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1   /*
2    * Copyright 2002,2004 The Apache Software Foundation.
3    *
4    * Licensed under the Apache License, Version 2.0 (the "License");
5    * you may not use this file except in compliance with the License.
6    * You may obtain a copy of the License at
7    *
8    *      http://www.apache.org/licenses/LICENSE-2.0
9    *
10   * Unless required by applicable law or agreed to in writing, software
11   * distributed under the License is distributed on an "AS IS" BASIS,
12   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13   * See the License for the specific language governing permissions and
14   * limitations under the License.
15   */
16  package org.apache.commons.jelly.tags.jms;
17  
18  import javax.jms.Destination;
19  import javax.jms.JMSException;
20  import javax.jms.MessageListener;
21  
22  import org.apache.commons.jelly.JellyTagException;
23  import org.apache.commons.jelly.XMLOutput;
24  import org.apache.commons.logging.Log;
25  import org.apache.commons.logging.LogFactory;
26  
27  /***
28   * Performs a subscription to some JMS connection to a destination maybe with a selector.
29   * A JMS MessageListener can be specified, or a special child tag can explicitly set it on
30   * its parent (so a special tag could construct a MessageListener object and register it with this tag).
31   *
32   * @author <a href="mailto:jstrachan@apache.org">James Strachan</a>
33   * @version $Revision: 155420 $
34   */
35  public class SubscribeTag extends MessageOperationTag implements ConsumerTag {
36  
37      /*** The Log to which logging calls will be made. */
38      private static final Log log = LogFactory.getLog(SubscribeTag.class);
39  
40      /*** the JMS Selector for the subscription */
41      private String selector;
42  
43      /*** The JMS MessageListener used to create the subscription */
44      private MessageListener messageListener;
45  
46      public SubscribeTag() {
47      }
48  
49      // Tag interface
50      //-------------------------------------------------------------------------
51      public void doTag(XMLOutput output) throws JellyTagException {
52  
53          // evaluate body as it may contain child tags to register a MessageListener
54          invokeBody(output);
55  
56          MessageListener listener = getMessageListener();
57          if (listener == null) {
58              throw new JellyTagException( "No messageListener attribute is specified so could not subscribe" );
59          }
60  
61          // clear the listener for the next tag invocation, if caching is employed
62          setMessageListener(null);
63  
64  
65          Destination destination = null;
66          try {
67              destination = getDestination();
68          }
69          catch (JMSException e) {
70              throw new JellyTagException(e);
71          }
72  
73          if ( destination == null ) {
74              throw new JellyTagException( "No destination specified. Either specify a 'destination' attribute or use a nested <jms:destination> tag" );
75          }
76  
77          if ( log.isDebugEnabled() ) {
78              log.debug( "About to consume to: " + destination + " with listener: " + listener );
79          }
80  
81          log.info( "About to consume to: " + destination + " with listener: " + listener );
82  
83          try {
84              if (selector == null ) {
85                  getConnection().addListener( destination, listener );
86              }
87              else {
88                  getConnection().addListener( destination, selector, listener );
89              }
90          }
91          catch (JMSException e) {
92              throw new JellyTagException(e);
93          }
94      }
95  
96      // Properties
97      //-------------------------------------------------------------------------
98  
99      /***
100      * Sets the optional JMS Message selector for the subscription
101      */
102     public void setSelector(String selector) {
103         this.selector = selector;
104     }
105 
106 
107     /***
108      * Returns the messageListener.
109      * @return MessageListener
110      */
111     public MessageListener getMessageListener() {
112         return messageListener;
113     }
114 
115 
116     /***
117      * Sets the JMS messageListener used ot consume JMS messages on the given destination
118      */
119     public void setMessageListener(MessageListener messageListener) {
120         this.messageListener = messageListener;
121     }
122 
123 }