The rtc module does most of the heavy lifting within the rtc.io suite. Primarily it handles the logic of coupling a local RTCPeerConnection with it's remote counterpart via an rtc-signaller signalling channel.

In most cases, it is recommended that you use one of the higher-level modules that uses the rtc module under the hood. Such as:

• rtc-quickconnect
• rtc-glue

If you decide that the rtc module is a better fit for you than either rtc-quickconnect or rtc-glue then the code snippet below will provide you a guide on how to get started using it in conjunction with the rtc-signaller and rtc-media modules:

var signaller = require('rtc-signaller')('http://rtc.io/switchboard/');
var rtc = require('rtc');
var media = require('rtc-media');
var localMedia = media();

// render the local media to the document body
localMedia.render(document.body);

// capture local media first as firefox
// will want a local stream and doesn't support onnegotiationneeded event
localMedia.once('capture', function(localStream) {
  // look for friends
  signaller.on('peer:announce', function(data) {
    // create a peer connection for our new friend
    var pc = rtc.createConnection();

    // couple our connection via the signalling channel
    var monitor = rtc.couple(pc, data.id, signaller);

    // add the stream to the connection
    pc.addStream(localStream);

    // once the connection is active, log a console message
    monitor.once('active', function() {
      console.log('connection active to: ' + data.id);
    });

    // when the peer connection receives a remote stream render it to the
    // screen
    pc.onaddstream = function(remoteStream) {
      media(remoteStream).render(document.body);
    };
  });

  // announce ourself in the rtc-getting-started room
  signaller.announce({ room: 'rtc-getting-started' });
});

This code definitely doesn't cover all the cases that you need to consider (i.e. peers leaving, etc) but it should demonstrate how to:

1. Capture video and add it to a peer connection
2. Couple a local peer connection with a remote peer connection
3. Deal with the remote steam being discovered and how to render that to the local interface.

Create a new RTCPeerConnection auto generating default opts as required.

var conn;

// this is ok
conn = rtc.createConnection();

// and so is this
conn = rtc.createConnection({
  iceServers: []
});

Couple a WebRTC connection with another webrtc connection identified by targetId via the signaller.

The following options can be provided in the opts argument:

• sdpfilter (default: null)

  A simple function for filtering SDP as part of the peer connection handshake (see the Using Filters details below).

• maxAttempts (default: 1)

  How many times should negotiation be attempted. This is experimental functionality for attempting connection negotiation if it fails.

• attemptDelay (default: 3000)

  The amount of ms to wait between connection negotiation attempts.

var couple = require('rtc/couple');

couple(pc, '54879965-ce43-426e-a8ef-09ac1e39a16d', signaller);

In certain instances you may wish to modify the raw SDP that is provided by the createOffer and createAnswer calls. This can be done by passing a sdpfilter function (or array) in the options. For example:

// run the sdp from through a local tweakSdp function.
couple(pc, '54879965-ce43-426e-a8ef-09ac1e39a16d', signaller, {
  sdpfilter: tweakSdp
});

Provide the rtc-core/detect functionality.

The generators package provides some utility methods for generating constraint objects and similar constructs.

var generators = require('rtc/generators');

Generate a configuration object suitable for passing into an W3C RTCPeerConnection constructor first argument, based on our custom config.

This is a helper function that will generate appropriate connection constraints for a new RTCPeerConnection object which is constructed in the following way:

var conn = new RTCPeerConnection(flags, constraints);

In most cases the constraints object can be left empty, but when creating data channels some additional options are required. This function can generate those additional options and intelligently combine any user defined constraints (in constraints) with shorthand flags that might be passed while using the rtc.createConnection helper.

This is a helper function that will extract known flags from a generic options object.

In most current implementations of RTCPeerConnection it is quite difficult to determine whether a peer connection is active and ready for use or not. The monitor provides some assistance here by providing a simple function that provides an EventEmitter which gives updates on a connections state.

var monitor = require('rtc/monitor');
var pc = new RTCPeerConnection(config);

// watch pc and when active do something
monitor(pc).once('active', function() {
  // active and ready to go
});

Events provided by the monitor are as follows:

• active: triggered when the connection is active and ready for use
• stable: triggered when the connection is in a stable signalling state
• unstable: trigger when the connection is renegotiating.

It should be noted, that the monitor does a check when it is first passed an RTCPeerConnection object to see if the active state passes checks. If so, the active event will be fired in the next tick.

If you require a synchronous check of a connection's "openness" then use the monitor.isActive test outlined below.

Provides a unified state definition for the RTCPeerConnection based on a few checks.

In emerging versions of the spec we have various properties such as readyState that provide a definitive answer on the state of the connection. In older versions we need to look at things like signalingState and iceGatheringState to make an educated guess as to the connection state.

Test an RTCPeerConnection to see if it's currently open. The test for "openness" looks at a combination of current signalingState and iceGatheringState.

The RTC library uses a number of helper modules that are contained within the lib/ folder of the rtc-io/rtc repository. While these are designed primarily for internal use, they can be accessed by directly requiring the modules, e.g. require('rtc/lib/helpermodule')

var listen = require('rtc/lib/listen');

// listen for negotiation needed events
listen(pc).on('negotiationneeded', function(evt) {

});

The listen helper provides an event emitter for a peer connection object that will bind to each of the core events WebRTC events (unless overriden by providing the listen function additional arguments).

Copyright 2014 National ICT Australia Limited (NICTA)

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

 http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.