All MQ messaging models are point-to-point, that is, messages are always sent to, or received from a queue that is managed by a queue manager.
MQ pub/sub is a publish-and-subscribe model built on MQ queues; the messages are not different types of objects. Interaction with MQ pub/sub uses MQ queues.
All messages are sent to the MQ pub/sub broker’s broker command queue. This includes registration of a publisher or subscriber, and control messages such as deleting a message, or requesting an update for a message.
A publisher sends a publication to a stream queue. The MQ pub/sub broker distributes the message to all subscribers that have interest in the message. The publisher describes the message using topics, which are subjects that describe the contents of the message.
Subscribers register interest in messages that are sent to a named stream queue by specifying one or more topics of interest. When such messages are sent to the stream queue, the MQ pub/sub broker copies the message to the local queue that the subscriber specified when the subscriber was registered.
