Web Services Description Language (WSDL) 1.1 is 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 end points are combined into abstract endpoints (services).
WSDL is extensible to allow the description of endpoints and their messages regardless of what message formats or network protocols are used to communicate. The WSDL 1.1 specification only defines bindings that describe how to use WSDL in conjunction with SOAP 1.1, HTTP GET and POST, and MIME.
The specification for WSDL is published by the World Wide Web Consortium (W3C) as a W3C Note at WSDL Version 1.1.