Web Services are given definitions with Web services description language or WDSL in order for them to be discovered by and interfaced with services and apps on computers. WDSL is one of the common languages used to write Web service interfaces. The Web service endpoint describes the point of contact for a service by stating the physical location of the service, or what computer it is coming from, and a formal definition of the interface for programs that are attempting to communicate with the service.
Web Services Description Language is an XML language used to describe a Web service's functionality. The Web service's description tells a computer what the service is called, what its parameters are and how the data will structure its returns. It is also used with simple object access protocol, or SOAP, which specifies how structured information is exchanged over a computer network.
Web Services Addressing
The Web services addressing, or WS-Addressing, makes definitions for two constructs; message address properties and endpoint references. These definitions "normalize" or translate the information provided by Internet protocols and messaging systems. The Web service endpoint is a processor, resource or entity that a Web service can send information to.
The endpoint is a connection point where HTML files or active server pages are exposed. Endpoints provide information needed to address a Web service endpoint. The endpoint provides a reference or specification that is used to define a group or family of message addressing properties and give end-to-end message characteristics, such as references for the source and destination of endpoints, and the identity of messages to allow for uniform addressing of "independent" messages. The endpoint can be a PC, PDA, or point-of-sale terminal.
WDSL Description Types
An endpoint definition can have an abstract description or a concrete description. An abstract description tells a program how to interface without referencing the type of technology used to host a Web service that transmits messages. This type of WDSL description is broken up into port type, operation and message. Port type sorts messages into groups of functions called operations, which is a specific action done by a service and operations, which consist of input and output parameters. A concrete description is the implemented technology used to create an abstract interface definition. It is the physical connection or physical transport protocol that defines the port, binding (requirements needed for a service to connect with the endpoint) the service or port and the physical address that a service accesses with the specified WSDL protocol.