A publish/subscribe bridge enables publish/subscribe messaging
between WebSphere® Application Server and WebSphere MQ through a WebSphere MQ link. The publish/subscribe
bridge provides a connection between the publish/subscribe function
of a service integration bus and the publish/subscribe function of
a WebSphere MQ network.
When you use
WebSphere MQ integrated
publish/subscribe, the publish/subscribe bridge can connect as a subscriber
or publisher to queue managers in the
WebSphere MQ network:
- To act as a subscriber, the publish/subscribe bridge connects
to a WebSphere MQ queue manager with
a durable subscription to the relevant topic, and so receives messages
when they are published on that topic. The publish/subscribe bridge
then passes the messages to subscribers connected to a service integration
bus in WebSphere Application Server. These subscribers
might be applications running in WebSphere Application Server,
or they might be bus clients running in Java Platform, Standard Edition
(Java SE) or third party application servers.
- To act as a publisher, the publish/subscribe bridge subscribes
to messages that applications have published to a service integration
JMS topic destination in WebSphere Application Server.
The publish/subscribe bridge then publishes the messages on the relevant
topic in WebSphere MQ, and the WebSphere MQ queue manager distributes
the messages to the subscribers in the WebSphere MQ network. Service integration
can also send the messages to other subscribers that are connected
to the service integration bus in WebSphere Application Server.
The publish/subscribe bridge acts in the same way if you use a
queued publish/subscribe capability provided by a compatibility interface
within WebSphere MQ Version 7, or
by a separate message broker product. The publish/subscribe bridge
attaches to the publish/subscribe broker as either a subscriber or
a publisher, and receives messages from the message broker or publishes
them to the message broker. The message broker distributes published
messages to its subscribers in the WebSphere MQ network.
If communication between the two ends of the publish/subscribe
bridge stops, messages are held until communication is reestablished
by the system or by the administrator. If you are using a separate
message broker product, the messages might be held on the input queues
for the broker, if the broker is not available, or on the transmission
queue for WebSphere MQ, if WebSphere MQ is not available.
The publish/subscribe bridge consists of the broker profiles and
topic mappings that you have defined on the
WebSphere MQ link:
- A broker profile defines a connection to a single WebSphere MQ queue manager or separate
publish/subscribe broker. For more information about broker profiles,
see Broker profile on a WebSphere MQ link.
- A topic mapping defines how messages on a particular topic flow
between the two ends of the publish/subscribe bridge. For more information
about topic mappings, see Topic mapping on a WebSphere MQ link.