How to make a Socket.IO client connect to a Python3 Websocket server
Question
I'm attempting to get a Socket.IO client to connect to a Python Websocket server I created using aaugustin's websockets library and asyncio. Using the example on the page I created the following web socket server:
import asyncio
import websockets
from datetime import datetime
@asyncio.coroutine
def producer():
return str(datetime.now())
@asyncio.coroutine
def handler(websocket, path):
while True:
message = yield from producer()
if not websocket.open:
break
yield from websocket.send(message)
yield from asyncio.sleep(3)
start_server = websockets.serve(handler, "localhost", 8765)
asyncio.get_event_loop().run_until_complete(start_server)
asyncio.get_event_loop().run_forever()
The view is served up using Flask and looks like the following:
<!doctype html>
<head>
<title>Websocket Client Test</title>
</head>
<body>
<script src="https://cdn.socket.io/socket.io-1.3.5.js"></script>
<script>
console.log(io);
var socket = io("ws://localhost:8765/");
console.log(socket);
</script>
</body>
Whenever Socket.IO tries to connect, it throws the following error:
XMLHttpRequest cannot load http://localhost:8765/socket.io/?EIO=3&transport=polling&t=1434254272412-0. No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'http://localhost:5001' is therefore not allowed access. The response had HTTP status code 400.
The Access-Control-Allow-Origin seems to imply I'm trying to make a request to a location with a different hostname, which I'm not doing. So I don't know why its throwing that error. I created a Python client script that connects to the server just fine, so I'm a little lost as to what I'm missing.
2 answers
solution1
2 2015-06-14 05:23:03
The Access-Control-Allow-Origin seems to imply I'm trying to make a request to a location with a different hostname, which I'm not doing.
Different port is considered a different origin for lots of implementations. From https://developer.mozilla.org/en-US/docs/Web/Security/Same-origin_policy :
Two pages have the same origin if the protocol, port (if one is specified), and host are the same for both pages
solution2
0 2020-05-10 09:38:42
I believe this is impossible. Socket.io implements its own protocol, so you cannot use socket.io-client with a non-socket.io server. See: https://stackoverflow.com/a/19522754/627663
Instead of using socket.io-client, you can use the standard javascript websocket API which works in most browsers these days.
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