rtc

A WebRTC component. Takes care of the handshake fuss and lets you focus on your app.

1. Connect
2. Add some listeners
3. Attach your stream (optional)

Features

• Reconnects automatically
• Re-attaches added streams upon reconnect
• Really simple signal-servers by using challenges on the client side

Example

A minimal example which opens one DataChannel and adds a webcam video stream:

var rtc = require('rtc');

// video elements in the DOM
var localVideo = document.getElementById('local');
var remoteVideo = document.getElementById('remote');

// create a connection (defaults to use the app channel signals)
var remote = rtc.connect({ dataChannels: 'example' });

// attaches the remote video the the <video>-element.
remote.on('addstream',function(e){
  remoteVideo.src = URL.createObjectURL(e.stream);
})

// 'open' is emitted whenever the connection is established
// and stable.
// NOTE: If a stream is added while being open it will close
// and then re-open when connection is ready again.
remote.on('open',function(e){
  // you can use `remote.initiator` to differentiate
  // between the two connected peers.
  if( remote.initiator ){
    remote.send('example','hello there from the master')
  } else {
    remote.send('example','hello there from the slave')
  }
})

// listen for data channel messages
remote.on('channel message',function(e){
  console.log('from remote: ',e.data);
})

// request webcam access and attach to both
// the local <video>-element and over WebRTC.
getUserMedia(function success(stream){
  localVideo.src = URL.createObjectURL(stream)
  remote.addStream(stream);
})

For more complete examples look in the example/ directory.

Installation

$ component install publicclass/rtc

Test

$ git clone https://github.com/publicclass/rtc
$ cd rtc
$ make build
$ make test-app-chan # for the app-channel signal (requires go-app-engine-sdk)
$ make test-ws # for the web socket signal (requires node)

API

rtc.servers

The RTCConfiguration Dictionary. Defaults to use the Google STUN server but if the turnConfigURL-option is set it will be updated when the TURN configuration server responds.

rtc.available

Set to true if PeerConnection and DataChannel is available. Otherwise false.

rtc.connect([opts]) => Rtc

Creates an Rtc-instance.

Available options:

• dataChannels - A string or array of labels of channels to add to the PeerConnection. Defaults to false, no data channels.
• connectionTimeout - The time, in milliseconds, it will wait during connection until considered it timed out.
• turnConfigURL - A URL to a TURN configuration server. Defaults to '', no server.
• autoNegotiate - A boolean which controls if the Rtc connection should automatically renegotiate when a stream has been added or removed. Defaults to true.
• signal - A string to decide which type of signal to create. If set to ws it will use the WebSocketSignal, otherwise the AppChannelSignal.

The rest of the opts will be passed into the Signal (see Rtc#signal below).

Rtc#addStream(stream,constraints)

Adds, and maintains, a stream on the Rtc-instance. Will be re-added upon reconnection.

Rtc#removeStream(stream)

Removes a stream from the Rtc-instance.

Rtc#reconnect()

Recreates the PeerConnection, the DataChannels and then re-attaches any missing streams. Should not be necessary but useful while testing.

Rtc#close([keepSignal])

Closes the underlying PeerConnection and all its DataChannels. If keepSignal is set to true it will not close the signal but leave it on, ready for new connections.

Rtc#signal

Either a WebSocketSignal-instance or an AppChannelSignal-instance depending on the opts passed into rtc.connect().

WebSocketSignal():

• url - The URL to the WebSocket relay.
• timeout - A time, in milliseconds, that it will attempt to connect before timing out.
• retryTimeout - A time, in milliseconds, that it will attempt to reconnect before timing out.
• maxAttempts - The number of retries it will attempt before giving up.

AppChannelSignal():

• room - A room name to connect to.
• timeout - A time, in milliseconds, that it will attempt to connect before timing out.
• retryTimeout - A time, in milliseconds, that it will attemp to reconnect before timing out.
• maxAttempts - The number of retries it will attempt before giving up.
• bufferCandidates - If true it will buffer all ice candidates and send them all at once. This is useful when running the AppEngine SDK because each request can take up to a second and if there's a lot of ice candidates this will speed it up significantly.

Events

• connected is emitted when two peers are connected to the same room.
• disconnected is emitted when one peer has left the room.
• reconnect is emitted when Rtc has reconnected.
• open is emitted when the rtc.open is set to true. That is when the connection handshake is complete, the candidates are gathered and the connection is considered stable.
• close is emitted when rtc.open has been changed from true to false. This happens when a stream has been added or removed and the connection is renegotiated.
• full is emitted when the room already has two peers.
• token (AppChannelSignal only) is emitted when the signal has received a token and username from the server.
• error is emitted in the case of a signalling error.

The DataChannel events are emitted on teh Rtc-instance but prefixed by 'channel' and 'channel {label}'.

• channel message, channel {label} message is emitted when a message has been received.
• channel open, channel {label} open is emitted when a channel has opened.
• channel close, channel {label} close is emitted when a channel has closed.
• channel error, channel {label} error is emitted when a channel has errored.

Then also the PeerConnection events are emitted on the Rtc-instance:

• icechange
• statechange
• gatheringchange
• datachannel
• addstream
• removestream
• icecandidate
• negotiationneeded

Signal#send(msg)

Sends a message over the signal connection. If msg is a string it will be converted to a custom event. Otherwise it will be JSON stringified first. If Signal#send() has been called before the signal connection has been opened it will be sent when opened.

Events (used internally)

• error is emitted when the signal connection emits an error.
• open is emitted when the signal connection has been opened. This is when the initial PeerConnections is created in Rtc.
• offer is emitted when an offer has been received from the peer over the signal.
• answer is emitted when an answer has been received from the peer over the signal.
• close is emitted when the peer or server has requested the connection to close.
• request-for-offer is emitted when the peer requests an offer.
• candidate is emitted when a peer has send an ice candidate.
• connected is emitted when two peers are connected to the same room.
• disconnected is emitted when one peer has left the room.
• challenge is emitted either when a challenge has been requested from peer (when null) or when a challenge has been received from peer.
• event is emitted for custom events to be re-emitted by Rtc.

License

MIT