Advanced Queuing - Oracle

Modeling Queue Entities
between different processing stages of the business process. By specifying delay
interval and expiration time for a message, a window of execution can be provided
for each of the applications.
Figure 7–8 Implementing Workflows using AQ
Application A
producer
Enqueue
(Message 1)
Dequeue
(Message 1)
Dequeue
(Message 2)
Application B
consumer & producer
From a workflow perspective, the passing of messages is a business asset above and
beyond the value of the payload data. Hence, AQ supports the optional retention of
messages for analysis of historical patterns and prediction of future trends.
AQ Implementation of Publish/Subscribe
Application C
consumer & producer
Note: The contents of the messages 1, 2 and 3 can be the same or
different. Even when they are different, messages may contain parts
of the of the contents of previous messages.
Figure 7–9 illustrates the use of AQ for implementing a publish/subscribe
messaging scheme between applications. Application A is a publisher application
which is publishing messages to a queue. Applications B, C, D are subscriber
7-12 Oracle9i Application Developer’s Guide - Advanced Queuing
Enqueue
(Message 3)
Enqueue
(Message 2)
Dequeue
(Message 3)
Application D
consumer