WSIF Structure
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.
WSDL allows there to be multiple implementations for a Web Service, and multiple Ports that share the same PortType. In other words, WSDL allows the same interface to have bindings to for example, SOAP and IIOP.
WSIF provides an API to allow the same client code to access any available binding. As the client code can then be written to the PortType it can be a deployment or configuration setting (or a code choice) which port and binding it uses.
WSIF uses 'providers' to support these multiple WSDL bindings. A provider is a piece of code that supports a WSDL extension and allows invocation of the service through that particular implementation. WSIF providers use the J2SE JAR service provider specification making them discoverable at runtime.
Clients can then utilize any new implementations and can delegate the choice of port to the infrastructure and runtime, which allows the implementation to be chosen on the basis of quality of service characteristics or business policy.
Read more about this topic: Web Services Invocation Framework
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