websocket：python服务器和客户端js->无法正常工作

Question

I am trying to use websocket over the web, with a python server and a javascript client . For python , I am using an Autobahn (http://autobahn.ws/python/) to create a websoket server . When I use a python client (still with autobahn), all work fine. But when I try to use a webpage client, nothing works.

Python (server) code :

from autobahn.asyncio.websocket import WebSocketServerProtocol, \
                                       WebSocketServerFactory

import asyncio
import json

def fastsquare(x):
   return x * x


def slowsquare(x):
   asyncio.sleep(2)
   return x * x

class SlowSquareServerProtocol(WebSocketServerProtocol):
   @asyncio.coroutine
   def onOpen(self):
      print("WebSocket connection open.")

   @asyncio.coroutine
   def onMessage(self, payload, isBinary):
      if not isBinary:
         obj_tmp = json.loads(payload.decode('utf8'))
         obj = json.loads(obj_tmp)
         print (obj)
         try:
            if obj[2] == "little" :
               res = slowsquare(obj[3]["valeur"])
            else :
               res = fastsquare(obj[3]["valeur"])
         except Exception as e:
            self.sendClose(1000, str(e))
         else:
            obj = json.dumps(res).encode('utf8')
            print (str(obj))
            self.sendMessage(json.dumps(res).encode('utf8'))



if __name__ == '__main__':

   import asyncio

   factory = WebSocketServerFactory("ws://localhost:9000", debug = False)
   factory.protocol = SlowSquareServerProtocol

   loop = asyncio.get_event_loop()
   coro = loop.create_server(factory, 'localhost', 9000)
   server = loop.run_until_complete(coro)

   try:
      loop.run_forever()
   except KeyboardInterrupt:
      pass
   finally:
      server.close()
      loop.close()

And this is my javascript code :

<script>
function carre(){
    ws = new WebSocket("ws://192.168.0.15:9000");

    ws.onopen = function(){
        console.log("Connection is open..."); 
        // Web Socket is connected, send data using send()
        val = document.getElementById("val").value;
        var_json = '[2, "2262626262", "big", {"valeur" : ' + val + '}]';
        ws.send(var_json);
        console.log("json envoyé : " + var_json);
    };

    ws.onmessage = function (evt){ 
        var received_msg = evt.data;
        document.getElementById('carre').value = received_msg;
        console.log("JSon reçu : " + received_msg);
    };

    ws.onclose = function(){ 
        // websocket is closed.
        console.log("Connection is closed..."); 
    };
}
</script>


<p><input type="text" id="val" value="6"/><input type="button" OnClick="carre();" value="mettre au carre !"/></p>
<p>resultat du carre : <input type="text" id="carre" /></p>

Answer 1

Replace

obj_tmp = json.loads(payload.decode('utf8'))
obj = json.loads(obj_tmp)

with

obj = json.loads(payload)