Persistent Messages, What heppens if a system is started!

Question

Hi,
I am new to JMS and trying to understand. I have a Web Service that put messges on a queue. Now on the consumer side I have a Message Driven Bean. What if my MDB is not available and the WS puts some messages in a queue. The messages are still in a queue but not consumed as MDB is not available. Now I restarted the whole system and server and redeployed the MDB but I don't see any messages being consumed by MDB even though there are some messages that are put by Web Service before starting the System. Are the messages lost if in a queue but not yet consumed and a system or server is restarted.
How can I make the messages available in a queue all the time even after a restart. Here is a snippet of code that ques the messages.
InitialContext context = new InitialContext();
QueueConnectionFactory fac = (QueueConnectionFactory)context.lookup("jms/MainQueueConnectionFactory");
QueueConnection conn = fac.createQueueConnection();
QueueSession session = conn.createQueueSession(false, Session.AUTO_ACKNOWLEDGE);
Queue que = (Queue)context.lookup("jms/MainQueue");
QueueSender sender = session.createSender(que);
MapMessage message = session.createMapMessage();
message.setString("Subject","subject");
message.setString("Content","Content");
sender.send(message);If messages gets lost if the system or server is restarted then what's the point of Persistent Messages. Any help is appreciated.
Thanks

Answer 1

How do I set it never to expireBy setting the message time-to-live to zero. This can be done on the message and possibly on the connection factory. I'm pretty sure the default is zero anyway, but couldn't find this in the spec - http://java.sun.com/products/jms/docs.html
I believe all the messages are by default persistentThis depends on your JMS Provider. See you providers docs for how to configure for persistent messaging.
Where exactly in queue definition any small sampleAgain this depends on your JMS provider. I don't have experience of your app server so I can't provide and example - sorry.