WS-Topics is a web services specification that works as part of the WS-Notification

WS-Notification

WS-Notification is a group of specifications related to the WS-Resource framework that allows event driven programming between web services.WS-Notification is based on the event notification pattern...

 specification family, providing a method to define and address topics (event notifications) to which web service consumers can subscribe, as well as organising them into complex structures allowing hierarchies

Hierarchy

A hierarchy is an arrangement of items in which the items are represented as being "above," "below," or "at the same level as" one another...

 (topic trees) and synonyms (topic aliasing).

In topic hierarchies (topic trees), subscribing to a node also implies a subscription to all child nodes.

Addressing Topics

Topics can be addressed in three main ways (each of which is a subset of the next):

• SimpleTopic - A QName
  QName
  QNames were introduced by XML Namespaces in order to be used as URI references. QName stands for "qualified name" and defines a valid identifier for elements and attributes. QNames are generally used to reference particular elements or attributes within XML documents...
  
   that describes a topic (this method can only address the root topics).
• ConcreteTopicPath - A list of QName
  QName
  QNames were introduced by XML Namespaces in order to be used as URI references. QName stands for "qualified name" and defines a valid identifier for elements and attributes. QNames are generally used to reference particular elements or attributes within XML documents...
  
  s that describes a path to a topic.
• FullTopicPath - An expression (in a subset of XPath
  XPath
  XPath is a language for selecting nodes from an XML document. In addition, XPath may be used to compute values from the content of an XML document...
  
  ) that addresses topics using wildcards.

Topic Aliasing

Topic aliasing provides a formal way to declare that a topic is identical to another topic or group of topics found elsewhere in the topic space.

Ad-Hoc Topics

The ad-hoc topic space allows the dynamic definition of topic trees without the overhead of defining a new topic space.

See also

WS-Topics 1.3 Specification