1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
|
/*
* Copyright 2015 Open Networking Laboratory
*
* 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.
*/
package org.onosproject.ui;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.node.ArrayNode;
import com.fasterxml.jackson.databind.node.ObjectNode;
import org.onlab.osgi.ServiceDirectory;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.Map;
import java.util.Set;
import static com.google.common.base.Preconditions.checkArgument;
import static com.google.common.base.Preconditions.checkNotNull;
/**
* Abstraction of an entity capable of processing JSON messages from the user
* interface client.
* <p>
* The message structure is:
* </p>
* <pre>
* {
* "type": "<em>event-type</em>",
* "payload": {
* <em>arbitrary JSON object structure</em>
* }
* }
* </pre>
* On {@link #init initialization} the handler will create and cache
* {@link RequestHandler} instances, each of which are bound to a particular
* <em>event-type</em>. On {@link #process arrival} of a new message,
* the <em>event-type</em> is determined, and the message dispatched to the
* corresponding <em>RequestHandler</em>'s
* {@link RequestHandler#process process} method.
*/
public abstract class UiMessageHandler {
private final Logger log = LoggerFactory.getLogger(getClass());
private final Map<String, RequestHandler> handlerMap = new HashMap<>();
private final ObjectMapper mapper = new ObjectMapper();
private UiConnection connection;
private ServiceDirectory directory;
/**
* Subclasses must create and return the collection of request handlers
* for the message types they handle.
* <p>
* Note that request handlers should be stateless. When we are
* {@link #destroy destroyed}, we will simply drop our references to them
* and allow them to be garbage collected.
*
* @return the message handler instances
*/
protected abstract Collection<RequestHandler> createRequestHandlers();
/**
* Returns the set of message types which this handler is capable of
* processing.
*
* @return set of message types
*/
public Set<String> messageTypes() {
return Collections.unmodifiableSet(handlerMap.keySet());
}
/**
* Processes a JSON message from the user interface client.
*
* @param message JSON message
*/
public void process(ObjectNode message) {
String type = JsonUtils.eventType(message);
ObjectNode payload = JsonUtils.payload(message);
// TODO: remove sid
exec(type, 0, payload);
}
/**
* Finds the appropriate handler and executes the process method.
*
* @param eventType event type
* @param sid sequence identifier
* @param payload message payload
*/
// TODO: remove sid from signature
void exec(String eventType, long sid, ObjectNode payload) {
RequestHandler requestHandler = handlerMap.get(eventType);
if (requestHandler != null) {
requestHandler.process(sid, payload);
} else {
log.warn("no request handler for event type {}", eventType);
}
}
/**
* Initializes the handler with the user interface connection and
* service directory context.
*
* @param connection user interface connection
* @param directory service directory
*/
public void init(UiConnection connection, ServiceDirectory directory) {
this.connection = connection;
this.directory = directory;
Collection<RequestHandler> handlers = createRequestHandlers();
checkNotNull(handlers, "Handlers cannot be null");
checkArgument(!handlers.isEmpty(), "Handlers cannot be empty");
for (RequestHandler h : handlers) {
h.setParent(this);
handlerMap.put(h.eventType(), h);
}
}
/**
* Destroys the message handler context.
*/
public void destroy() {
this.connection = null;
this.directory = null;
handlerMap.clear();
}
/**
* Returns the user interface connection with which this handler was primed.
*
* @return user interface connection
*/
public UiConnection connection() {
return connection;
}
/**
* Returns the user interface connection with which this handler was primed.
*
* @return user interface connection
*/
public ServiceDirectory directory() {
return directory;
}
/**
* Returns implementation of the specified service class.
*
* @param serviceClass service class
* @param <T> type of service
* @return implementation class
* @throws org.onlab.osgi.ServiceNotFoundException if no implementation found
*/
protected <T> T get(Class<T> serviceClass) {
return directory.get(serviceClass);
}
/**
* Returns a freshly minted object node.
*
* @return new object node
*/
protected ObjectNode objectNode() {
return mapper.createObjectNode();
}
/**
* Returns a freshly minted array node.
*
* @return new array node
*/
protected ArrayNode arrayNode() {
return mapper.createArrayNode();
}
/**
* Sends the specified data to the client.
* It is expected that the data is in the prescribed JSON format for
* events to the client.
*
* @param data data to be sent
*/
protected synchronized void sendMessage(ObjectNode data) {
UiConnection connection = connection();
if (connection != null) {
connection.sendMessage(data);
}
}
}
|
