def HalfDuplexCall(self, request_iter, unused_rpc_context):
        responses = []
        for request in request_iter:
            for parameter in request.response_parameters:
                response = self._responses_pb2.StreamingOutputCallResponse()
                response.payload.payload_type = self._payload_pb2.COMPRESSABLE
                response.payload.payload_compressable = 'a' * parameter.size
                self._control()
                responses.append(response)
        for response in responses:
            yield response