I'm receiving Engine.IO connection drop if i'm trying to call an event from connect on server side

[RolandMiculas]

Client Code :

import socketio
import sys

namespace = '/chat'

debug = True

sio = socketio.Client(logger=debug, engineio_logger=debug)

data = {'something': 'something_else'}


@sio.event(namespace=namespace)
def connect(auth, sig):
    print("I'm connected to namespace = %s" % namespace)

    # res = sio.call("my_event", data, namespace=namespace)
    # print(res)


@sio.event
def disconnect():
    print("I'm disconnected!")


@sio.on('my_event', namespace=namespace)
def my_event(received_data):
    print('Received {0}'.format(received_data))

    return "OK", "whatever"


if __name__ == "__main__":
    sio.connect('http://10.17.132.159:5000', namespaces=namespace)

    print('my sid is', sio.sid)
    while True:
        string = input()
        data["mydata"] = string
        s = sio.call('my_event', data, namespace=namespace)
        print(s)

Server Code :

import socketio
import sys

debug = True
sio = socketio.Server(logger=debug, engineio_logger=debug, async_mode='eventlet')

data = {'something' : 'something_else'}

@sio.event(namespace='/chat')
def connect(sid, auth, sig):
    print("received ", sid)
    res = sio.call("my_event", data, namespace=namespace, to=sid)
    print(res)

if __name__ == '__main__':

    app = socketio.WSGIApp(sio)
    import eventlet

    eventlet.wsgi.server(eventlet.listen(('', 5000)), app)

I'm receving the "received sid" on the server then i get the following error on the client side :

Received {'something': 'something_else'}
Received packet MESSAGE data 2/chat,1["my_event",{"something":"something_else"}]
Received event "my_event" [/chat]
Sending packet MESSAGE data 3/chat,1["OK","whatever"]
Sending packet CLOSE data None
Engine.IO connection dropped
Exiting write loop task
Received packet PING data 
Waiting for write loop task to end
Exiting read loop task

The following issue occurs only if i'm trying to make the call on the server side on connect, has anyone an idea why is that?

As a note, im using py3.6 for development
LE : i've replaced sio.call with sio.emit and now it's working, but i still want to use call , because i'm waiting for a response from the client

[miguelgrinberg]

In general the connect event handler's function is to decide if the client is accepted or rejected. You can't do complex things in there, because the connection is not fully established when this handler is invoked.

You can try using the always_connect=True option (docs) and that may help, but my recommendation is that you move this call() to a real event instead of in connect.