Unable to emit or trigger an event to a room id.

[sk-santhosh]

Problem
Unable to emit or trigger an event to a room id.

Link: https://codesandbox.io/s/socket-io-room-event-not-emitting-1ozu7

Code

Socket.IO server version: 4.1.1

Server

var app = require("http").createServer();

process.env.DEBUG = "*";

const customParser = require("socket.io-msgpack-parser");

var io = require("socket.io")(app, {
  parser: customParser,
});

io.listen(3000);

io.of("custom_namespace").on("connection", (socket) => {
  console.log("Connected");
  socket.on("join_room", () => {
    console.log("Join Room");

    // Working Fine
    socket.emit("direct_event");

    socket.join("ROOM_12345");

    setInterval(() => {
      console.log("Room Event");

      // *********** Problem ************
      // Event not emiting
      io.to("ROOM_12345").emit("room_event");
    }, 1000);
  });
});

Socket.IO client version: 4.1.1

Client

var _io = io("/custom_namespace", {
      parser: require("socket.io-msgpack-parser"),
});

_io.on("connect", () => {
      console.log("connected");
      _io.emit("join_room");
 });

_io.on("direct_event", () => {
      console.log("direct_event");
});

_io.on("room_event", () => {
      console.log("room_event");
});

Reference Image:

[Benedicht]

Joining to add some details.

io.to("ROOM_12345").emit("room_event"); uses socket.io-adapter's broadcast and sets the wsPreEncoded field:

    const firstPacketOpts = {
      wsPreEncoded: "4" + encodedPackets[0], // "4" being the "message" packet type in Engine.IO
      ...packetOpts
    };

However, wsPreEncoded is used only in the websocket transport:

    if (packet.options && typeof packet.options.wsPreEncoded === "string") {
      send(packet.options.wsPreEncoded);
    } else {
      this.parser.encodePacket(packet, this.supportsBinary, send);
    }

If the client is upgrading or can't upgrade to the websocket transport at all, no events using wsPreEncoded going to be sent over.

Another problem

is that the Buffer produced by the socket.io-msgpack-parser becomes a string ("4" + encodedPackets[0]). This string is sent through a websocket text frame, but its data might not be a valid utf-8 text while the websocket specification requires that it must be a valid one:

Text

  The "Payload data" is text data encoded as UTF-8.  Note that a
  particular text frame might include a partial UTF-8 sequence;
  however, the whole message MUST contain valid UTF-8.

[sk-santhosh]

This release socketio/socket.io-adapter@2.3.1 works for me

Reference: socketio/socket.io-adapter#70

thank you @yuhj86