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Advanced Queuing - Oracle

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Modeling Queue Entities<br />

list of subscribers for that queue. In the figure, Application D is specified as the sole<br />

recipient of a message enqueued by Application A.<br />

Figure 7–7 Explicit and Implicit Recipients of Messages<br />

Dequeue<br />

Application B<br />

consumer (subscriber)<br />

Implicit Recipient<br />

AQ Implementation of Workflows<br />

Application A<br />

producer<br />

Enqueue<br />

Dequeue<br />

Application D<br />

consumer (recipient)<br />

Explicit Recipient<br />

Application C<br />

consumer (subscriber)<br />

Implicit Recipient<br />

Note: Multiple producers may simultaneously enqueue messages<br />

aimed at different targeted recipients.<br />

Figure 7–8 illustrates the use of AQ for implementing workflows, also knows as<br />

chained application transactions. It shows the steps in the workflow performed by<br />

Applications A, B, C and D. The queues are used to buffer the flow of information<br />

Modeling and Design 7-11

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