Adding code for managing life cycle of SDC Client

* Adding init/start/stop methods in SDCReceptionHandler for managing lifecycle of SDC Client.
* Adding a handler status enum to hold all the possible status values.
* Adding test cases to cover code changes fully.

Change-Id: Ib6f370485ff330538bfada6030c592629ed3fd1c
Issue-ID: POLICY-956
Signed-off-by: ramverma <ram.krishna.verma@ericsson.com>

4 files changed, 219 insertions, 22 deletions

diff --git a/plugins/reception-plugins/src/main/java/org/onap/policy/distribution/reception/handling/sdc/PssdConfiguration.java b/plugins/reception-plugins/src/main/java/org/onap/policy/distribution/reception/handling/sdc/SdcConfiguration.java
index c5c877e1..945670b9 100644
--- a/plugins/reception-plugins/src/main/java/org/onap/policy/distribution/reception/handling/sdc/PssdConfiguration.java
+++ b/plugins/reception-plugins/src/main/java/org/onap/policy/distribution/reception/handling/sdc/SdcConfiguration.java
@@ -22,31 +22,26 @@ package org.onap.policy.distribution.reception.handling.sdc;
 
 import java.util.List;
 
-import org.onap.sdc.api.consumer.IConfiguration;
 import org.onap.policy.distribution.reception.parameters.PssdConfigurationParametersGroup;
+import org.onap.sdc.api.consumer.IConfiguration;
 
 /**
- * Properties for the handling Sdc
+ * This class represents the configurations needed for SDC Client.
  *
  */
-public class PssdConfiguration implements IConfiguration {
+public class SdcConfiguration implements IConfiguration {
 
-    // Configuration file structure
-
-    // Configuration file properties
     private PssdConfigurationParametersGroup configParameters = null;
 
     /**
-     * Original constructor
+     * Constructor for instantiating {@link SdcConfiguration}.
      *
-     * @param configParameters properties needed to be configured for the model loader
+     * @param configParameters the SDC Client configuration parameters
      */
-    public PssdConfiguration(final PssdConfigurationParametersGroup configParameters) {
+    public SdcConfiguration(final PssdConfigurationParametersGroup configParameters) {
         this.configParameters = configParameters;
-
     }
 
-
     @Override
     public String getAsdcAddress() {
         return configParameters.getAsdcAddress();
@@ -121,6 +116,4 @@ public class PssdConfiguration implements IConfiguration {
     public Boolean isUseHttpsWithDmaap() {
         return configParameters.isUseHttpsWithDmaap();
     }
-
-
 }
diff --git a/plugins/reception-plugins/src/main/java/org/onap/policy/distribution/reception/handling/sdc/SdcNotificationCallBack.java b/plugins/reception-plugins/src/main/java/org/onap/policy/distribution/reception/handling/sdc/SdcNotificationCallBack.java
new file mode 100644
index 00000000..0ea57799
--- /dev/null
+++ b/plugins/reception-plugins/src/main/java/org/onap/policy/distribution/reception/handling/sdc/SdcNotificationCallBack.java
@@ -0,0 +1,45 @@
+/*-
+ * ============LICENSE_START=======================================================
+ *  Copyright (C) 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.distribution.reception.handling.sdc;
+
+import org.onap.policy.common.logging.flexlogger.FlexLogger;
+import org.onap.policy.common.logging.flexlogger.Logger;
+import org.onap.sdc.api.consumer.INotificationCallback;
+import org.onap.sdc.api.notification.INotificationData;
+
+/**
+ * Class to provide an implementation of INotificationCallback interface for receiving the incoming distribution
+ * notifications from SDC.
+ *
+ * @author Ram Krishna Verma (ram.krishna.verma@ericsson.com)
+ */
+public class SdcNotificationCallBack implements INotificationCallback {
+
+    private static final Logger LOGGER = FlexLogger.getLogger(SdcNotificationCallBack.class);
+
+    @Override
+    public void activateCallback(final INotificationData notificationData) {
+
+        LOGGER.debug("Got the message from SDC:" + notificationData.getDistributionID());
+        // Code for handling notification will come here
+    }
+
+}
diff --git a/plugins/reception-plugins/src/main/java/org/onap/policy/distribution/reception/handling/sdc/SdcReceptionHandler.java b/plugins/reception-plugins/src/main/java/org/onap/policy/distribution/reception/handling/sdc/SdcReceptionHandler.java
index 494f47f6..60c94e2b 100644
--- a/plugins/reception-plugins/src/main/java/org/onap/policy/distribution/reception/handling/sdc/SdcReceptionHandler.java
+++ b/plugins/reception-plugins/src/main/java/org/onap/policy/distribution/reception/handling/sdc/SdcReceptionHandler.java
@@ -5,40 +5,150 @@
  * 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.distribution.reception.handling.sdc;
 
+import org.onap.policy.common.logging.flexlogger.FlexLogger;
+import org.onap.policy.common.logging.flexlogger.Logger;
+import org.onap.policy.common.parameters.ParameterService;
+import org.onap.policy.distribution.reception.decoding.PluginInitializationException;
+import org.onap.policy.distribution.reception.decoding.PluginTerminationException;
 import org.onap.policy.distribution.reception.handling.AbstractReceptionHandler;
+import org.onap.policy.distribution.reception.parameters.PssdConfigurationParametersGroup;
+import org.onap.sdc.api.IDistributionClient;
+import org.onap.sdc.api.results.IDistributionClientResult;
+import org.onap.sdc.impl.DistributionClientFactory;
+import org.onap.sdc.utils.DistributionActionResultEnum;
 
 /**
- * Handles reception of inputs from ONAP Service Design and Creation (SDC) from which policies may
- * be decoded.
+ * Handles reception of inputs from ONAP Service Design and Creation (SDC) from which policies may be decoded.
  */
 public class SdcReceptionHandler extends AbstractReceptionHandler {
 
+    private static final Logger LOGGER = FlexLogger.getLogger(SdcReceptionHandler.class);
+    private SdcReceptionHandlerStatus sdcReceptionHandlerStatus = SdcReceptionHandlerStatus.STOPPED;
+    private PssdConfigurationParametersGroup handlerParameters;
+    private IDistributionClient distributionClient;
+    private volatile int nbOfNotificationsOngoing = 0;
+
     @Override
-    protected void initializeReception(String parameterGroupName) {
-        // Set up subscription to SDC
+    protected void initializeReception(final String parameterGroupName) throws PluginInitializationException {
+        handlerParameters = (PssdConfigurationParametersGroup) ParameterService.get(parameterGroupName);
+        initializeSdcClient();
+        startSdcClient();
     }
 
     // Add functionality for receiving SDC distibutions and invoking AbstractReceptionHandler
     // inputReceived()
 
     @Override
-    public void destroy() {
-        // Tear down subscription etc
+    public void destroy() throws PluginTerminationException {
+        LOGGER.debug("Going to stop the SDC Client...");
+        if (distributionClient != null) {
+            final IDistributionClientResult clientResult = distributionClient.stop();
+            if (!clientResult.getDistributionActionResult().equals(DistributionActionResultEnum.SUCCESS)) {
+                final String message =
+                        "SDC client stop failed with reason:" + clientResult.getDistributionMessageResult();
+                LOGGER.error(message);
+                throw new PluginTerminationException(message);
+            }
+        }
+        changeSdcReceptionHandlerStatus(SdcReceptionHandlerStatus.STOPPED);
+        LOGGER.debug("SDC Client is stopped successfully");
+    }
+
+    /**
+     * Method to change the status of this reception handler instance.
+     *
+     * @param newStatus the new status
+     */
+    protected synchronized final void changeSdcReceptionHandlerStatus(final SdcReceptionHandlerStatus newStatus) {
+        switch (newStatus) {
+            case INIT:
+            case STOPPED:
+                sdcReceptionHandlerStatus = newStatus;
+                break;
+            case IDLE:
+                if (nbOfNotificationsOngoing > 1) {
+                    --nbOfNotificationsOngoing;
+                } else {
+                    nbOfNotificationsOngoing = 0;
+                    sdcReceptionHandlerStatus = newStatus;
+                }
+                break;
+            case BUSY:
+                ++nbOfNotificationsOngoing;
+                sdcReceptionHandlerStatus = newStatus;
+                break;
+        }
+    }
+
+    /**
+     * Creates an instance of {@link IDistributionClient} from {@link DistributionClientFactory}.
+     *
+     * @return the {@link IDistributionClient} instance
+     */
+    protected IDistributionClient createSdcDistributionClient() {
+        return DistributionClientFactory.createDistributionClient();
     }
 
+    /**
+     * Method to initialize the SDC client.
+     *
+     * @throws PluginInitializationException if the initialization of SDC Client fails
+     */
+    private void initializeSdcClient() throws PluginInitializationException {
+
+        LOGGER.debug("Going to initialize the SDC Client...");
+        if (sdcReceptionHandlerStatus != SdcReceptionHandlerStatus.STOPPED) {
+            final String message = "The SDC Client is already initialized";
+            LOGGER.error(message);
+            throw new PluginInitializationException(message);
+        }
+        final SdcConfiguration sdcConfig = new SdcConfiguration(handlerParameters);
+        distributionClient = createSdcDistributionClient();
+        final IDistributionClientResult clientResult =
+                distributionClient.init(sdcConfig, new SdcNotificationCallBack());
+        if (!clientResult.getDistributionActionResult().equals(DistributionActionResultEnum.SUCCESS)) {
+            changeSdcReceptionHandlerStatus(SdcReceptionHandlerStatus.STOPPED);
+            final String message =
+                    "SDC client initialization failed with reason:" + clientResult.getDistributionMessageResult();
+            LOGGER.error(message);
+            throw new PluginInitializationException(message);
+        }
+        LOGGER.debug("SDC Client is initialized successfully");
+        this.changeSdcReceptionHandlerStatus(SdcReceptionHandlerStatus.INIT);
+    }
+
+    /**
+     * Method to start the SDC client.
+     *
+     * @param configParameter the configuration parameters
+     * @throws PluginInitializationException if the start of SDC Client fails
+     */
+    private void startSdcClient() throws PluginInitializationException {
+
+        LOGGER.debug("Going to start the SDC Client...");
+        final IDistributionClientResult clientResult = distributionClient.start();
+        if (!clientResult.getDistributionActionResult().equals(DistributionActionResultEnum.SUCCESS)) {
+            changeSdcReceptionHandlerStatus(SdcReceptionHandlerStatus.STOPPED);
+            final String message = "SDC client start failed with reason:" + clientResult.getDistributionMessageResult();
+            LOGGER.error(message);
+            throw new PluginInitializationException(message);
+        }
+        LOGGER.debug("SDC Client is started successfully");
+        this.changeSdcReceptionHandlerStatus(SdcReceptionHandlerStatus.IDLE);
+    }
 }
diff --git a/plugins/reception-plugins/src/main/java/org/onap/policy/distribution/reception/handling/sdc/SdcReceptionHandlerStatus.java b/plugins/reception-plugins/src/main/java/org/onap/policy/distribution/reception/handling/sdc/SdcReceptionHandlerStatus.java
new file mode 100644
index 00000000..d0e04c78
--- /dev/null
+++ b/plugins/reception-plugins/src/main/java/org/onap/policy/distribution/reception/handling/sdc/SdcReceptionHandlerStatus.java
@@ -0,0 +1,49 @@
+/*-
+ * ============LICENSE_START=======================================================
+ *  Copyright (C) 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.distribution.reception.handling.sdc;
+
+/**
+ * Class to hold the possible values for status of {@link SdcReceptionHandler}.
+ *
+ * @author Ram Krishna Verma (ram.krishna.verma@ericsson.com)
+ */
+public enum SdcReceptionHandlerStatus {
+
+    /**
+     * The SdcReceptionHandler is not alive.
+     */
+    STOPPED,
+
+    /**
+     * The SdcReceptionHandler is initialized but not started yet.
+     */
+    INIT,
+
+    /**
+     * The SdcReceptionHandler is initialized, started & ready to handle incoming notifications.
+     */
+    IDLE,
+
+    /**
+     * The SdcReceptionHandler is currently busy in handling notifications.
+     */
+    BUSY
+}