WS-Federation

Web Services Federation Language

The Web Services Federation specification is another component of the Web Services Security model that defines mechanisms to allow different security realms to federate by allowing and brokering trust of identities, attributes, authentication between participating Web services. The mechanisms defined in this specification can be used by passive and active requestors. The Web service requestors are assumed to understand the new security mechanisms and be capable of interacting with Web service providers.

http://www.ibm.com/developerworks/library/specification/ws-fed/