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Metatopics

Brokers publish information about the publishers and subscribers that are registered with them. The information is published as a special set of topics, known as metatopics, within each supported stream.

Each broker publishes on metatopics to each stream to describe the publishers, subscribers and topics on that stream. Metatopics include subscribers to metatopics. All metatopic publications are global.

Metatopics always begin with 'MQ/', and topics starting with 'MQ/' are reserved for all streams. These metatopic strings are of the form:

• 'MQ/S/QMgrName/Publishers/Topics'

• 'MQ/S/QMgrName/Publishers/Summary'

• 'MQ/S/QMgrName/Publishers/Summary/Topic'

• 'MQ/S/QMgrName/Publishers/Identities'

• 'MQ/S/QMgrName/Publishers/Identities/Topic'

• 'MQ/SA/QMgrName/Publishers/AllIdentities'

• 'MQ/SA/QMgrName/Publishers/AllIdentities/Topic'

• 'MQ/S/QMgrName/Subscribers/Topics'

• 'MQ/S/QMgrName/Subscribers/Summary'

• 'MQ/S/QMgrName/Subscribers/Summary/Topic'

• 'MQ/S/QMgrName/Subscribers/Identities'

• 'MQ/S/QMgrName/Subscribers/Identities/Topic'

• 'MQ/SA/QMgrName/Subscribers/AllIdentities'

• 'MQ/SA/QMgrName/Subscribers/AllIdentities/Topic'

Where:

• QMgrName is the name of the broker's queue manager. This is 48 characters long padded with blanks if necessary.

• Topic is any topic for which the broker has a registered publisher or subscriber (depending on whether the subscription is for publishers or subscribers).

Metatopics that do not include Topic each represent a single metatopic (for one broker), so a broker receiving a Register Subscriber message for one of these metatopics generates one retained Publish message as a result (additional retained Publish messages are generated whenever the information changes). However, for metatopics that do include Topic, one retained Publish message is generated for each registered topic that matches the Topic specification (and again further messages are generated as the information changes).

The strings in the fifth part of the metatopic offer varying levels of detail, as follows:

Summary

Minimal information including counts. If Topic is included, one message is generated for each matching topic.

Topics

A list of registered topics in a single message.

Identities

Identities of publishers or subscribers, including user ID and time of registration. If Topic is included, one message is generated for each matching topic, otherwise all identities are packaged into a single message. Anonymous publishers or subscribers are not included (this means that no message is generated for topics that have only anonymous publishers and subscribers registered).

AllIdentities

This is the equivalent of Identities for authorized metatopics (see Authorized metatopics) and gives the same information, but also includes anonymous publishers and subscribers.

If an application subscribes to an 'AllIdentities' metatopic, the application requires altusr authority for the queue manager, as well as the normal browse authority for that stream queue.

 

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