I want to simply connect socket.io-client to python server, but for some reason it's keep failing. Initially I start my python server and then try to connect JavaScript as my client server after following that process what I see is JavaScript client server is keep trying to connect and failing with following error:
websocket.js:88 WebSocket connection to 'ws://localhost:5100/socket.io/?EIO=4&transport=websocket' failed:
and python server also repeating following error:
(10448) accepted ('127.0.0.1', 61471) 127.0.0.1 - - [01/Feb/2022 15:14:01] "GET /socket.io/?EIO=4&transport=websocket HTTP/1.1" 400 136 0.000000
I am using python3.10 with socketio following Document:
https://python-socketio.readthedocs.io/en/latest/.
Also tried version compatibility:
https://pypi.org/project/python-socketio/
pip3 freeze
I have tried multiple version for python-engineio and python-socketio to match my socket.io-client but no improvements.
eventlet==0.33.0
python-engineio==3.13.0
python-socketio==4.6.1
server.py
import eventlet
import socketio
sio = socketio.Server()
app = socketio.WSGIApp(sio)
@sio.event
def connect(sid, environ):
print('[INFO] Connect to client', sid)
@sio.event
def disconnect(sid):
print('disconnect ', sid)
#ESI.local 192.168.2.95
if __name__ == '__main__':
eventlet.wsgi.server(eventlet.listen(('0.0.0.0', 5100)), app)
HTML/JavaScript
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Document</title>
</head>
<body>
<h1>Socket IO Demo</h1>
<script type="module">
import { io } from "https://cdn.socket.io/4.3.2/socket.io.esm.min.js";
const sio = io("http://localhost:5100:", {
forceJSONP: true,
secure: true,
jsonp: true,
transports: [ "websocket","polling"]
});
sio.on("connect", () => {
console.log("connected");
});
sio.on("disconnect", () => {
console.log("Disconnected");
});
</script>
</body>
</html>
After many trial and error. I have finally cracked it. This was happening due to CORS even though I used CORS google extension to handle this situation, but I guess this was supposed to be handled on backend. Simply passing (cors_allowed_origins="*") to socketio.Server() it fixed everything.
sio = socketio.Server(cors_allowed_origins="*")
If you want to perform websocket, i'll recommend using WebSocket package built-in and websocket from gevent.
Here what I have done to achieve a thing similar as what you want to do :
let socket = new WebSocket('ws://localhost:8080');
console.log('Created socket');
// Connection opened
socket.addEventListener('open', function (event) {
socket.send('Hello Server!');
});
// Listen for messages
socket.addEventListener('message', function (event) {
console.log('Message from server ', event.data);
});
// For example : send array
socket.send(JSON.stringify([1, 2, 3]));
Python server:
from geventwebsocket import WebSocketServer, WebSocketApplication, Resource
from collections import OrderedDict
class Application(WebSocketApplication):
def on_open(self):
print("Connection opened")
def on_message(self, message):
print("Got message: ", message)
# self.ws.send(...) to make a response
def on_close(self, reason):
print(reason)
WebSocketServer(
('localhost', 8080),
Resource(OrderedDict([('/', Application)]))
).serve_forever()
Gevent (python) : https://pypi.org/project/gevent-websocket/