Bug fixes in models simulators

Fixed these issues:
- topics weren't started
- appc topics were reversed
- prevent appc simulator from responding to a response (i.e., infinite
  loop)

Issue-ID: POLICY-2434
Signed-off-by: Jim Hahn <jrh3@att.com>
Change-Id: I1f43be72d35f874fec98f48f1a112c055c00eee5

2 files changed, 19 insertions, 1 deletions

diff --git a/models-interactions/model-simulators/src/main/java/org/onap/policy/simulators/AppcLegacyTopicServer.java b/models-interactions/model-simulators/src/main/java/org/onap/policy/simulators/AppcLegacyTopicServer.java
index 5ebd3bd2a..0c259783d 100644
--- a/models-interactions/model-simulators/src/main/java/org/onap/policy/simulators/AppcLegacyTopicServer.java
+++ b/models-interactions/model-simulators/src/main/java/org/onap/policy/simulators/AppcLegacyTopicServer.java
@@ -36,6 +36,15 @@ public class AppcLegacyTopicServer extends TopicServer<Request> {
 
     @Override
     protected String process(Request request) {
+        /*
+         * The request and response are on the same topic, thus this may be invoked with a
+         * request or with a response object. If the "action" is null, then we know it's a
+         * response.
+         */
+        if (request.getAction() == null) {
+            return null;
+        }
+
         String response = ResourceUtils.getResourceAsString("org/onap/policy/simulators/appc/appc.legacy.success.json");
         return response.replace("${replaceMe}", request.getCommonHeader().getSubRequestId());
     }
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
index 0abe5f421..4c01511da 100644
--- 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
@@ -65,8 +65,17 @@ public abstract class TopicServer<Q> implements TopicListener {
             throw new IllegalArgumentException("cannot decode request from " + source.getTopic());
         }
 
-        sink.send(process(req));
+        String resp = process(req);
+        if (resp != null) {
+            sink.send(resp);
+        }
     }
 
+    /**
+     * Processes a request.
+     *
+     * @param request request to be processed
+     * @return the response, or {@code null} if no response is to be sent
+     */
     protected abstract String process(Q request);
 }