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Static propagation refers to message propagation that occurs in the absence of subscription information. Sometimes, because of the way a broker network is set up, it can make sense to move messages between brokers, even when there is no relevant subscription information.

Static propagation is configured by specifying the queue (or queues) that you want to statically propagate. Into the relevant networkConnector element, insert staticallyIncludedDestinations as a child element and then list the queues and topics you want to propagate using the queue and topic child elements. For example, to specify that messages in the queue, TEST.FOO, are statically propagated from A to B, you would define the network connector in broker A's configuration as follows:

[Note]Note

You cannot use wildcards when specifying statically included queue names or topic names.

Consider the network shown in Figure 3.2. This network is set up so that consumers only attach to broker D or to broker E Messages sent to the queue, TEST.FOO, are configured to propagate statically on all on all of the network connectors, (A,B), (B,C), (C,D), and (C,E).


The static message propagation in this example proceeds as follows:

  1. Initially, there are no consumers attached to the network. A producer, P, connects to broker A and sends 10 messages to the queue, TEST.FOO.

  2. Because the network connector, (A,B), has enabled static propagation for the queue, TEST.FOO, the 10 messages on broker A are forwarded to broker B.

  3. Likewise, because the network connector, (B,C), has enabled static propagation for the queue, TEST.FOO, the 10 messages on broker B are forwarded to broker C.

  4. Finally, because the network connectors, (C,D) and (C,E), have enabled static propagation for the queue, TEST.FOO, the 10 messages on broker C are alternately sent to broker D and broker E. In other words, the brokers, D and E, receive every second message. Hence, at the end of the static propagation, there are 5 messages on broker D and 5 messages on broker E.

[Note]Note

Using the preceding static configuration, it is possible for messages to get stuck in a particular broker. For example, if a consumer now connects to broker E, it will receive the 5 messages stored on broker E, but it will not receive the 5 messages stored on broker D. The messages remain stuck on broker D until a consumer connects directly to it.

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