This week's book giveaway is in the OCPJP forum. We're giving away four copies of OCA/OCP Java SE 7 Programmer I & II Study Guide and have Kathy Sierra & Bert Bates on-line! See this thread for details.
Thanks for your replies and the link.I have another question.That is will this operation of using an MDB for concurrent processing be asynchronous?I guess it will be because an MDB is like an asynchronous JMS listener.Juts wanted to double check.
If concurency is all you are after, then just use a Session Bean. MDBs most obvious feature is they are asynchronous, so you could use them to improve the response to a client (by queueing more resource-intensive work, so it doesn't have to happen synchronously).