WAS v8.5 > WebSphere applications > Messaging resources > Interoperation with WebSphere MQ > Interoperation using a WebSphere MQ link

Publish/subscribe messaging through a WebSphere MQ link

On a WebSphere MQ link, we can set up publish/subscribe messaging between WAS and the WebSphere MQ publish/subscribe function, or WebSphere Message Broker, or WebSphere Event Broker.

The following product versions provide publish/subscribe capability that we can use with WAS over a WebSphere MQ link:

WebSphere MQ v7

Provides publish/subscribe function that is integrated into WebSphere MQ queue managers. This capability is called integrated publish/subscribe. The publish/subscribe capability for earlier versions of WebSphere 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 v6

Provides a separate publish/subscribe broker for queued publish/subscribe. This version of queued publish/subscribe uses MQRFH2 message headers. If we are using WebSphere MQ v6, we can use WebSphere Message Broker v6 to provide publish/subscribe function that interoperates over a WebSphere MQ link with WAS. From WebSphere Message Broker v7, this product no longer provides a separate publish/subscribe broker, and all topic-based publish/subscribe operations made through the product use WebSphere 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 v6.

WebSphere MQ v6 (except v6 of WebSphere MQ for z/OS) provides queued publish/subscribe that is implemented by a publish/subscribe broker within WebSphere MQ. However, the publish/subscribe function provided by WebSphere MQ v6 uses MQRFH message headers, also known as MQRFH1 message headers, and it does not support the MQRFH2 message headers the WAS publish/subscribe bridge uses on the WebSphere MQ link. For WebSphere MQ v6 publish/subscribe to interoperate with WAS publish/subscribe over a WebSphere MQ link, use a separate message broker product that supports MQRFH2 message headers. Alternatively, instead of using a WebSphere MQ link, we can interoperate using the WebSphere MQ messaging provider, so the applications use WebSphere MQ publish/subscribe function and do not use the service integration bus. This requirement also applies to earlier versions of WebSphere 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 WebSphere MQ format.

Subtopics

• Publish/subscribe bridge on a WebSphere MQ link
  A publish/subscribe bridge enables publish/subscribe messaging between WAS 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.
• Broker profile on a WebSphere MQ link
  A broker profile on a WebSphere MQ link defines a connection through a WebSphere MQ link to a WebSphere MQ queue manager, for the purpose of publish/subscribe messaging with a WebSphere MQ network.
• Topic mapping on a WebSphere MQ link
  A topic mapping is an association that defines which messages published in WAS or the WebSphere MQ network, should be forwarded to the other publish/subscribe system.
• Publish/subscribe messaging through a WebSphere MQ link: example
  A publish/subscribe bridge over a WebSphere MQ link enables subscribers on the service integration bus in WAS to receive the same published messages as subscribers in a WebSphere MQ network. The broker profile in WAS allows these two separate publish/subscribe domains to appear as a single entity.

Related concepts:

Message exchange through a WebSphere MQ link
Bus topology that links to WebSphere MQ networks
How service integration converts messages to and from WebSphere MQ format

Reference:

WebSphere Message Broker Library web page

Related information:

Publish/subscribe broker profiles [Settings]
Broker profile subscriptions [Collection]

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