I am using JBoss 4.0.0alpha with JBossMQ. I have a question regarding
durable subscriptions. I am allowed to create a durable subscription as
follows (not in an EJB):
Context context = new InitialContext(props);
topicFactory = (TopicConnectionFactory)
context.lookup("UILConnectionFactory");
topicConnection = topicFactory.createTopicConnection("test", "test");
topicSession =
topicConnection.createTopicSession(false,Session.AUTO_ACKNOWLEDGE);
Topic topic = (Topic) context.lookup("topic/Test");
topicSubscriber = topicSession.createDurableSubscriber(topic, "TheClient");
I did not specify a ClientID on the TopicConnection so JBoss creates a
durable subscription with an Internal JBossMQ id. If my
subscriber then becomes inactive, I can not re-subscribe because any attempt
to use an Internal JBossMQ id (one that starts with "ID") will throw an exception. This means that any messages that are sent while the durable subscriber is not active can never be picked up. Further more, because the
durable subscription is stored in the jbossmq-state file, it will continue
to receive messages that can never be retrieved.
Should the call to createDurableSubscriber force you to set a valid client
id first? This way you could avoid the problem altogether when creating a
durable subscription.
I am willing to do the work to make the changes, I just wanted to know what others think about this issue.
The JMS spec says:
"At the cost of higher overhead, a subscriber can be made durable. A durable
subscriber registers a durable subscription with a unique identity that is
retained by JMS. Subsequent subscriber objects with the same identity resume
the subscription in the state it was left by the prior subscriber. If there
is no active subscriber for a durable subscription, JMS retains the
subscription's messages until they are received by the subscription or until
they expire."
