Adding client monitoring module to apex-pdp

Change-Id: I6b4d00a5e49326f62f3585526ede8e89df99d7e5
Issue-ID: POLICY-864
Signed-off-by: ramverma <ram.krishna.verma@ericsson.com>

8 files changed, 1136 insertions, 0 deletions

diff --git a/client/client-monitoring/src/main/java/org/onap/policy/apex/client/monitoring/rest/ApexMonitoringRest.java b/client/client-monitoring/src/main/java/org/onap/policy/apex/client/monitoring/rest/ApexMonitoringRest.java
new file mode 100644
index 000000000..d6f7e64ad
--- /dev/null
+++ b/client/client-monitoring/src/main/java/org/onap/policy/apex/client/monitoring/rest/ApexMonitoringRest.java
@@ -0,0 +1,80 @@
+/*-
+ * ============LICENSE_START=======================================================
+ *  Copyright (C) 2016-2018 Ericsson. All rights reserved.
+ * ================================================================================
+ * 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.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ * ============LICENSE_END=========================================================
+ */
+
+package org.onap.policy.apex.client.monitoring.rest;
+
+import org.glassfish.grizzly.http.server.HttpServer;
+import org.glassfish.jersey.grizzly2.httpserver.GrizzlyHttpServerFactory;
+import org.glassfish.jersey.server.ResourceConfig;
+import org.onap.policy.apex.model.utilities.Assertions;
+import org.slf4j.ext.XLogger;
+import org.slf4j.ext.XLoggerFactory;
+
+/**
+ * This class is used to launch the services. It creates a Grizzly embedded web server and runs the services.
+ */
+public class ApexMonitoringRest {
+    // Logger for this class
+    private static final XLogger logger = XLoggerFactory.getXLogger(ApexMonitoringRest.class);
+
+    // The HTTP server exposing JAX-RS resources defined in this application.
+    private HttpServer server;
+
+    /**
+     * Starts the HTTP server for the Apex services client on the default base URI and with the default REST packages
+     */
+    public ApexMonitoringRest() {
+        this(new ApexMonitoringRestParameters());
+    }
+
+    /**
+     * Starts the HTTP server for the Apex services client
+     *
+     * @param parameters: The Apex parameters to use to start the server
+     */
+    public ApexMonitoringRest(final ApexMonitoringRestParameters parameters) {
+        Assertions.argumentNotNull(parameters, "parameters may not be null");
+
+        logger.debug("Apex services RESTful client starting . . .");
+
+        // Create a resource configuration that scans for JAX-RS resources and providers
+        // in org.onap.policy.apex.services.client.monitoring.rest package
+        final ResourceConfig rc = new ResourceConfig().packages(parameters.getRESTPackages());
+
+        // create and start a new instance of grizzly http server
+        // exposing the Jersey application at BASE_URI
+        server = GrizzlyHttpServerFactory.createHttpServer(parameters.getBaseURI(), rc);
+
+        // Add static content
+        server.getServerConfiguration().addHttpHandler(new org.glassfish.grizzly.http.server.CLStaticHttpHandler(
+                ApexMonitoringRestMain.class.getClassLoader(), "/webapp/"), parameters.getStaticPath());
+
+        logger.debug("Apex services RESTful client started");
+    }
+
+    /**
+     * Shut down the web server
+     */
+    public void shutdown() {
+        logger.debug("Apex services RESTful client shutting down . . .");
+        server.shutdown();
+        logger.debug("Apex services RESTful client shut down");
+    }
+}
diff --git a/client/client-monitoring/src/main/java/org/onap/policy/apex/client/monitoring/rest/ApexMonitoringRestMain.java b/client/client-monitoring/src/main/java/org/onap/policy/apex/client/monitoring/rest/ApexMonitoringRestMain.java
new file mode 100644
index 000000000..fcc29ed29
--- /dev/null
+++ b/client/client-monitoring/src/main/java/org/onap/policy/apex/client/monitoring/rest/ApexMonitoringRestMain.java
@@ -0,0 +1,192 @@
+/*-
+ * ============LICENSE_START=======================================================
+ *  Copyright (C) 2016-2018 Ericsson. All rights reserved.
+ * ================================================================================
+ * 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.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ * ============LICENSE_END=========================================================
+ */
+
+package org.onap.policy.apex.client.monitoring.rest;
+
+import java.io.PrintStream;
+
+/**
+ * User: ewatkmi Date: 31 Jul 2017
+ */
+public class ApexMonitoringRestMain {
+    // Services state
+    public enum ServicesState {
+        STOPPED, READY, INITIALIZING, RUNNING
+    };
+
+    private ServicesState state = ServicesState.STOPPED;
+
+    // The parameters for the client
+    private ApexMonitoringRestParameters parameters = null;
+
+    // Output and error streams for messages
+    private final PrintStream outStream;
+
+    // The Apex services client this class is running
+    private ApexMonitoringRest apexMonitoringRest = null;
+
+    /**
+     * Main method, main entry point for command
+     *
+     * @param args The command line arguments for the client
+     */
+    public static void main(final String[] args) {
+        try {
+            final ApexMonitoringRestMain restMain = new ApexMonitoringRestMain(args, System.out);
+            restMain.init();
+        } catch (final Exception e) {
+            System.err.println(e.getMessage());
+        }
+    }
+
+    /**
+     * Constructor, kicks off the rest service
+     *
+     * @param args The command line arguments for the RESTful service
+     * @param outStream The stream for output messages
+     */
+    public ApexMonitoringRestMain(final String[] args, final PrintStream outStream) {
+        // Save the streams for output and error
+        this.outStream = outStream;
+
+        // Client parameter parsing
+        final ApexMonitoringRestParameterParser parser = new ApexMonitoringRestParameterParser();
+
+        try {
+            // Get and check the parameters
+            parameters = parser.parse(args);
+        } catch (final ApexMonitoringRestParameterException e) {
+            throw new ApexMonitoringRestParameterException(
+                    "Apex Services REST endpoint (" + this.toString() + ") parameter error, " + e.getMessage() + '\n'
+                            + parser.getHelp(ApexMonitoringRestMain.class.getCanonicalName()));
+        }
+
+        if (parameters.isHelpSet()) {
+            throw new ApexMonitoringRestParameterException(
+                    parser.getHelp(ApexMonitoringRestMain.class.getCanonicalName()));
+        }
+
+        // Validate the parameters
+        final String validationMessage = parameters.validate();
+        if (validationMessage.length() > 0) {
+            throw new ApexMonitoringRestParameterException(
+                    "Apex Services REST endpoint (" + this.toString() + ") parameters invalid, " + validationMessage
+                            + '\n' + parser.getHelp(ApexMonitoringRestMain.class.getCanonicalName()));
+        }
+
+        state = ServicesState.READY;
+    }
+
+    /**
+     * Initialize the rest service
+     */
+    public void init() {
+        outStream.println("Apex Services REST endpoint (" + this.toString() + ") starting at "
+                + parameters.getBaseURI().toString() + " . . .");
+
+        try {
+            state = ServicesState.INITIALIZING;
+
+            // Start the REST service
+            apexMonitoringRest = new ApexMonitoringRest(parameters);
+
+            // Add a shutdown hook to shut down the rest services when the process is exiting
+            Runtime.getRuntime().addShutdownHook(new Thread(new ApexServicesShutdownHook()));
+
+            state = ServicesState.RUNNING;
+
+            if (parameters.getTimeToLive() == ApexMonitoringRestParameters.INFINITY_TIME_TO_LIVE) {
+                outStream.println("Apex Services REST endpoint (" + this.toString() + ") started at "
+                        + parameters.getBaseURI().toString());
+            } else {
+                outStream.println("Apex Services REST endpoint (" + this.toString() + ") started");
+            }
+
+            // Find out how long is left to wait
+            long timeRemaining = parameters.getTimeToLive();
+            while (timeRemaining == ApexMonitoringRestParameters.INFINITY_TIME_TO_LIVE || timeRemaining > 0) {
+                // decrement the time to live in the non-infinity case
+                if (timeRemaining > 0) {
+                    timeRemaining--;
+                }
+
+                // Wait for a second
+                Thread.sleep(1000);
+            }
+        } catch (final Exception e) {
+            outStream.println(
+                    "Apex Services REST endpoint (" + this.toString() + ") failed at with error: " + e.getMessage());
+        } finally {
+            if (apexMonitoringRest != null) {
+                apexMonitoringRest.shutdown();
+                apexMonitoringRest = null;
+            }
+            state = ServicesState.STOPPED;
+        }
+
+    }
+
+    /**
+     * Get services state.
+     *
+     * @return the service state
+     */
+    public ServicesState getState() {
+        return state;
+    }
+
+    @Override
+    public String toString() {
+        final StringBuilder ret = new StringBuilder();
+        ret.append(this.getClass().getSimpleName()).append(": Config=[").append(this.parameters).append("], State=")
+                .append(this.getState());
+        return ret.toString();
+    }
+
+    /**
+     * Explicitly shut down the services
+     */
+    public void shutdown() {
+        if (apexMonitoringRest != null) {
+            outStream.println("Apex Services REST endpoint (" + this.toString() + ") shutting down");
+            apexMonitoringRest.shutdown();
+        }
+        state = ServicesState.STOPPED;
+        outStream.println("Apex Services REST endpoint (" + this.toString() + ") shut down");
+    }
+
+    /**
+     * This class is a shutdown hook for the Apex services command
+     */
+    private class ApexServicesShutdownHook implements Runnable {
+        /*
+         * (non-Javadoc)
+         *
+         * @see java.lang.Runnable#run()
+         */
+        @Override
+        public void run() {
+            if (apexMonitoringRest != null) {
+                apexMonitoringRest.shutdown();
+            }
+        }
+    }
+
+}
diff --git a/client/client-monitoring/src/main/java/org/onap/policy/apex/client/monitoring/rest/ApexMonitoringRestParameterException.java b/client/client-monitoring/src/main/java/org/onap/policy/apex/client/monitoring/rest/ApexMonitoringRestParameterException.java
new file mode 100644
index 000000000..cbbc2940a
--- /dev/null
+++ b/client/client-monitoring/src/main/java/org/onap/policy/apex/client/monitoring/rest/ApexMonitoringRestParameterException.java
@@ -0,0 +1,49 @@
+/*-
+ * ============LICENSE_START=======================================================
+ *  Copyright (C) 2016-2018 Ericsson. All rights reserved.
+ * ================================================================================
+ * 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.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ * ============LICENSE_END=========================================================
+ */
+
+package org.onap.policy.apex.client.monitoring.rest;
+
+/**
+ * A run time exception used to report parsing and parameter input errors
+ *
+ * User: ewatkmi Date: 31 Jul 2017
+ */
+public class ApexMonitoringRestParameterException extends IllegalArgumentException {
+    private static final long serialVersionUID = 6520231162404452427L;
+
+    /**
+     * Create an ApexServicesRestParameterException with a message.
+     *
+     * @param message the message
+     */
+    public ApexMonitoringRestParameterException(final String message) {
+        super(message);
+    }
+
+    /**
+     * Create an ApexServicesRestParameterException with a message and an exception.
+     *
+     * @param message the message
+     * @param throwable The exception that caused the exception
+     */
+    public ApexMonitoringRestParameterException(final String message, final Throwable throwable) {
+        super(message, throwable);
+    }
+}
diff --git a/client/client-monitoring/src/main/java/org/onap/policy/apex/client/monitoring/rest/ApexMonitoringRestParameterParser.java b/client/client-monitoring/src/main/java/org/onap/policy/apex/client/monitoring/rest/ApexMonitoringRestParameterParser.java
new file mode 100644
index 000000000..35ee6b4fa
--- /dev/null
+++ b/client/client-monitoring/src/main/java/org/onap/policy/apex/client/monitoring/rest/ApexMonitoringRestParameterParser.java
@@ -0,0 +1,116 @@
+/*-
+ * ============LICENSE_START=======================================================
+ *  Copyright (C) 2016-2018 Ericsson. All rights reserved.
+ * ================================================================================
+ * 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.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ * ============LICENSE_END=========================================================
+ */
+
+package org.onap.policy.apex.client.monitoring.rest;
+
+import java.io.PrintWriter;
+import java.io.StringWriter;
+import java.util.Arrays;
+
+import org.apache.commons.cli.CommandLine;
+import org.apache.commons.cli.DefaultParser;
+import org.apache.commons.cli.HelpFormatter;
+import org.apache.commons.cli.Option;
+import org.apache.commons.cli.Options;
+import org.apache.commons.cli.ParseException;
+
+/**
+ * This class reads and handles command line parameters to the Apex RESTful services
+ *
+ * User: ewatkmi Date: 31 Jul 2017
+ */
+public class ApexMonitoringRestParameterParser {
+    // Apache Commons CLI options
+    Options options;
+
+    /**
+     * Construct the options for the CLI RESTful services
+     */
+    public ApexMonitoringRestParameterParser() {
+        options = new Options();
+        options.addOption("h", "help", false, "outputs the usage of this command");
+        options.addOption(Option.builder("p").longOpt("port").desc("port to use for the Apex Services REST calls")
+                .hasArg().argName("PORT").required(false).type(Number.class).build());
+        options.addOption(Option.builder("t").longOpt("time-to-live")
+                .desc("the amount of time in seconds that the server will run for before terminating").hasArg()
+                .argName("TIME_TO_LIVE").required(false).type(Number.class).build());
+    }
+
+    /**
+     * Parse the command line options.
+     *
+     * @param args the arguments
+     * @return parsed parameters
+     */
+    public ApexMonitoringRestParameters parse(final String[] args) {
+        CommandLine commandLine = null;
+        try {
+            commandLine = new DefaultParser().parse(options, args);
+        } catch (final ParseException e) {
+            throw new ApexMonitoringRestParameterException(
+                    "invalid command line arguments specified : " + e.getMessage());
+        }
+
+        final ApexMonitoringRestParameters parameters = new ApexMonitoringRestParameters();
+        final String[] remainingArgs = commandLine.getArgs();
+
+        if (commandLine.getArgs().length > 0) {
+            throw new ApexMonitoringRestParameterException(
+                    "too many command line arguments specified : " + Arrays.toString(remainingArgs));
+        }
+
+        if (commandLine.hasOption('h')) {
+            parameters.setHelp(true);
+        }
+        try {
+            if (commandLine.hasOption('p')) {
+                parameters.setRESTPort(((Number) commandLine.getParsedOptionValue("port")).intValue());
+            }
+        } catch (final ParseException e) {
+            throw new ApexMonitoringRestParameterException("error parsing argument \"port\" :" + e.getMessage(), e);
+        }
+        try {
+            if (commandLine.hasOption('t')) {
+                parameters.setTimeToLive(((Number) commandLine.getParsedOptionValue("time-to-live")).longValue());
+            }
+        } catch (final ParseException e) {
+            throw new ApexMonitoringRestParameterException("error parsing argument \"time-to-live\" :" + e.getMessage(),
+                    e);
+        }
+
+        return parameters;
+    }
+
+    /**
+     * Get help information.
+     *
+     * @param mainClassName the main class name for the help output
+     * @return help string
+     */
+    public String getHelp(final String mainClassName) {
+        final StringWriter stringWriter = new StringWriter();
+        final PrintWriter stringPrintWriter = new PrintWriter(stringWriter);
+
+        final HelpFormatter helpFormatter = new HelpFormatter();
+        helpFormatter.printHelp(stringPrintWriter, 120, mainClassName + " [options...] ", "", options, 0, 0, "");
+
+        return stringWriter.toString();
+    }
+}
diff --git a/client/client-monitoring/src/main/java/org/onap/policy/apex/client/monitoring/rest/ApexMonitoringRestParameters.java b/client/client-monitoring/src/main/java/org/onap/policy/apex/client/monitoring/rest/ApexMonitoringRestParameters.java
new file mode 100644
index 000000000..a1a8efc57
--- /dev/null
+++ b/client/client-monitoring/src/main/java/org/onap/policy/apex/client/monitoring/rest/ApexMonitoringRestParameters.java
@@ -0,0 +1,115 @@
+/*-
+ * ============LICENSE_START=======================================================
+ *  Copyright (C) 2016-2018 Ericsson. All rights reserved.
+ * ================================================================================
+ * 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.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ * ============LICENSE_END=========================================================
+ */
+
+package org.onap.policy.apex.client.monitoring.rest;
+
+import java.net.URI;
+
+/**
+ * This class reads and handles command line parameters to the Apex RESTful services
+ *
+ * User: ewatkmi Date: 31 Jul 2017
+ */
+public class ApexMonitoringRestParameters {
+    public static final int DEFAULT_REST_PORT = 18989;
+    public static final int INFINITY_TIME_TO_LIVE = -1;
+
+    // Base URI the HTTP server will listen on
+    private static final String DEFAULT_SERVER_URI_ROOT = "http://localhost:";
+    private static final String DEFAULT_REST_PATH = "/apexservices/";
+    private static final String DEFAULT_STATIC_PATH = "/";
+
+    // Package that will field REST requests
+    public static final String[] DEFAULT_PACKAGES =
+            new String[] { "org.onap.policy.apex.services.client.monitoring.rest" };
+
+    // The services parameters
+    private boolean helpSet = false;
+    private int restPort = DEFAULT_REST_PORT;
+    private long timeToLive = INFINITY_TIME_TO_LIVE;
+
+    public String validate() {
+        String validationMessage = "";
+        validationMessage += validatePort();
+        validationMessage += validateTimeToLive();
+
+        return validationMessage;
+    }
+
+    public URI getBaseURI() {
+        return URI.create(DEFAULT_SERVER_URI_ROOT + restPort + DEFAULT_REST_PATH);
+    }
+
+    public String[] getRESTPackages() {
+        return DEFAULT_PACKAGES;
+    }
+
+    public String getStaticPath() {
+        return DEFAULT_STATIC_PATH;
+    }
+
+    private String validatePort() {
+        if (restPort < 1024 || restPort > 65535) {
+            return "port must be greater than 1023 and less than 65536\n";
+        } else {
+            return "";
+        }
+    }
+
+    private String validateTimeToLive() {
+        if (timeToLive < -1) {
+            return "time to live must be greater than -1 (set to -1 to wait forever)\n";
+        } else {
+            return "";
+        }
+    }
+
+    public boolean isHelpSet() {
+        return helpSet;
+    }
+
+    public void setHelp(final boolean helpSet) {
+        this.helpSet = helpSet;
+    }
+
+    public int getRESTPort() {
+        return restPort;
+    }
+
+    public void setRESTPort(final int restPort) {
+        this.restPort = restPort;
+    }
+
+    public long getTimeToLive() {
+        return timeToLive;
+    }
+
+    public void setTimeToLive(final long timeToLive) {
+        this.timeToLive = timeToLive;
+    }
+
+    @Override
+    public String toString() {
+        final StringBuilder ret = new StringBuilder();
+        ret.append(this.getClass().getSimpleName()).append(": URI=").append(this.getBaseURI()).append(", TTL=")
+                .append(this.getTimeToLive()).append("sec");
+        return ret.toString();
+    }
+}
diff --git a/client/client-monitoring/src/main/java/org/onap/policy/apex/client/monitoring/rest/ApexMonitoringRestResource.java b/client/client-monitoring/src/main/java/org/onap/policy/apex/client/monitoring/rest/ApexMonitoringRestResource.java
new file mode 100644
index 000000000..84f29dfe2
--- /dev/null
+++ b/client/client-monitoring/src/main/java/org/onap/policy/apex/client/monitoring/rest/ApexMonitoringRestResource.java
@@ -0,0 +1,346 @@
+/*-
+ * ============LICENSE_START=======================================================
+ *  Copyright (C) 2016-2018 Ericsson. All rights reserved.
+ * ================================================================================
+ * 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.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ * ============LICENSE_END=========================================================
+ */
+
+package org.onap.policy.apex.client.monitoring.rest;
+
+import com.google.gson.Gson;
+import com.google.gson.JsonArray;
+import com.google.gson.JsonObject;
+
+import java.io.PrintWriter;
+import java.io.StringWriter;
+import java.util.HashMap;
+import java.util.LinkedList;
+import java.util.List;
+import java.util.Map;
+
+import javax.ws.rs.Consumes;
+import javax.ws.rs.GET;
+import javax.ws.rs.Path;
+import javax.ws.rs.Produces;
+import javax.ws.rs.QueryParam;
+import javax.ws.rs.core.MediaType;
+import javax.ws.rs.core.Response;
+
+import org.onap.policy.apex.core.deployment.ApexDeploymentException;
+import org.onap.policy.apex.core.deployment.EngineServiceFacade;
+import org.onap.policy.apex.model.basicmodel.concepts.ApexException;
+import org.onap.policy.apex.model.basicmodel.concepts.AxArtifactKey;
+import org.onap.policy.apex.model.enginemodel.concepts.AxEngineModel;
+import org.slf4j.ext.XLogger;
+import org.slf4j.ext.XLoggerFactory;
+
+/**
+ * The class represents the root resource exposed at the base URL<br>
+ * The url to access this resource would be in the form {@code <baseURL>/rest/....} <br>
+ * For example: a GET request to the following URL
+ * {@code http://localhost:18989/apexservices/rest/?hostName=localhost&port=12345}
+ *
+ * <b>Note:</b> An allocated {@code hostName} and {@code port} query parameter must be included in all requests.
+ * Datasets for different {@code hostName} are completely isolated from one another.
+ *
+ */
+@Path("monitoring/")
+@Produces({ MediaType.APPLICATION_JSON })
+@Consumes({ MediaType.APPLICATION_JSON })
+
+public class ApexMonitoringRestResource {
+    // Get a reference to the logger
+    private static final XLogger LOGGER = XLoggerFactory.getXLogger(ApexMonitoringRestResource.class);
+
+    // Set the maximum number of stored data entries to be stored for each engine
+    private static final int maxCachedEntries = 50;
+
+    // Set up a map separated by host and engine for the data
+    private static final HashMap<String, HashMap<String, List<Counter>>> cache =
+            new HashMap<String, HashMap<String, List<Counter>>>();
+
+    // Set up a map separated by host for storing the state of periodic events
+    private static final HashMap<String, Boolean> periodicEventsStateCache = new HashMap<String, Boolean>();
+
+    /**
+     * Constructor, a new resource director is created for each request.
+     */
+    public ApexMonitoringRestResource() {}
+
+    /**
+     * Query the engine service for data
+     *
+     * @param hostName the host name of the engine service to connect to.
+     * @param port the port number of the engine service to connect to.
+     * @return a Response object containing the engines service, status and context data in JSON
+     */
+    @GET
+    public Response createSession(@QueryParam("hostName") final String hostName, @QueryParam("port") final int port) {
+        final Gson gson = new Gson();
+        final String host = hostName + ":" + port;
+        final EngineServiceFacade engineServiceFacade = new EngineServiceFacade(hostName, port);
+
+        try {
+            engineServiceFacade.init();
+        } catch (final ApexDeploymentException e) {
+            final String errorMessage = "Error connecting to Apex Engine Service at " + host;
+            LOGGER.warn(errorMessage + "<br>", e);
+            return Response.status(Response.Status.INTERNAL_SERVER_ERROR).entity(errorMessage + "\n" + e.getMessage())
+                    .build();
+        }
+
+        final JsonObject responseObject = new JsonObject();
+
+        // Engine Service data
+        responseObject.addProperty("engine_id", engineServiceFacade.getKey().getID());
+        responseObject.addProperty("model_id",
+                engineServiceFacade.getApexModelKey() != null ? engineServiceFacade.getApexModelKey().getID()
+                        : "Not Set");
+        responseObject.addProperty("server", hostName);
+        responseObject.addProperty("port", Integer.toString(port));
+        responseObject.addProperty("periodic_events", getPeriodicEventsState(host));
+
+        // Engine Status data
+        final JsonArray engineStatusList = new JsonArray();
+
+        for (final AxArtifactKey engineKey : engineServiceFacade.getEngineKeyArray()) {
+            try {
+                final JsonObject engineStatusObject = new JsonObject();
+                final AxEngineModel axEngineModel = engineServiceFacade.getEngineStatus(engineKey);
+                engineStatusObject.addProperty("timestamp", axEngineModel.getTimeStampString());
+                engineStatusObject.addProperty("id", engineKey.getID());
+                engineStatusObject.addProperty("status", axEngineModel.getState().toString());
+                engineStatusObject.addProperty("last_message", axEngineModel.getStats().getTimeStampString());
+                engineStatusObject.addProperty("up_time", axEngineModel.getStats().getUpTime() / 1000L);
+                engineStatusObject.addProperty("policy_executions", axEngineModel.getStats().getEventCount());
+                engineStatusObject.addProperty("last_policy_duration",
+                        gson.toJson(
+                                getValuesFromCache(host, engineKey.getID() + "_last_policy_duration",
+                                        axEngineModel.getTimestamp(), axEngineModel.getStats().getLastExecutionTime()),
+                                List.class));
+                engineStatusObject.addProperty("average_policy_duration",
+                        gson.toJson(getValuesFromCache(host, engineKey.getID() + "_average_policy_duration",
+                                axEngineModel.getTimestamp(),
+                                (long) axEngineModel.getStats().getAverageExecutionTime()), List.class));
+                engineStatusList.add(engineStatusObject);
+            } catch (final ApexException e) {
+                LOGGER.warn("Error getting status of engine with ID " + engineKey.getID() + "<br>", e);
+            }
+        }
+        responseObject.add("status", engineStatusList);
+
+        // Engine context data
+        final JsonArray engineContextList = new JsonArray();
+        for (final AxArtifactKey engineKey : engineServiceFacade.getEngineKeyArray()) {
+            try {
+                final String engineInfo = engineServiceFacade.getEngineInfo(engineKey);
+                if (engineInfo != null && !engineInfo.trim().isEmpty()) {
+                    final JsonObject engineContextObject = new JsonObject();
+                    engineContextObject.addProperty("id", engineKey.getID());
+                    engineContextObject.addProperty("engine_info", engineInfo);
+                    engineContextList.add(engineContextObject);
+                }
+            } catch (final ApexException e) {
+                LOGGER.warn("Error getting runtime information of engine with ID " + engineKey.getID() + "<br>", e);
+            }
+        }
+        responseObject.add("context", engineContextList);
+
+        return Response.ok(responseObject.toString(), MediaType.APPLICATION_JSON).build();
+    }
+
+    /**
+     * Start/Stop and Apex engine
+     *
+     * @param hostName the host name of the engine service to connect to.
+     * @param port the port number of the engine service to connect to.
+     * @param engineId the id of the engine to be started/stopped.
+     * @param startStop the parameter to start/stop the engine. Expects either "Start" or "Stop"
+     * @return a Response object of type 200
+     */
+    @GET
+    @Path("startstop/")
+    public Response startStop(@QueryParam("hostName") final String hostName, @QueryParam("port") final int port,
+            @QueryParam("engineId") final String engineId, @QueryParam("startstop") final String startStop) {
+        final EngineServiceFacade engineServiceFacade = new EngineServiceFacade(hostName, port);
+
+        try {
+            engineServiceFacade.init();
+        } catch (final ApexDeploymentException e) {
+            final String errorMessage = "Error connecting to Apex Engine Service at " + hostName + ":" + port;
+            LOGGER.warn(errorMessage + "<br>", e);
+            return Response.status(Response.Status.INTERNAL_SERVER_ERROR).entity(errorMessage + "\n" + e.getMessage())
+                    .build();
+        }
+
+        try {
+            final Map<String, String[]> parameterMap = new HashMap<String, String[]>();
+            parameterMap.put("hostname", new String[] { hostName });
+            parameterMap.put("port", new String[] { Integer.toString(port) });
+            parameterMap.put("AxArtifactKey#" + engineId, new String[] { startStop });
+            final AxArtifactKey engineKey = ParameterCheck.getEngineKey(parameterMap);
+            if (startStop.equals("Start")) {
+                engineServiceFacade.startEngine(engineKey);
+            } else if (startStop.equals("Stop")) {
+                engineServiceFacade.stopEngine(engineKey);
+            }
+        } catch (final Exception e) {
+            final String errorMessage = "Error calling " + startStop + " on Apex Engine: " + engineId;
+            LOGGER.warn(errorMessage + "<br>", e);
+            final StringWriter sw = new StringWriter();
+            e.printStackTrace(new PrintWriter(sw));
+            return Response.status(Response.Status.INTERNAL_SERVER_ERROR).entity(errorMessage + "\n" + sw.toString())
+                    .build();
+        }
+
+        return Response.ok("{}").build();
+    }
+
+    /**
+     * Start/Stop and Apex engine
+     *
+     * @param hostName the host name of the engine service to connect to.
+     * @param port the port number of the engine service to connect to.
+     * @param engineId the id of the engine to be started/stopped.
+     * @param startStop the parameter to start/stop the engine. Expects either "Start" or "Stop"
+     * @param period the time between each event in milliseconds
+     * @return a Response object of type 200
+     */
+    @GET
+    @Path("periodiceventstartstop/")
+    public Response periodiceventStartStop(@QueryParam("hostName") final String hostName,
+            @QueryParam("port") final int port, @QueryParam("engineId") final String engineId,
+            @QueryParam("startstop") final String startStop, @QueryParam("period") final long period) {
+        final EngineServiceFacade engineServiceFacade = new EngineServiceFacade(hostName, port);
+        final String host = hostName + ":" + port;
+        try {
+            engineServiceFacade.init();
+            final Map<String, String[]> parameterMap = new HashMap<String, String[]>();
+            parameterMap.put("hostname", new String[] { hostName });
+            parameterMap.put("port", new String[] { Integer.toString(port) });
+            parameterMap.put("AxArtifactKey#" + engineId, new String[] { startStop });
+            parameterMap.put("period", new String[] { Long.toString(period) });
+            final AxArtifactKey engineKey = ParameterCheck.getEngineKey(parameterMap);
+            if (startStop.equals("Start")) {
+                engineServiceFacade.startPerioidicEvents(engineKey, period);
+                setPeriodicEventsState(host, true);
+            } else if (startStop.equals("Stop")) {
+                engineServiceFacade.stopPerioidicEvents(engineKey);
+                setPeriodicEventsState(host, false);
+            }
+        } catch (final ApexDeploymentException e) {
+            final String errorMessage = "Error connecting to Apex Engine Service at " + host;
+            LOGGER.warn(errorMessage + "<br>", e);
+            return Response.status(Response.Status.INTERNAL_SERVER_ERROR).entity(errorMessage + "\n" + e.getMessage())
+                    .build();
+        }
+
+        return Response.ok("{}").build();
+    }
+
+    /**
+     * Check if periodic events are running
+     *
+     * @param host the engine's host url
+     * @return a boolean stating if periodic events are running for a given host
+     */
+    private Boolean getPeriodicEventsState(final String host) {
+        return periodicEventsStateCache.containsKey(host) ? periodicEventsStateCache.get(host) : false;
+    }
+
+    /**
+     * Sets the state of periodic events for a host
+     *
+     * @param host the engine's host url
+     * @param boolean that states if periodic events have been started or stopped
+     */
+    private void setPeriodicEventsState(final String host, final Boolean isRunning) {
+        periodicEventsStateCache.put(host, isRunning);
+    }
+
+    /**
+     * This method takes in the latest data entry for an engine, adds it to an existing data set and returns the full
+     * map for that host and engine
+     *
+     * @param host the engine's host url
+     * @param id the engines id
+     * @param timestamp the timestamp of the latest data entry
+     * @param latestValue the value of the latest data entry
+     * @return a list of {@code Counter} objects for that engine
+     */
+    private List<Counter> getValuesFromCache(final String host, final String id, final long timestamp,
+            final long latestValue) {
+        SlidingWindowList<Counter> valueList;
+
+        if (!cache.containsKey(host)) {
+            cache.put(host, new HashMap<String, List<Counter>>());
+        }
+
+        if (cache.get(host).containsKey(id)) {
+            valueList = (SlidingWindowList<Counter>) cache.get(host).get(id);
+        } else {
+            valueList = new SlidingWindowList<Counter>(maxCachedEntries);
+        }
+        valueList.add(new Counter(timestamp, latestValue));
+
+        cache.get(host).put(id, valueList);
+
+        return valueList;
+    }
+
+    /**
+     * A list of values that uses a FIFO sliding window of a fixed size.
+     */
+    public class SlidingWindowList<V> extends LinkedList<V> {
+        private static final long serialVersionUID = -7187277916025957447L;
+
+        private final int maxEntries;
+
+        public SlidingWindowList(final int maxEntries) {
+            this.maxEntries = maxEntries;
+        }
+
+        @Override
+        public boolean add(final V e) {
+            if (this.size() > (maxEntries - 1)) {
+                this.removeFirst();
+            }
+            return super.add(e);
+        };
+
+    }
+
+    /**
+     * A class used to storing a single data entry for an engine.
+     */
+    public class Counter {
+        private long timestamp;
+        private long value;
+
+        public Counter(final long timestamp, final long value) {
+            this.timestamp = timestamp;
+            this.value = value;
+        }
+
+        public long getTimestamp() {
+            return timestamp;
+        }
+
+        public long getValue() {
+            return value;
+        }
+    }
+}
diff --git a/client/client-monitoring/src/main/java/org/onap/policy/apex/client/monitoring/rest/ParameterCheck.java b/client/client-monitoring/src/main/java/org/onap/policy/apex/client/monitoring/rest/ParameterCheck.java
new file mode 100644
index 000000000..8edeb54f1
--- /dev/null
+++ b/client/client-monitoring/src/main/java/org/onap/policy/apex/client/monitoring/rest/ParameterCheck.java
@@ -0,0 +1,211 @@
+/*-
+ * ============LICENSE_START=======================================================
+ *  Copyright (C) 2016-2018 Ericsson. All rights reserved.
+ * ================================================================================
+ * 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.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ * ============LICENSE_END=========================================================
+ */
+
+package org.onap.policy.apex.client.monitoring.rest;
+
+import java.util.Map;
+
+import org.onap.policy.apex.model.basicmodel.concepts.AxArtifactKey;
+import org.slf4j.ext.XLogger;
+import org.slf4j.ext.XLoggerFactory;
+
+/**
+ * The Class ParameterCheck is used to check parameters passed to the servlet.
+ *
+ * @author Liam Fallon (liam.fallon@ericsson.com)
+ */
+public final class ParameterCheck {
+    private static final int MAX_PORT = 65535;
+
+    /**
+     * private constructor to prevent subclassing of this utility class.
+     */
+    private ParameterCheck() {}
+
+    /**
+     * The Enum StartStop is used to hold .
+     *
+     * @author Liam Fallon (liam.fallon@ericsson.com)
+     */
+    public enum StartStop {
+        /** Start of an Apex engine has been ordered. */
+        START,
+        /** Stop of an Apex engine has been ordered. */
+        STOP
+    };
+
+    private static final XLogger LOGGER = XLoggerFactory.getXLogger(ParameterCheck.class);
+
+    private static final String HOSTNAME_PAR = "hostname";
+    private static final String PORT_PAR = "port";
+    private static final String AXARTIFACTKEY_PAR = "AxArtifactKey";
+
+    /**
+     * Gets the host name.
+     *
+     * @param parameterMap the parameter map
+     * @return the host name
+     */
+    public static String getHostName(final Map<String, String[]> parameterMap) {
+        if (!parameterMap.containsKey(HOSTNAME_PAR)) {
+            LOGGER.warn("parameter \"" + HOSTNAME_PAR + "\" not found");
+            return null;
+        }
+
+        final String[] hostNameValue = parameterMap.get(HOSTNAME_PAR);
+
+        if (hostNameValue.length == 0 || hostNameValue[0].trim().length() == 0) {
+            LOGGER.warn("value of parameter \"" + HOSTNAME_PAR + "\" not found");
+            return null;
+        }
+
+        return hostNameValue[0];
+    }
+
+    /**
+     * Gets the port.
+     *
+     * @param parameterMap the parameter map
+     * @return the port
+     */
+    public static int getPort(final Map<String, String[]> parameterMap) {
+        if (!parameterMap.containsKey(PORT_PAR)) {
+            LOGGER.warn("parameter \"" + PORT_PAR + "\" not found");
+            return -1;
+        }
+
+        final String[] portValue = parameterMap.get(PORT_PAR);
+
+        if (portValue.length == 0 || portValue[0].trim().length() == 0) {
+            LOGGER.warn("value of parameter \"" + PORT_PAR + "\" not found");
+            return -1;
+        }
+
+        int port = -1;
+        try {
+            port = Integer.parseInt(portValue[0]);
+        } catch (final Exception e) {
+            LOGGER.warn("value \"" + portValue[0] + "\"of parameter \"" + PORT_PAR + "\" not a valid integer", e);
+            return -1;
+        }
+
+        if (port <= 0 || port > MAX_PORT) {
+            LOGGER.warn("value \"" + portValue[0] + "\"of parameter \"" + PORT_PAR
+                    + "\" not a valid port between 0 and 65535");
+            return -1;
+        }
+
+        return port;
+    }
+
+    /**
+     * Gets the engine key.
+     *
+     * @param parameterMap the parameter map
+     * @return the engine key
+     */
+    public static AxArtifactKey getEngineKey(final Map<String, String[]> parameterMap) {
+        String artifactKeyParameter = null;
+        for (final String parameter : parameterMap.keySet()) {
+            // Check for an AxArtifactKey parameter
+            if (parameter.startsWith(AXARTIFACTKEY_PAR)) {
+                artifactKeyParameter = parameter;
+                break;
+            }
+        }
+        if (artifactKeyParameter == null) {
+            LOGGER.warn("parameter \"" + AXARTIFACTKEY_PAR + "\" not found");
+            return null;
+        }
+
+        final String[] axArtifactKeyArray = artifactKeyParameter.split("#");
+
+        if (axArtifactKeyArray.length != 2) {
+            LOGGER.warn("value \"" + artifactKeyParameter + "\" of parameter \"" + AXARTIFACTKEY_PAR + "\" not valid");
+            return null;
+        }
+
+        return new AxArtifactKey(axArtifactKeyArray[1]);
+    }
+
+    /**
+     * Gets the start stop.
+     *
+     * @param parameterMap the parameter map
+     * @param engineKey the engine key
+     * @return the start stop
+     */
+    public static ParameterCheck.StartStop getStartStop(final Map<String, String[]> parameterMap,
+            final AxArtifactKey engineKey) {
+        final String startStopPar = AXARTIFACTKEY_PAR + '#' + engineKey.getID();
+        if (!parameterMap.containsKey(startStopPar)) {
+            LOGGER.warn("parameter \"" + startStopPar + "\" not found");
+            return null;
+        }
+
+        final String[] startStopValue = parameterMap.get(startStopPar);
+
+        if (startStopValue.length == 0 || startStopValue[0].trim().length() == 0) {
+            LOGGER.warn("value of parameter \"" + startStopPar + "\" not found");
+            return null;
+        }
+
+        ParameterCheck.StartStop startStop;
+        if (startStopValue[0].equalsIgnoreCase("start")) {
+            startStop = ParameterCheck.StartStop.START;
+        } else if (startStopValue[0].equalsIgnoreCase("stop")) {
+            startStop = ParameterCheck.StartStop.STOP;
+        } else {
+            LOGGER.warn("value \"" + startStopValue[0] + "\"of parameter \"" + startStopPar
+                    + "\" not \"start\" or \"stop\"");
+            return null;
+        }
+
+        return startStop;
+    }
+
+    /**
+     * Find and return a long value with the given name.
+     *
+     * @param parameterMap The parameter map containing the value
+     * @param longName The name of the long parameter
+     * @return The long value
+     */
+    public static long getLong(final Map<String, String[]> parameterMap, final String longName) {
+        if (!parameterMap.containsKey(longName)) {
+            LOGGER.warn("parameter \"" + longName + "\" not found");
+            return -1;
+        }
+
+        final String[] longValue = parameterMap.get(longName);
+
+        if (longValue.length == 0 || longValue[0].trim().length() == 0) {
+            LOGGER.warn("value of parameter \"" + longName + "\" not found");
+            return -1;
+        }
+
+        try {
+            return Long.parseLong(longValue[0]);
+        } catch (final Exception e) {
+            LOGGER.warn("value \"" + longValue[0] + "\"of parameter \"" + longName + "\" not a valid long", e);
+            return -1;
+        }
+    }
+}
diff --git a/client/client-monitoring/src/main/java/org/onap/policy/apex/client/monitoring/rest/package-info.java b/client/client-monitoring/src/main/java/org/onap/policy/apex/client/monitoring/rest/package-info.java
new file mode 100644
index 000000000..d6c8d3c5e
--- /dev/null
+++ b/client/client-monitoring/src/main/java/org/onap/policy/apex/client/monitoring/rest/package-info.java
@@ -0,0 +1,27 @@
+/*-
+ * ============LICENSE_START=======================================================
+ *  Copyright (C) 2016-2018 Ericsson. All rights reserved.
+ * ================================================================================
+ * 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.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ * ============LICENSE_END=========================================================
+ */
+
+/**
+ * Implements the RESTful monitoring client.
+ *
+ * @author Liam Fallon (liam.fallon@ericsson.com)
+ */
+
+package org.onap.policy.apex.client.monitoring.rest;