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Reviewing applications for message affinities

 

Before starting to use clusters with multiple definitions of the same queue, examine your applications to see whether there are any that have message affinities, that is, they exchange related messages. With clusters, a message can be routed to any queue manager that hosts a copy of the correct queue, affecting the logic of applications with message affinities.

Suppose for example, you have two applications that rely on a series of messages flowing between them in the form of questions and answers. It might be important that all the questions are sent to the same queue manager and that all the answers are sent back to the other queue manager. In this situation, it is important that the workload management routine does not send the messages to any queue manager that just happens to host a copy of the correct queue.

Similarly, you might have applications that require messages to be processed in sequence, for example a file transfer application or database replication application that sends batches of messages that must be retrieved in sequence.

The use of segmented messages can also cause an affinity problem.

• Handling message affinities
  

 

Parent topic:

Programming considerations

qc11010_

 

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