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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  package org.codehaus.activecluster.impl;
19  
20  import org.apache.commons.logging.Log;
21  import org.apache.commons.logging.LogFactory;
22  import org.codehaus.activecluster.Node;
23  
24  import javax.jms.Message;
25  import javax.jms.MessageListener;
26  import javax.jms.ObjectMessage;
27  
28  
29  /***
30   * A JMS MessageListener which processes inbound messages and
31   * applies them to a StateService
32   *
33   * @version $Revision: 1.3 $
34   */
35  public class StateConsumer implements MessageListener {
36  
37      private final static Log log = LogFactory.getLog(StateConsumer.class);
38  
39      private StateService stateService;
40  
41      public StateConsumer(StateService stateService) {
42          if (stateService == null) {
43              throw new IllegalArgumentException("Must specify a valid StateService implementation");
44          }
45          this.stateService = stateService;
46      }
47  
48      public void onMessage(Message message) {
49          if (log.isDebugEnabled()) {
50              log.debug("Received cluster data message!: " + message);
51          }
52  
53          if (message instanceof ObjectMessage) {
54              ObjectMessage objectMessage = (ObjectMessage) message;
55              try {
56                  Node node = (Node) objectMessage.getObject();
57                  String type = objectMessage.getJMSType();
58                  if (type != null && type.equals("shutdown")) {
59                      stateService.shutdown(node);
60                  }
61                  else {
62                      stateService.keepAlive(node);
63                  }
64              }
65              catch (Exception e) {
66                  log.error("Could not extract node from message: " + e + ". Message: " + message, e);
67              }
68          }
69          else {
70              log.warn("Ignoring message: " + message);
71          }
72      }
73  }