Using WSIF, WSDL can become the centerpiece of an integration framework for accessing software running on diverse platforms which use different protocols.
In WSDL, a binding defines how to map between the abstract PortType and a real service format and protocol.
For example, the SOAP binding defines the encoding style, the SOAPAction header, the namespace of the body (the targetURI), and so forth.
A provider is a piece of code that supports a WSDL extension and allows invocation of the service through that particular implementation.
WSIF is packaged with providers that enable transparent invocation based on the corresponding WSDL description.. WSIF enables developers to interact with abstract representations of Web services through their WSDL descriptions instead of working directly with the Simple Object Access Protocol (SOAP) APIs, which is the usual programming model.
With WSIF, developers can work with the same programming model regardless of how the Web service is implemented and accessed.
However, WSIF's API is WSDL-driven and protocol independent; it allows protocol-specific code ("providers") to be plugged in.