Publish/subscribe messaging through a IBM link
On a WebSphere® MQ link, you can set up publish/subscribe messaging between WebSphere Application Server and the IBM MQ publish/subscribe function, or a separate publish/subscribe broker.
- IBM MQ Version 7
- Provides publish/subscribe function that is integrated into IBM MQ queue managers. This capability is called integrated publish/subscribe. The publish/subscribe capability for earlier versions of IBM MQ is called queued publish/subscribe, because you communicate with a separate publish/subscribe broker by means of messages placed on queues.
- WebSphere Message Broker Version 6
- Provides a separate publish/subscribe broker for queued publish/subscribe. This version of queued publish/subscribe uses MQRFH2 message headers. If you are using IBM MQ Version 6, you can use WebSphere Message Broker Version 6 to provide publish/subscribe function that interoperates over an IBM MQ link with WebSphere Application Server. From WebSphere Message Broker Version 7, this product no longer provides a separate publish/subscribe broker, and all topic-based publish/subscribe operations made through the product use IBM MQ facilities.
- WebSphere Event Broker
- Provides a separate publish/subscribe broker for queued publish/subscribe. This version of queued publish/subscribe is the same as that in WebSphere Message Broker Version 6.
IBM MQ Version 6 (except Version 6 of IBM MQ for z/OS®) provides queued publish/subscribe that is implemented by a publish/subscribe broker within IBM MQ. However, the publish/subscribe function provided by IBM MQ Version 6 uses MQRFH message headers, also known as MQRFH1 message headers, and it does not support the MQRFH2 message headers that the WebSphere Application Server publish/subscribe bridge uses on the IBM MQ link. For IBM MQ Version 6 publish/subscribe to interoperate with WebSphere Application Server publish/subscribe over an IBM MQ link, you must use a separate message broker product that supports MQRFH2 message headers. Alternatively, instead of using a IBM MQ link, you can interoperate using the IBM MQ messaging provider, so that your applications use IBM MQ publish/subscribe function and do not use the service integration bus. This requirement also applies to earlier versions of IBM MQ where publish/subscribe function is provided by SupportPac MA0C.
Message headers and contents are mapped in the same way for both point-to-point messages and publish/subscribe messages. For more information about the mapping of messages see How service integration converts messages to and from IBM MQ format.