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Advanced Queuing - Oracle

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Third-Party Support<br />

Elements of <strong>Advanced</strong> <strong>Queuing</strong><br />

reported by the view can be used to diagnose and fix problems. The view also<br />

describes additional information such as the session ID of the session handling the<br />

propagation, and the process name of the job queue process handling the<br />

propagation.<br />

To see this feature applied in the context of the BooksOnLine scenario, refer to<br />

"Enhanced Propagation Scheduling Capabilities" on page 8-114.<br />

AQ allows messages to be enqueued in queues that can then be propagated to<br />

different messaging systems by third-party propagators. If the protocol number for<br />

a recipient is in the range 128 - 255, the address of the recipient is not interpreted by<br />

AQ and so the message is not propagated by the AQ system. Instead, a third-party<br />

propagator can then dequeue the message by specifying a reserved consumer name<br />

in the dequeue operation. The reserved consumer names are of the form AQ$_P#,<br />

where # is the protocol number in the range 128–255. For example, the consumer<br />

name AQ$_P128 can be used to dequeue messages for recipients with protocol<br />

number 128. The list of recipients for a message with the specific protocol number is<br />

returned in the recipient_list message property on dequeue.<br />

Another way for <strong>Advanced</strong> <strong>Queuing</strong> to propagate messages to and from third-party<br />

messaging systems is through Messaging Gateway, an Enterprise Edition feature of<br />

<strong>Advanced</strong> <strong>Queuing</strong>. Messaging Gateway dequeues messages from an AQ queue<br />

and guarantees delivery to a third-party messaging system like MQSeries.<br />

Messaging Gateway can also dequeue messages from third-party messaging<br />

systems and enqueue them to an AQ queue. Refer to Chapter 18, "Messaging<br />

Gateway" for more information.<br />

Elements of <strong>Advanced</strong> <strong>Queuing</strong><br />

Message<br />

By integrating transaction processing with queuing technology, persistent<br />

messaging in the form of <strong>Advanced</strong> <strong>Queuing</strong> is possible. This section defines a<br />

number of <strong>Advanced</strong> <strong>Queuing</strong> terms.<br />

A message is the smallest unit of information inserted into and retrieved from a<br />

queue. A message consists of the following:<br />

Control information (metadata)<br />

Payload (data)<br />

Introduction to <strong>Oracle</strong> <strong>Advanced</strong> <strong>Queuing</strong> 1-21

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