A class intended to form the final link in the chain calling into a Future which represents
the response to an asynchronous service invocation
Most methods are dummies, required to fulfil the contracts for ImplementationProvider, Implementation
and Invoker, since this class collapses together the functions of these separate interfaces, due to its
specialized nature, where most of the function will never be used.
The class acts as the implementation object that terminates the chain - and also as the provider of the implementation.
The class accepts Future objects which represent individual invocations of forward operations on the async service
and expects that the responses it handles as invocations will carry the unique ID of one of the Future objects in the
message header. On receipt of each message, the class seeks out the Future with that unique ID and completes the future
either with a response message or with a Fault.
This class is its own invoker...
Add a future to this response handler
future - the future
Method which is the termination for the invocation chain from the callback endpoint
msg - the Tuscany message containing the response from the async service invocation
which is either the Response message or an exception of some kind
response = ((Object)payload);