1 /***
2 *
3 * Copyright 2004 Protique Ltd
4 *
5 * Licensed under the Apache License, Version 2.0 (the "License");
6 * you may not use this file except in compliance with the License.
7 * You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 *
17 **/
18
19 package org.codehaus.activemq;
20
21 import javax.jms.ConnectionConsumer;
22 import javax.jms.IllegalStateException;
23 import javax.jms.JMSException;
24 import javax.jms.ServerSession;
25 import javax.jms.ServerSessionPool;
26
27 import org.codehaus.activemq.message.ActiveMQMessage;
28 import org.codehaus.activemq.message.ConsumerInfo;
29 import org.codehaus.activemq.message.util.MemoryBoundedQueue;
30
31 /***
32 * For application servers, <CODE>Connection</CODE> objects provide a special
33 * facility for creating a <CODE>ConnectionConsumer</CODE> (optional). The
34 * messages it is to consume are specified by a <CODE>Destination</CODE> and
35 * a message selector. In addition, a <CODE>ConnectionConsumer</CODE> must be
36 * given a <CODE>ServerSessionPool</CODE> to use for processing its messages.
37 * <p/>
38 * <P>
39 * Normally, when traffic is light, a <CODE>ConnectionConsumer</CODE> gets a
40 * <CODE>ServerSession</CODE> from its pool, loads it with a single message,
41 * and starts it. As traffic picks up, messages can back up. If this happens, a
42 * <CODE>ConnectionConsumer</CODE> can load each <CODE>ServerSession</CODE>
43 * with more than one message. This reduces the thread context switches and
44 * minimizes resource use at the expense of some serialization of message
45 * processing.
46 *
47 * @see javax.jms.Connection#createConnectionConsumer
48 * @see javax.jms.Connection#createDurableConnectionConsumer
49 * @see javax.jms.QueueConnection#createConnectionConsumer
50 * @see javax.jms.TopicConnection#createConnectionConsumer
51 * @see javax.jms.TopicConnection#createDurableConnectionConsumer
52 */
53
54 public class ActiveMQConnectionConsumer implements ConnectionConsumer,
55 ActiveMQMessageDispatcher {
56
57 private ActiveMQConnection connection;
58
59 private ServerSessionPool sessionPool;
60
61 private ConsumerInfo consumerInfo;
62
63 private boolean closed;
64
65 private int maximumMessages;
66
67 protected MemoryBoundedQueue messageQueue;
68
69
70 /***
71 * Create a ConnectionConsumer
72 *
73 * @param theConnection
74 * @param theSessionPool
75 * @param theConsumerInfo
76 * @param theMaximumMessages
77 * @throws JMSException
78 */
79 protected ActiveMQConnectionConsumer(ActiveMQConnection theConnection,
80 ServerSessionPool theSessionPool, ConsumerInfo theConsumerInfo,
81 int theMaximumMessages) throws JMSException {
82 this.connection = theConnection;
83 this.sessionPool = theSessionPool;
84 this.consumerInfo = theConsumerInfo;
85 this.maximumMessages = theMaximumMessages;
86 this.connection.addConnectionConsumer(this);
87 this.consumerInfo.setStarted(true);
88 this.connection.syncSendPacket(this.consumerInfo);
89
90 String queueName = connection.clientID + ":" + theConsumerInfo.getConsumerName()+":"+
91 theConsumerInfo.getConsumerNo();
92 this.messageQueue = connection.getMemoryBoundedQueue(queueName);
93 }
94
95 /***
96 * Tests to see if the Message Dispatcher is a target for this message
97 *
98 * @param message the message to test
99 * @return true if the Message Dispatcher can dispatch the message
100 */
101 public boolean isTarget(ActiveMQMessage message) {
102 return message.isConsumerTarget(this.consumerInfo.getConsumerNo());
103 }
104
105 /***
106 * Dispatch an ActiveMQMessage
107 *
108 * @param message
109 */
110 public void dispatch(ActiveMQMessage message) {
111 if (message.isConsumerTarget(this.consumerInfo.getConsumerNo())) {
112 message.setConsumerId(this.consumerInfo.getConsumerId());
113 try {
114 if( sessionPool != null )
115 dispatchToSession(message);
116 else
117 dispatchToQueue(message);
118 }
119 catch (JMSException jmsEx) {
120 this.connection.handleAsyncException(jmsEx);
121 }
122 }
123 }
124
125 /***
126 * @param message
127 * @throws JMSException
128 */
129 private void dispatchToQueue(ActiveMQMessage message) throws JMSException {
130 messageQueue.enqueue(message);
131 }
132
133 /***
134 * Receives the next message that arrives within the specified timeout interval.
135 * @throws JMSException
136 */
137 public ActiveMQMessage receive(long timeout) throws JMSException {
138 try {
139 ActiveMQMessage message = (ActiveMQMessage) messageQueue.dequeue(timeout);
140 return message;
141 }
142 catch (InterruptedException ioe) {
143 return null;
144 }
145 }
146
147
148 /***
149 * @param message
150 * @throws JMSException
151 */
152 private void dispatchToSession(ActiveMQMessage message) throws JMSException {
153 ServerSession serverSession = sessionPool.getServerSession();
154 ActiveMQSession session = (ActiveMQSession) serverSession
155 .getSession();
156 session.dispatch(message);
157 serverSession.start();
158 }
159
160 /***
161 * Gets the server session pool associated with this connection consumer.
162 *
163 * @return the server session pool used by this connection consumer
164 * @throws JMSException if the JMS provider fails to get the server session pool
165 * associated with this consumer due to some internal error.
166 */
167
168 public ServerSessionPool getServerSessionPool() throws JMSException {
169 if (closed) {
170 throw new IllegalStateException("The Connection Consumer is closed");
171 }
172 return this.sessionPool;
173 }
174
175 /***
176 * Closes the connection consumer.
177 * <p/>
178 * <P>
179 * Since a provider may allocate some resources on behalf of a connection
180 * consumer outside the Java virtual machine, clients should close these
181 * resources when they are not needed. Relying on garbage collection to
182 * eventually reclaim these resources may not be timely enough.
183 *
184 * @throws JMSException
185 */
186
187 public void close() throws JMSException {
188 if (!closed) {
189 closed = true;
190 this.consumerInfo.setStarted(false);
191 this.connection.asyncSendPacket(this.consumerInfo);
192 this.connection.removeConnectionConsumer(this);
193 }
194
195 }
196 }