Pushing store and forward queues

MQe has a queue type that accepts messages on a queue manager basis rather than on a queue basis. These are called Store and Forward (S&F) queues. S&F queues maintain a list of queue manager names, called Queue Manager Entries (QMEs). The S&F queue will accept messages for any queue manager represented by a QME. This acceptance is independent of the destination queue name, and so allows one queue (the S&F queue) to route all messages for a given, or several given queue managers.

S&F queues can operate in two modes, pushing mode and pulling mode. In pushing mode the messages are moved to the next queue manager just as with remote queue references. In pulling mode the messages are removed from the S&F queue by the action of a Home Server Queue. This section deals only with the pushing of messages, pulling messages with a home server queue is described in another section. A typical pushing S&F queue system might look like this:

Figure 1. A typical pushing S&F queue system

A S&F queue called SafQueue has a queue manager entry (QME) for TargetQM. This allows it to accept messages for any queue on TargetQM. In common with ordinary Remote Queues, a Store and Forward queue requires a connection definition/listener pair set up in order to push messages. Unlike a normal Remote Queue Definition, a Store and Forward Queue effectively pushes to a Queue Manager rather than to a queue. The message arrives at the Queue Manager, where queue resolution is performed. When a message is put to LocalQM addressed to TargetQ@TargetQM the resolution is as follows:

Figure 2. Routing of a message put to LocalQM and addressed to TargetQ@TargetQM

The Store and Forward queue forms part of a Multi Message Route. This abstract entity represents the potential for messages addressed to any queue on TargetQM, and so is called *@TargetQM, as shown in the following diagram:

Figure 3. A multi message route

If there is no queue to which the message can be put, then it is not delivered. This prevents any further messages from being pushed from that Store and Forward queue to that Queue Manager.


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