This week's book giveaway is in the Mac OS forum. We're giving away four copies of a choice of "Take Control of Upgrading to Yosemite" or "Take Control of Automating Your Mac" and have Joe Kissell on-line! See this thread for details.
Message consumer can receive messages synchronously by explicitly calling the consumer�s receive() method or asynchronously by registering a callback object that implements MessageListner interface. If you just need to be notified when a message arrives, then you'll mostly need an asynchronous listener. Regards.