Session ID differences between client and server

[jamesbraza]

I have the following code:

import time
import socketio

sio_client = socketio.Client()

@sio_client.event
def on_connect(sid: str) -> None:
    """Connect event from server emits its SID to this function."""
    print(f"server connect SID: {sid}.")

sio_client.connect("http://127.0.0.1:8000", socketio_path="/ws/socket.io")
print(f"client connect SID: {sio_client.sid}.")

time.sleep(0.1)
sio_client.disconnect()

Running this code with python-socketio==5.10.0:

server connect SID: 4zzPeLZ8C58cbBtdAAAD.
client connect SID: sjmQ_ysKU_uPeAHaAAAC.

Why is the server's session ID different from the client's session ID?

[miguelgrinberg]

You are mixing up two different identifiers. The Socket.IO protocol assigns an identifier to the Engine.IO transport, and a different one for each connected Socket.IO namespace. The sid that you get in the server on the connect handler is the Socket.IO identifier. But the sio_client.sid that you are printing on the client is actually a private variable of the client, not supposed to be used by the application. Instead, use sio_client.get_sid() to get the identifier for the Socket.IO session associated with the default namespace. documentation link