i want to interrupt the file sending. but i can't change the client. so i need change the server. All things go well, but the message i wanna response seem not work. is the self.transport.loseConnection() (the last line) blocking the messages? in fact, i work on Cumulus(nimbus project) which based on twisted. And i use s3cmd as the client. here is the my code: def headerReceived(self,line): pycb.log(logging.INFO, "===== def headerReceived of cumulus.py") http.HTTPChannel.headerReceived(self,line) pycb.log(logging.INFO, "===== self.length is %s"%self.length) header, data = line.split(':', 1) header = header.lower() data = data.strip() if header=='authorization': self.authorization=data if self.length and self.authorization: user_id = self.authorization.split(':')[0].split()[1].strip() user = pycb.config.auth.get_user(user_id) pycb.log(logging.INFO, "===== user who put this object is %s"%user) remaining_quota = user.get_remaining_quota() pycb.log(logging.INFO, "===== remaining_quota is %s"%remaining_quota) quota_check=self.length-remaining_quota pycb.log(logging.INFO, "===== quota_check=self.length-remaining_quota of cumulus.py") if quota_check>0: requestId = str(uuid.uuid1()).replace("-", "") ex=cbException('AccountProblem') m_msg = "HTTP/1.1 %s %s\r\n" % (ex.httpCode, ex.httpDesc) self.transport.write(m_msg) m_msg = "%s: %s\r\n" % (('x-amz-request-id', requestId)) self.transport.write(m_msg) #req.setHeader('x-amz-request-id', requestId) m_msg = "%s: %s\r\n" % (('x-amz-id-2', str(uuid.uuid1()))) self.transport.write(m_msg) e_msg = ex.make_xml_string(self._path, str(uuid.uuid1())) pycb.log(logging.INFO, "===== e_msg is %s"%e_msg) #self.transport.write("\r\n") self.transport.write(e_msg) pycb.log(logging.INFO, "===== self.transport.write(e_msg)") self.transport.loseConnection()