WebSphere Message Brokers
File: aq13300_
Writer: Terry Cowling

Reference topic

This build: July 31, 2007 21:35:34

Topic semantics and usage

When you build an application, the design of the topic tree should take into account the following principles of topic name syntax and semantics:
  • Topic names are case sensitive.

    For example, "ACCOUNTS" and "Accounts" are two different topics.

  • Topic names can include the space character.

    For example, "Accounts payable" is a valid topic.

  • A leading "/" creates a distinct topic.

    For example, "/USA" is different from "USA" and "/USA' matches "+/+" and "/+", but not "+".

  • A topic name that contains '//' is not a valid name. An attempt to subscribe to a topic with such a name causes an error.
  • Do not include the null character (Unicode \x0000) in any topic.
  • The wildcard characters "+" and "#" are not treated as wild cards if they are mixed with any other characters (including themselves but excluding the topic level separator "/") within a topic level.
The following principles apply to the construction and content of a topic tree:
  • There is no limit to the number of levels in a topic tree.
  • There is no limit to the length of the name of a level in a topic tree.
  • There can be any number of "root" nodes; that is, there can be any number of topic trees. These are defined below the root "", which is the root of all root nodes. It is referred to as "topicRoot", although there is no corresponding topic name. Applications cannot publish or subscribe to this virtual root.
  • The topic trees with roots of "$SYS" and "$ISYS" are reserved for use by WebSphere Message Broker only.

    If you are using topic-based security, only brokers can publish messages on these topics, and only brokers can subscribe to messages with a topic of "$ISYS", regardless of the content of the topic Access Control Lists (ACLs) that are defined.

    For more details about topic-based security and ACLs, see Topic-based security.

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Copyright IBM Corporation 1999, 2007Copyright IBM Corporation 1999, 2007. All Rights Reserved.
This build: July 31, 2007 21:35:34

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