Topic objects

A topic object is an IBM MQ object that allows you to assign specific, non-default attributes to topics.

A topic is defined by an application publishing or subscribing to a particular topic string. A topic string can specify a hierarchy of topics by separating them with a forward slash character (/). This can be visualized by a topic tree. For example, if an application publishes to the topic strings /Sport/American Football and /Sport/Soccer, a topic tree is created that has a parent node Sport with two children, American Football, and Soccer.

Topics inherit their attributes from the first parent administrative node found in their topic tree. If there are no administrative topic nodes in a particular topic tree, then all topics inherit their attributes from the base topic object, SYSTEM.BASE.TOPIC.

We can create a topic object at any node in a topic tree by specifying that node's topic string in the TOPICSTR attribute of the topic object. We can also define other attributes for the administrative topic node. For more information about these attributes, see The MQSC commands, or Automating administration using PCF commands. Each topic object, by default, inherits its attributes from its closest parent administrative topic node.

Topic objects can also be used to hide the full topic tree from application developers. If a topic object named FOOTBALL.US is created for the topic /Sport/American Football, an application can publish or subscribe to the object named FOOTBALL.US instead of the string /Sport/American Football with the same result.

If you enter a #, +, /, or * character within a topic string on a topic object, the character is treated as a normal character within the string, and is considered to be part of the topic string associated with a topic object.

For more information about topic objects, see Publish/subscribe messaging.