Name
JMSDestination — Purpose: Routing
Message objects are always sent to some kind of destination. In
the pub/sub model, Message
objects
are delivered to a topic, identified by a Topic
object. In Chapter 2, you learned that the destination of a
Message
object is established when
the TopicPublisher
is
created:
Topic chatTopic = (Topic)ctx.lookup(topicName); TopicPublisher publisher = session.createPublisher(chatTopic);
The JMSDestination
header
identifies the destination of a Message
object using a javax.jms.Destination
object. The Destination
class is the superclass of both
Topic
(pub/sub) and Queue
(p2p). The JMSDestination
header is obtained using the
Message.getJMSDestination()
method.
Identifying the destination to which a message was delivered is
valuable to JMS clients that consume messages from more than one topic
or queue. MessageListener
objects
might, for example, listen to multiple consumers (TopicSubscriber
or QueueReceiver
types) so that they receive
messages from more than one topic or queue. For example, the Chat
client from Chapter 2 could be modified to subscribe to more than
one chat topic at a time. In this scenario, the onMessage()
method of the MessageListener
would use the JMSDestination
header to identify which chat
topic a message came from:
public void onMessage(Message message){ try { TextMessage textMessage = (TextMessage)message; String text = textMessage.getText();Topic topic = (Topic)textMessage.getJMSDestination();
System.out.println(topic.getTopicName() ...
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