About Enterprise Manager Topic and Queue Management

Enterprise Manager enables you to manage topics and queues from various JMS vendors. You can perform the following tasks:

• Monitor topics and queues

• Send and publish messages

• View message properties

• View and edit message payload

A topic conforms to the publish-and-subscribe (pub/sub) messaging domain, where one publisher broadcasts messages to potentially many subscribers. When the message server publishes a message on a topic, it ensures that all subscribers receive the message.

A queue conforms to the point-to-point (p2p, or PTP) messaging domain, where one sender delivers a message to exactly one receiver. When the message server sends a message to a queue, it ensures that the message is received once and only once, even though there might be many receivers “listening” to the queue. This is equivalent to the subscriber pooling in other queue implementations.

Except for this distinction between pub/sub and PTP, topics and queues are quite similar.

• Each topic or queue maintains a sequence of messages in progress.

• Each message has a timestamp called the enqueue time, which indicates when the message was published or sent.

• Messages that have been read and committed by their subscribers or receivers are subject to cleanup. After cleanup, the lowest sequence number is increased by the number of messages that were delivered and successfully committed.