Python websocket-client 如何保持长连接呢？

最近在了解 websocket，但是发现死活不能保持长连接，用 tornado 实现了一个 server：

# coding=utf8

from tornado.websocket import WebSocketHandler
from tornado.web import asynchronous, Application
from tornado.httpserver import HTTPServer
from tornado.ioloop import IOLoop
from tornado.gen import coroutine, sleep


class WSHandler(WebSocketHandler):

    @asynchronous
    def open(self, *args, **kwargs):
        print '{0} connected'.format(self.request.remote_ip)

    @coroutine
    def on_message(self, message):
        if message:
            if message:
                yield sleep(5)
                self.write_message("it\'s is done")

    def on_close(self):
        print 'client is exit'


def main():

    app = Application([(r'/', WSHandler)],
                      static_path='static')
    server = HTTPServer(app)
    server.listen(8088)
    IOLoop.instance().start()

if __name__ == '__main__':
    main()

客户端代码：

import socket
from websocket import create_connection
import websocket
while 1:
    ws = create_connection("ws://localhost:8088/", timeout=5)
    if ws.connected:
        ws.send('am coming', opcode=websocket.ABNF.OPCODE_TEXT)
        print ws.recv()
    # ws.close()

当 client 调用recv()函数后就退出了,有什么办法可以做到一直保持链接，然后客户端得到消息可以正常处理