2 * ============LICENSE_START=======================================================
4 * ================================================================================
5 * Copyright (C) 2018-2019 AT&T Intellectual Property. All rights reserved.
6 * ================================================================================
7 * Licensed under the Apache License, Version 2.0 (the "License");
8 * you may not use this file except in compliance with the License.
9 * You may obtain a copy of the License at
11 * http://www.apache.org/licenses/LICENSE-2.0
13 * Unless required by applicable law or agreed to in writing, software
14 * distributed under the License is distributed on an "AS IS" BASIS,
15 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
16 * See the License for the specific language governing permissions and
17 * limitations under the License.
18 * ============LICENSE_END=========================================================
21 package org.onap.policy.drools.pooling;
23 import com.google.gson.Gson;
24 import com.google.gson.JsonElement;
25 import com.google.gson.JsonParseException;
26 import java.util.HashMap;
28 import org.onap.policy.drools.pooling.message.Forward;
29 import org.onap.policy.drools.pooling.message.Heartbeat;
30 import org.onap.policy.drools.pooling.message.Identification;
31 import org.onap.policy.drools.pooling.message.Leader;
32 import org.onap.policy.drools.pooling.message.Message;
33 import org.onap.policy.drools.pooling.message.Offline;
34 import org.onap.policy.drools.pooling.message.Query;
37 * Serialization helper functions.
39 public class Serializer {
42 * The message type is stored in fields of this name within the JSON.
44 private static final String TYPE_FIELD = "type";
47 * Used to encode & decode JSON messages sent & received, respectively, on the
48 * internal DMaaP topic.
50 private final Gson gson = new Gson();
53 * Maps a message subclass to its type.
55 private static final Map<Class<? extends Message>, String> class2type = new HashMap<>();
58 * Maps a message type to the appropriate subclass.
60 private static final Map<String, Class<? extends Message>> type2class = new HashMap<>();
63 class2type.put(Forward.class, "forward");
64 class2type.put(Heartbeat.class, "heartbeat");
65 class2type.put(Identification.class, "identification");
66 class2type.put(Leader.class, "leader");
67 class2type.put(Offline.class, "offline");
68 class2type.put(Query.class, "query");
70 class2type.forEach((clazz, type) -> type2class.put(type, clazz));
83 * @param filter filter to be encoded
84 * @return the filter, serialized as a JSON string
85 * @throws JsonParseException if it cannot be de-serialized
87 public String encodeFilter(Map<String, Object> filter) throws JsonParseException {
88 return gson.toJson(filter);
94 * @param msg message to be encoded
95 * @return the message, serialized as a JSON string
96 * @throws JsonParseException if it cannot be de-serialized
98 public String encodeMsg(Message msg) throws JsonParseException {
99 JsonElement jsonEl = gson.toJsonTree(msg);
101 String type = class2type.get(msg.getClass());
103 throw new JsonParseException("cannot serialize " + msg.getClass());
106 jsonEl.getAsJsonObject().addProperty(TYPE_FIELD, type);
108 return gson.toJson(jsonEl);
112 * Decodes a JSON string into a Message.
114 * @param msg JSON string representing the message
115 * @return the message
116 * @throws JsonParseException if it cannot be serialized
118 public Message decodeMsg(String msg) throws JsonParseException {
119 JsonElement jsonEl = gson.fromJson(msg, JsonElement.class);
121 JsonElement typeEl = jsonEl.getAsJsonObject().get(TYPE_FIELD);
122 if (typeEl == null) {
123 throw new JsonParseException("cannot deserialize " + Message.class
124 + " because it does not contain a field named " + TYPE_FIELD);
128 Class<? extends Message> clazz = type2class.get(typeEl.getAsString());
130 throw new JsonParseException("cannot deserialize " + typeEl);
133 return gson.fromJson(jsonEl, clazz);