WS-Notification is a Publish/Subscribe notification framework for Web services. An article at WebServices.org describes WS-Notification as "a family of related white papers and specifications that define a standard Web services approach to notification using a topic-based publish/subscribe pattern." There are three parts to the specification:

• WS-BaseNotification defines the basic interfaces for producers and consumers of notifications.
• WS-BrokeredNotification defines the interface for notification intermediaries.
• WS-Topics defines how topics, which producers create and send to, and consumers read, are managed.

There's a white paper at IBM DeveloperWorks that "introduces the notification pattern, sets the goals and requirements for the WS-Notification family of specifications and describes each of the specifications that make up this family." The white paper "also defines a set of terms and concepts used in the specifications, provides some examples, and includes a discussion of security considerations."