can i use socketio as multiple callback?

[JongHyeonSong]

below is some part nodejs server code

socket.on("cli-offer", (data, cb1) => {
  function cb2(res) {
    console.log("🚀 ~ SocketIoService ~ cb2 ~ res:", res);
    // BELLOW IS ERROR
    // Error: operation has timed out
    // at Timeout._onTimeout (C:\Users\user\Desktop\project\company\new-kiosk-project\webrtc-peerjs\node_modules\socket.io\dist\broadcast-operator.js:182:17)
    // at listOnTimeout (node:internal/timers:559:17)
    // at processTimers (node:internal/timers:502:7)
    cb1(res);
  }

  socket.to(target1).emit("srv-offer", { offer }, cb2);
  // socket.emit("srv-offer", { offer }, cb2); // it works
});

1. P1 emit to server
2. -> server emit to P2
3. -> P2 exec server's callback with res
4. -> server get res
5. -> server exec P1's callback with res of P2

1way callback works well client->server, server-> client

but 2way seem not work, erorr go out immediatly. (but it is weired if re-emit to himself, it works...)

wanna know if it is not work theoreticaly or not

[darrachequesne]

Hi!

Yes it can work, you're just missing to set a timeout value:

socket.on("cli-offer", (data, cb1) => {
  function cb2(err, responses) {
    console.log("🚀 ~ SocketIoService ~ cb2 ~ res:", responses[0]);
    // BELLOW IS ERROR
    // Error: operation has timed out
    // at Timeout._onTimeout (C:\Users\user\Desktop\project\company\new-kiosk-project\webrtc-peerjs\node_modules\socket.io\dist\broadcast-operator.js:182:17)
    // at listOnTimeout (node:internal/timers:559:17)
    // at processTimers (node:internal/timers:502:7)
    cb1(responses[0]);
  }

  socket.timeout(5000).to(target1).emit("srv-offer", { offer }, cb2);
  // socket.emit("srv-offer", { offer }, cb2); // it works
});

Please be aware that the arguments of cb2 are:

• an optional error (timeout)
• an array of responses (since the room named target1 may or may not contain multiple sockets)

Reference: https://socket.io/docs/v4/emit-cheatsheet/#acknowledgements

[JongHyeonSong]

thank you it works well!
timeout must be super small(cannot find default value in library..)

"an array of responses (since the room named target1 may or may not contain multiple sockets)"

is this mean if broadcast to 5 peer, it never fired until all the 5peer execute callback?

[darrachequesne]

is this mean if broadcast to 5 peer, it never fired until all the 5peer execute callback?

Yes, either after receiving the 5 responses, or after the timeout delay.