Python-socketio: Client cannot connect to server when transports is websocket

[sdvcrx]

Server demo:

from aiohttp import web

import socketio

sio = socketio.AsyncServer(async_mode='aiohttp')
app = web.Application()
sio.attach(app)

async def index(request):
    pass

@sio.on('connection')
async def on_connect():
    print('client connected')

@sio.on('schedule')
async def ping(sid):
    await sio.emit('schedule', {
        'data': 'ok'
    })

app.router.add_get('/', index)

if __name__ == '__main__':
    web.run_app(app)

Client code (default transports):

import socketio

sio = socketio.Client()


@sio.on('connect')
def on_connect():
    print('connected to server')
    sio.emit('schedule')


@sio.on('schedule')
def on_pong(data):
    print(data)

if __name__ == '__main__':
    sio.connect('http://localhost:8080')
    sio.wait()

When transports is default (['polling', 'websocket']), everything is fine, output is expected:

connected to server
{'data': 'ok'}

But when transports set to websocket, client exited without msg and server did not receive any msg.

sio.connect('http://localhost:8080', transports='websocket')

[miguelgrinberg]

Hmm. The transport set to websocket works for me. Are you using the latest versions of both python-socketio and python-engineio?

You may also want to enable logging to see what's happening. On the client:

sio = socketio.Client(engineio_logger=True)

This is the output that I get here:

Attempting WebSocket connection to ws://localhost:8080/socket.io/?transport=websocket&EIO=3
WebSocket connection accepted with {'upgrades': [], 'pingInterval': 25000, 'pingTimeout': 60000, 'sid': '8af68c42863449628d3727cbc78d4c6c'}
Sending packet PING data None
Received packet MESSAGE data 0
connected to server
Sending packet MESSAGE data 2["schedule"]
Received packet PONG data None
Received packet MESSAGE data 2["schedule",{"data":"ok"}]
{'data': 'ok'}

[sdvcrx]

Thanks for the quick response.

My mistake! I didn't install websocket lib...

FYI: I found https://github.com/miguelgrinberg/python-engineio/blob/master/engineio/client.py#L306 logging a warning message, but if I initialize Client without engineio_logger=True, self.logger level is ERROR, so the warning message will never show. Maybe it is a good idea that setting log level to WARNING or using self.logger.error(msg) here?

[miguelgrinberg]

As documented, you can install the dependencies for the client if you install this package with:

pip install "python-socketio[client]"

These are not installed by default because most people use just the server.

Maybe it is a good idea that setting log level to WARNING or using self.logger.error(msg) here?

The log level does not matter if you don't have a logger attached. Maybe I'll make it an error, as you suggest.