This week's book giveaway is in the OCAJP forum. We're giving away four copies of OCA Java SE 8 Programmer I Study Guide 1Z0-808 and have Jeanne Boyarsky & Scott Selikoff on-line! See this thread for details.
Question What are the benefits of asynchronous messaging?
A Less coupling between the sender and receiver. B Blocks until message is processed C Suitable for transaction processing D Network is not required to be available E Can be implemented using EJB
Choices A, D are correct.
My doubts are Why Choices E is not correct.
what is meaning of Network is not required to be available?
1) Network is not required to be available - it might be not well worded statement, which means that message consumer may be offline when message is sent, and this won't mean messsage lost (should be reliable subscription though).
2) Why Choices E is not correct. If this mock is for old version of SCEA, it assumed EJB 1.1, and probably MDB EJB was introduced later (EJB 2.0, IIRC).
I think E is incorrect because it really does not states a benefit of using Asynchronous messaging. maybe this could be rewritten as "The use of MDBs improves the portability of the asynchronous system" or "The use of MDBs as async solution improves the reliability because the server will manage the persistence of the incoming messages."