WSDL (Web Services Description Language) is an XML-based language for describing Web services and how to access them.
Files with the WSDL extension contain web service interfaces expressed in the Web Service Description Language (WSDL). WSDL is a standard XML document
WSDL files are used to communicate interface information between web service producers and consumers. A WSDL description allows a client to utilize a web service’s capabilities without knowledge of the implementation details of the web service.
