Resolve mapping between TOSCA policies and APEX policy models

Change-Id: Ifaedc5074bcc51a5d495e342feae89b6a2aac1cf
Issue-ID: POLICY-1626
Signed-off-by: a.sreekumar <ajith.sreekumar@est.tech>

4 files changed, 259 insertions, 123 deletions

diff --git a/services/services-engine/src/main/java/org/onap/policy/apex/service/engine/main/ApexActivator.java b/services/services-engine/src/main/java/org/onap/policy/apex/service/engine/main/ApexActivator.java
index 3aa1f17ff..2c3fac151 100644
--- a/services/services-engine/src/main/java/org/onap/policy/apex/service/engine/main/ApexActivator.java
+++ b/services/services-engine/src/main/java/org/onap/policy/apex/service/engine/main/ApexActivator.java
@@ -24,17 +24,24 @@ package org.onap.policy.apex.service.engine.main;
 import java.util.LinkedHashMap;
 import java.util.Map;
 import java.util.Map.Entry;
-
+import java.util.stream.Stream;
+import lombok.Getter;
 import org.onap.policy.apex.model.basicmodel.concepts.ApexException;
+import org.onap.policy.apex.model.basicmodel.handling.ApexModelException;
 import org.onap.policy.apex.model.basicmodel.service.ModelService;
+import org.onap.policy.apex.model.policymodel.concepts.AxPolicyModel;
+import org.onap.policy.apex.model.policymodel.handling.PolicyModelMerger;
 import org.onap.policy.apex.model.utilities.TextFileUtils;
 import org.onap.policy.apex.service.engine.engdep.EngDepMessagingService;
+import org.onap.policy.apex.service.engine.event.ApexEventException;
 import org.onap.policy.apex.service.engine.runtime.EngineService;
 import org.onap.policy.apex.service.engine.runtime.impl.EngineServiceImpl;
 import org.onap.policy.apex.service.parameters.ApexParameters;
+import org.onap.policy.apex.service.parameters.engineservice.EngineServiceParameters;
 import org.onap.policy.apex.service.parameters.eventhandler.EventHandlerParameters;
 import org.onap.policy.apex.service.parameters.eventhandler.EventHandlerPeeredMode;
 import org.onap.policy.common.parameters.ParameterService;
+import org.onap.policy.models.tosca.authorative.concepts.ToscaPolicyIdentifier;
 import org.slf4j.ext.XLogger;
 import org.slf4j.ext.XLoggerFactory;
 
@@ -45,11 +52,14 @@ import org.slf4j.ext.XLoggerFactory;
  * @author Liam Fallon (liam.fallon@ericsson.com)
  */
 public class ApexActivator {
+    private static final String APEX_ENGINE_FAILED_MSG = "Apex engine failed to start as a service";
+
     // The logger for this class
     private static final XLogger LOGGER = XLoggerFactory.getXLogger(ApexActivator.class);
 
-    // The parameters of this Apex activator
-    private final ApexParameters apexParameters;
+    // The parameters of the Apex activator when running with multiple policies
+    @Getter
+    private Map<ToscaPolicyIdentifier, ApexParameters> apexParametersMap;
 
     // Event unmarshalers are used to receive events asynchronously into Apex
     private final Map<String, ApexEventUnmarshaller> unmarshallerMap = new LinkedHashMap<>();
@@ -62,13 +72,16 @@ public class ApexActivator {
     // and synchronous events from the engine.
     private ApexEngineServiceHandler engineServiceHandler = null;
 
+    // The engine service
+    private EngineService apexEngineService;
+
     /**
      * Instantiate the activator for the Apex engine as a complete service.
      *
-     * @param parameters the apex parameters for the Apex service
+     * @param parametersMap the apex parameters map for the Apex service
      */
-    public ApexActivator(final ApexParameters parameters) {
-        apexParameters = parameters;
+    public ApexActivator(Map<ToscaPolicyIdentifier, ApexParameters> parametersMap) {
+        apexParametersMap = parametersMap;
     }
 
     /**
@@ -80,61 +93,118 @@ public class ApexActivator {
         LOGGER.debug("Apex engine starting as a service . . .");
 
         try {
-            // Create engine with specified thread count
-            LOGGER.debug("starting apex engine service . . .");
-            final EngineService apexEngineService =
-                    EngineServiceImpl.create(apexParameters.getEngineServiceParameters());
-
-            // Instantiate and start the messaging service for Deployment
-            LOGGER.debug("starting apex deployment service . . .");
-            final EngDepMessagingService engDepService = new EngDepMessagingService(apexEngineService,
-                    apexParameters.getEngineServiceParameters().getDeploymentPort());
-            engDepService.start();
-
-            // Create the engine holder to hold the engine's references and act as an event receiver
-            engineServiceHandler = new ApexEngineServiceHandler(apexEngineService, engDepService);
-
-            // Check if a policy model file has been specified
-            if (apexParameters.getEngineServiceParameters().getPolicyModelFileName() != null) {
-                LOGGER.debug("deploying policy model in \""
-                        + apexParameters.getEngineServiceParameters().getPolicyModelFileName()
+            ApexParameters apexParameters = apexParametersMap.values().iterator().next();
+            // totalInstanceCount is the sum of instance counts required as per each policy
+            int totalInstanceCount = apexParametersMap.values().stream()
+                .mapToInt(p -> p.getEngineServiceParameters().getInstanceCount()).sum();
+            apexParameters.getEngineServiceParameters().setInstanceCount(totalInstanceCount);
+            instantiateEngine(apexParameters);
+            Map<ToscaPolicyIdentifier, AxPolicyModel> policyModelsMap = new LinkedHashMap<>();
+            Map<String, EventHandlerParameters> inputParametersMap = new LinkedHashMap<>();
+            Map<String, EventHandlerParameters> outputParametersMap = new LinkedHashMap<>();
+
+            for (Entry<ToscaPolicyIdentifier, ApexParameters> apexParamsEntry : apexParametersMap.entrySet()) {
+                ApexParameters apexParams = apexParamsEntry.getValue();
+                boolean duplicateInputParameterExist =
+                    apexParams.getEventInputParameters().keySet().stream().anyMatch(inputParametersMap::containsKey);
+                boolean duplicateOutputParameterExist =
+                    apexParams.getEventOutputParameters().keySet().stream().anyMatch(outputParametersMap::containsKey);
+                if (duplicateInputParameterExist || duplicateOutputParameterExist) {
+                    LOGGER.error("I/O Parameters for " + apexParamsEntry.getKey().getName() + ":"
+                        + apexParamsEntry.getKey().getVersion()
+                        + " has duplicates. So this policy is not executed");
+                    apexParametersMap.remove(apexParamsEntry.getKey());
+                    continue;
+                } else {
+                    inputParametersMap.putAll(apexParams.getEventInputParameters());
+                    outputParametersMap.putAll(apexParams.getEventOutputParameters());
+                }
+                // Check if a policy model file has been specified
+                if (apexParams.getEngineServiceParameters().getPolicyModelFileName() != null) {
+                    LOGGER.debug("deploying policy model in \""
+                        + apexParams.getEngineServiceParameters().getPolicyModelFileName()
                         + "\" to the apex engines . . .");
 
-                // Set the policy model in the engine
-                final String policyModelString = TextFileUtils
-                        .getTextFileAsString(apexParameters.getEngineServiceParameters().getPolicyModelFileName());
-                apexEngineService.updateModel(apexParameters.getEngineServiceParameters().getEngineKey(),
-                        policyModelString, true);
+                    final String policyModelString = TextFileUtils
+                        .getTextFileAsString(apexParams.getEngineServiceParameters().getPolicyModelFileName());
+                    AxPolicyModel policyModel = EngineServiceImpl
+                        .createModel(apexParams.getEngineServiceParameters().getEngineKey(), policyModelString);
+                    policyModelsMap.put(apexParamsEntry.getKey(), policyModel);
+                }
             }
+            AxPolicyModel finalPolicyModel = aggregatePolicyModels(policyModelsMap);
+            // Set the policy model in the engine
+            apexEngineService.updateModel(apexParameters.getEngineServiceParameters().getEngineKey(),
+                finalPolicyModel, true);
+            setUpMarshallerAndUnmarshaller(apexParameters.getEngineServiceParameters(), inputParametersMap,
+                outputParametersMap);
+            setUpmarshalerPairings(inputParametersMap);
+        } catch (final Exception e) {
+            LOGGER.debug(APEX_ENGINE_FAILED_MSG, e);
+            throw new ApexActivatorException(APEX_ENGINE_FAILED_MSG, e);
+        }
 
-            // Producer parameters specify what event marshalers to handle events leaving Apex are
-            // set up and how they are set up
-            for (final Entry<String, EventHandlerParameters> outputParameters : apexParameters
-                    .getEventOutputParameters().entrySet()) {
-                final ApexEventMarshaller marshaller = new ApexEventMarshaller(outputParameters.getKey(),
-                        apexParameters.getEngineServiceParameters(), outputParameters.getValue());
-                marshaller.init();
-                apexEngineService.registerActionListener(outputParameters.getKey(), marshaller);
-                marshallerMap.put(outputParameters.getKey(), marshaller);
-            }
+        LOGGER.debug("Apex engine started as a service");
+    }
 
-            // Consumer parameters specify what event unmarshalers to handle events coming into Apex
-            // are set up and how they are set up
-            for (final Entry<String, EventHandlerParameters> inputParameters : apexParameters.getEventInputParameters()
-                    .entrySet()) {
-                final ApexEventUnmarshaller unmarshaller = new ApexEventUnmarshaller(inputParameters.getKey(),
-                        apexParameters.getEngineServiceParameters(), inputParameters.getValue());
-                unmarshallerMap.put(inputParameters.getKey(), unmarshaller);
-                unmarshaller.init(engineServiceHandler);
-            }
+    private AxPolicyModel aggregatePolicyModels(Map<ToscaPolicyIdentifier, AxPolicyModel> policyModelsMap) {
+        Map.Entry<ToscaPolicyIdentifier, AxPolicyModel> firstEntry = policyModelsMap.entrySet().iterator().next();
+        Stream<Entry<ToscaPolicyIdentifier, AxPolicyModel>> policyModelStream =
+            policyModelsMap.entrySet().stream().skip(1);
+        Entry<ToscaPolicyIdentifier, AxPolicyModel> finalPolicyModelEntry =
+            policyModelStream.reduce(firstEntry, ((entry1, entry2) -> {
+                try {
+                    entry1.setValue(
+                        PolicyModelMerger.getMergedPolicyModel(entry1.getValue(), entry2.getValue(), true, true));
+                } catch (ApexModelException exc) {
+                    LOGGER.error("Policy model for " + entry2.getKey().getName() + ":" + entry2.getKey().getVersion()
+                        + " is having duplicates. So this policy is not executed", exc.getMessage());
+                    apexParametersMap.remove(entry2.getKey());
+                }
+                return entry1;
+            }));
+        return finalPolicyModelEntry.getValue();
+    }
 
-            setUpmarshalerPairings();
-        } catch (final Exception e) {
-            LOGGER.debug("Apex engine failed to start as a service", e);
-            throw new ApexActivatorException("Apex engine failed to start as a service", e);
+    private void setUpMarshallerAndUnmarshaller(EngineServiceParameters engineServiceParameters,
+        Map<String, EventHandlerParameters> inputParametersMap, Map<String, EventHandlerParameters> outputParametersMap)
+        throws ApexEventException {
+        // Producer parameters specify what event marshalers to handle events leaving Apex are
+        // set up and how they are set up
+        for (Entry<String, EventHandlerParameters> outputParameters : outputParametersMap.entrySet()) {
+            final ApexEventMarshaller marshaller = new ApexEventMarshaller(outputParameters.getKey(),
+                engineServiceParameters, outputParameters.getValue());
+            marshaller.init();
+            apexEngineService.registerActionListener(outputParameters.getKey(), marshaller);
+            marshallerMap.put(outputParameters.getKey(), marshaller);
         }
+        // Consumer parameters specify what event unmarshalers to handle events coming into Apex
+        // are set up and how they are set up
+        for (final Entry<String, EventHandlerParameters> inputParameters : inputParametersMap.entrySet()) {
+            final ApexEventUnmarshaller unmarshaller = new ApexEventUnmarshaller(inputParameters.getKey(),
+                engineServiceParameters, inputParameters.getValue());
+            unmarshallerMap.put(inputParameters.getKey(), unmarshaller);
+            unmarshaller.init(engineServiceHandler);
+        }
+    }
 
-        LOGGER.debug("Apex engine started as a service");
+    private void instantiateEngine(ApexParameters apexParameters) throws ApexException {
+        if (null != apexEngineService
+            && apexEngineService.getKey().equals(apexParameters.getEngineServiceParameters().getEngineKey())) {
+            throw new ApexException("Apex Engine already initialized.");
+        }
+        // Create engine with specified thread count
+        LOGGER.debug("starting apex engine service . . .");
+        apexEngineService = EngineServiceImpl.create(apexParameters.getEngineServiceParameters());
+
+        // Instantiate and start the messaging service for Deployment
+        LOGGER.debug("starting apex deployment service . . .");
+        final EngDepMessagingService engDepService = new EngDepMessagingService(apexEngineService,
+                apexParameters.getEngineServiceParameters().getDeploymentPort());
+        engDepService.start();
+
+        // Create the engine holder to hold the engine's references and act as an event receiver
+        engineServiceHandler = new ApexEngineServiceHandler(apexEngineService, engDepService);
     }
 
     /**
@@ -143,10 +213,10 @@ public class ApexActivator {
      * unmarshalers and marshalers are paired one to one uniquely so if we find a
      * synchronized unmarshaler we'll also find its
      * paired marshaler
+     * @param inputParametersMap the apex parameters
      */
-    private void setUpmarshalerPairings() {
-        for (final Entry<String, EventHandlerParameters> inputParameters : apexParameters.getEventInputParameters()
-                .entrySet()) {
+    private void setUpmarshalerPairings(Map<String, EventHandlerParameters> inputParametersMap) {
+        for (final Entry<String, EventHandlerParameters> inputParameters : inputParametersMap.entrySet()) {
             final ApexEventUnmarshaller unmarshaller = unmarshallerMap.get(inputParameters.getKey());
 
             // Pair up peered unmarshalers and marshalers
@@ -193,13 +263,4 @@ public class ApexActivator {
         ModelService.clear();
         ParameterService.clear();
     }
-
-    /**
-     * Get the parameters used by the adapter.
-     *
-     * @return the parameters of the adapter
-     */
-    public ApexParameters getApexParameters() {
-        return apexParameters;
-    }
 }
diff --git a/services/services-engine/src/main/java/org/onap/policy/apex/service/engine/main/ApexMain.java b/services/services-engine/src/main/java/org/onap/policy/apex/service/engine/main/ApexMain.java
index 3bf842c92..4600690e7 100644
--- a/services/services-engine/src/main/java/org/onap/policy/apex/service/engine/main/ApexMain.java
+++ b/services/services-engine/src/main/java/org/onap/policy/apex/service/engine/main/ApexMain.java
@@ -23,6 +23,8 @@ package org.onap.policy.apex.service.engine.main;
 
 import java.util.Arrays;
 import java.util.Base64;
+import java.util.LinkedHashMap;
+import java.util.Map;
 import java.util.Map.Entry;
 import lombok.Getter;
 import lombok.Setter;
@@ -30,6 +32,7 @@ import org.onap.policy.apex.model.basicmodel.concepts.ApexException;
 import org.onap.policy.apex.service.parameters.ApexParameterHandler;
 import org.onap.policy.apex.service.parameters.ApexParameters;
 import org.onap.policy.apex.service.parameters.eventhandler.EventHandlerParameters;
+import org.onap.policy.models.tosca.authorative.concepts.ToscaPolicyIdentifier;
 import org.slf4j.ext.XLogger;
 import org.slf4j.ext.XLoggerFactory;
 
@@ -39,13 +42,16 @@ import org.slf4j.ext.XLoggerFactory;
  * @author Liam Fallon (liam.fallon@ericsson.com)
  */
 public class ApexMain {
+    private static final String APEX_SERVICE_FAILED_MSG = "start of Apex service failed";
+
     private static final XLogger LOGGER = XLoggerFactory.getXLogger(ApexMain.class);
 
     // The Apex Activator that activates the Apex engine
     private ApexActivator activator;
 
-    // The parameters read in from JSON
-    private ApexParameters parameters;
+    // The parameters read in from JSON for each policy
+    @Getter
+    private Map<ToscaPolicyIdentifier, ApexParameters> apexParametersMap;
 
     @Getter
     @Setter(lombok.AccessLevel.PRIVATE)
@@ -54,11 +60,75 @@ public class ApexMain {
     /**
      * Instantiates the Apex service.
      *
-     * @param args the commaind line arguments
+     * @param args the command line arguments
      */
     public ApexMain(final String[] args) {
         LOGGER.entry("Starting Apex service with parameters " + Arrays.toString(args) + " . . .");
+        apexParametersMap = new LinkedHashMap<>();
+        try {
+            apexParametersMap.put(new ToscaPolicyIdentifier(), populateApexParameters(args));
+        } catch (ApexException e) {
+            LOGGER.error(APEX_SERVICE_FAILED_MSG, e);
+            return;
+        }
+
+        // Now, create the activator for the Apex service
+        activator = new ApexActivator(apexParametersMap);
+
+        // Start the activator
+        try {
+            activator.initialize();
+            setAlive(true);
+        } catch (final ApexActivatorException e) {
+            LOGGER.error("start of Apex service failed, used parameters are " + Arrays.toString(args), e);
+            return;
+        }
+
+        // Add a shutdown hook to shut everything down in an orderly manner
+        Runtime.getRuntime().addShutdownHook(new ApexMainShutdownHookClass());
+        LOGGER.exit("Started Apex");
+    }
 
+    /**
+     * Instantiates the Apex service for multiple policies.
+     *
+     * @param policyArgumentsMap the map with command line arguments as value and policy-id as key
+     * @throws ApexException on errors
+     */
+    public ApexMain(Map<ToscaPolicyIdentifier, String[]> policyArgumentsMap) throws ApexException {
+        apexParametersMap = new LinkedHashMap<>();
+        for ( Entry<ToscaPolicyIdentifier, String[]> policyArgsEntry: policyArgumentsMap.entrySet()) {
+            try {
+                apexParametersMap.put(policyArgsEntry.getKey(), populateApexParameters(policyArgsEntry.getValue()));
+            } catch (ApexException e) {
+                LOGGER.error("Invalid arguments specified for policy - " + policyArgsEntry.getKey().getName() + ":"
+                    + policyArgsEntry.getKey().getVersion(), e);
+            }
+        }
+        if (apexParametersMap.isEmpty()) {
+            LOGGER.error(APEX_SERVICE_FAILED_MSG);
+            return;
+        }
+        // Now, create the activator for the Apex service
+        activator = new ApexActivator(apexParametersMap);
+
+        // Start the activator
+        try {
+            activator.initialize();
+            apexParametersMap = activator.getApexParametersMap();
+            setAlive(true);
+        } catch (final ApexActivatorException e) {
+            LOGGER.error(APEX_SERVICE_FAILED_MSG, e);
+            activator.terminate();
+            return;
+        }
+
+        // Add a shutdown hook to shut everything down in an orderly manner
+        Runtime.getRuntime().addShutdownHook(new ApexMainShutdownHookClass());
+        LOGGER.exit("Started Apex");
+    }
+
+    private ApexParameters populateApexParameters(String[] args) throws ApexException {
         // Check the arguments
         final ApexCommandLineArguments arguments = new ApexCommandLineArguments();
         try {
@@ -66,65 +136,46 @@ public class ApexMain {
             final String argumentMessage = arguments.parse(args);
             if (argumentMessage != null) {
                 LOGGER.info(argumentMessage);
-                return;
+                throw new ApexException(argumentMessage);
             }
 
             // Validate that the arguments are sane
             arguments.validate();
         } catch (final ApexException e) {
-            LOGGER.error("start of Apex service failed", e);
-            return;
+            LOGGER.error("Arguments validation failed.", e);
+            throw new ApexException("Arguments validation failed.", e);
         }
 
+        ApexParameters axParameters;
         // Read the parameters
         try {
-            parameters = new ApexParameterHandler().getParameters(arguments);
+            ApexParameterHandler apexParameterHandler = new ApexParameterHandler();
+            // In case of multiple policies received from PAP, do not clear ParameterService if parameters of one policy
+            // already registered
+            apexParameterHandler.setKeepParameterServiceFlag(null != apexParametersMap && !apexParametersMap.isEmpty());
+            axParameters = apexParameterHandler.getParameters(arguments);
         } catch (final Exception e) {
-            LOGGER.error("start of Apex service failed", e);
-            return;
+            LOGGER.error("Cannot create APEX Parameters from the arguments provided.", e);
+            throw new ApexException("Cannot create APEX Parameters from the arguments provided.", e);
         }
 
         // Set incoming Java properties
-        setJavaProperties(parameters);
+        setJavaProperties(axParameters);
 
         // Set the name of the event handler parameters for producers and consumers
-        for (final Entry<String, EventHandlerParameters> ehParameterEntry : parameters.getEventOutputParameters()
+        for (final Entry<String, EventHandlerParameters> ehParameterEntry : axParameters.getEventOutputParameters()
             .entrySet()) {
             if (!ehParameterEntry.getValue().checkSetName()) {
                 ehParameterEntry.getValue().setName(ehParameterEntry.getKey());
             }
         }
-        for (final Entry<String, EventHandlerParameters> ehParameterEntry : parameters.getEventInputParameters()
+        for (final Entry<String, EventHandlerParameters> ehParameterEntry : axParameters.getEventInputParameters()
             .entrySet()) {
             if (!ehParameterEntry.getValue().checkSetName()) {
                 ehParameterEntry.getValue().setName(ehParameterEntry.getKey());
             }
         }
-
-        // Now, create the activator for the Apex service
-        activator = new ApexActivator(parameters);
-
-        // Start the activator
-        try {
-            activator.initialize();
-            setAlive(true);
-        } catch (final ApexActivatorException e) {
-            LOGGER.error("start of Apex service failed, used parameters are " + Arrays.toString(args), e);
-            return;
-        }
-
-        // Add a shutdown hook to shut everything down in an orderly manner
-        Runtime.getRuntime().addShutdownHook(new ApexMainShutdownHookClass());
-        LOGGER.exit("Started Apex");
-    }
-
-    /**
-     * Get the parameters specified in JSON.
-     *
-     * @return the parameters
-     */
-    public ApexParameters getParameters() {
-        return parameters;
+        return axParameters;
     }
 
     /**
diff --git a/services/services-engine/src/main/java/org/onap/policy/apex/service/engine/runtime/impl/EngineServiceImpl.java b/services/services-engine/src/main/java/org/onap/policy/apex/service/engine/runtime/impl/EngineServiceImpl.java
index e9edd40e2..152425711 100644
--- a/services/services-engine/src/main/java/org/onap/policy/apex/service/engine/runtime/impl/EngineServiceImpl.java
+++ b/services/services-engine/src/main/java/org/onap/policy/apex/service/engine/runtime/impl/EngineServiceImpl.java
@@ -1,19 +1,20 @@
 /*-
  * ============LICENSE_START=======================================================
  *  Copyright (C) 2016-2018 Ericsson. All rights reserved.
+ *  Modifications Copyright (C) 2019 Nordix Foundation.
  * ================================================================================
  * 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=========================================================
  */
@@ -28,7 +29,6 @@ import java.util.Map;
 import java.util.Map.Entry;
 import java.util.concurrent.BlockingQueue;
 import java.util.concurrent.LinkedBlockingQueue;
-
 import org.onap.policy.apex.context.ContextException;
 import org.onap.policy.apex.core.infrastructure.threading.ApplicationThreadFactory;
 import org.onap.policy.apex.core.infrastructure.threading.ThreadUtilities;
@@ -134,13 +134,13 @@ public final class EngineServiceImpl implements EngineService, EngineServiceEven
             LOGGER.warn("Engine service configuration parameters is null");
             throw new ApexException("engine service configuration parameters are null");
         }
-        
+
         final GroupValidationResult validation = config.validate();
         if (!validation.isValid()) {
             LOGGER.warn("Invalid engine service configuration parameters: {}" + validation.getResult());
             throw new ApexException("Invalid engine service configuration parameters: " + validation);
         }
-        
+
         final AxArtifactKey engineServiceKey = config.getEngineKey();
         final int threadCount = config.getInstanceCount();
 
@@ -235,6 +235,24 @@ public final class EngineServiceImpl implements EngineService, EngineServiceEven
     @Override
     public void updateModel(final AxArtifactKey incomingEngineServiceKey, final String apexModelString,
                     final boolean forceFlag) throws ApexException {
+        AxPolicyModel apexPolicyModel = createModel(incomingEngineServiceKey, apexModelString);
+
+        // Update the model
+        updateModel(incomingEngineServiceKey, apexPolicyModel, forceFlag);
+
+        LOGGER.exit();
+    }
+
+    /**
+    * Method to create model.
+    *
+    * @param incomingEngineServiceKey incoming engine service key
+    * @param apexModelString apex model string
+    * @return apexPolicyModel the policy model
+    * @throws ApexException apex exception
+    */
+    public static AxPolicyModel createModel(final AxArtifactKey incomingEngineServiceKey, final String apexModelString)
+        throws ApexException {
         // Check if the engine service key specified is sane
         if (incomingEngineServiceKey == null) {
             String message = ENGINE_KEY_NOT_SPECIFIED;
@@ -260,11 +278,7 @@ public final class EngineServiceImpl implements EngineService, EngineServiceEven
             LOGGER.error(message, e);
             throw new ApexException(message, e);
         }
-
-        // Update the model
-        updateModel(incomingEngineServiceKey, apexPolicyModel, forceFlag);
-
-        LOGGER.exit();
+        return apexPolicyModel;
     }
 
     /**
@@ -314,7 +328,7 @@ public final class EngineServiceImpl implements EngineService, EngineServiceEven
 
     /**
      * Execute the model update on the engine instances.
-     * 
+     *
      * @param incomingEngineServiceKey the engine service key to update
      * @param apexModel the model to update the engines with
      * @param forceFlag if true, ignore compatibility problems
@@ -322,7 +336,7 @@ public final class EngineServiceImpl implements EngineService, EngineServiceEven
      */
     private void executeModelUpdate(final AxArtifactKey incomingEngineServiceKey, final AxPolicyModel apexModel,
                     final boolean forceFlag) throws ApexException {
-        
+
         if (!isStopped()) {
             stopEngines(incomingEngineServiceKey);
         }
@@ -458,7 +472,7 @@ public final class EngineServiceImpl implements EngineService, EngineServiceEven
 
         // Start the engine
         engineWorkerMap.get(engineKey).start(engineKey);
-        
+
         // Check if periodic events should be turned on
         if (periodicEventPeriod > 0) {
             startPeriodicEvents(periodicEventPeriod);
@@ -478,7 +492,7 @@ public final class EngineServiceImpl implements EngineService, EngineServiceEven
             periodicEventGenerator.cancel();
             periodicEventGenerator = null;
         }
-        
+
         // Stop each engine
         for (final EngineService engine : engineWorkerMap.values()) {
             if (engine.getState() != AxEngineState.STOPPED) {
diff --git a/services/services-engine/src/main/java/org/onap/policy/apex/service/parameters/ApexParameterHandler.java b/services/services-engine/src/main/java/org/onap/policy/apex/service/parameters/ApexParameterHandler.java
index 4312793e4..c1ef50bd7 100644
--- a/services/services-engine/src/main/java/org/onap/policy/apex/service/parameters/ApexParameterHandler.java
+++ b/services/services-engine/src/main/java/org/onap/policy/apex/service/parameters/ApexParameterHandler.java
@@ -1,6 +1,7 @@
 /*-
  * ============LICENSE_START=======================================================
  *  Copyright (C) 2016-2018 Ericsson. All rights reserved.
+ *  Modifications Copyright (C) 2019 Nordix Foundation.
  * ================================================================================
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -22,9 +23,8 @@ package org.onap.policy.apex.service.parameters;
 
 import com.google.gson.Gson;
 import com.google.gson.GsonBuilder;
-
 import java.io.FileReader;
-
+import lombok.Setter;
 import org.onap.policy.apex.core.engine.EngineParameters;
 import org.onap.policy.apex.service.engine.main.ApexCommandLineArguments;
 import org.onap.policy.apex.service.parameters.carriertechnology.CarrierTechnologyParameters;
@@ -46,6 +46,9 @@ import org.slf4j.ext.XLoggerFactory;
 public class ApexParameterHandler {
     private static final XLogger LOGGER = XLoggerFactory.getXLogger(ApexParameterHandler.class);
 
+    @Setter
+    private boolean keepParameterServiceFlag;
+
     /**
      * Read the parameters from the parameter file.
      *
@@ -54,8 +57,11 @@ public class ApexParameterHandler {
      * @throws ParameterException on parameter exceptions
      */
     public ApexParameters getParameters(final ApexCommandLineArguments arguments) throws ParameterException {
-        // Clear all existing parameters
-        ParameterService.clear();
+        // when populating parameters for multiple policies, do not clear the ParameterService already registered
+        // otherwise clear all existing parameters
+        if (!keepParameterServiceFlag) {
+            ParameterService.clear();
+        }
 
         ApexParameters parameters = null;
 
@@ -112,8 +118,12 @@ public class ApexParameterHandler {
             LOGGER.info(returnMessage);
         }
 
-        // Register the parameters with the parameter service
-        registerParameters(parameters);
+        // engine parameters in multiple policies are expected to be same.
+        // no need to do registration if already registered
+        if (!keepParameterServiceFlag) {
+            // Register the parameters with the parameter service
+            registerParameters(parameters);
+        }
 
         return parameters;
     }