Introduction to IBM WebSphere MQ publish/subscribe messaging

Publish/subscribe messaging allows you to decouple the provider of information, from the consumers of that information. The sending application and receiving application do not need to know anything about each other for the information to be sent and received.

Before a point-to-point IBM® WebSphere® MQ application can send a message to another application, it needs to know something about that application. For example, it needs to know the name of the queue to which to send the information, and might also specify a queue manager name.

IBM WebSphere MQ publish/subscribe removes the need for your application to know anything about the target application. All the sending application has to do, is put a IBM WebSphere MQ message, containing the information that it wants, and assign it a topic, that denotes the subject of the information, and let IBM WebSphere MQ handle the distribution of that information. Similarly, the target application does not have to know anything about the source of the information it receives.

Figure 1 shows the simplest publish/subscribe system. There is one publisher, one queue manager, and one subscriber. A subscription is sent from the subscriber to the queue manager, a publication is sent from the publisher to the queue manager, and the publication is then forwarded by the queue manager to the subscriber.
Figure 1. Simple publish/subscribe configuration
This figure shows a simple publish/subscribe system.
A typical publish/subscribe system has more than one publisher and more than one subscriber, and often, more than one queue manager. An application can be both a publisher and a subscriber.