
+	}
+
+	/**
+	 * Gets an attribute value
+	 *
+	 * @param attrName
+	 *            the attribute name
+	 * @return the object
+	 */
+	public Object get(String attrName) {
+		return this.map.get(attrName);
+	}
+
+	/**
+	 * Converts the attribute values into a report-friendly format
+	 *
+	 * @return a Map which is a copy of the AttributeValues, formatted for reporting
+	 */
+	public Map<String, Object> generateReport() {
+		return map;
+	}
+
+}
diff --git a/src/main/java/org/onap/aai/validation/reader/data/Entity.java b/src/main/java/org/onap/aai/validation/reader/data/Entity.java
new file mode 100644
index 0000000..415298f
--- /dev/null
+++ b/src/main/java/org/onap/aai/validation/reader/data/Entity.java
@@ -0,0 +1,135 @@
+/*
+ * ============LICENSE_START===================================================
+ * Copyright (c) 2018 Amdocs
+ * ============================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=====================================================
+ */
+package org.onap.aai.validation.reader.data;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Optional;
+import org.onap.aai.validation.exception.ValidationServiceException;
+import org.onap.aai.validation.reader.EntityReader;
+
+/**
+ * An A&AI entity.
+ */
+public class Entity {
+
+	private String json;
+	private String type;
+	private EntityReader reader;
+	private List<EntityId> ids = new ArrayList<>();
+	private Optional<String> resourceVersion = Optional.empty();
+	private String entityLink;
+
+	/**
+	 *
+	 * @param json
+	 *            the full entity JSON supplied in the event
+	 * @param entityType
+	 *            the entity type
+	 * @param entityLink
+	 * @param entityReader
+	 *            an {@link EntityReader}
+	 */
+	public Entity(final String json, final String entityType, final String entityLink, final EntityReader entityReader) {
+		this.json = json;
+		this.type = entityType;
+		this.entityLink = entityLink;
+		this.reader = entityReader;
+	}
+
+	/**
+	 * Get the full entity JSON.
+	 *
+	 * @return the entity JSON
+	 */
+	public String getJson() {
+		return json;
+	}
+
+	/**
+	 * Get the entity type.
+	 *
+	 * @return the entity type
+	 */
+	public String getType() {
+		return type;
+	}
+
+	/**
+	 * Get the entity identifiers. More than one identifier may be provided for composite keys.
+	 *
+	 * @return a list of entity identifiers
+	 * @throws ValidationServiceException
+	 */
+	public List<EntityId> getIds() throws ValidationServiceException {
+		if (ids.isEmpty()) {
+			ids = reader.getIds(getJson(), getType());
+		}
+		return ids;
+	}
+
+	/**
+	 * Get the resource version.
+	 *
+	 * @return the resource version
+	 * @throws ValidationServiceException
+	 */
+	public Optional<String> getResourceVersion() throws ValidationServiceException {
+		if (!resourceVersion.isPresent()) {
+			resourceVersion = reader.getResourceVersion(getJson());
+		}
+		return resourceVersion;
+	}
+
+	/**
+	 * Get the event entity link.
+	 *
+	 * @return the event entity link
+	 */
+	public String getEntityLink() {
+		return entityLink;
+	}
+
+	/**
+	 * Get collection of attributes
+	 *
+	 * @param attributes
+	 *            the names of the attributes
+	 * @return an {@link AttributeValues} object containing the attribute values
+	 * @throws ValidationServiceException
+	 */
+	public AttributeValues getAttributeValues(List<String> attributes) throws ValidationServiceException {
+		AttributeValues attributeValues = new AttributeValues();
+
+		if (attributes == null || attributes.isEmpty()) {
+			return attributeValues;
+		}
+
+		for (String attribute : attributes) {
+			attributeValues.put(attribute, reader.getObject(getJson(), attribute));
+		}
+
+		return attributeValues;
+	}
+
+	@Override
+	public String toString() {
+		return json;
+	}
+
+}
\ No newline at end of file
diff --git a/src/main/java/org/onap/aai/validation/reader/data/EntityId.java b/src/main/java/org/onap/aai/validation/reader/data/EntityId.java
new file mode 100644
index 0000000..83c1bf6
--- /dev/null
+++ b/src/main/java/org/onap/aai/validation/reader/data/EntityId.java
@@ -0,0 +1,91 @@
+/*
+ * ============LICENSE_START===================================================
+ * Copyright (c) 2018 Amdocs
+ * ============================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=====================================================
+ */
+package org.onap.aai.validation.reader.data;
+
+import java.util.Objects;
+import org.apache.commons.lang3.builder.EqualsBuilder;
+
+/**
+ * Describes an identifier for an entity.
+ */
+public class EntityId {
+
+	private String primaryKey;
+	private String value;
+
+	/**
+	 * Construct an entity Id
+	 */
+	public EntityId() {
+		// Deliberately empty
+	}
+
+	/**
+	 * Construct an entity Id (key-value pair)
+	 *
+	 * @param primaryKey
+	 * @param value
+	 */
+	public EntityId(String primaryKey, String value) {
+		this.primaryKey = primaryKey;
+		this.value = value;
+	}
+
+	public String getPrimaryKey() {
+		return primaryKey;
+	}
+
+	public void setPrimaryKey(String primaryKey) {
+		this.primaryKey = primaryKey;
+	}
+
+	public String getValue() {
+		return value;
+	}
+
+	public void setValue(String value) {
+		this.value = value;
+	}
+
+	@Override
+	public int hashCode() {
+		return Objects.hash(this.primaryKey, this.value);
+	}
+
+	@Override
+	public boolean equals(Object obj) {
+        if (!(obj instanceof EntityId)) {
+            return false;
+     } else if (obj == this) {
+            return true;
+     }
+        EntityId rhs = (EntityId) obj;
+     // @formatter:off
+     return new EqualsBuilder()
+                  .append(primaryKey, rhs.primaryKey)
+                  .append(value, rhs.value)
+                  .isEquals();
+     // @formatter:on
+	}
+
+	@Override
+	public String toString() {
+		return primaryKey + "=" + value;
+	}
+
+}
diff --git a/src/main/java/org/onap/aai/validation/result/ValidationResult.java b/src/main/java/org/onap/aai/validation/result/ValidationResult.java
new file mode 100644
index 0000000..b632a0f
--- /dev/null
+++ b/src/main/java/org/onap/aai/validation/result/ValidationResult.java
@@ -0,0 +1,244 @@
+/*
+ * ============LICENSE_START===================================================
+ * Copyright (c) 2018 Amdocs
+ * ============================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=====================================================
+ */
+package org.onap.aai.validation.result;
+
+import com.google.gson.JsonElement;
+import com.google.gson.JsonObject;
+import com.google.gson.JsonParser;
+import com.google.gson.annotations.Expose;
+import java.time.Instant;
+import java.time.ZoneOffset;
+import java.time.format.DateTimeFormatter;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Objects;
+import java.util.UUID;
+import org.apache.commons.lang3.builder.EqualsBuilder;
+import org.onap.aai.validation.exception.ValidationServiceException;
+import org.onap.aai.validation.reader.data.Entity;
+import org.onap.aai.validation.reader.data.EntityId;
+import org.onap.aai.validation.util.JsonUtil;
+
+/**
+ * The result of an instance validation. This can include zero or more {@link Violation} objects.
+ */
+public class ValidationResult {
+
+    @Expose
+    private String validationId;
+
+    @Expose
+    private String validationTimestamp;
+
+    @Expose
+    private JsonElement entityId;
+
+    @Expose
+    private String entityType;
+
+    @Expose
+    private String entityLink;
+
+    @Expose
+    private String resourceVersion;
+    
+    @Expose
+    private JsonElement entity;
+
+
+	@Expose
+    private List<Violation> violations = new ArrayList<>();
+
+    /**
+     * Create the validation payload initialised with an event identifier and a timestamp.
+     *
+     * @param entity
+     * @throws ValidationServiceException
+     */
+    public ValidationResult(Entity entity) throws ValidationServiceException {
+        this.validationId = UUID.randomUUID().toString();
+        this.validationTimestamp =
+                DateTimeFormatter.ofPattern("yyyyMMdd'T'HHmmssX").withZone(ZoneOffset.UTC).format(Instant.now());
+        this.entityId = new JsonObject();
+        for (EntityId id : entity.getIds()) {
+            this.entityId.getAsJsonObject().addProperty(id.getPrimaryKey(), id.getValue());
+        }
+        this.entityType = entity.getType();
+        this.entityLink = entity.getEntityLink();
+        this.resourceVersion = entity.getResourceVersion().orElse(null);   
+        this.entity = entity.getJson()!=null ?new JsonParser().parse(entity.getJson()): new JsonObject();
+    }    
+ 
+
+    /**
+     * Add a validation violation.
+     *
+     * @param violation a single {@link Violation} to add to the validation result
+     */
+    public void addViolation(Violation violation) {
+        this.violations.add(violation);
+    }
+
+    /**
+     * Add a list of validation violations.
+     *
+     * @param violations a List of {@link Violation} objects to add to the validation result
+     */
+    public void addViolations(List<Violation> violations) {
+        this.violations.addAll(violations);
+    }
+
+    public String getValidationId() {
+        return validationId;
+    }
+
+    public void setValidationId(String eventId) {
+        this.validationId = eventId;
+    }
+
+    public String getValidationTimestamp() {
+        return validationTimestamp;
+    }
+
+    public void setValidationTimestamp(String timestamp) {
+        this.validationTimestamp = timestamp;
+    }
+
+    public JsonElement getEntityId() {
+        return entityId;
+    }
+
+    public void setEntityId(JsonElement entityId) {
+        this.entityId = entityId;
+    }
+
+    public String getEntityType() {
+        return entityType;
+    }
+
+    public void setEntityType(String entityType) {
+        this.entityType = entityType;
+    }
+
+    public String getEntityLink() {
+        return entityLink;
+    }
+
+    public void setEntityLink(String uri) {
+        this.entityLink = uri;
+    }
+
+    public String getResourceVersion() {
+        return resourceVersion;
+    }
+
+    public void setResourceVersion(String resourceVersion) {
+        this.resourceVersion = resourceVersion;
+    }
+
+    public JsonElement getEntity() {
+		return entity;
+	}
+
+	public void setEntity(JsonElement entity) {
+		this.entity = entity;
+	}
+	
+    public List<Violation> getViolations() {
+        return violations;
+    }
+
+    public void setViolations(List<Violation> violations) {
+        this.violations = violations;
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(this.entityId, this.entityLink, this.entityType, this.resourceVersion, this.validationId,
+                this.validationTimestamp, this.violations, this.entity);
+    }
+
+    /*
+     * validationId is checked first, as this is meant to be unique
+     *
+     * @see java.lang.Object#equals(java.lang.Object)
+     */
+    @Override
+    public boolean equals(Object obj) {
+        if (!(obj instanceof ValidationResult)) {
+            return false;
+        } else if (obj == this) {
+            return true;
+        }
+        ValidationResult rhs = (ValidationResult) obj;
+     // @formatter:off
+     return new EqualsBuilder()
+                  .append(entityId, rhs.entityId)
+                  .append(entityLink, rhs.entityLink)
+                  .append(entityType, rhs.entityType)
+                  .append(resourceVersion, rhs.resourceVersion)
+                  .append(validationId, rhs.validationId)
+                  .append(validationTimestamp, rhs.validationTimestamp)
+                  .append(violations, rhs.violations)
+                  .append(entity, rhs.entity)
+                  .isEquals();
+     // @formatter:on
+    }
+
+    @Override
+    public String toString() {
+        return JsonUtil.toJson(this);
+    }
+
+    /**
+     * Create a JSON representation of the object, with each violation's validationRule omitted when it has a null value
+     *
+     * @return this object formatted as a JSON string ready for publishing
+     */
+    public String toJson() {
+        return toString();
+    }
+
+    /**
+     * Create a new object from the JSON representation
+     *
+     * @param json representation of the Validation Result
+     * @return a ValidationResult object
+     */
+    public static ValidationResult fromJson(String json) {
+        ValidationResult validationResult = JsonUtil.toAnnotatedClassfromJson(json, ValidationResult.class);
+        if (validationResult != null) {
+            validationResult.initialiseValues();
+        }
+        return validationResult;
+    }
+
+    /**
+     * Ensure that any unset fields are properly initialised. This is particularly useful when the object has been
+     * deserialised from a JSON string, as any missing/undefined values will not be read by the deserialiser and thus
+     * the corresponding fields will not be set.
+     */
+    private void initialiseValues() {
+        List<Violation> violationList = getViolations();
+        if (violationList != null) {
+            for (Violation violation : violationList) {
+                violation.initialiseValues();
+            }
+        }
+    }
+}
diff --git a/src/main/java/org/onap/aai/validation/result/Violation.java b/src/main/java/org/onap/aai/validation/result/Violation.java
new file mode 100644
index 0000000..29baed3
--- /dev/null
+++ b/src/main/java/org/onap/aai/validation/result/Violation.java
@@ -0,0 +1,418 @@
+/*
+ * ============LICENSE_START===================================================
+ * Copyright (c) 2018 Amdocs
+ * ============================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=====================================================
+ */
+package org.onap.aai.validation.result;
+
+import com.google.gson.JsonElement;
+import com.google.gson.JsonObject;
+import com.google.gson.annotations.Expose;
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.io.ObjectOutputStream;
+import java.security.MessageDigest;
+import java.security.NoSuchAlgorithmException;
+import java.util.Map;
+import java.util.Objects;
+import java.util.Optional;
+import org.apache.commons.lang3.builder.EqualsBuilder;
+import org.onap.aai.validation.exception.ValidationServiceError;
+import org.onap.aai.validation.exception.ValidationServiceException;
+import org.onap.aai.validation.reader.data.Entity;
+import org.onap.aai.validation.reader.data.EntityId;
+import org.onap.aai.validation.util.JsonUtil;
+
+/**
+ * A validation violation.
+ */
+public class Violation {
+
+	public static final String ENTITY_TYPE_PROPERTY = "entityType";
+	public static final String ENTITY_ID_PROPERTY = "entityId";
+	public static final String ENTITY_MODELNAME_PROPERTY = "modelName";
+
+	@Expose
+	private final String violationId;
+
+	@Expose
+	private String modelName;
+
+	@Expose
+	private final String category;
+
+	@Expose
+	private final String severity;
+
+	@Expose
+	private final String violationType;
+
+	/**
+	 * The rule name (not applicable for model-driven) is not final as the value may be set to null via deserialisation
+	 * and we will need to update the field.
+	 */
+	@Expose
+	private Optional<String> validationRule;
+
+	@Expose
+	private final JsonElement violationDetails;
+
+	@Expose
+	private String errorMessage;
+
+	/**
+	 * rule-based or model-driven?
+	 */
+	public enum ViolationType {
+		NONE, RULE, MODEL
+	}
+
+	/**
+	 * Builder for a Violation.
+	 */
+	public static class Builder {
+
+		private final MessageDigest messageDigest;
+		private final JsonElement entityId;
+		private final String entityType;
+		private final String entityLink;
+		private final String resourceVersion;
+		private String category = null;
+		private String severity = null;
+		private String violationType = null;
+		private Optional<String> validationRule = Optional.empty();
+		private JsonElement violationDetails = new JsonObject();
+		private String errorMessage = null;
+
+		/**
+		 * Create a Violation Builder for the supplied entity.
+		 *
+		 * @param entity
+		 *            the entity
+		 * @throws ValidationServiceException
+		 *             the validation service exception
+		 */
+		public Builder(Entity entity) throws ValidationServiceException {
+			this.entityId = new JsonObject();
+			for (EntityId id : entity.getIds()) {
+				this.entityId.getAsJsonObject().addProperty(id.getPrimaryKey(), id.getValue());
+			}
+			this.entityType = entity.getType();
+			this.entityLink = entity.getEntityLink();
+			this.resourceVersion = entity.getResourceVersion().orElse(null);
+			try {
+				messageDigest = MessageDigest.getInstance("SHA-256");
+			} catch (NoSuchAlgorithmException e) {
+				throw new ValidationServiceException(ValidationServiceError.MESSAGE_DIGEST_ERROR, e);
+			}
+		}
+
+		/**
+		 * Category.
+		 *
+		 * @param val
+		 *            the val
+		 * @return the builder
+		 */
+		public Builder category(String val) {
+			category = val;
+			return this;
+		}
+
+		/**
+		 * Severity.
+		 *
+		 * @param val
+		 *            the val
+		 * @return the builder
+		 */
+		public Builder severity(String val) {
+			severity = val;
+			return this;
+		}
+
+		/**
+		 * Violation type.
+		 *
+		 * @param val
+		 *            the val
+		 * @return the builder
+		 */
+		public Builder violationType(String val) {
+			violationType = val;
+			return this;
+		}
+
+		/**
+		 * Violation type.
+		 *
+		 * @param type
+		 *            the type
+		 * @return the builder
+		 */
+		public Builder violationType(ViolationType type) {
+			String name = type.name();
+			// Convert to Camel Case
+			return violationType(name.substring(0, 1).toUpperCase() + name.substring(1, name.length()).toLowerCase());
+		}
+
+		/**
+		 * Validation rule.
+		 *
+		 * @param val
+		 *            the val
+		 * @return the builder
+		 */
+		public Builder validationRule(String val) {
+			validationRule = Optional.ofNullable(val);
+			return this;
+		}
+
+		/**
+		 * Violation details.
+		 *
+		 * @param map
+		 *            the map
+		 * @return the builder
+		 */
+		public Builder violationDetails(Map<String, Object> map) {
+			violationDetails = JsonUtil.toJsonElement(map);
+			return this;
+		}
+
+		/**
+		 * Error message.
+		 *
+		 * @param val
+		 *            the val
+		 * @return the builder
+		 */
+		public Builder errorMessage(String val) {
+			errorMessage = val;
+			return this;
+		}
+
+		/**
+		 * Generate violation id.
+		 *
+		 * @return a deterministic identifier of the violation (from its details) which may be used to compare the
+		 *         equality of violations which are created at different times
+		 * @throws ValidationServiceException
+		 *             the validation service exception
+		 */
+		public String generateViolationId() throws ValidationServiceException {
+			try (ByteArrayOutputStream baos = new ByteArrayOutputStream()) {
+				StringBuilder result = new StringBuilder();
+				writeObjectToStream(baos);
+				messageDigest.reset(); // Not strictly needed as digest() will cause a reset
+				for (byte byt : messageDigest.digest(baos.toByteArray())) {
+					result.append(Integer.toString((byt & 0xff) + 0x100, 16).substring(1));
+				}
+				return result.toString();
+			} catch (IOException e) {
+				throw new ValidationServiceException(ValidationServiceError.JSON_READER_PARSE_ERROR, e);
+			}
+		}
+
+		/**
+		 * Builds the.
+		 *
+		 * @return a new Violation object
+		 * @throws ValidationServiceException
+		 *             the validation service exception
+		 */
+		public Violation build() throws ValidationServiceException {
+			return new Violation(this);
+		}
+
+		/*
+		 * (non-Javadoc)
+		 *
+		 * @see java.lang.Object#toString()
+		 */
+		@Override
+		public String toString() {
+			return "Builder [entityId=" + entityId + ", entityType=" + entityType + ", entityLink=" + entityLink + ", resourceVersion=" + resourceVersion
+					+ ", category=" + category + ", severity=" + severity + ", violationType=" + violationType + ", validationRule=" + validationRule
+					+ ", violationDetails=" + violationDetails + ", errorMessage=" + errorMessage + "]";
+		}
+
+		/**
+		 * Stream all fields that are required for generating a deterministic violation ID field. Note that
+		 * resourceVersion is not included as this is allowed to vary
+		 *
+		 * @param baos
+		 *            the byte array output stream
+		 * @throws IOException
+		 *             Signals that an I/O exception has occurred.
+		 */
+		private void writeObjectToStream(ByteArrayOutputStream baos) throws IOException {
+			ObjectOutputStream oos = new ObjectOutputStream(baos);
+			oos.writeObject(this.category);
+			oos.writeObject(this.entityId.toString());
+			oos.writeObject(this.entityType);
+			oos.writeObject(this.entityLink);
+			oos.writeObject(this.severity);
+			oos.writeObject(this.validationRule.toString());
+			oos.writeObject(this.violationDetails.toString());
+			oos.writeObject(this.violationType);
+			oos.close();
+		}
+
+	}
+
+	/**
+	 * Instantiates a new Violation object via a builder.
+	 *
+	 * @param builder
+	 *            the builder storing the Violation values
+	 * @throws ValidationServiceException
+	 *             the validation service exception
+	 */
+	private Violation(Builder builder) throws ValidationServiceException {
+		violationId = builder.generateViolationId();
+		category = builder.category;
+		severity = builder.severity;
+		violationType = builder.violationType;
+		validationRule = builder.validationRule;
+		// Clone by serialising and deserialising!
+		violationDetails = JsonUtil.fromJson(JsonUtil.toJson(builder.violationDetails), JsonElement.class);
+		errorMessage = builder.errorMessage;
+	}
+
+	/**
+	 * Gets the violation id.
+	 *
+	 * @return the violation id
+	 */
+	public String getViolationId() {
+		return violationId;
+	}
+
+	/**
+	 * Gets the model name.
+	 *
+	 * @return the model name
+	 */
+	public String getModelName() {
+		return modelName;
+	}
+
+	/**
+	 * Sets the model name.
+	 *
+	 * @param modelName
+	 *            the new model name
+	 */
+	// Naughty and breaks the builder pattern but it saves a lot of faffing about.
+	public void setModelName(String modelName) {
+		this.modelName = modelName;
+	}
+
+	/**
+	 * Gets the category.
+	 *
+	 * @return the category
+	 */
+	public String getCategory() {
+		return category;
+	}
+
+	/**
+	 * Gets the severity.
+	 *
+	 * @return the severity
+	 */
+	public String getSeverity() {
+		return severity;
+	}
+
+	/**
+	 * Gets the violation type.
+	 *
+	 * @return the violation type
+	 */
+	public String getViolationType() {
+		return violationType;
+	}
+
+	/**
+	 * Gets the violation details.
+	 *
+	 * @return the violation details
+	 */
+	@SuppressWarnings("unchecked")
+	public Map<String, Object> getViolationDetails() {
+		return JsonUtil.toAnnotatedClassfromJson(violationDetails.getAsJsonObject().toString(), Map.class);
+	}
+
+	/**
+	 * Gets the error message.
+	 *
+	 * @return the error message
+	 */
+	public String getErrorMessage() {
+		return errorMessage;
+	}
+
+	@Override
+	public int hashCode() {
+		return Objects.hash(this.modelName, this.category, this.errorMessage, this.severity, this.validationRule, this.violationDetails, this.violationId, this.violationType);
+	}
+
+	/*
+	 * A hand-crafted equivalence relation to compare two Violation objects. Note that the violationId is compared
+	 * first, because this value is deterministically generated from the majority of the object's fields.
+	 *
+	 * @see java.lang.Object#equals(java.lang.Object)
+	 */
+	@Override
+	public boolean equals(Object obj) {
+        if (!(obj instanceof Violation)) {
+            return false;
+     } else if (obj == this) {
+            return true;
+     }
+        Violation rhs = (Violation) obj;
+     // @formatter:off
+     return new EqualsBuilder()
+                  .append(modelName, rhs.modelName)
+                  .append(category, rhs.category)
+                  .append(errorMessage, rhs.errorMessage)
+                  .append(severity, rhs.severity)
+                  .append(validationRule, rhs.validationRule)
+                  .append(violationDetails, rhs.violationDetails)
+                  .append(violationId, rhs.violationId)
+                  .append(violationType, rhs.violationType)
+                  .isEquals();
+     // @formatter:on
+	}
+
+	@Override
+	public String toString() {
+		return JsonUtil.toJson(this);
+	}
+
+	/**
+	 * Ensure that any unset fields are properly initialised. This is particularly useful when the object has been
+	 * deserialised from a JSON string, as any missing/undefined values will not be read by the deserialiser and thus
+	 * the corresponding fields will not be set.
+	 */
+	public void initialiseValues() {
+		if (validationRule == null) { // NOSONAR
+			validationRule = Optional.empty();
+		}
+	}
+}
diff --git a/src/main/java/org/onap/aai/validation/ruledriven/RuleDrivenValidator.java b/src/main/java/org/onap/aai/validation/ruledriven/RuleDrivenValidator.java
new file mode 100644
index 0000000..476c098
--- /dev/null
+++ b/src/main/java/org/onap/aai/validation/ruledriven/RuleDrivenValidator.java
@@ -0,0 +1,278 @@
+/*
+ * ============LICENSE_START===================================================
+ * Copyright (c) 2018 Amdocs
+ * ============================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=====================================================
+ */
+package org.onap.aai.validation.ruledriven;
+
+import java.io.File;
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Locale;
+import java.util.Map;
+import java.util.Optional;
+import java.util.function.Consumer;
+import java.util.stream.Stream;
+import org.onap.aai.validation.Validator;
+import org.onap.aai.validation.config.RuleIndexingConfig;
+import org.onap.aai.validation.exception.ValidationServiceError;
+import org.onap.aai.validation.exception.ValidationServiceException;
+import org.onap.aai.validation.logging.ApplicationMsgs;
+import org.onap.aai.validation.logging.LogHelper;
+import org.onap.aai.validation.reader.EventReader;
+import org.onap.aai.validation.reader.OxmReader;
+import org.onap.aai.validation.reader.data.AttributeValues;
+import org.onap.aai.validation.reader.data.Entity;
+import org.onap.aai.validation.result.ValidationResult;
+import org.onap.aai.validation.result.Violation;
+import org.onap.aai.validation.result.Violation.ViolationType;
+import org.onap.aai.validation.ruledriven.configuration.EntitySection;
+import org.onap.aai.validation.ruledriven.configuration.GroovyConfigurationException;
+import org.onap.aai.validation.ruledriven.configuration.RulesConfigurationLoader;
+import org.onap.aai.validation.ruledriven.rule.Rule;
+
+/**
+ * Validator using explicit rules
+ *
+ */
+public class RuleDrivenValidator implements Validator {
+
+    private static LogHelper applicationLogger = LogHelper.INSTANCE;
+
+    private static final String RULES_CONFIG_FILE_SUFFIX = ".groovy";
+
+    private Path configurationPath;
+    private OxmReader oxmReader;
+    private EventReader eventReader;
+    private Optional<RuleIndexingConfig> ruleIndexingConfig;
+    // Map of event type name against RuleManager for that event type
+    private Map<String, RuleManager> ruleManagers;
+
+
+    /**
+     * Construct a Validator that is configured using rule files
+     *
+     * @param configurationPath path to the Groovy rules files
+     * @param oxmReader required for validating entity types
+     * @param eventReader a reader for extracting entities from each event to be validated
+     */
+    public RuleDrivenValidator(final Path configurationPath, final OxmReader oxmReader,
+            final EventReader eventReader, final RuleIndexingConfig ruleIndexingConfig) {
+        this.configurationPath = configurationPath;
+        this.oxmReader = oxmReader;
+        this.eventReader = eventReader;
+        this.ruleIndexingConfig = Optional.ofNullable(ruleIndexingConfig);
+        this.ruleManagers = null;
+    }
+
+    @Override
+    public void initialise() throws ValidationServiceException {
+        ruleManagers = new HashMap<>();
+        for (String eventType : getSupportedEventTypes()) {
+            ruleManagers.put(eventType.toLowerCase(Locale.getDefault()), loadRulesConfiguration(eventType));
+        }
+        validateRulesConfiguration();
+    }
+
+    private RuleManager loadRulesConfiguration(String eventType) throws ValidationServiceException {
+        StringBuilder rulesText = new StringBuilder();
+        try (Stream<Path> paths = Files.find(configurationPath.resolve(eventType), 1,
+                (path, basicFileAttributes) -> path.toFile().getName().matches(".*\\" + RULES_CONFIG_FILE_SUFFIX));) {
+            paths.forEach(appendFileContent(rulesText));
+        } catch (IOException e) {
+            throw new ValidationServiceException(ValidationServiceError.RULES_FILE_ERROR,
+                    configurationPath.toAbsolutePath(), e);
+        }
+
+        try {
+            return RulesConfigurationLoader.loadConfiguration(rulesText.toString());
+        } catch (GroovyConfigurationException e) {
+            throw new ValidationServiceException(ValidationServiceError.RULES_FILE_ERROR, e,
+                    configurationPath.toAbsolutePath() + File.separator + "*" + RULES_CONFIG_FILE_SUFFIX);
+        }
+    }
+
+    private void validateRulesConfiguration() throws ValidationServiceException {
+        for (RuleManager ruleManager : ruleManagers.values()) {
+            for (EntitySection entity : ruleManager.getEntities()) {
+                if(ruleIndexingConfig.isPresent() && ruleIndexingConfig.get().skipOxmValidation(entity.getName())) {
+                    continue;
+                }
+                if (oxmReader != null && oxmReader.getPrimaryKeys(entity.getName()).isEmpty()) {
+                    throw new ValidationServiceException(ValidationServiceError.OXM_MISSING_KEY,
+                            entity.getName() + " defined in " + configurationPath.toAbsolutePath() + File.separator
+                                    + "*" + RULES_CONFIG_FILE_SUFFIX);
+                }
+            }
+        }
+    }
+
+    /**
+     * Helper method to expose the configured rules. This simplifies testing of the validator.
+     *
+     * @param entityType
+     * @param eventType
+     * @return the rules defined for this entityType
+     */
+    public List<Rule> getRulesForEntity(String entityType, String eventType) {
+        return ruleManagers.get(eventType.toLowerCase(Locale.getDefault())).getRulesForEntity(entityType);
+    }
+
+    /*
+     * (non-Javadoc)
+     *
+     * @see org.onap.aai.validation.Validator#validate(java.lang.String)
+     */
+    @Override
+    public List<ValidationResult> validate(String event) throws ValidationServiceException {
+        List<ValidationResult> validationResults = new ArrayList<>();
+
+        Entity entity = getEventReader().getEntity(event);
+        Optional<String> eventType = eventReader.getEventType(event);
+        List<Rule> rules = getRulesToApply(entity, eventType).orElse(null);
+        if (rules == null) {
+            throw new ValidationServiceException(ValidationServiceError.RULES_NOT_DEFINED, eventType.orElse(null));
+        }
+        ValidationResult validationResult = new ValidationResult(entity);
+        Violation.Builder builder = new Violation.Builder(entity);
+
+        for (Rule rule : rules) {
+            AttributeValues attributeValues = entity.getAttributeValues(rule.getAttributePaths());
+
+            // Execute the rule for this particular set of attribute values.
+            boolean valid = false;
+            try {
+                valid = rule.execute(attributeValues);
+            } catch (IllegalArgumentException e) {
+                throw new ValidationServiceException(ValidationServiceError.RULE_EXECUTION_ERROR, e, rule,
+                        attributeValues);
+            }
+
+            applicationLogger.debug(String.format("%s|%s|\"%s\"|%s", entity.getType(), entity.getIds(), rule.getName(),
+                    valid ? "pass" : "fail"));
+
+            if (!valid) {
+                //@formatter:off
+				Violation violation = builder
+									.category(rule.getErrorCategory())
+									.severity(rule.getSeverity())
+									.violationType(ViolationType.RULE)
+									.validationRule(rule.getName())
+									.violationDetails(attributeValues.generateReport())
+									.errorMessage(rule.getErrorMessage())
+									.build();
+				//@formatter:on
+
+                validationResult.addViolation(violation);
+            }
+        }
+        validationResults.add(validationResult);
+
+        return validationResults;
+    }
+
+    private Optional<List<Rule>> getRulesToApply(Entity entity, Optional<String> eventType)
+            throws ValidationServiceException {
+        Optional<List<Rule>> rules = Optional.empty();
+        if (eventType.isPresent()) {
+            Optional<RuleManager> ruleManager = getRuleManager(eventType.get().toLowerCase(Locale.getDefault()));
+            if (ruleManager.isPresent()) {
+                if (ruleIndexingConfig.isPresent() && ruleIndexingConfig.get().getIndexedEvents() != null &&
+                        ruleIndexingConfig.get().getIndexedEvents().contains(eventType.get())) {
+                    rules = getRulesByIndex(entity, eventType.get(), ruleManager.get());
+                } else {
+                    rules = Optional.of(ruleManager.get().getRulesForEntity(entity.getType()));
+                }
+            }
+        }
+        return rules;
+    }
+
+    private Optional<List<Rule>> getRulesByIndex(Entity entity, String eventType, RuleManager ruleManager) {
+        String rulesKey = generateKey(entity, eventType);
+        applicationLogger.debug(String.format("Retrieving indexed rules for key '%s'", rulesKey));
+        Optional<List<Rule>> rules = Optional.of(ruleManager.getRulesForEntity(rulesKey));
+        if (rules.get().isEmpty() && ruleIndexingConfig.isPresent()) {
+            if (ruleIndexingConfig.get().getDefaultIndexKey() == null || ruleIndexingConfig.get().getDefaultIndexKey().isEmpty()) {
+                applicationLogger.debug("Default index value not configured, unable to get rules");
+                applicationLogger.error(ApplicationMsgs.CANNOT_VALIDATE_ERROR, eventType);
+                return rules;
+            }
+            String defaultKey = RuleManager.generateKey(new String[] {ruleIndexingConfig.get().getDefaultIndexKey()});
+            rules = Optional.of(ruleManager.getRulesForEntity(defaultKey));
+        }
+        return rules;
+    }
+
+    private String generateKey(Entity entity, String eventType) {
+        if (!ruleIndexingConfig.isPresent() || ruleIndexingConfig.get().getIndexAttributes() == null ||
+                ruleIndexingConfig.get().getIndexAttributes().isEmpty()) {
+            applicationLogger.debug(String.format(
+                    "Event '%s' is configured to use indexed rules but indexing attributes are not configured", eventType));
+            return "";
+        }
+        try {
+            AttributeValues attributeValues = entity.getAttributeValues(ruleIndexingConfig.get().getIndexAttributes());
+            applicationLogger.debug("Generating index using attributes: " + attributeValues.generateReport().toString());
+            Collection<Object> values = attributeValues.generateReport().values();
+            return RuleManager.generateKey(values.stream().toArray(String[]::new));
+        } catch (ValidationServiceException e) {
+            applicationLogger.debug("Failed to retrieve index key attributes from event");
+            applicationLogger.error(ApplicationMsgs.CANNOT_VALIDATE_ERROR, eventType);
+            return "";
+        }
+    }
+
+    private EventReader getEventReader() {
+        return this.eventReader;
+    }
+
+    private Optional<RuleManager> getRuleManager(String eventType) throws ValidationServiceException {
+        if (ruleManagers == null) {
+            initialise();
+        }
+        return Optional.ofNullable(ruleManagers.get(eventType));
+    }
+
+    /**
+     * Read the text content of the specified Path and append this to the specified String
+     *
+     * @param sb StringBuilder for the rule configuration text
+     * @return a Consumer function that appends file content
+     */
+    private Consumer<? super Path> appendFileContent(StringBuilder sb) {
+        return path -> {
+            try {
+                for (String line : Files.readAllLines(path)) {
+                    sb.append(line).append("\n");
+                }
+            } catch (IOException e) {
+                applicationLogger.error(ApplicationMsgs.READ_FILE_ERROR, e, path.toString());
+            }
+        };
+    }
+
+    private Collection<String> getSupportedEventTypes() {
+        String[] list = configurationPath.toFile().list((current, name) -> new File(current, name).isDirectory());
+        return list == null ? Collections.emptyList() : Arrays.asList(list);
+    }
+}
diff --git a/src/main/java/org/onap/aai/validation/ruledriven/RuleManager.java b/src/main/java/org/onap/aai/validation/ruledriven/RuleManager.java
new file mode 100644
index 0000000..c21ce24
--- /dev/null
+++ b/src/main/java/org/onap/aai/validation/ruledriven/RuleManager.java
@@ -0,0 +1,91 @@
+/*
+ * ============LICENSE_START===================================================
+ * Copyright (c) 2018 Amdocs
+ * ============================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=====================================================
+ */
+package org.onap.aai.validation.ruledriven;
+
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.Iterator;
+import java.util.LinkedHashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.SortedSet;
+import java.util.TreeSet;
+import org.onap.aai.validation.ruledriven.configuration.EntitySection;
+import org.onap.aai.validation.ruledriven.configuration.GroovyConfigurationException;
+import org.onap.aai.validation.ruledriven.configuration.RuleSection;
+import org.onap.aai.validation.ruledriven.rule.GroovyRule;
+import org.onap.aai.validation.ruledriven.rule.Rule;
+
+/**
+ * Helper class storing the relationships from entity type to rules. This class constructs the actual rules from the
+ * supplied configuration.
+ *
+ */
+public class RuleManager {
+
+    private Map<String, List<Rule>> rulesMap = new LinkedHashMap<>();
+    private List<EntitySection> entities;
+
+    /**
+     * Create the rules for each type of entity based on the supplied configuration
+     *
+     * @param entities configuration (all entities)
+     * @throws InstantiationException
+     * @throws IllegalAccessException
+     * @throws GroovyConfigurationException
+     * @throws IOException
+     */
+    public RuleManager(List<EntitySection> entities)
+            throws InstantiationException, IllegalAccessException, GroovyConfigurationException, IOException {
+        this.entities = entities;
+        for (EntitySection entity : entities) {
+            List<Rule> rules = new ArrayList<>();
+            for (RuleSection section : entity.getRules()) {
+                rules.add(new GroovyRule(section));
+            }
+            rulesMap.put(entity.getType(), rules);
+        }
+    }
+
+    public List<EntitySection> getEntities() {
+        return entities;
+    }
+
+    /**
+     * @param entityType
+     * @return the rules configured for this entity type
+     */
+    public List<Rule> getRulesForEntity(String entityType) {
+        List<Rule> rules = rulesMap.get(entityType);
+        return rules == null ? Collections.emptyList() : rules;
+    }
+
+    public static String generateKey(String[] indices) {
+        SortedSet<String> sortedIndices = new TreeSet<>();
+        Collections.addAll(sortedIndices, indices);
+        StringBuilder sb = new StringBuilder();
+        Iterator<String> iterator = sortedIndices.iterator();
+        while (iterator.hasNext()) {
+            sb.append("[");
+            sb.append(iterator.next());
+            sb.append("]");
+        }
+        return sb.toString();
+    }
+}
diff --git a/src/main/java/org/onap/aai/validation/ruledriven/configuration/EntitySection.java b/src/main/java/org/onap/aai/validation/ruledriven/configuration/EntitySection.java
new file mode 100644
index 0000000..357ed87
--- /dev/null
+++ b/src/main/java/org/onap/aai/validation/ruledriven/configuration/EntitySection.java
@@ -0,0 +1,101 @@
+/*
+ * ============LICENSE_START===================================================
+ * Copyright (c) 2018 Amdocs
+ * ============================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=====================================================
+ */
+package org.onap.aai.validation.ruledriven.configuration;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.SortedSet;
+import java.util.TreeSet;
+import org.onap.aai.validation.ruledriven.configuration.build.EntityBuilder;
+
+/**
+ * Rules Configuration: entity {} section.
+ */
+public class EntitySection {
+
+	private String name;
+	private String type;
+	private final SortedSet<String> indices = new TreeSet<>();
+	private final List<RuleSection> rules = new ArrayList<>();
+
+	/**
+	 * Rules are specified within an entity section.
+	 */
+	public EntitySection() {
+		// Deliberately empty - invoked when an entity section is read from the rules DSL
+	}
+
+	@Override
+	public String toString() {
+		return new EntityBuilder(this).toString();
+	}
+
+	public String getName() {
+		return name;
+	}
+
+	public String getType() {
+		return type;
+	}
+
+	public void setName(String name) {
+		this.name = name;
+	}
+
+	public void setType(String entityType) {
+		this.type = entityType;
+	}
+
+    public void setIndices(List<String> indices) {
+        for(String index : indices) {
+            this.indices.add(index.trim());
+        }
+    }
+
+    public void setIndices(String[] indices) {
+        for(String index : indices) {
+            this.indices.add(index.trim());
+        }
+    }
+
+    public SortedSet<String> getIndices() {
+        return this.indices;
+    }
+
+	/**
+	 * Adds the rule.
+	 *
+	 * @param rule
+	 *            the rule
+	 */
+	public void addRule(RuleSection rule) {
+		this.rules.add(rule);
+	}
+
+	/**
+	 * <p>
+	 * Getter for property {@link #rules}.
+	 * </p>
+	 *
+	 * @return Value for property <tt>rules</tt>.
+	 */
+	public List<RuleSection> getRules() {
+		return this.rules;
+	}
+
+}
\ No newline at end of file
diff --git a/src/main/java/org/onap/aai/validation/ruledriven/configuration/GroovyConfigurationException.java b/src/main/java/org/onap/aai/validation/ruledriven/configuration/GroovyConfigurationException.java
new file mode 100644
index 0000000..3b1b98a
--- /dev/null
+++ b/src/main/java/org/onap/aai/validation/ruledriven/configuration/GroovyConfigurationException.java
@@ -0,0 +1,103 @@
+/*
+ * ============LICENSE_START===================================================
+ * Copyright (c) 2018 Amdocs
+ * ============================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=====================================================
+ */
+package org.onap.aai.validation.ruledriven.configuration;
+
+import groovy.lang.MissingMethodException;
+import groovy.lang.MissingPropertyException;
+import org.codehaus.groovy.control.CompilationFailedException;
+import org.codehaus.groovy.control.MultipleCompilationErrorsException;
+import org.onap.aai.validation.exception.BaseValidationServiceException;
+import org.onap.aai.validation.exception.ValidationServiceError;
+
+/**
+ * Configuration load/parse exceptions
+ *
+ */
+@SuppressWarnings("serial")
+public class GroovyConfigurationException extends BaseValidationServiceException {
+
+	private String invalidToken; // NOSONAR
+	private String configText; // NOSONAR
+
+	/**
+	 * @param text
+	 */
+	public GroovyConfigurationException(String text) {
+		super(ValidationServiceError.RULE_UNEXPECTED_TOKEN.getId(), ValidationServiceError.RULE_UNEXPECTED_TOKEN.getId() + ", " + text);
+	}
+
+	/**
+	 * @param text
+	 * @param configuration
+	 */
+	public GroovyConfigurationException(String text, String configuration) {
+		super(text);
+		this.configText = configuration;
+	}
+
+	/**
+	 * @param e
+	 *            exception for a missing method
+	 * @param configuration
+	 */
+	public GroovyConfigurationException(MissingMethodException e, String configuration) {
+		super(ValidationServiceError.RULE_UNEXPECTED_TOKEN.getId(), "Invalid keyword " + e.getMethod(), e);
+		setInvalidToken(e.getMethod());
+		this.configText = configuration;
+	}
+
+	/**
+	 * @param e
+	 * @param configuration
+	 */
+	public GroovyConfigurationException(MissingPropertyException e, String configuration) {
+		super(ValidationServiceError.RULE_UNEXPECTED_TOKEN.getId(), "Invalid keyword " + e.getProperty(), e);
+		setInvalidToken(e.getProperty());
+		this.configText = configuration;
+	}
+
+	/**
+	 * @param e
+	 */
+	public GroovyConfigurationException(CompilationFailedException e) {
+		super(ValidationServiceError.RULE_UNEXPECTED_TOKEN.getId(), ValidationServiceError.RULE_UNEXPECTED_TOKEN.getId() + ", "
+				+ ValidationServiceError.RULE_UNEXPECTED_TOKEN.getMessage() + "; Caused by: " + e.getMessage(), e);
+	}
+
+	/**
+	 * @param e
+	 * @param configuration
+	 */
+	public GroovyConfigurationException(MultipleCompilationErrorsException e, String configuration) {
+		super(ValidationServiceError.RULE_UNEXPECTED_TOKEN.getId(), "", e);
+		this.configText = configuration;
+	}
+
+	public String getInvalidToken() {
+		return invalidToken;
+	}
+
+	public void setInvalidToken(String token) {
+		this.invalidToken = token;
+	}
+
+	public String getConfigText() {
+		return configText;
+	}
+
+}
diff --git a/src/main/java/org/onap/aai/validation/ruledriven/configuration/RuleSection.java b/src/main/java/org/onap/aai/validation/ruledriven/configuration/RuleSection.java
new file mode 100644
index 0000000..b03bcf3
--- /dev/null
+++ b/src/main/java/org/onap/aai/validation/ruledriven/configuration/RuleSection.java
@@ -0,0 +1,200 @@
+/*
+ * ============LICENSE_START===================================================
+ * Copyright (c) 2018 Amdocs
+ * ============================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=====================================================
+ */
+package org.onap.aai.validation.ruledriven.configuration;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+import org.onap.aai.validation.ruledriven.configuration.build.RuleBuilder;
+
+/**
+ * Rules Configuration: rule {} section.
+ */
+public class RuleSection {
+
+	private String name;
+	private boolean isGenericRule;
+	private String description;
+	private String category;
+	private String errorMessage;
+	private String type;
+	private String objectId;
+	private String severity;
+	private List<String> attributes = new ArrayList<>();
+	private List<String> fields = new ArrayList<>();
+	private String expression;
+
+	/**
+	 * Rules may be defined within an entity {} section.
+	 */
+	public RuleSection() {
+		isGenericRule = false;
+	}
+
+	/**
+	 * @param attribute
+	 */
+	public void addAttribute(String attribute) {
+		if (this.attributes == null) {
+			this.attributes = new ArrayList<>();
+		}
+		this.attributes.add(attribute);
+	}
+
+	private void addAttributeMapping(String field) {
+		if (this.fields == null) {
+			this.fields = new ArrayList<>();
+		}
+		this.fields.add(field);
+	}
+
+	private void addAttributeNames(List<String> fieldNames) {
+		for (String attribute : fieldNames) {
+			addAttributeMapping(attribute);
+		}
+	}
+
+	private void addAttributes(List<String> attributes) {
+		for (String attribute : attributes) {
+			addAttribute(attribute);
+		}
+	}
+
+	/**
+	 * Make a copy of a generically defined rule so that we can tailor it for our specific entity.
+	 *
+	 * @param genericRule
+	 */
+	public void copyFrom(RuleSection genericRule) {
+		setCategory(genericRule.getCategory());
+		setDescription(genericRule.getDescription());
+		setSeverity(genericRule.getSeverity());
+		setExpression(genericRule.getExpression());
+		setErrorMessage(genericRule.getErrorMessage());
+		if (genericRule.getAttributes() != null) {
+			if (getAttributes().isEmpty()) {
+				addAttributes(genericRule.getAttributes());
+			} else {
+				// Map the attributes
+				addAttributeNames(genericRule.getAttributes());
+			}
+		}
+
+		if (getAttributes().isEmpty()) {
+			throw new IllegalArgumentException("No attributes defined");
+		}
+	}
+
+	public List<String> getAttributes() {
+		return new ArrayList<>(attributes);
+	}
+
+	public String getCategory() {
+		return category;
+	}
+
+	public String getDescription() {
+		return description;
+	}
+
+	public String getErrorMessage() {
+		return errorMessage;
+	}
+
+	public String getExpression() {
+		return expression;
+	}
+
+	public List<String> getExpressionFieldNames() {
+		if (fields.size() < attributes.size()) {
+			return attributes;
+		} else {
+			return fields;
+		}
+	}
+
+	public String getName() {
+		return name;
+	}
+
+	public String getType() {
+		return type;
+	}
+
+	public String getObjectId() {
+		return objectId;
+	}
+
+	public String getSeverity() {
+		return severity;
+	}
+
+	public boolean isGeneric() {
+		return isGenericRule;
+	}
+
+	public void setAttributes(List<String> attributes) {
+		this.attributes = attributes;
+	}
+
+	public void setAttributes(String[] attributes) {
+		this.attributes = new ArrayList<>(Arrays.asList(attributes));
+	}
+
+	public void setCategory(String category) {
+		this.category = category;
+	}
+
+	public void setDescription(String description) {
+		this.description = description;
+	}
+
+	public void setErrorMessage(String errorMessage) {
+		this.errorMessage = errorMessage;
+	}
+
+	public void setExpression(String expression) {
+		this.expression = expression;
+	}
+
+	public void setIsGeneric(boolean isGenericRule) {
+		this.isGenericRule = isGenericRule;
+	}
+
+	public void setName(String name) {
+		this.name = name;
+	}
+
+	public void setObject(String object) {
+		this.type = object;
+	}
+
+	public void setObjectId(String objectId) {
+		this.objectId = objectId;
+	}
+
+	public void setSeverity(String severity) {
+		this.severity = severity;
+	}
+
+	@Override
+	public String toString() {
+		return new RuleBuilder(this, "").toString();
+	}
+
+}
\ No newline at end of file
diff --git a/src/main/java/org/onap/aai/validation/ruledriven/configuration/RulesConfigurationLoader.groovy b/src/main/java/org/onap/aai/validation/ruledriven/configuration/RulesConfigurationLoader.groovy
new file mode 100644
index 0000000..5fabde9
--- /dev/null
+++ b/src/main/java/org/onap/aai/validation/ruledriven/configuration/RulesConfigurationLoader.groovy
@@ -0,0 +1,309 @@
+/*
+ * ============LICENSE_START===================================================
+ * Copyright (c) 2018 Amdocs
+ * ============================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=====================================================
+ */
+package org.onap.aai.validation.ruledriven.configuration
+
+import groovy.lang.Closure
+import groovy.lang.DelegatesTo
+import groovy.lang.ExpandoMetaClass
+import java.io.File
+import java.util.List
+import org.onap.aai.validation.ruledriven.RuleManager
+
+class RulesConfigurationLoader {
+
+	static RuleManager loadConfiguration(File dsl) {
+		return loadConfiguration(dsl.text)
+	}
+
+	static RuleManager loadConfiguration(String dsl) throws GroovyConfigurationException {
+		SettingsSection globalConfiguration = new SettingsSection()
+		def List<EntitySection> entities = []
+		def List<RuleSection> rules = []
+		Script dslScript
+
+		try {
+			dslScript = new GroovyShell().parse(dsl)
+		} catch (org.codehaus.groovy.control.MultipleCompilationErrorsException e) {
+			throw new GroovyConfigurationException(e, dsl)
+		}
+
+		dslScript.metaClass = createEMC(dslScript.class, { ExpandoMetaClass emc ->
+
+			emc.settings = { Closure cl ->
+				cl.delegate = new SettingsDelegate(globalConfiguration)
+				cl.resolveStrategy = Closure.DELEGATE_FIRST
+				cl()
+			}
+
+			emc.entity = { Closure cl ->
+				EntitySection entityConfiguration = new EntitySection()
+				cl.delegate = new EntityDelegate(entityConfiguration)
+				cl.resolveStrategy = Closure.DELEGATE_FIRST
+				cl()
+				entities.add(entityConfiguration)
+			}
+
+			emc.rule = { Closure cl ->
+				RuleSection ruleConfiguration = new RuleSection()
+				cl.delegate = new RuleDelegate(ruleConfiguration)
+				cl.resolveStrategy = Closure.DELEGATE_FIRST
+				cl()
+				rules.add(ruleConfiguration)
+			}
+		})
+
+		try {
+			dslScript.run()
+		} catch (MissingMethodException | MissingPropertyException e) {
+			throw new GroovyConfigurationException(e, dsl)
+		}
+
+		loadGenericRules(entities, rules)
+		checkForDuplicateRules(rules)
+
+		return new RuleManager(entities)
+	}
+
+	static void loadGenericRules(List<EntitySection> entities, List<RuleSection> rules) {
+		for (entity in entities) {
+			for (rule in entity.getRules()) {
+				if (rule.isGeneric()) {
+					def namedRule = rules.find() { item ->
+						item.getName() == rule.getName()
+					}
+					if (namedRule == null) {
+						throw new GroovyConfigurationException("rule '" + rule.getName() + "' is not defined")
+					}
+					try {
+						rule.copyFrom(namedRule)
+					} catch (IllegalArgumentException e) {
+						throw new GroovyConfigurationException("rule '" + rule.getName() + "' has no attributes defined, referenced by entity '" + entity.getName() + "'")
+					}
+				}
+				if (rule.getExpression() == null) {
+					throw new GroovyConfigurationException("rule '" + rule.getName() + "' does not have an expression defined")
+				}
+			}
+		}
+	}
+
+	static void checkForDuplicateRules(List<RuleSection> rules) {
+		def duplicates = rules.countBy{ rule -> rule.name }.grep{ it.value > 1 }.collect{ it.key }
+
+		rules.each { rule ->
+			if (rule.name in duplicates) {
+				throw new GroovyConfigurationException("Generic rule '" + rule.name + "' is duplicated")
+			}
+		}
+	}
+
+	static ExpandoMetaClass createEMC(Class scriptClass, Closure cl) {
+		ExpandoMetaClass emc = new ExpandoMetaClass(scriptClass, false)
+		cl(emc)
+		emc.initialize()
+		return emc
+	}
+}
+
+// Parse the settings {} block
+class SettingsDelegate {
+	private SettingsSection configuration
+
+	SettingsDelegate(SettingsSection configuration) {
+		this.configuration = configuration
+	}
+
+	void environment(String environment) {
+		this.configuration.setEnvironment environment
+	}
+}
+
+// Parse an entity {} block
+class EntityDelegate {
+	private EntitySection configuration
+
+	EntityDelegate(EntitySection configuration) {
+		this.configuration = configuration
+	}
+
+	void name(String name) {
+		this.configuration.setName name
+	}
+
+	void type(String name) {
+		if (!configuration.name) configuration.name = name
+		configuration.type = name
+		configuration.getRules().each { rule ->
+			rule.setObject configuration.type
+		}
+	}
+
+    def indexing(@DelegatesTo(strategy=Closure.DELEGATE_FIRST, value=IndexingDelegate) Closure cl) {
+        cl.delegate = new IndexingDelegate(configuration)
+        cl.resolveStrategy = Closure.DELEGATE_FIRST
+        cl()
+    }
+
+	def validation(@DelegatesTo(strategy=Closure.DELEGATE_FIRST, value=ValidationDelegate) Closure cl) {
+		cl.delegate = new ValidationDelegate(configuration)
+		cl.resolveStrategy = Closure.DELEGATE_FIRST
+		cl()
+	}
+
+	void methodMissing(String name, Object args) {
+		throw new MissingMethodException(name, this.class, args as Object[])
+	}
+
+	def propertyMissing(String name) {
+		throw new MissingMethodException(name, this.class)
+	}
+}
+
+
+// Parse an indexing {} block within an entity block
+class IndexingDelegate {
+    private EntitySection configuration
+
+    IndexingDelegate(EntitySection configuration) {
+        this.configuration = configuration
+    }
+
+    void indices(String... indices) {
+        this.configuration.setIndices indices
+        def index = RuleManager.generateKey(indices)
+        this.configuration.type = index
+        this.configuration.getRules().each { rule ->
+            rule.setObject configuration.type
+        }
+    }
+
+    void methodMissing(String name, Object args) {
+        throw new MissingMethodException(name, this.class, args as Object[])
+    }
+
+    def propertyMissing(String name) {
+        throw new MissingMethodException(name, this.class)
+    }
+}
+
+// Parse a validation {} block within an entity block
+class ValidationDelegate {
+	private EntitySection configuration
+	private String id
+
+	ValidationDelegate(EntitySection configuration) {
+		this.configuration = configuration
+	}
+
+	void useRule(@DelegatesTo(strategy=Closure.DELEGATE_FIRST, value=UseRuleDelegate) Closure cl) {
+		cl.delegate = new UseRuleDelegate(configuration, configuration.type, id)
+		cl.resolveStrategy = Closure.DELEGATE_FIRST
+		cl()
+	}
+
+	void rule(@DelegatesTo(strategy=Closure.DELEGATE_FIRST, value=RuleDelegate) Closure cl) {
+		RuleSection ruleConfiguration = new RuleSection()
+		ruleConfiguration.setObject configuration.type
+		ruleConfiguration.setObjectId this.id
+		cl.delegate = new RuleDelegate(ruleConfiguration)
+		cl.resolveStrategy = Closure.DELEGATE_FIRST
+		cl()
+		configuration.addRule(ruleConfiguration)
+	}
+
+	void methodMissing(String name, Object args) {
+		throw new MissingMethodException(name, this.class, args as Object[])
+	}
+}
+
+// Parse a rule {} block
+class RuleDelegate {
+	private RuleSection configuration
+
+	RuleDelegate(RuleSection configuration) {
+		this.configuration = configuration
+	}
+
+	void name(String name) {
+		this.configuration.setName name
+	}
+
+	void category(String category) {
+		this.configuration.setCategory category
+	}
+
+	void description(String description) {
+		this.configuration.setDescription description
+	}
+
+	void errorText(String text) {
+		this.configuration.setErrorMessage text
+	}
+
+	void severity(String severity) {
+		this.configuration.setSeverity severity
+	}
+
+	void attributes(String... attributesList) {
+		this.configuration.setAttributes attributesList
+	}
+
+	void validate(String validate) {
+		this.configuration.setExpression validate
+	}
+
+	void methodMissing(String name, Object args) {
+		throw new MissingMethodException(name, this.class, args as Object[])
+	}
+
+	def propertyMissing(String name) {
+		throw new MissingMethodException(name, this.class)
+	}
+}
+
+class UseRuleDelegate {
+	private EntitySection configuration
+	private String objectName
+	private String id
+	private RuleSection ruleConfig
+
+	UseRuleDelegate(EntitySection configuration, String objectName, String id) {
+		this.configuration = configuration
+		this.objectName = objectName
+		this.id = id
+	}
+
+	void name(String name) {
+		ruleConfig = new RuleSection()
+		ruleConfig.setIsGeneric true;
+		ruleConfig.setName name;
+		ruleConfig.setObject this.objectName
+		ruleConfig.setObjectId this.id
+		this.configuration.addRule ruleConfig
+	}
+
+	void attributes(String[] attributes) {
+		if (ruleConfig.attributes.empty) {
+			attributes.each {ruleConfig.addAttribute it}
+		}
+	}
+
+	def propertyMissing(String name) {
+		throw new MissingMethodException(name, this.class)
+	}
+}
diff --git a/src/main/java/org/onap/aai/validation/ruledriven/configuration/SettingsSection.java b/src/main/java/org/onap/aai/validation/ruledriven/configuration/SettingsSection.java
new file mode 100644
index 0000000..d59d07d
--- /dev/null
+++ b/src/main/java/org/onap/aai/validation/ruledriven/configuration/SettingsSection.java
@@ -0,0 +1,48 @@
+/*
+ * ============LICENSE_START===================================================
+ * Copyright (c) 2018 Amdocs
+ * ============================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=====================================================
+ */
+package org.onap.aai.validation.ruledriven.configuration;
+
+import org.onap.aai.validation.ruledriven.configuration.build.EntityBuilder;
+
+/**
+ * Parse the settings configuration block.
+ */
+public class SettingsSection {
+
+	private String environment;
+
+	public SettingsSection() {
+		// Deliberately empty
+	}
+
+	@Override
+	public String toString() {
+		StringBuilder sb = new StringBuilder();
+		sb.append(new EntityBuilder());
+		return sb.toString();
+	}
+
+	public String getEnvironment() {
+		return environment;
+	}
+
+	public void setEnvironment(String environment) {
+		this.environment = environment;
+	}
+
+}
\ No newline at end of file
diff --git a/src/main/java/org/onap/aai/validation/ruledriven/configuration/build/ContentBuilder.java b/src/main/java/org/onap/aai/validation/ruledriven/configuration/build/ContentBuilder.java
new file mode 100644
index 0000000..320e29e
--- /dev/null
+++ b/src/main/java/org/onap/aai/validation/ruledriven/configuration/build/ContentBuilder.java
@@ -0,0 +1,198 @@
+/*
+ * ============LICENSE_START===================================================
+ * Copyright (c) 2018 Amdocs
+ * ============================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=====================================================
+ */
+package org.onap.aai.validation.ruledriven.configuration.build;
+
+import java.util.ArrayList;
+import java.util.Enumeration;
+import java.util.List;
+import java.util.Properties;
+
+
+/**
+ * Helper class for building internal configuration settings.
+ */
+public class ContentBuilder {
+
+	private final String contentName;
+	protected List<ContentBuilder> items = new ArrayList<>();
+	private StringBuilder content = new StringBuilder();
+	protected String indent = "";
+
+	/**
+	 * Construct an empty section.
+	 */
+	public ContentBuilder() {
+		this.contentName = null;
+	}
+
+	/**
+	 * Instantiates a new content builder.
+	 *
+	 * @param contentName
+	 *            the content name
+	 */
+	public ContentBuilder(String contentName) {
+		this.contentName = contentName;
+	}
+
+	@Override
+	public String toString() {
+		return build();
+	}
+
+	/**
+	 * Builds the configuration section
+	 *
+	 * @return the configuration as a string
+	 */
+	public String build() {
+		StringBuilder sb = new StringBuilder();
+		appendPrefix(sb);
+		// Build child items
+		for (ContentBuilder item : items) {
+			sb.append(item.build());
+		}
+		// Any ad-hoc content goes here
+		sb.append(content);
+		appendSuffix(sb);
+		return sb.toString();
+	}
+
+	/**
+	 * Adds the content.
+	 *
+	 * @param item
+	 *            the item
+	 */
+	public void addContent(ContentBuilder item) {
+		items.add(item);
+	}
+
+	/**
+	 * Adds the content.
+	 *
+	 * @param stringContent
+	 *            the string content
+	 */
+	public void addContent(String stringContent) {
+		content.append(stringContent);
+	}
+
+	/**
+	 * Append content as a new line.
+	 *
+	 * @param stringContent
+	 *            the string
+	 */
+	public void appendLine(String stringContent) {
+		content.append(indent).append(stringContent).append(System.lineSeparator());
+	}
+
+	/**
+	 * Append properties.
+	 *
+	 * @param props
+	 *            the props
+	 */
+	public void appendProperties(Properties props) {
+		@SuppressWarnings("unchecked")
+		Enumeration<String> e = (Enumeration<String>) props.propertyNames();
+		while (e.hasMoreElements()) {
+			String key = e.nextElement();
+			appendValue(key, props.get(key));
+		}
+	}
+
+	/**
+	 * Append value.
+	 *
+	 * @param key
+	 *            the key
+	 * @param value
+	 *            the value
+	 * @return
+	 */
+	public ContentBuilder appendValue(String key, Object value) {
+		if (value == null) {
+			return this;
+		}
+
+		addContent(indent + "\t" + key + " ");
+
+		if (value instanceof String) {
+			addStringValue((String) value);
+		} else if (value instanceof Number) {
+			addStringValue(value.toString());
+		} else if (value instanceof List<?>) {
+			boolean first = true;
+			for (Object element : (List<?>) value) {
+				if (!first) {
+					addContent(", ");
+				}
+				addStringValue((String) element);
+				first = false;
+			}
+		} else if (value instanceof Properties) {
+			appendLine("{");
+			appendProperties((Properties) value);
+			appendLine("}");
+		} else {
+			throw new IllegalArgumentException(key);
+		}
+		addContent(System.lineSeparator());
+
+		return this;
+	}
+
+	/**
+	 * Adds the string value.
+	 *
+	 * @param value
+	 *            the value
+	 */
+	private void addStringValue(String value) {
+		addContent("'" + value + "'");
+	}
+
+	/**
+	 * Append suffix.
+	 *
+	 * @param sb
+	 *            the sb
+	 */
+	private void appendSuffix(StringBuilder sb) {
+		if (contentName != null) {
+			sb.append(indent).append("}").append(System.lineSeparator());
+		}
+	}
+
+	/**
+	 * Append prefix.
+	 *
+	 * @param sb
+	 *            the sb
+	 */
+	private void appendPrefix(StringBuilder sb) {
+		if (contentName != null) {
+			sb.append(indent);
+			sb.append(contentName);
+			sb.append(" {").append(System.lineSeparator());
+		}
+	}
+
+}
\ No newline at end of file
diff --git a/src/main/java/org/onap/aai/validation/ruledriven/configuration/build/EntityBuilder.java b/src/main/java/org/onap/aai/validation/ruledriven/configuration/build/EntityBuilder.java
new file mode 100644
index 0000000..166ae50
--- /dev/null
+++ b/src/main/java/org/onap/aai/validation/ruledriven/configuration/build/EntityBuilder.java
@@ -0,0 +1,70 @@
+/*
+ * ============LICENSE_START===================================================
+ * Copyright (c) 2018 Amdocs
+ * ============================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=====================================================
+ */
+package org.onap.aai.validation.ruledriven.configuration.build;
+
+import java.util.Properties;
+import org.onap.aai.validation.ruledriven.configuration.EntitySection;
+import org.onap.aai.validation.ruledriven.configuration.RuleSection;
+
+/**
+ * Builder for entity config section
+ *
+ */
+public class EntityBuilder extends ContentBuilder {
+
+	/**
+	 * Create an empty entity section
+	 */
+	public EntityBuilder() {
+		super("entity");
+	}
+
+	/**
+	 * @param auditConfiguration
+	 */
+	public EntityBuilder(EntitySection auditConfiguration) {
+		this();
+		appendValue("name", auditConfiguration.getName());
+
+		for (RuleSection rule : auditConfiguration.getRules()) {
+			addContent(new ValidationBuilder(rule).toString());
+		}
+	}
+
+	/**
+	 * Add an empty validation section to this entity
+	 *
+	 * @return
+	 */
+	public ValidationBuilder validation() {
+		ValidationBuilder item = new ValidationBuilder();
+		addContent(item);
+		return item;
+	}
+
+	/**
+	 * @param props
+	 * @return
+	 */
+	public ValidationBuilder validation(Properties props) {
+		ValidationBuilder item = validation();
+		item.appendProperties(props);
+		return item;
+	}
+
+}
\ No newline at end of file
diff --git a/src/main/java/org/onap/aai/validation/ruledriven/configuration/build/RuleBuilder.java b/src/main/java/org/onap/aai/validation/ruledriven/configuration/build/RuleBuilder.java
new file mode 100644
index 0000000..07fb5b4
--- /dev/null
+++ b/src/main/java/org/onap/aai/validation/ruledriven/configuration/build/RuleBuilder.java
@@ -0,0 +1,59 @@
+/*
+ * ============LICENSE_START===================================================
+ * Copyright (c) 2018 Amdocs
+ * ============================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=====================================================
+ */
+package org.onap.aai.validation.ruledriven.configuration.build;
+
+import org.onap.aai.validation.ruledriven.configuration.RuleSection;
+
+/**
+ * Builder for rule config section.
+ */
+public class RuleBuilder extends ContentBuilder {
+
+	/**
+	 * Instantiates a new rule builder.
+	 */
+	public RuleBuilder() {
+		super("rule");
+	}
+
+	/**
+	 * Instantiates a new rule builder using the existing rule configuration
+	 *
+	 * @param ruleConfig
+	 *            the rule configuration to clone
+	 * @param indent
+	 *            the indent/prefix for the section
+	 */
+	public RuleBuilder(RuleSection ruleConfig, String indent) {
+		this();
+		this.indent = indent;
+		if (ruleConfig.isGeneric()) {
+			appendLine(indent + "\t// Generic Rule");
+		}
+		appendValue("name", ruleConfig.getName());
+		appendValue("category", ruleConfig.getCategory());
+		appendValue("description", ruleConfig.getDescription());
+		appendValue("severity", ruleConfig.getSeverity());
+		if (ruleConfig.isGeneric()) {
+			appendLine(indent + "\t// Passing " + ruleConfig.getAttributes());
+		}
+		appendValue("attributes", ruleConfig.getExpressionFieldNames());
+		appendValue("validate", ruleConfig.getExpression());
+	}
+
+}
\ No newline at end of file
diff --git a/src/main/java/org/onap/aai/validation/ruledriven/configuration/build/UseRuleBuilder.java b/src/main/java/org/onap/aai/validation/ruledriven/configuration/build/UseRuleBuilder.java
new file mode 100644
index 0000000..fe72bac
--- /dev/null
+++ b/src/main/java/org/onap/aai/validation/ruledriven/configuration/build/UseRuleBuilder.java
@@ -0,0 +1,46 @@
+/*
+ * ============LICENSE_START===================================================
+ * Copyright (c) 2018 Amdocs
+ * ============================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=====================================================
+ */
+package org.onap.aai.validation.ruledriven.configuration.build;
+
+import org.onap.aai.validation.ruledriven.configuration.RuleSection;
+
+/**
+ * Content Builder for a useRule section
+ *
+ */
+public class UseRuleBuilder extends ContentBuilder {
+
+	/**
+	 * Build a useRule section
+	 */
+	public UseRuleBuilder() {
+		super("useRule");
+	}
+
+	/**
+	 * @param ruleConfig
+	 * @param indent
+	 */
+	public UseRuleBuilder(RuleSection ruleConfig, String indent) {
+		this();
+		this.indent = indent;
+		appendValue("name", ruleConfig.getName());
+		appendValue("attributes", ruleConfig.getAttributes());
+	}
+
+}
\ No newline at end of file
diff --git a/src/main/java/org/onap/aai/validation/ruledriven/configuration/build/ValidationBuilder.java b/src/main/java/org/onap/aai/validation/ruledriven/configuration/build/ValidationBuilder.java
new file mode 100644
index 0000000..44f3c4c
--- /dev/null
+++ b/src/main/java/org/onap/aai/validation/ruledriven/configuration/build/ValidationBuilder.java
@@ -0,0 +1,78 @@
+/*
+ * ============LICENSE_START===================================================
+ * Copyright (c) 2018 Amdocs
+ * ============================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=====================================================
+ */
+package org.onap.aai.validation.ruledriven.configuration.build;
+
+import org.onap.aai.validation.ruledriven.configuration.RuleSection;
+
+/**
+ * Builder for validation config section
+ *
+ */
+public class ValidationBuilder extends ContentBuilder {
+	/**
+	 * Create an empty validation section
+	 */
+	public ValidationBuilder() {
+		super("validation");
+		indent = "\t";
+	}
+
+	/**
+	 * Create a validation section using the existing rule configuration
+	 *
+	 * @param ruleConfig
+	 */
+	public ValidationBuilder(RuleSection ruleConfig) {
+		this();
+		appendValue("object", ruleConfig.getType());
+		appendValue("objectId", ruleConfig.getObjectId());
+		if (ruleConfig.isGeneric()) {
+			addContent(new UseRuleBuilder(ruleConfig, indent + "\t").toString());
+		} else {
+			addContent(new RuleBuilder(ruleConfig, indent + "\t").toString());
+		}
+	}
+
+	/**
+	 * Add a useRule section
+	 *
+	 * @param name
+	 * @return the new useRule section
+	 */
+	public UseRuleBuilder useRule(String name) {
+		UseRuleBuilder item = new UseRuleBuilder();
+		item.indent = "\t\t";
+		item.appendValue("name", name);
+		addContent(item);
+		return item;
+	}
+
+	/**
+	 * Add a rule section comprising the specified name item
+	 *
+	 * @param name
+	 * @return
+	 */
+	public RuleBuilder rule(String name) {
+		RuleBuilder item = new RuleBuilder();
+		item.indent = "\t\t";
+		item.appendValue("name", name);
+		addContent(item);
+		return item;
+	}
+}
\ No newline at end of file
diff --git a/src/main/java/org/onap/aai/validation/ruledriven/rule/GroovyRule.java b/src/main/java/org/onap/aai/validation/ruledriven/rule/GroovyRule.java
new file mode 100644
index 0000000..b151f6b
--- /dev/null
+++ b/src/main/java/org/onap/aai/validation/ruledriven/rule/GroovyRule.java
@@ -0,0 +1,323 @@
+/*
+ * ============LICENSE_START===================================================
+ * Copyright (c) 2018 Amdocs
+ * ============================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=====================================================
+ */
+package org.onap.aai.validation.ruledriven.rule;
+
+import groovy.lang.GroovyClassLoader;
+import groovy.lang.GroovyObject;
+import groovy.lang.MetaMethod;
+import groovy.lang.MissingMethodException;
+import groovy.lang.MissingPropertyException;
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+import java.util.Scanner;
+import java.util.regex.Pattern;
+import org.codehaus.groovy.control.CompilationFailedException;
+import org.codehaus.groovy.runtime.InvokerInvocationException;
+import org.onap.aai.cl.api.Logger;
+import org.onap.aai.validation.logging.LogHelper;
+import org.onap.aai.validation.reader.data.AttributeValues;
+import org.onap.aai.validation.ruledriven.configuration.GroovyConfigurationException;
+import org.onap.aai.validation.ruledriven.configuration.RuleSection;
+import org.onap.aai.validation.util.StringUtils;
+
+/**
+ * Rule based on a Groovy script
+ *
+ */
+public class GroovyRule implements Rule {
+
+    private static final Logger applicationLogger = LogHelper.INSTANCE;
+
+    /**
+     * Do not allow special characters (e.g. ?) in an attribute name. Hyphens and underscores are accepted.
+     */
+    private static final Pattern ATTRIBUTE_NAME_WHITELIST = Pattern.compile("^[a-zA-Z0-9-_.\\*\\[\\]]*$");
+    private static final Pattern ATTRIBUTE_NAME_BLACKLIST = Pattern.compile("^(|null)$");
+
+    private String errorCategory;
+    private String errorMessage;
+    private String severity;
+    private List<String> attributes;
+    private List<String> attributePaths; // where in the JSON entity to read the attributes from
+
+    private String methodName;
+    private GroovyObject groovyObject;
+    private List<String> originalFields;
+    private String originalExpression;
+    private String groovyExpression; // NOSONAR stored for debugging purposes
+    private boolean ruleIsValid = true;
+    private String name;
+
+
+    /**
+     * @param ruleConfig
+     * @throws InstantiationException
+     * @throws IllegalAccessException
+     * @throws IOException
+     * @throws GroovyConfigurationException
+     */
+    public GroovyRule(RuleSection ruleConfig)
+            throws InstantiationException, IllegalAccessException, IOException, GroovyConfigurationException {
+        setName(ruleConfig.getName());
+        setErrorCategory(ruleConfig.getCategory());
+        setErrorMessage(ruleConfig.getErrorMessage());
+        setSeverity(ruleConfig.getSeverity());
+        setAttributes(ruleConfig.getAttributes());
+        setAttributePaths(ruleConfig.getAttributes());
+
+        this.originalFields = new ArrayList<>();
+        for (String field : ruleConfig.getExpressionFieldNames()) {
+            originalFields.add(StringUtils.stripPrefix(field, "."));
+        }
+
+        Class<?> groovyClass = createRule(ruleConfig.getExpressionFieldNames(), ruleConfig.getExpression());
+
+        if (groovyClass != null) {
+            groovyObject = (GroovyObject) groovyClass.newInstance();
+
+            for (MetaMethod method : groovyObject.getMetaClass().getMethods()) {
+                if (method.getName().startsWith("rule")) {
+                    methodName = method.getName();
+                }
+            }
+
+            try {
+                executeWithSampleData();
+            } catch (IllegalArgumentException e) { // NOSONAR
+                if (e.getCause() instanceof InvokerInvocationException
+                        && e.getCause().getCause() instanceof MissingMethodException) {
+                    applicationLogger
+                            .debug("WARNING: Rule \"" + getName() + "\" does not accept \"1\" for all input values");
+                } else {
+                    ruleIsValid = false;
+                }
+            }
+        } else {
+            ruleIsValid = false;
+        }
+    }
+
+    public boolean isValid() {
+        return ruleIsValid;
+    }
+
+    /**
+     * Run the rule expression on the specified attribute values
+     *
+     * @param attributeValues
+     * @return
+     */
+    @Override
+    public Boolean execute(AttributeValues attributeValues) {
+        // Obtain the values of each of the attributes to pass into the rule
+        List<Object> valueList = new ArrayList<>();
+        for (String attrName : this.attributePaths) {
+            valueList.add(attributeValues.get(attrName));
+        }
+        Object[] attrValuesArray = valueList.toArray();
+        return execute(attrValuesArray);
+    }
+
+    /**
+     * Apply the rule to some attribute(s)
+     *
+     * @param values
+     *
+     * @param groovyObject an instance/object of a Groovy class that implements one or more rule methods
+     * @return the Boolean result of evaluating the expression
+     */
+    @Override
+    public Boolean execute(Object... values) {
+        Object result = null;
+        try {
+            result = groovyObject.invokeMethod(getRuleMethod(), values);
+        } catch (MissingPropertyException | MissingMethodException | InvokerInvocationException e) {
+            throw new IllegalArgumentException(e);
+        } catch (NullPointerException e) {
+            throw new IllegalArgumentException("Argument is null", e);
+        }
+
+        if (result instanceof Number) {
+            return !result.equals(0);
+        } else {
+            return (Boolean) result;
+        }
+    }
+
+    @Override
+    public String toString() {
+        return "GroovyRule \"" + name + "\" " + attributePaths + " -> " + originalFields + " {" + originalExpression
+                + "}";
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    @Override
+    public String getName() {
+        return name;
+    }
+
+    @Override
+    public String getErrorCategory() {
+        return errorCategory;
+    }
+
+    public void setErrorCategory(String errorCategory) {
+        this.errorCategory = errorCategory;
+    }
+
+    @Override
+    public String getErrorMessage() {
+        return errorMessage;
+    }
+
+    public void setErrorMessage(String errorMessage) {
+        this.errorMessage = errorMessage;
+    }
+
+    @Override
+    public String getSeverity() {
+        return severity;
+    }
+
+    public void setSeverity(String severity) {
+        this.severity = severity;
+    }
+
+    @Override
+    public List<String> getAttributePaths() {
+        return attributePaths;
+    }
+
+    private String getRuleMethod() {
+        return methodName;
+    }
+
+    private void setAttributePaths(List<String> attributePaths) {
+        this.attributePaths = attributePaths;
+    }
+
+    private void setAttributes(List<String> attributes) {
+        this.attributes = new ArrayList<>();
+        for (String attribute : attributes) {
+            // Strip any prefixes containing the . character
+            this.attributes.add(attribute.substring(attribute.lastIndexOf('.') + 1));
+        }
+    }
+
+    /**
+     * @param fields
+     * @param expression
+     * @return
+     * @throws IOException
+     * @throws GroovyConfigurationException
+     */
+    private Class<?> createRule(List<String> fields, String expression)
+            throws IOException, GroovyConfigurationException {
+        originalExpression = expression;
+        groovyExpression = expression;
+        String methodParams = "";
+
+        int i = 1;
+        for (String attribute : fields) {
+            if (isValidAttributeName(attribute)) {
+                String fieldName = "field" + i++;
+                methodParams = appendParameter(methodParams, fieldName);
+                // Strip any prefixes from the attribute name in case of JayWay expression attributes.
+                attribute = StringUtils.stripPrefix(attribute, ".");
+                String regex = "\\b" + attribute + "\\b(?!\\()";
+                groovyExpression = groovyExpression.replaceAll(regex, fieldName);
+            } else {
+                ruleIsValid = false;
+                return null;
+            }
+        }
+
+        return loadGroovyClass("def rule(" + methodParams + ") {" + groovyExpression + "}");
+    }
+
+    private String appendParameter(String methodParams, String fieldName) {
+        StringBuilder newParams = new StringBuilder();
+        if (methodParams.length() > 0) {
+            newParams.append(methodParams).append(", ");
+        }
+        newParams.append("Object ").append(fieldName);
+        return newParams.toString();
+    }
+
+    private boolean isValidAttributeName(String attributeName) {
+        if (ATTRIBUTE_NAME_BLACKLIST.matcher(attributeName).matches()) {
+            return false;
+        }
+
+        if (!ATTRIBUTE_NAME_WHITELIST.matcher(attributeName).matches()) {
+            return false;
+        }
+
+        // Make sure that the attribute name is NOT purely a number
+        try (Scanner sc = new Scanner(attributeName.trim())) {
+            if (sc.hasNextInt()) {
+                sc.nextInt(); // Consume the integer
+                return sc.hasNext(); // Name is valid if there is more content
+            }
+        }
+
+        return true; // Not an integer
+    }
+
+    private void executeWithSampleData() {
+        Object[] values = new Object[attributes.size()];
+        int i = 0;
+        for (String attribute : attributes) {
+            if (attribute.contains("[*]")) {
+                values[i++] = Arrays.asList("{}");
+            } else {
+                values[i++] = "1";
+            }
+        }
+        execute(values);
+    }
+
+    /**
+     * Load and parse a Groovy script to create an anonymous class
+     *
+     * @param script a file containing the Groovy scripting language
+     * @return the Java Class for accessing the Groovy methods
+     * @throws IOException
+     * @throws GroovyConfigurationException
+     */
+    @SuppressWarnings("rawtypes")
+    private static Class loadGroovyClass(String expression) throws IOException, GroovyConfigurationException {
+        ClassLoader parent = GroovyRule.class.getClassLoader();
+        GroovyClassLoader loader = new GroovyClassLoader(parent);
+        Class groovyClass;
+        try {
+            groovyClass = loader.parseClass(expression);
+        } catch (CompilationFailedException e) {
+            throw new GroovyConfigurationException(e);
+        } finally {
+            loader.close();
+        }
+        return groovyClass;
+    }
+
+}
diff --git a/src/main/java/org/onap/aai/validation/ruledriven/rule/Rule.java b/src/main/java/org/onap/aai/validation/ruledriven/rule/Rule.java
new file mode 100644
index 0000000..1196db0
--- /dev/null
+++ b/src/main/java/org/onap/aai/validation/ruledriven/rule/Rule.java
@@ -0,0 +1,81 @@
+/*
+ * ============LICENSE_START===================================================
+ * Copyright (c) 2018 Amdocs
+ * ============================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=====================================================
+ */
+package org.onap.aai.validation.ruledriven.rule;
+
+import java.util.List;
+import org.onap.aai.validation.reader.data.AttributeValues;
+
+/**
+ * A rule that accepts one or more attributes and returns a Boolean result (when executed)
+ */
+public interface Rule {
+
+	/**
+	 * Gets the name of the rule
+	 *
+	 * @return the name
+	 */
+	String getName();
+
+	/**
+	 * Gets the error message.
+	 *
+	 * @return the error message
+	 */
+	String getErrorMessage();
+
+	/**
+	 * Gets the error category.
+	 *
+	 * @return the error category
+	 */
+	String getErrorCategory();
+
+	/**
+	 * Gets the severity.
+	 *
+	 * @return the severity
+	 */
+	String getSeverity();
+
+	/**
+	 * Gets the paths to the attributes to pass to the rule
+	 *
+	 * @return the attribute paths
+	 */
+	List<String> getAttributePaths();
+
+	/**
+	 * Execute the rule.
+	 *
+	 * @param values
+	 *            the attribute values to pass to the rule
+	 * @return a boolean representing the rule evaluation (meaning success/failure)
+	 */
+	Boolean execute(AttributeValues values);
+
+	/**
+	 * Execute the rule.
+	 *
+	 * @param values
+	 *            the attribute values to pass to the rule
+	 * @return a boolean representing the rule evaluation (meaning success/failure)
+	 */
+	Boolean execute(Object... values);
+
+}
diff --git a/src/main/java/org/onap/aai/validation/services/EventPollingService.java b/src/main/java/org/onap/aai/validation/services/EventPollingService.java
new file mode 100644
index 0000000..8b38031
--- /dev/null
+++ b/src/main/java/org/onap/aai/validation/services/EventPollingService.java
@@ -0,0 +1,121 @@
+/*
+ * ============LICENSE_START===================================================
+ * Copyright (c) 2018 Amdocs
+ * ============================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=====================================================
+ */
+package org.onap.aai.validation.services;
+
+import java.net.MalformedURLException;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.UUID;
+
+import javax.inject.Inject;
+
+import org.springframework.stereotype.Service;
+
+import org.onap.aai.event.client.DMaaPEventConsumer;
+import org.onap.aai.validation.config.TopicConfig;
+import org.onap.aai.validation.config.TopicConfig.Topic;
+import org.onap.aai.validation.controller.ValidationController;
+import org.onap.aai.validation.exception.ValidationServiceError;
+import org.onap.aai.validation.exception.ValidationServiceException;
+import org.onap.aai.validation.logging.ApplicationMsgs;
+import org.onap.aai.validation.logging.LogHelper;
+import org.onap.aai.validation.logging.LogHelper.MdcParameter;
+import com.google.common.collect.Iterables;
+
+/**
+ * Event Polling Service
+ *
+ */
+@Service
+public class EventPollingService implements Runnable {
+
+    private static final LogHelper applicationLogger = LogHelper.INSTANCE;
+
+    private List<DMaaPEventConsumer> consumers;
+
+    private ValidationController validationController;
+
+    /**
+     * Instantiates an EventPollingService instance using the supplied configuration.
+     *
+     * @param topicConfig
+     * @throws ValidationServiceException
+     */
+    @Inject
+    public EventPollingService(TopicConfig topicConfig) throws ValidationServiceException {
+        consumers = new ArrayList<>();
+        for (Topic topic : topicConfig.getConsumerTopics()) {
+            try {
+                consumers.add(new DMaaPEventConsumer(topic.getHost(), topic.getName(), topic.getUsername(),
+                        topic.getPassword(), topic.getConsumerGroup(), topic.getConsumerId(),
+                        DMaaPEventConsumer.DEFAULT_MESSAGE_WAIT_TIMEOUT, DMaaPEventConsumer.DEFAULT_MESSAGE_LIMIT,
+                        topic.getTransportType()));
+            } catch (MalformedURLException e) {
+                throw new ValidationServiceException(ValidationServiceError.EVENT_CLIENT_CONSUMER_INIT_ERROR, e);
+            }
+        }
+    }
+
+    @Override
+    public void run() {
+        applicationLogger.info(ApplicationMsgs.POLL_EVENTS);
+        try {
+            for (DMaaPEventConsumer consumer : consumers) {
+                for (String event : consumeEvents(consumer)) {
+                    // The event does not have a transaction ID so create one for logging purposes
+                    applicationLogger.setContextValue(MdcParameter.REQUEST_ID, UUID.randomUUID().toString());
+                    validationController.execute(event, "topic");
+                }
+            }
+        } catch (Exception e) {
+            // This could be a temporary issue, so the exception is swallowed
+            applicationLogger.error(ApplicationMsgs.INVOKE_EVENT_CONSUMER_ERROR, e);
+        } catch (Throwable t) { // NOSONAR
+            // E.g. We may catch an IllegalArgumentException caused by invalid configuration
+            applicationLogger.error(ApplicationMsgs.INVOKE_EVENT_CONSUMER_ERROR, t);
+
+            // Add these details to the status report available via the controller
+            validationController.recordThrowable(t);
+
+            // For non IO exceptions, rethrow in order to cause the executor to stop scheduling
+            throw t;
+        } finally {
+            applicationLogger.clearContextValue(MdcParameter.REQUEST_ID);
+        }
+    }
+
+    /* Getters and Setters for Spring injection */
+
+    public ValidationController getValidationController() {
+        return validationController;
+    }
+
+    public void setValidationController(ValidationController validationController) throws ValidationServiceException {
+        this.validationController = validationController;
+        // Instruct the validation controller to load and validate its configuration
+        this.validationController.initialise();
+    }
+
+    private Iterable<String> consumeEvents(DMaaPEventConsumer consumer) throws Exception {
+        applicationLogger.clearContextValue(MdcParameter.REQUEST_ID);
+        applicationLogger.debug("Querying consumer " + consumer);
+        Iterable<String> events = consumer.consume();
+        applicationLogger.info(ApplicationMsgs.NUMBER_OF_MESSAGES_CONSUMED, Integer.toString(Iterables.size(events)));
+        return events;
+    }
+}
diff --git a/src/main/java/org/onap/aai/validation/services/InfoService.java b/src/main/java/org/onap/aai/validation/services/InfoService.java
new file mode 100644
index 0000000..5f2b625
--- /dev/null
+++ b/src/main/java/org/onap/aai/validation/services/InfoService.java
@@ -0,0 +1,57 @@
+/*
+ * ============LICENSE_START===================================================
+ * Copyright (c) 2018 Amdocs
+ * ============================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=====================================================
+ */
+package org.onap.aai.validation.services;
+
+import org.onap.aai.validation.controller.ValidationController;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.RequestMethod;
+import org.springframework.web.bind.annotation.ResponseBody;
+import org.springframework.web.bind.annotation.RestController;
+
+/**
+ * Information Service for the Validation Controller. Return status details to the caller.
+ * 
+ */
+@RestController
+@RequestMapping("/services/validation-service/v1/core/core-service")
+public class InfoService {
+
+    @Autowired
+    private ValidationController validationController;
+
+    public ValidationController getValidationController() {
+        return validationController;
+    }
+
+    public void setValidationController(ValidationController validationController) {
+        this.validationController = validationController;
+    }
+
+    /**
+     * @param format is an optional setting - html requests an HTML format
+     * @return a formatted status report
+     */
+    @RequestMapping(value = "/info", method = RequestMethod.GET, produces = "text/plain")
+    @ResponseBody
+    public String getInfo() {
+        validationController.incrementInfoCount();
+        return "Status: Up\n" + validationController.statusReport().toString() + "\n";
+    }
+
+}
diff --git a/src/main/java/org/onap/aai/validation/services/RequestHeaders.java b/src/main/java/org/onap/aai/validation/services/RequestHeaders.java
new file mode 100644
index 0000000..1d12600
--- /dev/null
+++ b/src/main/java/org/onap/aai/validation/services/RequestHeaders.java
@@ -0,0 +1,53 @@
+/*
+ * ============LICENSE_START===================================================
+ * Copyright (c) 2018 Amdocs
+ * ============================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=====================================================
+ */
+package org.onap.aai.validation.services;
+
+import org.springframework.http.HttpHeaders;
+
+/**
+ * Bean to represent the ONAP request/transaction IDs required for EELF logging.
+ *
+ */
+public class RequestHeaders {
+
+    // ONAP request ID a.k.a. transaction ID or correlation ID
+    public static final String HEADER_REQUEST_ID = "X-ECOMP-RequestID";
+    public static final String HEADER_SERVICE_INSTANCE_ID = "X-ECOMP-ServiceInstanceID";
+
+    private String requestId;
+    private String instanceId;
+
+    public RequestHeaders(HttpHeaders headers) {
+        requestId = headers.getFirst(RequestHeaders.HEADER_REQUEST_ID);
+        instanceId = headers.getFirst(RequestHeaders.HEADER_SERVICE_INSTANCE_ID);
+    }
+
+    public String getRequestId() {
+        return requestId;
+    }
+
+    public String getInstanceId() {
+        return instanceId;
+    }
+
+    @Override
+    public String toString() {
+        return "RequestHeaders [requestId=" + requestId + ", instanceId=" + instanceId + "]";
+    }
+
+}
diff --git a/src/main/java/org/onap/aai/validation/services/ValidateService.java b/src/main/java/org/onap/aai/validation/services/ValidateService.java
new file mode 100644
index 0000000..4ef5e7f
--- /dev/null
+++ b/src/main/java/org/onap/aai/validation/services/ValidateService.java
@@ -0,0 +1,77 @@
+/*
+ * ============LICENSE_START===================================================
+ * Copyright (c) 2018 Amdocs
+ * ============================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=====================================================
+ */
+package org.onap.aai.validation.services;
+
+import javax.servlet.http.HttpServletRequest;
+import org.springframework.http.HttpHeaders;
+import org.springframework.http.ResponseEntity;
+import org.springframework.web.bind.annotation.RequestBody;
+import org.springframework.web.bind.annotation.RequestHeader;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.RequestMethod;
+import org.springframework.web.bind.annotation.ResponseBody;
+import org.springframework.web.bind.annotation.RestController;
+
+/**
+ * Validates an event (containing details of an entity) and synchronously returns the details of the validation
+ * result(s) including any violations that were detected. Note that in the current version there is expected to be one
+ * and only one validation result per event.
+ */
+@RestController
+@RequestMapping("/services/validation-service/v1/app")
+public interface ValidateService { // NOSONAR
+    /**
+     * Validate an event and, if successful, return the result(s) in JSON format. Note that not every event is validated
+     * and so the set of results may be empty. In the event of an error/exception then plain text is returned containing
+     * the exception details.
+     *
+     * <h4>The HTTP message body must be comprised of a single JSON object containing the following members (nested JSON
+     * elements)</h4> <B>event-header</B> a JSON object which contains the following members:
+     * <ul>
+     * <li><B>domain</B> the value must match with the event domain expected by the Validation Service
+     * <li><B>action</B> the value must not be present in the list of excluded event actions (default list: DELETE)</li>
+     * <li><B>event-type</B> the value must match with one of the expected event types (either for rule-driven or for
+     * model-driven validation)</li>
+     * <li><B>top-entity-type</B> indicating the type of the entity member (see below)</li>
+     * <li><B>entity-type</B> the value must match with an A&AI entity defined by the OXM model. This value identifies
+     * the object to be validated</li>
+     * <li><B>entity-link</B> the value indicates the source of the entity. This is expected to begin with the text
+     * https://host/aai/vX/</li>
+     * </ul>
+     * <B> entity</B> a JSON object representing the top-level entity. This object must contain the single entity
+     * instance to be validated, either
+     * <ul>
+     * <li>contained by a parent entity of a different type (indicated by top-entity-type)</li>
+     * <li>or as a stand-alone JSON object (entity-type will have the same value as top-entity-type)</li>
+     * </ul>
+     *
+     * @param event a JSON object representing an event
+     * @return an HTTP Response containing either a JSON array of ValidationResult objects or a plain-text error message
+     *
+     * @responseMessage 200 Success
+     * @responseMessage 400 Bad Request
+     * @responseMessage 500 Internal Server Error
+     *
+     */
+    @RequestMapping(value = "/validate", method = RequestMethod.POST, produces = {"application/json", "text/plain"})
+    @ResponseBody
+    public ResponseEntity<String> validate(@RequestHeader HttpHeaders headers, HttpServletRequest servletRequest,
+            @RequestBody String event);
+
+    public ResponseEntity<String> validate(String event);
+}
diff --git a/src/main/java/org/onap/aai/validation/services/ValidateServiceImpl.java b/src/main/java/org/onap/aai/validation/services/ValidateServiceImpl.java
new file mode 100644
index 0000000..54f8b5a
--- /dev/null
+++ b/src/main/java/org/onap/aai/validation/services/ValidateServiceImpl.java
@@ -0,0 +1,160 @@
+/*
+ * ============LICENSE_START===================================================
+ * Copyright (c) 2018 Amdocs
+ * ============================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=====================================================
+ */
+package org.onap.aai.validation.services;
+
+import java.util.Optional;
+import java.util.UUID;
+import javax.inject.Inject;
+import javax.servlet.http.HttpServletRequest;
+import javax.ws.rs.core.Response;
+import org.onap.aai.auth.AAIMicroServiceAuth;
+import org.onap.aai.validation.controller.ValidationController;
+import org.onap.aai.validation.controller.ValidationController.Result;
+import org.onap.aai.validation.logging.ApplicationMsgs;
+import org.onap.aai.validation.logging.LogHelper;
+import org.onap.aai.validation.logging.LogHelper.MdcParameter;
+import org.onap.aai.validation.logging.LogHelper.StatusCode;
+import org.springframework.http.HttpHeaders;
+import org.springframework.http.HttpStatus;
+import org.springframework.http.MediaType;
+import org.springframework.http.ResponseEntity;
+import org.springframework.web.bind.annotation.RequestBody;
+import org.springframework.web.bind.annotation.RequestHeader;
+import org.springframework.web.servlet.HandlerMapping;
+
+/**
+ * Validation Service HTTP interface implementation.
+ *
+ */
+public class ValidateServiceImpl implements ValidateService {
+
+    private static final LogHelper applicationLogger = LogHelper.INSTANCE;
+
+    /**
+     * This message is returned in the HTTP Response when an event is filtered (deliberately not validated).
+     */
+    public static final String DEFAULT_MESSAGE_FOR_FILTERED_EVENTS =
+            "No validation results available. The action value may have caused the event to be filtered. Otherwise the event type or domain may be invalid.";
+
+    /**
+     * Events are passed to the controller which will execute the validation(s).
+     */
+    private ValidationController controller;
+    private AAIMicroServiceAuth aaiMicroServiceAuth;
+
+    /**
+     * @param controller
+     */
+    @Inject
+    public ValidateServiceImpl(final ValidationController controller, final AAIMicroServiceAuth aaiMicroServiceAuth) {
+        this.controller = controller;
+        this.aaiMicroServiceAuth = aaiMicroServiceAuth;
+    }
+
+    @Override
+    public ResponseEntity<String> validate(@RequestHeader HttpHeaders headers, HttpServletRequest servletRequest,
+            @RequestBody String event) {
+        applicationLogger.startAudit(headers, servletRequest);
+        applicationLogger.info(ApplicationMsgs.MESSAGE_VALIDATION_REQUEST, headers + event);
+
+        String path = (String) servletRequest.getAttribute(HandlerMapping.PATH_WITHIN_HANDLER_MAPPING_ATTRIBUTE);
+
+        if (applicationLogger.isDebugEnabled()) {
+            applicationLogger.debug(String.format(
+                    "Received request. Path \"%s\", HttpHeaders \"%s\", ServletRequest \"%s\", Request Body \"%s\"",
+                    path, headers, servletRequest.getMethod(), event));
+        }
+
+        // Additional name/value pairs according to EELF guidelines
+        applicationLogger.setContextValue("Protocol", "https");
+        applicationLogger.setContextValue("Method", "POST");
+        applicationLogger.setContextValue("Path", path);
+        applicationLogger.setContextValue("Query", servletRequest.getQueryString());
+
+        RequestHeaders requestHeaders = new RequestHeaders(headers);
+        String requestId = requestHeaders.getRequestId();
+        if (requestId == null) {
+            requestId = UUID.randomUUID().toString();
+            applicationLogger.info(ApplicationMsgs.MISSING_REQUEST_ID, requestId);
+            applicationLogger.setContextValue(MdcParameter.REQUEST_ID, requestId);
+        }
+
+        ResponseEntity<String> response;
+
+        try {
+            boolean authorized =
+                    aaiMicroServiceAuth.validateRequest(servletRequest, servletRequest.getMethod(), "validate");
+
+            if (!authorized) {
+                response = ResponseEntity.status(HttpStatus.UNAUTHORIZED)
+                        .body("User not authorized to perform the operation.");
+            } else {
+                response = validate(event);
+            }
+        } catch (Exception e) {
+            applicationLogger.error(ApplicationMsgs.PROCESS_REQUEST_ERROR, e);
+            return ResponseEntity.status(HttpStatus.INTERNAL_SERVER_ERROR).body(
+                    "Error while processing request. Please check the validation service logs for more details.\n");
+        }
+
+        StatusCode statusDescription;
+        int statusCode = response.getStatusCodeValue();
+        if (Response.Status.Family.familyOf(statusCode).equals(Response.Status.Family.SUCCESSFUL)) {
+            statusDescription = StatusCode.COMPLETE;
+        } else {
+            statusDescription = StatusCode.ERROR;
+        }
+        applicationLogger.logAudit(statusDescription, Integer.toString(statusCode),
+                response.getStatusCode().getReasonPhrase(), response.getBody());
+
+        return response;
+    }
+
+    /*
+     * (non-Javadoc)
+     *
+     * @see org.onap.aai.validation.services.ValidateService#validate(java.lang.String)
+     */
+    @Override
+    public ResponseEntity<String> validate(String event) {
+
+        try {
+            // Attempt to validate the event
+            Result result = controller.execute(event, "http");
+
+            if (result.validationSuccessful()) {
+                return ResponseEntity.ok().contentType(MediaType.APPLICATION_JSON)
+                        .body(result.getValidationResultAsJson());
+            } else {
+                Optional<String> errorText = result.getErrorText();
+                if (!errorText.isPresent() || errorText.get().isEmpty()) {
+                    errorText = Optional.of(DEFAULT_MESSAGE_FOR_FILTERED_EVENTS);
+                } else {
+                    applicationLogger.error(ApplicationMsgs.MALFORMED_REQUEST_ERROR, event);
+                }
+                return ResponseEntity.badRequest().body(errorText.orElse(""));
+            }
+        } catch (Exception e) {
+            // Unchecked runtime exception - this is intended to catch potential programming errors.
+            applicationLogger.error(ApplicationMsgs.PROCESS_REQUEST_ERROR, e);
+            return ResponseEntity.status(HttpStatus.INTERNAL_SERVER_ERROR).body(
+                    "Error while processing request. Please check the validation service logs for more details.\n" + e);
+        }
+    }
+
+}
diff --git a/src/main/java/org/onap/aai/validation/servlet/StartupServlet.java b/src/main/java/org/onap/aai/validation/servlet/StartupServlet.java
new file mode 100644
index 0000000..01fdc31
--- /dev/null
+++ b/src/main/java/org/onap/aai/validation/servlet/StartupServlet.java
@@ -0,0 +1,95 @@
+/*
+ * ============LICENSE_START===================================================
+ * Copyright (c) 2018 Amdocs
+ * ============================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=====================================================
+ */
+package org.onap.aai.validation.servlet;
+
+import java.util.concurrent.Executors;
+import java.util.concurrent.TimeUnit;
+
+import javax.annotation.PostConstruct;
+import javax.inject.Inject;
+
+import org.onap.aai.cl.api.Logger;
+import org.onap.aai.validation.config.TopicAdminConfig;
+import org.onap.aai.validation.logging.ApplicationMsgs;
+import org.onap.aai.validation.logging.LogHelper;
+import org.onap.aai.validation.services.EventPollingService;
+import org.springframework.stereotype.Service;
+
+/**
+ * Main application service
+ *
+ */
+@Service
+public class StartupServlet {
+
+    private static final Logger applicationLogger = LogHelper.INSTANCE;
+
+    private static final long DEFAULT_POLLING_INTERVAL = 10;
+
+    private final EventPollingService eventPollingService;
+    private final TopicAdminConfig topicAdminConfig;
+
+    /**
+     * @param eventPollingService
+     * @param topicAdminConfig
+     */
+    @Inject
+    public StartupServlet(EventPollingService eventPollingService, TopicAdminConfig topicAdminConfig) {
+        this.eventPollingService = eventPollingService;
+        this.topicAdminConfig = topicAdminConfig;
+    }
+
+    /**
+     * Called from Spring
+     */
+    @PostConstruct
+    public void init() {
+        applicationLogger.info(ApplicationMsgs.STARTUP_SERVLET_INIT);
+
+        // Schedule a polling service if consuming is enabled.
+        boolean consumingEnabled = topicAdminConfig.isConsumeEnable();
+        if (consumingEnabled) {
+            Long consumerPollingIntervalSeconds = topicAdminConfig.getConsumePollingIntervalSeconds();
+
+            long interval;
+            if (consumerPollingIntervalSeconds == null) {
+                applicationLogger.info(ApplicationMsgs.POLLING_INTERVAL_CONFIG_NOT_PRESENT,
+                        Long.toString(DEFAULT_POLLING_INTERVAL));
+                interval = DEFAULT_POLLING_INTERVAL;
+            } else {
+                interval = consumerPollingIntervalSeconds;
+            }
+
+            applicationLogger.info(ApplicationMsgs.POLLING_FOR_EVENTS, Long.toString(interval));
+            Executors.newSingleThreadScheduledExecutor().scheduleWithFixedDelay(eventPollingService, 0, interval,
+                    TimeUnit.SECONDS);
+        } else {
+            applicationLogger.info(ApplicationMsgs.POLLING_DISABLED);
+        }
+
+        applicationLogger.info(ApplicationMsgs.STARTUP_SERVLET_INIT_SUCCESS);
+    }
+
+    public EventPollingService getEventPollingService() {
+        return eventPollingService;
+    }
+
+    public TopicAdminConfig getTopicAdminConfig() {
+        return topicAdminConfig;
+    }
+}
diff --git a/src/main/java/org/onap/aai/validation/util/GsonUtil.java b/src/main/java/org/onap/aai/validation/util/GsonUtil.java
new file mode 100644
index 0000000..f6525c8
--- /dev/null
+++ b/src/main/java/org/onap/aai/validation/util/GsonUtil.java
@@ -0,0 +1,124 @@
+/*
+ * ============LICENSE_START===================================================
+ * Copyright (c) 2018 Amdocs
+ * ============================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=====================================================
+ */
+package org.onap.aai.validation.util;
+
+import com.google.gson.Gson;
+import com.google.gson.GsonBuilder;
+import com.google.gson.TypeAdapter;
+import com.google.gson.TypeAdapterFactory;
+import com.google.gson.reflect.TypeToken;
+import com.google.gson.stream.JsonReader;
+import com.google.gson.stream.JsonToken;
+import com.google.gson.stream.JsonWriter;
+import java.io.IOException;
+import java.lang.reflect.ParameterizedType;
+import java.lang.reflect.Type;
+import java.util.Optional;
+
+/**
+ * Static utility class
+ *
+ */
+public class GsonUtil {
+
+	/**
+	 * All methods are static.
+	 */
+	private GsonUtil() {
+		// Do not instantiate
+	}
+
+	/**
+	 * Tell Gson how to handle Optional fields. This factory builds a Type Adapter for a class wrapped with Optional
+	 *
+	 */
+	public static class OptionalTypeAdapterFactory implements TypeAdapterFactory {
+		@SuppressWarnings({ "unchecked", "rawtypes" })
+		@Override
+		public <T> TypeAdapter<T> create(Gson gson, TypeToken<T> type) {
+			Class<T> rawType = (Class<T>) type.getRawType();
+			if (rawType != Optional.class) {
+				return null;
+			}
+			final ParameterizedType parameterizedType = (ParameterizedType) type.getType();
+			final Type actualType = parameterizedType.getActualTypeArguments()[0];
+			return new OptionalTypeAdapter(gson.getAdapter(TypeToken.get(actualType)));
+		}
+	}
+
+	/**
+	 * Implementation of the Optional Type Adapter
+	 *
+	 * @param <E>
+	 */
+	public static class OptionalTypeAdapter<E> extends TypeAdapter<Optional<E>> {
+
+		private final TypeAdapter<E> adapter;
+
+		public static final TypeAdapterFactory FACTORY = new OptionalTypeAdapterFactory();
+
+		/**
+		 * @param adapter
+		 */
+		public OptionalTypeAdapter(TypeAdapter<E> adapter) {
+			this.adapter = adapter;
+		}
+
+		@Override
+		public void write(JsonWriter out, Optional<E> value) throws IOException {
+			if (value != null && value.isPresent()) { // NOSONAR
+				adapter.write(out, value.get());
+			} else {
+				boolean nullsAllowed = out.getSerializeNulls();
+				if (nullsAllowed) {
+					out.setSerializeNulls(false);
+				}
+				out.nullValue();
+				if (nullsAllowed) {
+					out.setSerializeNulls(true);
+				}
+			}
+		}
+
+		@Override
+		public Optional<E> read(JsonReader in) throws IOException {
+			final JsonToken peek = in.peek();
+			if (peek != JsonToken.NULL) {
+				return Optional.ofNullable(adapter.read(in));
+			}
+			return Optional.empty();
+		}
+
+	}
+
+	/**
+	 * @return a new GsonBuilder with standard settings
+	 */
+	public static GsonBuilder createGsonBuilder() {
+		return new GsonBuilder().disableHtmlEscaping().serializeNulls().excludeFieldsWithoutExposeAnnotation()
+				.registerTypeAdapterFactory(OptionalTypeAdapter.FACTORY);
+	}
+
+	/**
+	 * @return a new Gson instance
+	 */
+	public static Gson createGson() {
+		return createGsonBuilder().create();
+	}
+
+}
diff --git a/src/main/java/org/onap/aai/validation/util/JsonUtil.java b/src/main/java/org/onap/aai/validation/util/JsonUtil.java
new file mode 100644
index 0000000..910eb63
--- /dev/null
+++ b/src/main/java/org/onap/aai/validation/util/JsonUtil.java
@@ -0,0 +1,94 @@
+/*
+ * ============LICENSE_START===================================================
+ * Copyright (c) 2018 Amdocs
+ * ============================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=====================================================
+ */
+package org.onap.aai.validation.util;
+
+import com.google.gson.Gson;
+import com.google.gson.JsonElement;
+import java.util.Map;
+
+/**
+ * Wrapper to hide the actual JSON API.
+ */
+public class JsonUtil {
+
+	// General purpose. Excludes null values.
+	private static final Gson gsonDefault = new Gson();
+
+	// Only serialises fields with the Expose annotation
+	private static final Gson gsonForAnnotatedClasses = GsonUtil.createGson();
+
+	/**
+	 * Purely a static class.
+	 */
+	private JsonUtil() {
+		// Deliberately empty
+	}
+
+	/**
+	 * Serialise the annotated object to a JSON string.
+	 *
+	 * @param obj
+	 *            the object to serialise
+	 * @return the JSON representation of the object
+	 */
+	public static String toJson(Object obj) {
+		return gsonForAnnotatedClasses.toJson(obj);
+	}
+
+	/**
+	 * Deserialise the annotated object from a JSON string.
+	 *
+	 * @param <T>
+	 *            the type of the object
+	 * @param json
+	 *            the JSON string
+	 * @param classOfT
+	 *            the class of type T
+	 * @return a new object instance
+	 */
+	public static <T> T toAnnotatedClassfromJson(String json, Class<T> classOfT) {
+		return gsonForAnnotatedClasses.fromJson(json, classOfT);
+	}
+
+	/**
+	 * Deserialise the object from a JSON string.
+	 *
+	 * @param <T>
+	 *            the type of the object
+	 * @param json
+	 *            the JSON string
+	 * @param classOfT
+	 *            the class of type T
+	 * @return a new object instance
+	 */
+	public static <T> T fromJson(String json, Class<T> classOfT) {
+		return gsonDefault.fromJson(json, classOfT);
+	}
+
+	/**
+	 * To json element.
+	 *
+	 * @param map
+	 *            the map
+	 * @return the json element
+	 */
+	public static JsonElement toJsonElement(Map<String, Object> map) {
+		return gsonForAnnotatedClasses.toJsonTree(map).getAsJsonObject();
+	}
+
+}
diff --git a/src/main/java/org/onap/aai/validation/util/StringUtils.java b/src/main/java/org/onap/aai/validation/util/StringUtils.java
new file mode 100644
index 0000000..d50b5bf
--- /dev/null
+++ b/src/main/java/org/onap/aai/validation/util/StringUtils.java
@@ -0,0 +1,100 @@
+/*
+ * ============LICENSE_START===================================================
+ * Copyright (c) 2018 Amdocs
+ * ============================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=====================================================
+ */
+package org.onap.aai.validation.util;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.regex.Pattern;
+import java.util.regex.PatternSyntaxException;
+import org.onap.aai.cl.api.Logger;
+import org.onap.aai.validation.exception.ValidationServiceError;
+import org.onap.aai.validation.exception.ValidationServiceException;
+import org.onap.aai.validation.logging.ApplicationMsgs;
+import org.onap.aai.validation.logging.LogHelper;
+
+/**
+ * Utility class for String manipulation.
+ */
+public class StringUtils {
+
+    private static final Logger applicationLogger = LogHelper.INSTANCE;
+
+    /**
+     * All methods are static.
+     */
+    private StringUtils() {
+        // Do not instantiate
+    }
+
+    /**
+     * Utility method to strip a prefix or set of prefixes (identified by a delimiter sequence) from the string. This is
+     * achieved by finding the index of the last prefix delimiter in the string and removing all characters before and
+     * including this index.
+     *
+     * @param string the String to strip prefixes from
+     * @param prefixDelimiter the String that acts as the delimiter for the prefix(es)
+     * @return the String minus the prefixes
+     */
+    public static String stripPrefix(String string, String prefixDelimiter) {
+        return string.contains(prefixDelimiter)
+                ? string.substring(string.lastIndexOf(prefixDelimiter) + prefixDelimiter.length()) : string;
+    }
+
+    /**
+     * Strips a prefix identified by a delimiter. This is achieved by splitting the string in two around matches of the
+     * first occurrence of the given regular expression.
+     *
+     * @param string a String from which to strip a prefix
+     * @param regex the delimiting regular expression
+     * @return
+     * @throws ValidationServiceException If there is a problem with the provided regular expression.
+     */
+    public static String stripPrefixRegex(String string, String regex) throws ValidationServiceException {
+        String[] strings = validParameters(string, regex) ? string.split(regex, 2) : new String[0];
+        return strings.length == 2 ? strings[1] : string;
+    }
+
+    /**
+     * Process a list of strings and strip the given suffix from each string in the list.
+     *
+     * @param stringList a list of strings
+     * @param suffix a suffix to be removed from the strings
+     * @return stripped list of strings.
+     */
+    public static List<String> stripSuffix(List<String> stringList, String suffix) {
+        List<String> result = new ArrayList<>();
+        for (String str : stringList) {
+            String stripped = str.endsWith(suffix) ? str.substring(0, str.indexOf(suffix)) : str;
+            result.add(stripped);
+        }
+        return result;
+    }
+
+    private static boolean validParameters(String string, String regex) throws ValidationServiceException {
+        if (string != null && !string.isEmpty() && regex != null && !regex.isEmpty()) {
+            try {
+                Pattern.compile(regex);
+                return true;
+            } catch (PatternSyntaxException e) {
+                applicationLogger.error(ApplicationMsgs.STRING_UTILS_INVALID_REGEX, regex);
+                throw new ValidationServiceException(ValidationServiceError.STRING_UTILS_INVALID_REGEX, e, regex);
+            }
+        }
+        return false;
+    }
+}