A WebRTC library that makes it easy to embed scalable peer to peer communication into UI components.

LioWebRTC works standalone, but it is also compatible with React, Vue, Electron, etc. It can be configured for scalability using partial mesh networks, making it possible to emit data to thousands of peers in a room, while only needing to be connected to at least one other peer in the room.

Click here to see a chatroom demo built with LioWebRTC.

Click here to see a video conferencing demo app built with LioWebRTC.

React developers may want to take a look at react-liowebrtc.

yarn add liowebrtc
// Or
npm i liowebrtc

import LioWebRTC from 'liowebrtc';

By default, this enables video, audio, and data channels.

const webrtc = new LioWebRTC({
    localVideoEl: localVideoIdOrRef, // The local video element
    autoRequestMedia: true, // Immediately request camera and mic access upon initialization
    debug: true, // Displays events emitted by liowebrtc in the console
    url: 'https://your-signaling-server.com:443/' // The url for your signaling server. If no url is passed, liowebrtc uses the default demo signaling server. (The default server is for demo purposes only, and is not reliable. Plus, I'm the only one paying for it 🙁. Please use your own in production!)
});

Disable video/audio streaming, and only allow data channels.

const webrtc = new LioWebRTC({
    dataOnly: true
});

Great for voice calls.

const webrtc = new LioWebRTC({
    autoRequestMedia: true,
    media: {
        video: false,
        audio: true
    }
});

Peers only form direct connections with a maximum of maxPeers and a minimum of minPeers. shout()ing still works because peers wil re-propagate messages to other peers. Note: partial mesh networks only work if you're only using dataOnly.

const webrtc = new LioWebRTC({
  dataOnly: true,
  network: {
    maxPeers: 8,
    minPeers: 4
  }
})

webrtc.on('ready', () => {
    // Joins a room if it exists, creates it if it doesn't
    webrtc.joinRoom('your room name');
});

Sometimes a peer wants to let every other peer in the room to know about something. This can be accomplished with shout(messageType, payload)

webrtc.shout('event-label', { success: true, payload: '137' });

Now for the recipients, handle the peer event with a listener:

webrtc.on('receivedPeerData', (type, data, peer) => {
    if (type === 'event-label' && data.success) {
        console.log(`Peer ${peer.id} emitted ${data.payload}`);
    }
});

Sometimes a peer only wants to send data directly to another peer. This can be accomplished with whisper(peer, messageType, payload)

webrtc.whisper(peer, 'directMessage', { msg: 'Hello world!' });

Receiving the message is the same as handling a peer event:

webrtc.on('receivedPeerData', (type, data, peer) => {
    if (type === 'directMessage') console.log(`Peer ${peer.id} says: ${data.msg}`);
});

componentDidUpdate(prevProps, prevState) {
    if (this.state.position !== prevState.position) {
        this.webrtc.shout('stateUpdate', this.state);
    }
}
});

All communications via shout/whisper are sent over the default data channel and emitted by the LioWebRTC instance as events. You can create your own custom listeners suited for whatever purpose you'd like.

webrtc.on('peerStreamAdded', (stream, peer) => {
    webrtc.attachStream(stream, yourVideoElementOrRef);
});

import React, { Component } from 'react';
import LioWebRTC from 'liowebrtc';

class Party extends Component {
  constructor(props) {
    super(props);
    this.state = {
      nick: this.props.nick,
      roomID: `party-${this.props.roomName}`,
      muted: false,
      camPaused: false,
      peers: []
    };
    this.remoteVideos = {};
  }

  componentDidMount() {
    this.webrtc = new LioWebRTC({
      // The url for your signaling server. Use your own in production!
      url: 'https://sm1.lio.app:443/',
      // The local video ref set within your render function
      localVideoEl: this.localVid,
      // Immediately request camera access
      autoRequestMedia: true,
      // Optional: nickname
      nick: this.state.nick,
      debug: true
    });

    this.webrtc.on('peerStreamAdded', this.addVideo);
    this.webrtc.on('removedPeer', this.removeVideo);
    this.webrtc.on('ready', this.readyToJoin);
    this.webrtc.on('iceFailed', this.handleConnectionError);
    this.webrtc.on('connectivityError', this.handleConnectionError);
  }

  addVideo = (stream, peer) => {
    this.setState({ peers: [...this.state.peers, peer] }, () => {
      this.webrtc.attachStream(stream, this.remoteVideos[peer.id]);
    });
  }

  removeVideo = (peer) => {
    this.setState({
      peers: this.state.peers.filter(p => !p.closed)
    });
  }

  handleConnectionError = (peer) => {
    const pc = peer.pc;
    console.log('had local relay candidate', pc.hadLocalRelayCandidate);
    console.log('had remote relay candidate', pc.hadRemoteRelayCandidate);
  }

  readyToJoin = () => {
    // Starts the process of joining a room.
    this.webrtc.joinRoom(this.state.roomID, (err, desc) => {
    });
  }

  // Show fellow peers in the room
  generateRemotes = () => this.state.peers.map((p) => (
    <div key={p.id}>
      <div id={/* The video container needs a special id */ `${this.webrtc.getContainerId(p)}`}>
        <video
          // Important: The video element needs both an id and ref
          id={this.webrtc.getDomId(p)}
          ref={(v) => this.remoteVideos[p.id] = v}
          />
      </div>
        <p>{p.nick}</p>
    </div>
    ));

  disconnect = () => {
    this.webrtc.quit();
  }

  componentWillUnmount() {
    this.disconnect();
  }

  render() {
    return (
      <div>
        <div>
            <video
              // Important: The local video element needs to have a ref
              ref={(vid) => { this.localVid = vid; }}
            />
            <p>{this.state.nick}</p>
        </div>
        {this.generateRemotes()}
      </div>
    );
  }
}

export default Party;

new LioWebRTC(options)

• object options
  • string url - url for your socket.io signaling server
  • bool debug - optional logs all webrtc events
  • string nick - optional sets your nickname. Peers' nicknames can be accessed with peer.nick
  • [string|DomElement|Ref] localVideoEl - Can be a ref, DOM element, or ID of the local video
  • bool autoRequestMedia - optional(=false) automatically request user media. Use true to request automatically, or false to request media later with startLocalVideo
  • bool dataOnly optional(=false) option to ensure that video and audio stream channels are turned off
  • bool autoRemoveVideos - optional(=true) option to automatically remove video elements when streams are stopped.
  • bool adjustPeerVolume - optional(=true) option to reduce peer volume when the local participant is speaking
  • number peerVolumeWhenSpeaking - optional(=.0.25) value used in conjunction with adjustPeerVolume. Uses values between 0 and 1
  • object media - media options to be passed to getUserMedia. Defaults to { video: true, audio: true }. Valid configurations described on MDN with official spec at w3c.
  • object receiveMedia - optional RTCPeerConnection options. Defaults to { offerToReceiveAudio: 1, offerToReceiveVideo: 1 }.
  • object localVideo - optional options for attaching the local video stream to the page. Defaults to

  {
      autoplay: true, // automatically play the video stream on the page
      mirror: true, // flip the local video to mirror mode (for UX)
      muted: true // mute local video stream to prevent echo
  }

  • object constraints - optional options for setting minimum and maximum peers to connect to. Defaults to

  {
    minPeers: 2, // connect to at least 2 peers
    maxPeers: 0 // when 0, maxPeers is infinite
  }

  • bool selfOptimize - optional(=true) whether or not peers in a partial mesh network should self-optimize their connections. LioWebRTC uses a more object-oriented version of an adjacency list to represent the p2p graph, with the weights of the edges representing roundtrip latency between two nodes. With selfOptimize set to true, peers automatically disconnect from neighbors with latencies >=1 std. deviation from the mean, and reconnect to a new random peer.

connection - the socket signaling connection

webrtc - the underlying WebRTC session manager

To set up event listeners, use the LioWebRTC instance created with the constructor. Example:

// Emitted when a peer's media stream becomes available
this.webrtc.on('peerStreamAdded', (stream, peer) => {
    // Attach the MediaStream to a video element
    // this.webrtc.attachStream(stream, this.remoteVideos[peer.id]);
});
// Emitted when we receive data from a peer via the data channel
this.webrtc.on('receivedPeerData', (type, payload, peer) => {
    // Find something to do with the data
});

'channelOpen', RTCDataChannel, peer - emitted when a new channel is established with a peer.

'connectionReady', sessionId - emitted when the signaling connection emits the connect event, with the unique id for the session.

'createdPeer', peer - this will be emitted when:

• joining a room with existing peers, once for each peer
• a new peer joins your room

'joinedRoom', roomName - emitted after successfully joining a room.

'leftRoom', roomName - emitted after successfully leaving the current room, ending all peers, and stopping local stream

'mute', data - emitted when a peer mutes their video or audioOn

• data an object that contains an id property that returns the id of the peer, and a name property that indicates which stream was muted, video or audio

'removedPeer', peer - emitted when a peer loses connection or exits the room

• peer - the peer associated with the stream that was removed

'ready', sessionId - emitted when liowebrtc is ready to join a room

• sessionId - the socket.io connection session ID

'receivedPeerData', type, payload, peer - emitted when data is received from a peer that sent the data with shout or whisper

• type a label, usually a string, that describes the payload
• payload any kind of data sent by the peer, usually an object
• peer the object representing the peer and its peer connection

'receivedSignalData', type, payload, peer - emitted when data is received from a peer that sent the data via the socket.io signaling server with broadcast or transmit

• type a label, usually a string, that describes the payload
• payload any kind of data sent by the peer, usually an object
• peer the object representing the peer and its peer connection

'stunservers', [...args] - emitted when the signaling server emits a list of stun servers.

'turnservers', [...args] - emitted when the signaling server emits a list of turn servers.

'unmute', data - emitted when a peer mutes their video or audioOn

• data an object that contains an id property for the id of the peer that sent the event, and a name property that indicates which stream was muted, video or audio

'peerStreamAdded', stream, peer - emitted when a peer's MediaStream becomes available

• stream - the MediaStream associated with the peer
• peer - the peer associated with the stream that was added

'peerStreamRemoved', peer - emitted when a peer stream is removed

• peer - the peer associated with the stream that was removed

attachStream(stream, el, opts) - attaches a media stream to a video or audio element

• MediaStream stream - an object representing a local or peer media stream
• HTMLElement el - the element (or ref if you're using React) to attach the media stream to, usually a video or audio element
• object opts - optional optional configuration for attachStream
  • bool autoplay - autoplay the video once attached. Defaults to true
  • bool muted - mute the video once attached. Defaults to false
  • bool mirror - mirror the video once attached. Defaults to true
  • bool audio - attach to <audio> element instead of <video> element. Defaults to false

broadcast(messageType, payload) - broadcasts a message to all peers in the room via the signaling server (similar to shout, but not p2p). Listen for peers' broadcasts on the receivedSignalData event.

• string messageType an arbitrary label, usually a string, that describes the payload
• object payload - an arbitrary value or object to send to peers

createRoom(name, callback) - emits the create event and optionally invokes callback on response

disconnect() - calls disconnect on the signaling connection and deletes it. Peers will still be available

emit(eventLabel, ...args) - emit arbitrary event (Emits locally. To emit stuff other peers, use shout)

getClients((err, clients)) - asks the socket.io signaling server for a list of peers currently in the room.

• object clients - An object whose keys are the client IDs and values are client types.

getContainerId(peer) - get the DOM id associated with a peer's media element. In JSX, you will need to set the id of the container element to this value

• Peer peer - the object representing the peer and its peer connection

getMyId() - get your own peer ID

getDomId(peer) - get the DOM id associated with a peer's media stream. In JSX, you will need to set the id of the peer's media element to this value.

• Peer peer - the object representing the peer and its peer connection

getPeerById(id) - returns a peer with a given id

• string id - the id of the peer

getPeerByNick(nick) - returns a peer with a given nick

• string nick - the peer's nickname

getPeers(sessionId) - returns all peers by sessionId

• string sessionId - the sid of the current room. Will return all peers if no sessionId is provided.

joinRoom(name, callback) - joins the room name. Callback is invoked with callback(err, roomDescription) where roomDescription is yielded by the connection on the join event. See SignalBuddy for more info.

leaveRoom() - leaves the currently joined room and stops local streams

mute() - mutes the local audio stream to your peers (stops sending audio in the WebRTC audio channel)

on(ev, fn) - creates an event listener for event ev handled by fn

pause() - pauses both video and audio streams to your peers

pauseVideo() - pauses the video stream to your peers (stops sending video in the WebRTC video channel)

quit() - stops the local video, leaves the currently joined room, and disconnects from the signaling server

resume() - resumes sending video and audio to your peers

resumeVideo() - resumes the video stream to your peers (resumes sending video in the WebRTC video channel)

sendDirectlyToAll(messageType, payload, channel) - sends a message to all peers in the room via a data channel (same as shout, except you can specify your own data channel. Use this if you need to set up a new data channel, e.g. a dedicated file-sharing channel, etc.)

• string channel - (optional) the name of the data channel. If it doesn't exist, it will be created.

setVolumeForAll(volume) - set the volume level for all peers

shout(messageType, payload) - sends a message to all peers in the room via the default p2p data channel. Listen for peers' shouts on the receivedPeerData event.

• string messageType - an arbitrary label, usually a string, that describes the payload
• object payload - an arbitrary value or object to send to peers

startLocalVideo() - starts the local video or audio streams with the media options provided in the config. Use this if autoRequestMedia is set to false

stopLocalVideo() - stops all local media streams

transmit(peer, messageType, payload) - sends a message to a single peer in the room via the signaling server (similar to whisper, but not p2p). Listen for peers' transmissions on the receivedSignalData event.

• Peer peer - the object representing the peer and its peer connection
• string messageType - an arbitrary label, usually a string, that describes the payload
• object payload - any kind of data sent by the peer, usually an object

unmute() - unmutes the audio stream to your peers (resumes sending audio in the WebRTC audio channel)

• float volume - the volume level, between 0 and 1

whisper(peer, messageType, payload) - sends a message to a single peer in the room via the default p2p data channel. Listen for peers' whispers on the receivedPeerData event.

• Peer peer - the object representing the peer and its peer connection
• string messageType - an arbitrary label, usually a string, that describes the payload
• object payload - any kind of data sent by the peer, usually an object

WebRTC needs to be facilitated with signaling; a service that acts as a matchmaker for peers before they establish direct video/audio/data channels. Signaling can be done in any way, e.g. via good old fashioned carrier pigeons. Signaling services only need to fulfill the absolute minimal role of matchmaking peers.

SignalBuddy is a scalable socket.io signaling server, and is very easy to set up. socket.io enables real-time, bidirectional communication between a client and server via web sockets. It also allows us to easily segment peers into rooms.

For emitting data to peers, LioWebRTC provides a unified, event-based API that enables peers to seamlessly switch between shouting (p2p data channels) or broadcasting (socket.io) to all the peers in a room. It's up to you to decide which protocol to use, but socket.io should ideally only be used for transmitting things like metadata, one-off events, etc. Both protocols are real-time, bidirectional, and event-based.

LioWebRTC wraps socketio-client and returns a connection object. This the connection to the signaling server. The connection object comes with the following methods:

• on(ev, fn) - a method to set a listener for event ev
• emit() - send/emit arbitrary events on the connection
• getSessionId() - returns the session ID of the connection
• disconnect() - disconnect from the signaling server (closes the web socket)

LioWebRTC uses SignalBuddy to facilitate signaling. LioWebRTC works out of the box with a demo SignalBuddy server that was intended for testing purposes. However, for production purposes, IT IS NOT RELIABLE. In production, you will need to set up your own SignalBuddy server (or any other socket.io solution that implements matchmaking).