WSDL(Web Services Description Language) is an XML based protocol for information exchange in decentralized and distributed environments which was was jointly developed by Microsoft and IBM. It is the standard format for describing a web service which describes how to access a web service and what operations it will perform. It is also describes how to interface with XML-based services.
WSDL is also an integral part of UDDI, an XML-based worldwide business registry.
WSDL Usage:
WSDL is often used in combination with SOAP and XML Schema to provide web services over the Internet. A client program connecting to a web service can read the WSDL to determine what functions are available on the server. Any special datatypes used are embedded in the WSDL file in the form of XML Schema. The client can then use SOAP to actually call one of the functions listed in the WSDL.
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