WS-Eventing

Web Services Eventing (WS-Eventing)

Web services often want to receive messages when events occur in other services and applications. A mechanism for registering interest is needed because the set of Web services interested in receiving such messages is often unknown in advance or will change over time. This specification defines a protocol for one Web service (called a "subscriber") to register interest (called a "subscription") with another Web service (called an "event source") in receiving messages about events (called "notifications" or "event messages"). The subscriber may manage the subscription by interacting with a Web service (called the "subscription manager") designated by the event source.

http://www.w3.org/Submission/WS-Eventing/