2 * ============LICENSE_START=======================================================
4 * ================================================================================
5 * Copyright (C) 2018-2021 AT&T Intellectual Property. All rights reserved.
6 * Modifications Copyright (C) 2024 Nordix Foundation.
7 * ================================================================================
8 * Licensed under the Apache License, Version 2.0 (the "License");
9 * you may not use this file except in compliance with the License.
10 * You may obtain a copy of the License at
12 * http://www.apache.org/licenses/LICENSE-2.0
14 * Unless required by applicable law or agreed to in writing, software
15 * distributed under the License is distributed on an "AS IS" BASIS,
16 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
17 * See the License for the specific language governing permissions and
18 * limitations under the License.
19 * ============LICENSE_END=========================================================
22 package org.onap.policy.drools.pooling;
24 import com.google.gson.Gson;
25 import com.google.gson.JsonElement;
26 import com.google.gson.JsonParseException;
27 import java.util.HashMap;
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
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(Heartbeat.class, "heartbeat");
64 class2type.put(Identification.class, "identification");
65 class2type.put(Leader.class, "leader");
66 class2type.put(Offline.class, "offline");
67 class2type.put(Query.class, "query");
69 class2type.forEach((clazz, type) -> type2class.put(type, clazz));
75 * @param filter filter to be encoded
76 * @return the filter, serialized as a JSON string
78 public String encodeFilter(Map<String, Object> filter) {
79 return gson.toJson(filter);
85 * @param msg message to be encoded
86 * @return the message, serialized as a JSON string
88 public String encodeMsg(Message msg) {
89 JsonElement jsonEl = gson.toJsonTree(msg);
91 String type = class2type.get(msg.getClass());
93 throw new JsonParseException("cannot serialize " + msg.getClass());
96 jsonEl.getAsJsonObject().addProperty(TYPE_FIELD, type);
98 return gson.toJson(jsonEl);
102 * Decodes a JSON string into a Message.
104 * @param msg JSON string representing the message
105 * @return the message
107 public Message decodeMsg(String msg) {
108 JsonElement jsonEl = gson.fromJson(msg, JsonElement.class);
110 JsonElement typeEl = jsonEl.getAsJsonObject().get(TYPE_FIELD);
111 if (typeEl == null) {
112 throw new JsonParseException("cannot deserialize " + Message.class
113 + " because it does not contain a field named " + TYPE_FIELD);
117 Class<? extends Message> clazz = type2class.get(typeEl.getAsString());
119 throw new JsonParseException("cannot deserialize " + typeEl);
122 return gson.fromJson(jsonEl, clazz);