Allows a client to communicate with the server using http calls.

The client asks for a service using the HttpServiceFactory. He gets a reference on a service which is in reality a dynamic proxy (@see java.lang.reflect.Proxy). This Proxy dispatches all the method invocation to the Service which implements the InvocationHandler interface. The Service then delegates the invocation to the HttpSessionClient singleton. This class is responsible for the communication with the server. It encapsulates the method invocation in http request using HttpServiceRequest instances. On theserver, the servlet HttpSessionServer gets the HttpServiceRequest and performs the invocation on the EJB reference corresponding to the service.