A Topic object encapsulates a provider-specific topic name.

It is the way a client specifies the identity of a topic to Jakarta Messaging API methods. For those methods that use a Destination as a parameter, a Topic object may used as an argument . For example, a Topic can be used to create a MessageConsumer and a MessageProducer by calling:

• Session.CreateConsumer(Destination destination)
• Session.CreateProducer(Destination destination)

Many publish/subscribe (pub/sub) providers group topics into hierarchies and provide various options for subscribing to parts of the hierarchy. The Jakarta Messaging API places no restriction on what a Topic object represents. It may be a leaf in a topic hierarchy, or it may be a larger part of the hierarchy.

The organization of topics and the granularity of subscriptions to them is an important part of a pub/sub application's architecture. The Jakarta Messaging API does not specify a policy for how this should be done. If an application takes advantage of a provider-specific topic-grouping mechanism, it should document this. If the application is installed using a different provider, it is the job of the administrator to construct an equivalent topic architecture and create equivalent Topic objects.