Request-reply across the WebSphere MQ link

This topic describes the types of request-reply messages that can be exchanged across the WebSphere® MQ link.

Request-reply exchanges can be:
  1. Point-to-point messages.
    1. Queue type reply-to destination.
    2. Topic type reply-to destination.
  2. Publication messages.
    1. Queue type reply-to destination.
    2. Topic type reply-to destination.

Queue type reply messages (replies sent to a queue-type destination) cross the WebSphere MQ link automatically in the same way as point-to-point request messages.

Topic type replies cross the WebSphere MQ link through the publish/subscribe bridge and are of two varieties:
  1. Permanent reply-to topics. For a reply message published to a permanent topic to cross between a WebSphere Application Server and a WebSphere MQ network, the administrator must first define an appropriate topic mapping (defining the topic name and direction) on the publish/subscribe bridge associated with the WebSphere MQ link.
  2. Temporary topic replies. A temporary topic reply message is automatically routed between a WebSphere Application Server and a WebSphere MQ network by the publish/subscribe bridge. This is because the temporary topic name is assigned at runtime and so a topic mapping cannot be defined. The exception to this is that only temporary topic replies to publication messages are supported (that is, point-to-point request messages with temporary topic reply destinations are not supported).
    Note: for temporary topic reply messages to be routed from the service integration bus back to WebSphere MQ through the publish/subscribe bridge, you must configure the broker stream queue of the mapping on which the request message is sent. This field will already be specified for bi-directional topic mappings. While it is not a mandatory field for "From MQ" topic mappings, it must be completed if you want temporary topic reply messages to be routed.



Related concepts
Point-to-point messaging with a WebSphere MQ network
Concept topic    

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Last updated: Aug 29, 2010 5:25:00 PM CDT
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