To create a web service client that can access and consume a web service provider, you must obtain the information that defines the interoperability requirements of the web service provider. Providers make this information available by means of WSDL files. WSDL files may be made available in service registries or published on the Internet using a URL (or both). You can use a web browser or NetBeans IDE to obtain WSDL files.
A WSDL file contains descriptions of the following:
Network services: The description includes the name of the service, the location of the service, and ways to communicate with the service, that is, what transport to use.
Web services policies: Policies express the capabilities, requirements, and general characteristics of a web service. Web service providers use policies to specify policy information in a standardized way. Policies convey conditions on interactions between two web service endpoints. Typically, the provider of a web service exposes a policy to convey conditions under which it provides the service. A requester (a client) might use the policy to decide whether or not to use the service.
Web Services Metadata Exchange (WS-MEX) is the protocol for requesting and transferring the WSDL from the provider to the client. This protocol is a bootstrap mechanism for communication. When the type of metadata desired is clearly known (for example, WS-Policy), a client request may indicate that only that type should be returned.