Websocket connection is not working

[ihrigb]

I have problems establishing a websocket connection. This issue should be related to an Issue on Stackoverflow.
For testing-purposes I have the following small flask app:

from flask import Flask, render_template
from flask_socketio import SocketIO, emit

app = Flask(__name__)
socketio = SocketIO(app)

@socketio.on('connect')
def connect():
    print('Connect')

@app.route('/')
def index():
    return render_template('app.html')

if __name__ == '__main__':
    socketio.run(app, host='0.0.0.0', debug=True)

The server commes up but engaging a websocket connection does not work

var socket = new WebSocket('ws://localhost:5000');

This JS call causes server side exception:

(6192) accepted ('127.0.0.1', 64292)
127.0.0.1 - - [16/Mar/2016 23:13:12] "GET /socket HTTP/1.1" 404 342 0.000000
Traceback (most recent call last):
  File "C:\Users\Benjamin\AppData\Local\Programs\Python\Python35\lib\site-packages\eventlet\greenpool.py", line 82, in _spawn_n_impl
    func(*args, **kwargs)
  File "C:\Users\Benjamin\AppData\Local\Programs\Python\Python35\lib\site-packages\eventlet\wsgi.py", line 719, in process_request
    proto.__init__(sock, address, self)
  File "C:\Users\Benjamin\AppData\Local\Programs\Python\Python35\lib\socketserver.py", line 684, in __init__
    self.handle()
  File "C:\Users\Benjamin\AppData\Local\Programs\Python\Python35\lib\http\server.py", line 417, in handle
    self.handle_one_request()
  File "C:\Users\Benjamin\AppData\Local\Programs\Python\Python35\lib\site-packages\eventlet\wsgi.py", line 330, in handle_one_request
    self.raw_requestline = self.rfile.readline(self.server.url_length_limit)
OSError: raw readinto() returned invalid length -1 (should have been between 0 and 8192)

and client side exception:

WebSocket connection to 'ws://localhost:5000/socket' failed: Error during WebSocket handshake: Unexpected response code: 404

[ihrigb]

FYI: pip freeze gives following output:

eventlet==0.18.4
Flask==0.10.1
Flask-SocketIO==2.2
gevent==1.1.0
gevent-websocket==0.9.5
greenlet==0.4.9
itsdangerous==0.24
Jinja2==2.8
MarkupSafe==0.23
Pygments==2.1.3
pyserial==3.0.1
python-engineio==0.9.0
python-socketio==1.1
six==1.10.0
virtualenv==15.0.0
Werkzeug==0.11.4

[miguelgrinberg]

SocketIO is not the same as WebSocket. To connect to a SocketIO server you need to use a SocketIO client. See the Javascript code in the example included in this repository for an example.

[ihrigb]

Ok, thanks for the info! That was not obvious for me!