From the jaxws api :
Creates a Dispatch instance for use with objects of the user's choosing. If there are any reference parameters in the endpointReference, then those reference parameters MUST appear as SOAP headers, indicating them to be reference parameters, on all messages sent to the endpoint. The endpointReference's address MUST be used for invocations on the endpoint. In the implementation of this method, the JAX-WS runtime system takes the responsibility of selecting a protocol binding (and a port) and configuring the dispatch accordingly from the WSDL associated with this Service instance or from the metadata from the endpointReference. If this Service instance has a WSDL and the endpointReference also has a WSDL in its metadata, then the WSDL from this instance MUST be used. If this Service instance does not have a WSDL and the endpointReference does have a WSDL, then the WSDL from the endpointReference MAY be used. An implementation MUST be able to retrieve the portName from the endpointReference metadata.
This method behaves the same as calling
dispatch = service.createDispatch(portName, type, mode, features);
where the portName is retrieved from the WSDL or EndpointReference metadata.