This topic describes what is referred to as the publish/subscribe
bridge, which consists of broker profiles and topic mappings on the WebSphere MQ link.
Defining a publish/subscribe bridge, that is, broker profiles and topics
mappings, allows publication and subscription between WebSphere Application Server and
a broker in a WebSphere MQ network making a WebSphere Application Server and
WebSphere MQ look like part of the same system. Publications can flow to and
from the WebSphere Business Integration brokers, even simultaneously in both
directions on the same topic.
- Multiple broker profiles can be defined. See Broker profile.
Publications flow between the two sides of the publish/subscribe bridge according
to the topic mappings that are defined. See Topic mapping.
- The bridge itself connects as a regular subscriber and publisher to message
brokers in a WebSphere MQ network. For example, for publications to move between WebSphere Application Server and WebSphere
MQ, the publish/subscribe bridge attaches as a durable subscriber to the relevant
topic space and so receives messages when they are published on that topic.
The publish/subscribe bridge then attaches as a publisher to, say IBM WebSphere
Business Integration Event Broker, and republishes the message into the WebSphere
MQ network where it can be received by Event Broker subscribers.
- If communication between the two sides of the publish/subscribe bridge
fails messages are held on each side until communication is reestablished
by the system or by the administrator. If a WebSphere Business Integration
message broker fails it will publish no new messages. You may wish to contact
the broker administrator to ask for the failure to be resolved and for the
publication flow to resume. Messages published by WebSphere Application Server applications
are transferred to WebSphere MQ and build up on broker input queues until
the broker resumes processing. If WebSphere MQ fails, the message broker is
unable to publish messages. Messages published by WebSphere Application Server applications
cannot be transferred to WebSphere MQ so they build up on the transmission
queue, waiting for server channel communications to be resumed.