Web Service Definition Language definition architecture
(WSDL) An XML
format for describing network services
as a set of endpoints operating on messages containing either "document oriented" or "procedure oriented" information. The operations and messages are described abstractly, and then bound to a concrete network protocol and message format to define an endpoint. Related concrete endpoints are combined into abstract endpoints (services).
WSDL is typically used with SOAP
but it is extensible to allow description of endpoints and their messages independent of what message formats or network protocols.