1 files changed, 72 insertions, 0 deletions
diff --git a/models-interactions/model-simulators/src/main/java/org/onap/policy/simulators/TopicServer.java b/models-interactions/model-simulators/src/main/java/org/onap/policy/simulators/TopicServer.java
new file mode 100644
index 000000000..0abe5f421
--- /dev/null
+++ b/models-interactions/model-simulators/src/main/java/org/onap/policy/simulators/TopicServer.java
@@ -0,0 +1,72 @@
+/*-
+ * ============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.simulators;
+
+import org.onap.policy.common.endpoints.event.comm.Topic.CommInfrastructure;
+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;
+import org.onap.policy.common.utils.coder.Coder;
+import org.onap.policy.common.utils.coder.CoderException;
+
+/**
+ * Server whose requests are received from a topic, and whose responses are sent to a
+ * topic.
+ */
+public abstract class TopicServer<Q> implements TopicListener {
+    private final TopicSink sink;
+    private final TopicSource source;
+    private final Coder coder;
+    private final Class<Q> reqClass;
+
+    /**
+     * Constructs the object.
+     *
+     * @param sink sink to which responses should be published
+     * @param source source from which requests arrive
+     */
+    public TopicServer(TopicSink sink, TopicSource source, Coder coder, Class<Q> reqClass) {
+        this.sink = sink;
+        this.source = source;
+        this.coder = coder;
+        this.reqClass = reqClass;
+
+        source.register(this);
+    }
+
+    public void shutdown() {
+        source.unregister(this);
+    }
+
+    @Override
+    public void onTopicEvent(CommInfrastructure commType, String topic, String request) {
+        Q req;
+        try {
+            req = coder.decode(request, reqClass);
+        } catch (CoderException e) {
+            throw new IllegalArgumentException("cannot decode request from " + source.getTopic());
+        }
+
+        sink.send(process(req));
+    }
+
+    protected abstract String process(Q request);
+}