TopicSubscriber


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9    * glassfish/bootstrap/legal/CDDLv1.0.txt.
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21   * Copyright 2006 Sun Microsystems, Inc. All rights reserved.
22   */
23  
24  
25  package javax.jms;
26  
27  /** A client uses a <CODE>TopicSubscriber</CODE> object to receive messages that
28    * have been published to a topic. A <CODE>TopicSubscriber</CODE> object is the
29    * publish/subscribe form of a message consumer. A <CODE>MessageConsumer</CODE>
30    * can be created by using <CODE>Session.createConsumer</CODE>. 
31    *
32    * <P>A <CODE>TopicSession</CODE> allows the creation of multiple 
33    * <CODE>TopicSubscriber</CODE> objects per topic.  It will deliver each 
34    * message for a topic to each
35    * subscriber eligible to receive it. Each copy of the message
36    * is treated as a completely separate message. Work done on one copy has
37    * no effect on the others; acknowledging one does not acknowledge the
38    * others; one message may be delivered immediately, while another waits
39    * for its subscriber to process messages ahead of it.
40    *
41    * <P>Regular <CODE>TopicSubscriber</CODE> objects are not durable. They 
42    * receive only messages that are published while they are active.
43    *
44    * <P>Messages filtered out by a subscriber's message selector will never 
45    * be delivered to the subscriber. From the subscriber's perspective, they 
46    * do not exist.
47    *
48    * <P>In some cases, a connection may both publish and subscribe to a topic.
49    * The subscriber <CODE>NoLocal</CODE> attribute allows a subscriber to inhibit
50    * the 
51    * delivery of messages published by its own connection.
52    *
53    * <P>If a client needs to receive all the messages published on a topic, 
54    * including the ones published while the subscriber is inactive, it uses 
55    * a durable <CODE>TopicSubscriber</CODE>. The JMS provider retains a record of
56    * this durable 
57    * subscription and insures that all messages from the topic's publishers 
58    * are retained until they are acknowledged by this durable 
59    * subscriber or they have expired.
60    *
61    * <P>Sessions with durable subscribers must always provide the same client 
62    * identifier. In addition, each client must specify a name that uniquely 
63    * identifies (within client identifier) each durable subscription it creates.
64    * Only one session at a time can have a <CODE>TopicSubscriber</CODE> for a 
65    * particular durable subscription. 
66    *
67    * <P>A client can change an existing durable subscription by creating a 
68    * durable <CODE>TopicSubscriber</CODE> with the same name and a new topic 
69    * and/or message 
70    * selector. Changing a durable subscription is equivalent to unsubscribing 
71    * (deleting) the old one and creating a new one.
72    *
73    * <P>The <CODE>unsubscribe</CODE> method is used to delete a durable 
74    * subscription. The <CODE>unsubscribe</CODE> method can be used at the 
75    * <CODE>Session</CODE> or <CODE>TopicSession</CODE> level.
76    * This method deletes the state being 
77    * maintained on behalf of the subscriber by its provider.
78    *
79    * <P>Creating a <CODE>MessageConsumer</CODE> provides the same features as
80    * creating a <CODE>TopicSubscriber</CODE>. To create a durable subscriber, 
81    * use of <CODE>Session.CreateDurableSubscriber</CODE> is recommended. The 
82    * <CODE>TopicSubscriber</CODE> is provided to support existing code.
83    * 
84    * 
85    * @version     1.1 - February 2, 2002
86    * @author      Mark Hapner
87    * @author      Rich Burridge
88    * @author      Kate Stout
89    *
90    * @see         javax.jms.Session#createConsumer
91    * @see         javax.jms.Session#createDurableSubscriber
92    * @see         javax.jms.TopicSession
93    * @see         javax.jms.TopicSession#createSubscriber
94    * @see         javax.jms.MessageConsumer
95    */
96  
97  public interface TopicSubscriber extends MessageConsumer   {
98  
99      /** Gets the <CODE>Topic</CODE> associated with this subscriber.
100       *  
101       * @return this subscriber's <CODE>Topic</CODE>
102       *  
103       * @exception JMSException if the JMS provider fails to get the topic for
104       *                         this topic subscriber
105       *                         due to some internal error.
106       */ 
107 
108     Topic  
109     getTopic() throws JMSException  ;
110 
111 
112     /** Gets the <CODE>NoLocal</CODE> attribute for this subscriber. 
113       * The default value for this attribute is false.
114       *  
115       * @return true if locally published messages are being inhibited
116       *  
117       * @exception JMSException if the JMS provider fails to get the
118       *                         <CODE>NoLocal</CODE> attribute for
119       *                         this topic subscriber
120       *                         due to some internal error.
121       */ 
122 
123     boolean
124     getNoLocal() throws JMSException  ;
125 }
126
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