rtc.io-server

Node signaling server for rtc.io. Thin wrapper on top of socket.io that wires up the rtc.io signaling protocol.

npm install rtc.io-server

Usage

import { Server } from "rtc.io-server";

const server = new Server({ cors: { origin: "*" } });

server.on("connection", (socket) => {
  socket.on("join-room", ({ roomId, name }) => {
    socket.data.name = name;
    socket.join(roomId);
    // Tell every existing peer in the room to initiate an offer to the new one.
    socket.to(roomId).emit("#rtcio:init-offer", { source: socket.id });
  });

  // No `disconnecting` handler needed for peer cleanup — the rtc.io-server
  // core emits `#rtcio:peer-left` automatically. Add one only if you have
  // app-level cleanup (presence rosters, room password registries, etc.).
});

server.listen(3001);

What this server does

The rtc.io client multiplexes all WebRTC signaling (offers, answers, ICE candidates, stream metadata) into a single #rtcio:message event. This server registers default handlers that:

1. Relay #rtcio:message envelopes to the addressed peer (socket.to(target).emit(...)).
2. Emit a #rtcio:peer-left notification to a leaving socket's rooms on disconnecting, so existing peers can short-circuit ICE consent-freshness (~30 s) when a tab closes. The client treats this as a hint that's cross-checked against the local WebRTC state; it never tears down a healthy P2P call on the basis of a signaling-only event. See the signaling protocol for the full contract.

Everything else — room management, app-level events, presence — is your code.

What you implement

• Room/lobby logic. socket.join(roomId), fan-out on join, presence broadcasts.
• The #rtcio:init-offer kickoff. When a new peer joins a room, emit this to existing peers so they initiate offers to the newcomer. The client listens for it and starts the WebRTC handshake.
• App-level events. Chat persistence, auth, etc.

The server has no opinion about any of these — it's just a relay.

API

import { Server, ServerOptions, RtcioEvents } from "rtc.io-server";

• Server — extends socket.io's Server. Same options. addDefaultListeners is attached automatically on every connection.
• RtcioEvents — string constants for the rtc.io reserved event names (use RtcioEvents.INIT_OFFER instead of typing "#rtcio:init-offer" by hand).
• addDefaultListeners(socket) — registers the message-relay handler. Called automatically; expose for advanced use.

Wire compatibility

This server speaks the rtc.io signaling protocol — pair it with rtc.io@^1.1.0 clients. The envelope format changed in 1.1, so older clients are not wire-compatible.

License

MIT