invokes callback that should return a (request,response) tuple.
        representing the SOAP request and response respectively.
        ps -- ParsedSoap instance representing HTTP Body.
        request -- twisted.web.server.Request

def processRequest(cls, ps, **kw):
        """invokes callback that should return a (request,response) tuple.
        representing the SOAP request and response respectively.
        ps -- ParsedSoap instance representing HTTP Body.
        request -- twisted.web.server.Request
        """
        resource = kw['resource']
        request = kw['request']
        method =  getattr(resource, 'soap_%s' %
                           _get_element_nsuri_name(ps.body_root)[-1])
                                              
        try:
            req_pyobj,rsp_pyobj = method(ps, request=request)
        except TypeError, ex:
            log.err(
                'ERROR: service %s is broken, method MUST return request, response'\
                    % cls.__name__
            )
            raise
        except Exception, ex:
            log.err('failure when calling bound method')
            raise
        
        return rsp_pyobj