WSDL 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 endpoints are combined into abstract endpoints (services). WSDL is extensible to allow description of endpoints and their messages regardless of what message formats or network protocols are used to communicate, however, the only bindings described in this document describe how to use WSDL in conjunction with SOAP 1.1. See Section .
As communications protocols and message formats are standardized in the web community, it becomes increasingly possible and important to be able to describe the communications in some structured way. WSDL addresses this need by defining an XML grammar for describing network services as collections of communication endpoints capable of exchanging messages. WSDL service definitions provide documentation for distributed systems and serve as a recipe for automating the details involved in applications communication.
A WSDL document defines services as collections of network endpoints, or ports. In WSDL, the abstract definition of endpoints and messages is separated from their concrete network deployment or data format bindings. This allows the reuse of abstract definitions: messages, which are abstract descriptions of the data being exchanged, and port types which are abstract collections of operations. The concrete protocol and data format specifications for a particular port type constitutes a reusable binding. A port is defined by associating a network address with a reusable binding, and a collection of ports define a service. Hence, a WSDL document uses the following elements in the definition of network services:
- Types– a container for data type definitions using some type system (such as XSD).
- Message– an abstract, typed definition of the data being communicated.
- Operation– an abstract description of an action supported by the service.
- Port Type–an abstract set of operations supported by one or more endpoints.
- Binding– a concrete protocol and data format specification for a particular port type.
- Port– a single endpoint defined as a combination of a binding and a network address.
- Service– a collection of related endpoints.
The complete definition of all these terms, and more, can be found at http://www.w3.org/TR/wsdl#_introduction\
Navigate here for an example WSDL file.