Changes related to multi policy handling improvement in APEX

This review fixes an issue identified during testing the changes done
for improving multiple policy handling in APEX.
Changes done to a few test files in the previous review are reverted as
well.

Change-Id: I98324da708239d314aadd4c45dc377137fd552ba
Issue-ID: POLICY-2883
Signed-off-by: a.sreekumar <ajith.sreekumar@bell.ca>

3 files changed, 141 insertions, 133 deletions

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 65c2acffa..3e9072dd4 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
@@ -71,7 +71,7 @@ public class ApexMain {
      * @param args the command line arguments
      * @throws ApexException the apex exception.
      */
-    public ApexMain(final String[] args) throws ApexException {
+    public ApexMain(final String[] args) {
         LOGGER.entry("Starting Apex service with parameters " + Arrays.toString(args) + " . . .");
         try {
             apexParameters = populateApexParameters(args);
@@ -79,17 +79,18 @@ public class ApexMain {
             LOGGER.error(APEX_SERVICE_FAILED_MSG, e);
             return;
         }
-        aggregateParametersAndRegister();
+        try {
+            aggregateParametersAndRegister();
 
-        // Now, create the activator for the Apex service
-        activator = new ApexActivator(apexParameters);
+            // Now, create the activator for the Apex service
+            activator = new ApexActivator(apexParameters);
 
-        // Start the activator
-        try {
+            // Start the activator
             activator.initialize();
             setAlive(true);
-        } catch (final ApexActivatorException e) {
-            throw new ApexException("start of Apex service failed, used parameters are " + Arrays.toString(args), e);
+        } catch (final ApexException 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
@@ -246,7 +247,7 @@ public class ApexMain {
      * @param args the arguments
      * @throws ApexException the apex exception.
      */
-    public static void main(final String[] args) throws ApexException {
+    public static void main(final String[] args) {
         new ApexMain(args);
     }
 }
diff --git a/services/services-engine/src/test/java/org/onap/policy/apex/service/engine/main/ApexMainTest.java b/services/services-engine/src/test/java/org/onap/policy/apex/service/engine/main/ApexMainTest.java
index 2cb12c397..5764a5275 100644
--- a/services/services-engine/src/test/java/org/onap/policy/apex/service/engine/main/ApexMainTest.java
+++ b/services/services-engine/src/test/java/org/onap/policy/apex/service/engine/main/ApexMainTest.java
@@ -23,7 +23,6 @@
 package org.onap.policy.apex.service.engine.main;
 
 import static org.assertj.core.api.Assertions.assertThat;
-import static org.assertj.core.api.Assertions.assertThatThrownBy;
 import static org.awaitility.Awaitility.await;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
@@ -31,10 +30,10 @@ import static org.junit.Assert.assertNotNull;
 import static org.junit.Assert.assertTrue;
 
 import java.io.ByteArrayOutputStream;
-import java.io.OutputStream;
 import java.io.PrintStream;
 import java.util.concurrent.TimeUnit;
 import org.junit.After;
+import org.junit.Before;
 import org.junit.Test;
 import org.onap.policy.apex.model.basicmodel.concepts.ApexException;
 import org.onap.policy.apex.model.basicmodel.service.ModelService;
@@ -44,7 +43,20 @@ import org.onap.policy.common.parameters.ParameterService;
  * Test the ApexMain class.
  */
 public class ApexMainTest {
-    private PrintStream stdout = System.out;
+    private final ByteArrayOutputStream outContent = new ByteArrayOutputStream();
+    private final PrintStream stdout = System.out;
+    private ApexMain apexMain1;
+    private ApexMain apexMain2;
+
+    /**
+     * Method for set up before each test.
+     *
+     * @throws Exception if an error occurs
+     */
+    @Before
+    public void setUp() throws Exception {
+        System.setOut(new PrintStream(outContent));
+    }
 
     /**
      * Method for cleanup after each test.
@@ -53,14 +65,17 @@ public class ApexMainTest {
      */
     @After
     public void teardown() throws Exception {
+        if (null != apexMain1) {
+            apexMain1.shutdown();
+        }
+        if (null != apexMain2) {
+            apexMain2.shutdown();
+        }
         System.setOut(stdout);
     }
 
     @Test
     public void testNullParameters() throws ApexException {
-        OutputStream outContent = new ByteArrayOutputStream();
-        System.setOut(new PrintStream(outContent));
-
         ApexMain.main(null);
         await().atMost(200, TimeUnit.MILLISECONDS).until(() -> outContent.toString()
                 .contains("Tosca Policy file was not specified as an argument"));
@@ -70,95 +85,71 @@ public class ApexMainTest {
 
     @Test
     public void testBadArguments() throws ApexException {
-        OutputStream outContent = new ByteArrayOutputStream();
-        System.setOut(new PrintStream(outContent));
-
         String[] args = { "-whee" };
 
-        final ApexMain apexMain = new ApexMain(args);
+        apexMain1 = new ApexMain(args);
         await().atMost(200, TimeUnit.MILLISECONDS).until(() -> outContent.toString()
                 .contains("invalid command line arguments specified : Unrecognized option: -whee"));
-        assertNotNull(apexMain);
-        apexMain.shutdown();
+        assertNotNull(apexMain1);
     }
 
     @Test
     public void testHelp() throws ApexException {
-        OutputStream outContent = new ByteArrayOutputStream();
-        System.setOut(new PrintStream(outContent));
-
         String[] args = { "-h" };
 
-        final ApexMain apexMain = new ApexMain(args);
+        apexMain1 = new ApexMain(args);
         await().atMost(200, TimeUnit.MILLISECONDS).until(() -> outContent.toString()
                 .contains("usage: org.onap.policy.apex.service.engine.main.ApexMain [options...]"));
-        assertNotNull(apexMain);
-        apexMain.shutdown();
+        assertNotNull(apexMain1);
     }
 
     @Test
     public void testBadParameters() throws ApexException {
-        OutputStream outContent = new ByteArrayOutputStream();
-        System.setOut(new PrintStream(outContent));
-
         String[] args = { "-p", "src/test/resources/parameters/badParams.json" };
 
-        final ApexMain apexMain = new ApexMain(args);
+        apexMain1 = new ApexMain(args);
         await().atMost(200, TimeUnit.MILLISECONDS).until(() -> outContent.toString()
                 .contains("parameter group has status INVALID"));
-        assertNotNull(apexMain);
-        apexMain.shutdown();
+        assertNotNull(apexMain1);
     }
 
     @Test
     public void testCorrectParameters() throws ApexException {
-        OutputStream outContent = new ByteArrayOutputStream();
-        System.setOut(new PrintStream(outContent));
-
         String[] args = {"-p", "src/test/resources/parameters/correctParams.json"};
 
-        final ApexMain apexMain = new ApexMain(args);
-        assertEquals("MyApexEngine", apexMain.getApexParameters().getEngineServiceParameters().getName());
+        apexMain1 = new ApexMain(args);
+        assertEquals("MyApexEngine", apexMain1.getApexParameters().getEngineServiceParameters().getName());
         await().atMost(200, TimeUnit.MILLISECONDS)
             .until(() -> outContent.toString().contains("Added the action listener to the engine"));
-        assertTrue(apexMain.isAlive());
-        apexMain.shutdown();
+        assertTrue(apexMain1.isAlive());
     }
 
     @Test
     public void testJavaProperties() throws ApexException {
-        OutputStream outContent = new ByteArrayOutputStream();
-        System.setOut(new PrintStream(outContent));
-
         String[] args = {"-p", "src/test/resources/parameters/correctParamsJavaProperties.json"};
 
-        final ApexMain apexMain = new ApexMain(args);
-        assertEquals("MyApexEngine", apexMain.getApexParameters().getEngineServiceParameters().getName());
+        apexMain1 = new ApexMain(args);
+        assertEquals("MyApexEngine", apexMain1.getApexParameters().getEngineServiceParameters().getName());
 
         assertEquals("trust-store-file", System.getProperty("javax.net.ssl.trustStore"));
         assertEquals("Pol1cy_0nap", System.getProperty("javax.net.ssl.trustStorePassword"));
         await().atMost(10000, TimeUnit.MILLISECONDS)
             .until(() -> outContent.toString().contains("Added the action listener to the engine"));
-        apexMain.shutdown();
     }
 
     @Test
     public void testCorrectParametersWithMultiplePolicies() throws ApexException {
-        OutputStream outContent = new ByteArrayOutputStream();
-        System.setOut(new PrintStream(outContent));
         String[] args1 = {"-p", "src/test/resources/parameters/correctParams.json"};
         String[] args2 = {"-p", "src/test/resources/parameters/correctParams2.json"};
-        final ApexMain apexMain1 = new ApexMain(args1);
-        final ApexMain apexMain2 = new ApexMain(args2);
+        apexMain1 = new ApexMain(args1);
+        apexMain2 = new ApexMain(args2);
         assertEquals("MyApexEngine", apexMain1.getApexParameters().getEngineServiceParameters().getName());
         assertEquals("MyApexEngine2", apexMain2.getApexParameters().getEngineServiceParameters().getName());
+        assertTrue(apexMain1.isAlive());
+        assertTrue(apexMain2.isAlive());
         final String outString = outContent.toString();
         assertThat(outString).contains("Added the action listener to the engine")
             .contains("Created apex engine MyApexEngine").contains("Created apex engine MyApexEngine2");
-        assertTrue(apexMain1.isAlive());
-        assertTrue(apexMain2.isAlive());
-        apexMain1.shutdown();
-        apexMain2.shutdown();
         ModelService.clear();
         ParameterService.clear();
     }
@@ -166,21 +157,21 @@ public class ApexMainTest {
     @Test
     public void testInCorrectParametersWithMultiplePolicies() throws ApexException {
         String[] args = {"-p", "src/test/resources/parameters/correctParams.json"};
-        final ApexMain apexMain1 = new ApexMain(args);
-        assertThatThrownBy(() -> new ApexMain(args)).hasMessage("start of Apex service failed because this"
+        apexMain1 = new ApexMain(args);
+        apexMain2 = new ApexMain(args);
+        assertTrue(apexMain1.isAlive());
+        assertFalse(apexMain2.isAlive());
+        final String outString = outContent.toString();
+        assertThat(outString).contains("start of Apex service failed because this"
             + " policy has the following duplicate I/O parameters: [TheFileConsumer1]/[FirstProducer]");
-        apexMain1.shutdown();
     }
 
     @Test
     public void testInvalidArgsWithMultiplePolicies() throws ApexException {
-        OutputStream outContent = new ByteArrayOutputStream();
-        System.setOut(new PrintStream(outContent));
         String[] args = {"-c", "file1", "-m", "file2"};
-        final ApexMain apexMain = new ApexMain(args);
+        apexMain1 = new ApexMain(args);
+        assertFalse(apexMain1.isAlive());
         final String outString = outContent.toString();
-        apexMain.shutdown();
         assertThat(outString).contains("Arguments validation failed", "start of Apex service failed");
-        assertFalse(apexMain.isAlive()); // No policy is running in the engine
     }
 }
diff --git a/services/services-onappf/src/main/java/org/onap/policy/apex/services/onappf/handler/ApexEngineHandler.java b/services/services-onappf/src/main/java/org/onap/policy/apex/services/onappf/handler/ApexEngineHandler.java
index 03e97215b..5a113a77d 100644
--- a/services/services-onappf/src/main/java/org/onap/policy/apex/services/onappf/handler/ApexEngineHandler.java
+++ b/services/services-onappf/src/main/java/org/onap/policy/apex/services/onappf/handler/ApexEngineHandler.java
@@ -72,7 +72,7 @@ public class ApexEngineHandler {
 
     private static final Logger LOGGER = LoggerFactory.getLogger(ApexEngineHandler.class);
 
-    private Map<ToscaConceptIdentifier, ApexMain> apexMainMap;
+    private Map<ToscaConceptIdentifier, ApexMain> apexMainMap = new LinkedHashMap<>();
 
     /**
      * Constructs the object. Extracts the config and model files from each policy and instantiates the apex engine.
@@ -82,12 +82,7 @@ public class ApexEngineHandler {
      */
     public ApexEngineHandler(List<ToscaPolicy> policies) throws ApexStarterException {
         LOGGER.debug("Starting apex engine.");
-        apexMainMap = initiateApexEngineForPolicies(policies);
-        if (apexMainMap.isEmpty()) {
-            ModelService.clear();
-            ParameterService.clear();
-            throw new ApexStarterException("Apex Engine failed to start.");
-        }
+        initiateApexEngineForPolicies(policies);
     }
 
     /**
@@ -118,11 +113,7 @@ public class ApexEngineHandler {
             updateModelAndParameterServices(undeployedPoliciesMainMap);
         }
         if (!policiesToDeploy.isEmpty()) {
-            Map<ToscaConceptIdentifier, ApexMain> mainMap = initiateApexEngineForPolicies(policiesToDeploy);
-            if (mainMap.isEmpty()) {
-                throw new ApexStarterException("Updating the APEX engine with new policies failed.");
-            }
-            apexMainMap.putAll(mainMap);
+            initiateApexEngineForPolicies(policiesToDeploy);
         }
         if (apexMainMap.isEmpty()) {
             ModelService.clear();
@@ -168,65 +159,80 @@ public class ApexEngineHandler {
             policyKeystoRetain.addAll(main.getActivator().getPolicyModel().getPolicies().getPolicyMap().keySet());
         });
         for (ApexMain main : undeployedPoliciesMainMap.values()) {
-            ApexParameters existingParameters = ParameterService.get(ApexParameterConstants.MAIN_GROUP_NAME);
-            List<String> eventInputParamKeysToRemove = main.getApexParameters().getEventInputParameters().keySet()
-                .stream().filter(key -> !inputParamKeysToRetain.contains(key)).collect(Collectors.toList());
-            List<String> eventOutputParamKeysToRemove = main.getApexParameters().getEventOutputParameters().keySet()
-                .stream().filter(key -> !outputParamKeysToRetain.contains(key)).collect(Collectors.toList());
-            eventInputParamKeysToRemove.forEach(existingParameters.getEventInputParameters()::remove);
-            eventOutputParamKeysToRemove.forEach(existingParameters.getEventOutputParameters()::remove);
-            EngineParameters engineParameters =
-                main.getApexParameters().getEngineServiceParameters().getEngineParameters();
-            final List<TaskParameters> taskParametersToRemove = engineParameters.getTaskParameters().stream()
-                .filter(taskParameter -> !taskParametersToRetain.contains(taskParameter)).collect(Collectors.toList());
-            final List<String> executorParamKeysToRemove = engineParameters.getExecutorParameterMap().keySet().stream()
-                .filter(key -> !executorParamKeysToRetain.contains(key)).collect(Collectors.toList());
-            final List<String> schemaParamKeysToRemove =
-                engineParameters.getContextParameters().getSchemaParameters().getSchemaHelperParameterMap().keySet()
-                    .stream().filter(key -> !schemaParamKeysToRetain.contains(key)).collect(Collectors.toList());
-            EngineParameters aggregatedEngineParameters =
-                existingParameters.getEngineServiceParameters().getEngineParameters();
-            aggregatedEngineParameters.getTaskParameters().removeAll(taskParametersToRemove);
-            executorParamKeysToRemove.forEach(aggregatedEngineParameters.getExecutorParameterMap()::remove);
-            schemaParamKeysToRemove.forEach(aggregatedEngineParameters.getContextParameters().getSchemaParameters()
-                .getSchemaHelperParameterMap()::remove);
+            handleParametersRemoval(inputParamKeysToRetain, outputParamKeysToRetain, taskParametersToRetain,
+                executorParamKeysToRetain, schemaParamKeysToRetain, main);
+
+            if (null != main.getActivator() && null != main.getActivator().getPolicyModel()) {
+                handleAxConceptsRemoval(keyInfoKeystoRetain, schemaKeystoRetain, eventKeystoRetain, albumKeystoRetain,
+                    taskKeystoRetain, policyKeystoRetain, main);
+            }
+        }
+    }
 
-            final AxPolicyModel policyModel = main.getActivator().getPolicyModel();
-            final List<AxArtifactKey> keyInfoKeystoRemove = policyModel.getKeyInformation().getKeyInfoMap().keySet()
-                .stream().filter(key -> !keyInfoKeystoRetain.contains(key)).collect(Collectors.toList());
-            final List<AxArtifactKey> schemaKeystoRemove = policyModel.getSchemas().getSchemasMap().keySet().stream()
-                .filter(key -> !schemaKeystoRetain.contains(key)).collect(Collectors.toList());
-            final List<AxArtifactKey> eventKeystoRemove = policyModel.getEvents().getEventMap().keySet().stream()
-                .filter(key -> !eventKeystoRetain.contains(key)).collect(Collectors.toList());
-            final List<AxArtifactKey> albumKeystoRemove = policyModel.getAlbums().getAlbumsMap().keySet().stream()
-                .filter(key -> !albumKeystoRetain.contains(key)).collect(Collectors.toList());
-            final List<AxArtifactKey> taskKeystoRemove = policyModel.getTasks().getTaskMap().keySet().stream()
-                .filter(key -> !taskKeystoRetain.contains(key)).collect(Collectors.toList());
-            final List<AxArtifactKey> policyKeystoRemove = policyModel.getPolicies().getPolicyMap().keySet().stream()
-                .filter(key -> !policyKeystoRetain.contains(key)).collect(Collectors.toList());
+    private void handleParametersRemoval(Set<String> inputParamKeysToRetain, Set<String> outputParamKeysToRetain,
+        List<TaskParameters> taskParametersToRetain, List<String> executorParamKeysToRetain,
+        List<String> schemaParamKeysToRetain, ApexMain main) {
+        ApexParameters existingParameters = ParameterService.get(ApexParameterConstants.MAIN_GROUP_NAME);
+        List<String> eventInputParamKeysToRemove = main.getApexParameters().getEventInputParameters().keySet().stream()
+            .filter(key -> !inputParamKeysToRetain.contains(key)).collect(Collectors.toList());
+        List<String> eventOutputParamKeysToRemove = main.getApexParameters().getEventOutputParameters().keySet()
+            .stream().filter(key -> !outputParamKeysToRetain.contains(key)).collect(Collectors.toList());
+        eventInputParamKeysToRemove.forEach(existingParameters.getEventInputParameters()::remove);
+        eventOutputParamKeysToRemove.forEach(existingParameters.getEventOutputParameters()::remove);
+        EngineParameters engineParameters = main.getApexParameters().getEngineServiceParameters().getEngineParameters();
+        final List<TaskParameters> taskParametersToRemove = engineParameters.getTaskParameters().stream()
+            .filter(taskParameter -> !taskParametersToRetain.contains(taskParameter)).collect(Collectors.toList());
+        final List<String> executorParamKeysToRemove = engineParameters.getExecutorParameterMap().keySet().stream()
+            .filter(key -> !executorParamKeysToRetain.contains(key)).collect(Collectors.toList());
+        final List<String> schemaParamKeysToRemove =
+            engineParameters.getContextParameters().getSchemaParameters().getSchemaHelperParameterMap().keySet()
+                .stream().filter(key -> !schemaParamKeysToRetain.contains(key)).collect(Collectors.toList());
+        EngineParameters aggregatedEngineParameters =
+            existingParameters.getEngineServiceParameters().getEngineParameters();
+        aggregatedEngineParameters.getTaskParameters().removeAll(taskParametersToRemove);
+        executorParamKeysToRemove.forEach(aggregatedEngineParameters.getExecutorParameterMap()::remove);
+        schemaParamKeysToRemove.forEach(aggregatedEngineParameters.getContextParameters().getSchemaParameters()
+            .getSchemaHelperParameterMap()::remove);
+    }
 
-            final Map<AxArtifactKey, AxKeyInfo> keyInfoMap =
-                ModelService.getModel(AxKeyInformation.class).getKeyInfoMap();
-            final Map<AxArtifactKey, AxContextSchema> schemasMap =
-                ModelService.getModel(AxContextSchemas.class).getSchemasMap();
-            final Map<AxArtifactKey, AxEvent> eventMap = ModelService.getModel(AxEvents.class).getEventMap();
-            final Map<AxArtifactKey, AxContextAlbum> albumsMap =
-                ModelService.getModel(AxContextAlbums.class).getAlbumsMap();
-            final Map<AxArtifactKey, AxTask> taskMap = ModelService.getModel(AxTasks.class).getTaskMap();
-            final Map<AxArtifactKey, AxPolicy> policyMap = ModelService.getModel(AxPolicies.class).getPolicyMap();
+    private void handleAxConceptsRemoval(List<AxArtifactKey> keyInfoKeystoRetain,
+        List<AxArtifactKey> schemaKeystoRetain, List<AxArtifactKey> eventKeystoRetain,
+        List<AxArtifactKey> albumKeystoRetain, List<AxArtifactKey> taskKeystoRetain,
+        List<AxArtifactKey> policyKeystoRetain, ApexMain main) {
+        final AxPolicyModel policyModel = main.getActivator().getPolicyModel();
+        final List<AxArtifactKey> keyInfoKeystoRemove = policyModel.getKeyInformation().getKeyInfoMap().keySet()
+            .stream().filter(key -> !keyInfoKeystoRetain.contains(key)).collect(Collectors.toList());
+        final List<AxArtifactKey> schemaKeystoRemove = policyModel.getSchemas().getSchemasMap().keySet().stream()
+            .filter(key -> !schemaKeystoRetain.contains(key)).collect(Collectors.toList());
+        final List<AxArtifactKey> eventKeystoRemove = policyModel.getEvents().getEventMap().keySet().stream()
+            .filter(key -> !eventKeystoRetain.contains(key)).collect(Collectors.toList());
+        final List<AxArtifactKey> albumKeystoRemove = policyModel.getAlbums().getAlbumsMap().keySet().stream()
+            .filter(key -> !albumKeystoRetain.contains(key)).collect(Collectors.toList());
+        final List<AxArtifactKey> taskKeystoRemove = policyModel.getTasks().getTaskMap().keySet().stream()
+            .filter(key -> !taskKeystoRetain.contains(key)).collect(Collectors.toList());
+        final List<AxArtifactKey> policyKeystoRemove = policyModel.getPolicies().getPolicyMap().keySet().stream()
+            .filter(key -> !policyKeystoRetain.contains(key)).collect(Collectors.toList());
 
-            keyInfoKeystoRemove.forEach(keyInfoMap::remove);
-            schemaKeystoRemove.forEach(schemasMap::remove);
-            eventKeystoRemove.forEach(eventMap::remove);
-            albumKeystoRemove.forEach(albumsMap::remove);
-            taskKeystoRemove.forEach(taskMap::remove);
-            policyKeystoRemove.forEach(policyMap::remove);
-        }
+        final Map<AxArtifactKey, AxKeyInfo> keyInfoMap = ModelService.getModel(AxKeyInformation.class).getKeyInfoMap();
+        final Map<AxArtifactKey, AxContextSchema> schemasMap =
+            ModelService.getModel(AxContextSchemas.class).getSchemasMap();
+        final Map<AxArtifactKey, AxEvent> eventMap = ModelService.getModel(AxEvents.class).getEventMap();
+        final Map<AxArtifactKey, AxContextAlbum> albumsMap =
+            ModelService.getModel(AxContextAlbums.class).getAlbumsMap();
+        final Map<AxArtifactKey, AxTask> taskMap = ModelService.getModel(AxTasks.class).getTaskMap();
+        final Map<AxArtifactKey, AxPolicy> policyMap = ModelService.getModel(AxPolicies.class).getPolicyMap();
+
+        keyInfoKeystoRemove.forEach(keyInfoMap::remove);
+        schemaKeystoRemove.forEach(schemasMap::remove);
+        eventKeystoRemove.forEach(eventMap::remove);
+        albumKeystoRemove.forEach(albumsMap::remove);
+        taskKeystoRemove.forEach(taskMap::remove);
+        policyKeystoRemove.forEach(policyMap::remove);
     }
 
-    private Map<ToscaConceptIdentifier, ApexMain> initiateApexEngineForPolicies(List<ToscaPolicy> policies)
+    private void initiateApexEngineForPolicies(List<ToscaPolicy> policies)
         throws ApexStarterException {
-        Map<ToscaConceptIdentifier, ApexMain> mainMap = new LinkedHashMap<>();
+        Map<ToscaConceptIdentifier, ApexMain> failedPoliciesMainMap = new LinkedHashMap<>();
         for (ToscaPolicy policy : policies) {
             String policyName = policy.getIdentifier().getName();
             final StandardCoder standardCoder = new StandardCoder();
@@ -243,14 +249,24 @@ public class ApexEngineHandler {
             }
             final String[] apexArgs = {"-p", file.getAbsolutePath()};
             LOGGER.info("Starting apex engine for policy {}", policy.getIdentifier());
-            try {
-                ApexMain apexMain = new ApexMain(apexArgs);
-                mainMap.put(policy.getIdentifier(), apexMain);
-            } catch (Exception e) {
-                LOGGER.error("Execution of policy {} failed", policy.getIdentifier(), e);
+            ApexMain apexMain = new ApexMain(apexArgs);
+            if (apexMain.isAlive()) {
+                apexMainMap.put(policy.getIdentifier(), apexMain);
+            } else {
+                failedPoliciesMainMap.put(policy.getIdentifier(), apexMain);
+                LOGGER.error("Execution of policy {} failed", policy.getIdentifier());
+            }
+        }
+        if (apexMainMap.isEmpty()) {
+            ModelService.clear();
+            ParameterService.clear();
+            throw new ApexStarterException("Apex Engine failed to start.");
+        } else if (failedPoliciesMainMap.size() > 0) {
+            updateModelAndParameterServices(failedPoliciesMainMap);
+            if (failedPoliciesMainMap.size() == policies.size()) {
+                throw new ApexStarterException("Updating the APEX engine with new policies failed.");
             }
         }
-        return mainMap;
     }
 
     /**