Added BidirectionalTopicClient to policy-common

Added review comments:
- check for too many topic sources

Issue-ID: POLICY-2363
Signed-off-by: Jim Hahn <jrh3@att.com>
Change-Id: I89f34c4f756fb0c938dd7dda5896f3426cfc7ac2

2 files changed, 158 insertions, 0 deletions

diff --git a/policy-endpoints/src/main/java/org/onap/policy/common/endpoints/event/comm/client/BidirectionalTopicClient.java b/policy-endpoints/src/main/java/org/onap/policy/common/endpoints/event/comm/client/BidirectionalTopicClient.java
new file mode 100644
index 00000000..a1e03155
--- /dev/null
+++ b/policy-endpoints/src/main/java/org/onap/policy/common/endpoints/event/comm/client/BidirectionalTopicClient.java
@@ -0,0 +1,109 @@
+/*-
+ * ============LICENSE_START=======================================================
+ * ONAP
+ * ================================================================================
+ * Copyright (C) 2020 AT&T Intellectual Property. 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.
+ * ============LICENSE_END=========================================================
+ */
+
+package org.onap.policy.common.endpoints.event.comm.client;
+
+import java.util.Arrays;
+import java.util.List;
+import lombok.Getter;
+import org.onap.policy.common.endpoints.event.comm.Topic.CommInfrastructure;
+import org.onap.policy.common.endpoints.event.comm.TopicEndpoint;
+import org.onap.policy.common.endpoints.event.comm.TopicEndpointManager;
+import org.onap.policy.common.endpoints.event.comm.TopicListener;
+import org.onap.policy.common.endpoints.event.comm.TopicSink;
+import org.onap.policy.common.endpoints.event.comm.TopicSource;
+
+/**
+ * A "bidirectional" topic, which is a pair of topics, one of which is used to publish
+ * requests and the other to receive responses.
+ */
+@Getter
+public class BidirectionalTopicClient {
+    private final String sinkTopic;
+    private final String sourceTopic;
+    private final TopicSinkClient sinkClient;
+    private final TopicSource source;
+    private final CommInfrastructure sinkTopicCommInfrastructure;
+    private final CommInfrastructure sourceTopicCommInfrastructure;
+
+    /**
+     * Constructs the object.
+     *
+     * @param sinkTopic sink topic name
+     * @param sourceTopic source topic name
+     * @throws BidirectionalTopicClientException if either topic does not exist
+     */
+    public BidirectionalTopicClient(String sinkTopic, String sourceTopic) throws BidirectionalTopicClientException {
+        this.sinkTopic = sinkTopic;
+        this.sourceTopic = sourceTopic;
+
+        // init sinkClient
+        try {
+            // if the manager is overridden here, then override it in the sink client, too
+            this.sinkClient = new TopicSinkClient(sinkTopic) {
+                @Override
+                protected List<TopicSink> getTopicSinks(String topic) {
+                    return BidirectionalTopicClient.this.getTopicEndpointManager().getTopicSinks(topic);
+                }
+            };
+        } catch (TopicSinkClientException e) {
+            throw new BidirectionalTopicClientException(e);
+        }
+
+        // init source
+        List<TopicSource> sources = getTopicEndpointManager().getTopicSources(Arrays.asList(sourceTopic));
+        if (sources.isEmpty()) {
+            throw new BidirectionalTopicClientException("no sources for topic: " + sourceTopic);
+        } else if (sources.size() > 1) {
+            throw new BidirectionalTopicClientException("too many sources for topic: " + sourceTopic);
+        }
+
+        this.source = sources.get(0);
+
+        this.sinkTopicCommInfrastructure = sinkClient.getSink().getTopicCommInfrastructure();
+        this.sourceTopicCommInfrastructure = source.getTopicCommInfrastructure();
+    }
+
+    public TopicSink getSink() {
+        return sinkClient.getSink();
+    }
+
+    public boolean send(Object message) {
+        return sinkClient.send(message);
+    }
+
+    public void register(TopicListener topicListener) {
+        source.register(topicListener);
+    }
+
+    public boolean offer(String event) {
+        return source.offer(event);
+    }
+
+    public void unregister(TopicListener topicListener) {
+        source.unregister(topicListener);
+    }
+
+    // these may be overridden by junit tests
+
+    protected TopicEndpoint getTopicEndpointManager() {
+        return TopicEndpointManager.getManager();
+    }
+}
diff --git a/policy-endpoints/src/main/java/org/onap/policy/common/endpoints/event/comm/client/BidirectionalTopicClientException.java b/policy-endpoints/src/main/java/org/onap/policy/common/endpoints/event/comm/client/BidirectionalTopicClientException.java
new file mode 100644
index 00000000..3a5d727b
--- /dev/null
+++ b/policy-endpoints/src/main/java/org/onap/policy/common/endpoints/event/comm/client/BidirectionalTopicClientException.java
@@ -0,0 +1,49 @@
+/*-
+ * ============LICENSE_START=======================================================
+ * ONAP
+ * ================================================================================
+ * Copyright (C) 2020 AT&T Intellectual Property. 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.
+ * ============LICENSE_END=========================================================
+ */
+
+package org.onap.policy.common.endpoints.event.comm.client;
+
+/**
+ * Exception thrown by BidirectionalTopicClient class.
+ */
+public class BidirectionalTopicClientException extends Exception {
+    private static final long serialVersionUID = 1L;
+
+    public BidirectionalTopicClientException() {
+        super();
+    }
+
+    public BidirectionalTopicClientException(String message) {
+        super(message);
+    }
+
+    public BidirectionalTopicClientException(Throwable cause) {
+        super(cause);
+    }
+
+    public BidirectionalTopicClientException(String message, Throwable cause) {
+        super(message, cause);
+    }
+
+    public BidirectionalTopicClientException(String message, Throwable cause, boolean enableSuppression,
+                    boolean writableStackTrace) {
+        super(message, cause, enableSuppression, writableStackTrace);
+    }
+}