WSDL is XML based language used to locate and describe web service.
The WSDL palette is used for creating, editing, validating, importing, and viewing WSDL files.
A WSDL resource is composed of a series of definitions that describe the format and roles of messages used in web services.
Messages- which describe the data being exchanged
Port Type – which define a set of operations.
Operations – describes the message formats for the incoming and outgoing messages required by the activities supported by the port Type.