Subscribers are durable and are stored in a catalog. The database represents a significant source for publishing information. An event framework is proposed to allow declarative definition of database event publication. As these pre-defined events occur, the framework detects and publishes such events. Registration Registration is the process of associated delivery information by a given client, acting on behalf of an agent.
Subscription indicates an interest in a particular queue by an agent.
It does not specify where and how delivery must occur. A specific client process acting on behalf of an agent registers delivery information by associating a host and port, indicating where the delivery should be done, and a callback, indicating how there delivery should be done. Publish Message Publishers publish messages to queues by using the appropriate queuing interfaces. The interfaces may depend on which model the queue is implemented on. For example, an enqueue call represents the publishing of a message.