Websockets with tornado

2018-06-15 18:53:49

I'm relatively new to the tornado framework and so far things have been pretty confusing, especially when dealing with web sockets. So far my code looks like this:

import tornado.options
import tornado.web
import tornado.websocket
import tornado.ioloop

from tornado.options import options, define

define(name='port', default=8000, help='.', type=int)

class WSHandler(tornado.websocket.WebSocketHandler):
    clients = []

    def open(self):
        WSHandler.clients.append(self)
        self.write('client connected')

    def on_close(self):
        WSHandler.clients.remove(self)
        self.write('client removed')

    def on_message(self, message):
        for client in WSHandler.clients:
            WSHandler.client.write_message(message)

    def check_origin(self, origin):
        return True

if __name__ == '__main__':
    tornado.options.parse_command_line()
    application = tornado.web.Application(
        handlers=[
            (r'/webSocket', WSHandler),
        ],
    )
    application.listen(options.port)
    tornado.ioloop.IOLoop.instance().start()

and the javascript file looks like this

var ws = new WebSocket("ws://localhost:8000/webSocket")
ws.onopen = function() {
  ws.setData('Hello World');
};
ws.onmessage = function(evt) {
  ws.send(evt.data);
};

I think you can see tornado source,and you can find following:

# Upgrade header should be present and should be equal to WebSocket
    if self.request.headers.get("Upgrade", "").lower() != 'websocket':
        self.set_status(400)
        log_msg = "Can "Upgrade" only to "WebSocket"."
        self.finish(log_msg)
        gen_log.debug(log_msg)
        return

Obviously,HTML5 WebSocket protocol is a new protocol. It implements the browser and the server full-duplex communication (full-duplex).But use http can only make single communite.So I advice you try another demo.

Server:

    #!/usr/bin/python
#coding:utf-8
import os.path

import tornado.httpserver
import tornado.web
import tornado.ioloop
import tornado.options
import tornado.httpclient
import tornado.websocket

import json
class IndexHandler(tornado.web.RequestHandler):
  def get(self):
    self.render("index.html")

class SocketHandler(tornado.websocket.WebSocketHandler):
  """docstring for SocketHandler"""
  clients = set()

  @staticmethod
  def send_to_all(message):
      for c in SocketHandler.clients:
          c.write_message(json.dumps(message))

  def open(self):
      self.write_message(json.dumps({
          'type': 'sys',
          'message': 'Welcome to WebSocket',
      }))
      SocketHandler.send_to_all({
          'type': 'sys',
          'message': str(id(self)) + ' has joined',
      })
      SocketHandler.clients.add(self)

  def on_close(self):
      SocketHandler.clients.remove(self)
      SocketHandler.send_to_all({
          'type': 'sys',
          'message': str(id(self)) + ' has left',
      })

  def on_message(self, message):
    SocketHandler.send_to_all({
  'type': 'user',
  'id': id(self),
  'message': message,
        })

##MAIN
if __name__ == '__main__':
  app = tornado.web.Application(
    handlers=[
      (r"/", IndexHandler),
      (r"/chat", SocketHandler)
    ],
    debug = True,
    template_path = os.path.join(os.path.dirname(__file__), "templates"),
        static_path = os.path.join(os.path.dirname(__file__), "static")
  )
  app.listen(8000)
  tornado.ioloop.IOLoop.instance().start()

Client:

    <html>
<head>
<script type="text/javascript">
var ws = new WebSocket("ws://localhost:8000/chat");
ws.onmessage = function(event) {
  console.log(event);
}
function send() {
  ws.send(document.getElementById('chat').value );
}
</script>
</head>

<body>
  <div>
    hello
    <input id="chat">
    <button  onclick="send()">send</button>
  </div>    
</body>
</html>

链接地址: http://www.djcxy.com/p/44774.html

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