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An application needs to consume Messages, but it wants to control when it consumes each message.

How can an application consume a message when the application is ready?

The aplication should use a Polling Consumer, one that explicitly makes a call when it wants to receive a message.

This is also known as a synchronous receiver, because the receiver thread blocks until a message is received. We call it a Polling Consumer because the receiver polls for a message, processes it, then polls for another. As a convenience, messaging API’s usually provide a receive method that blocks until a message is delivered, in addition to methods like receiveNoWait() and Receive(0) that return immediately if no message is available. This difference is only apparent when the receiver is polling faster than messages are arriving.

Related patterns: Competing Consumers, Durable Subscriber, Event-Driven Consumer, Message, Message Dispatcher, Selective Consumer, Transactional Client

For a full description of the pattern see:

Enterprise Integration Patterns Gregor Hohpe and Bobby Woolf ISBN 0321200683 650 pages Addison-Wesley

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© 2003 • Bobby Woolf • All rights reserved.