Publishers and publications

In IBM MQ publish/subscribe a publisher is an application that makes information about a specified topic available to a queue manager in the form of a standard IBM MQ message called a publication. A publisher can publish information about more than one topic.

Publishers use the MQPUT verb to put a message to a previously opened topic, this message is a publication. The local queue manager then routes the publication to any subscribers who have subscriptions to the topic of the publication. A published message can be consumed by more than one subscriber.

In addition to distributing publications to all local subscribers that have appropriate subscriptions, a queue manager can also distribute the publication to any other queue managers connected to it, either directly or through a network of queue managers that have subscribers to the topic.

In an IBM MQ publish/subscribe network, a publishing application can also be a subscriber.

Publications under syncpoint

Publishers can issue MQPUT or MQPUT1 calls in syncpoint to include all messages delivered to subscribers in a unit of work. If the MQPMO_RETAIN option, or topic delivery options NPMSGDLV or PMSGDLV with values ALL or ALLDUR are specified, the queue manager uses internal MQPUT or MQPUT1 calls in syncpoint, within the scope of the publisher MQPUT or MQPUT1 call.

• State and event information
  Publications can be categorized as either state publications, such as the current price of a stock, or event publications, such as a trade in that stock.
• Retained publications
  By default, after a publication is sent to all interested subscribers it is discarded. However, a publisher can specify that a copy of a publication is retained so that it can be sent to future subscribers who register an interest in the topic.
• Publications under syncpoint
  In IBM MQ publish/subscribe, syncpoint can be used by publishers or internally by the queue manager.

Parent topic: Publish/subscribe components