backend-webrtc

Beep backend handling WebRTC Selective Forwarding Units (SFUs). Pushes bites (chunks of audio) to NATS. Checks backend-permissions for user's permission to join the conversation.

The security of this service is handled by backend-auth called by traefik.

Environment variables

Supply environment variables by either exporting them or editing .env.

ENV	Description	Default
LISTEN	Host and port to listen on	:80
NATS	Host and port of NATs	nats://localhost:4222
PERMISSIONS_HOST	URL of backend-permissions	http://permissions

API

All endpoints require a populated X-User-Claim header from backend-auth.

Contents
New Connection
Join Conversation

---

New Connection

GET /connect

Creates a new WebRTC peer connection with the server. Connection gets upgraded to a websocket through which signalling occurs before it is closed once the peer connection is established. Please supply the token via GET querystring since Websockets do not support Auth headers.

Example (Javascript)

const wsuri = `wss:\/\/localhost:80/connect`;

let localSDP = '';
let remoteSDP = '';

const socket = new WebSocket(wsuri);
socket.onmessage = (e) => {
  remoteSDP = e.data;
  try {
    pc.setRemoteDescription(new RTCSessionDescription({ type: 'answer', sdp: remoteSDP });
  } catch(e) {
    console.error(e);
  }
};

const pc = new RTCPeerConnection({
  iceServers: [
    {
      urls: 'stun:stun.l.google.com:19302',
    },
  ],
});
pc.onicecandidate = (e) => {
  if (e.candidate === null) {
    localSDP = pc.localDescription.sdp;
    socket.send(localSDP);
  }
};

navigator.mediaDevices
         .getUserMedia({ audio: true })
         .then((stream) => {
           for (const track of stream.getAudioTracks()) {
             pc.addTrack(track);
           }
           pc.createOffer()
             .then((d) => {
               p.setLocalDescription(d);
             })
             .catch((e) => console.error(e));
         })
         .catch((e) => console.error(e));

pc.ontrack = (event) => {
  // Do stuff with event.streams
};

Errors

Code	Description
400	Error parsing X-User-Claims header
500	Error establishing WebRTC connection

---

Join Conversation

POST /join/:conversationid

Signify a user's intention to join a conversation.

Params

Name	Type	Description
conversationid	String	ID of conversation to be joined

Success (200 OK)

Empty body

Errors

Code	Description
400	Error parsing X-User-Claims header
401	backend-permissions denied permission to join conversation