Via Connections

Via connection allow messages to be routed via an intermediate queue manager. For example, we might wish messages from LocalQM to travel to TargetQM via RemoteQM. We can already do this with 'pushing' store and forward queues, but via connections provide an alternate mechanism, see Figure 81.

Figure 81. Via connections


The diagram illustrates the components being used. The connection definition called 'TargetQM' on LocalQM does not contain the address of TargetQM, but simply refers to the connection definition called 'RemoteQM'. This means that any messages destined for TargetQM will be sent to RemoteQM, and we assume that RemoteQM will be able to move the messages onward. In the diagram above, RemoteQM has the necessary connection to move the message to TargetQM.

The message flows as expected, see Figure 82.

Figure 82. Message flow using a via connection


The Remote Queue on LocalQM uses Connection Resolution to find the Via Connection. This then passes the message on to the real connection which moves the message to RemoteQM. On RemoteQM queue resolution proceeds as for the simple case. We can show the topology most clearly using Message Routes, see Figure 83.

Figure 83. Via connections expressed using message route schema


This is known as 'chaining remote queues'. The central remote queue can be synchronous, asynchronous, or even a store and forward queue.



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