Response response,
                    long timeout ) throws IOException {
            makeKey( request );
            response.isReceived = false;
            try {
                response_map.put( request, response );
                doSend( request );
                response.expiration = System.currentTimeMillis() + timeout;
                while (!response.isReceived) {

                            for ( Response response : this.response_map.values() ) {
                                response.error();
                            }
                        }
                        throw new IOException("end of stream");
                    }

                    Response response = this.response_map.get(key);
                    if ( response == null ) {