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Getting started with WebRTC and SkylinkJS

by Thomas Gorissen

You may have heard of WebRTC and its magical abilities recently and, like many, you might have found yourself struggling with trying to get even a simple demo going. The team here at Temasys built SkylinkJS to address this and make it easy to build reliable peer connectivity solutions on any website, with the help of WebRTC. This post will help people who are getting started with WebRTC.

Here is an example Codepen that we’ve created that shows how you can create a very simple audio/video conference with JavaScript client-side code, with no additional server code required.

See the Pen WebRTC Audio/Video conference demo with SkylinkJS by Temasys (@temasys) on CodePen.

To further demonstrate the possibilities and flexibility of SkylinkJS, we have also created a more elaborate demo created with the help of Facebook's React at Check it out, share it, and use it if you like it.

How does this work?

Skylink: BaaS for multi-media peer connectivity

Temasys has created the super scalable Skylink backend-as-a-service, that helps to connect two or more peers very reliably and easily. It was designed specifically for WebRTC, which enables your browser to send data directly to another browser. That data can be a chat message, a file or even an audio/video stream from your device’s camera and microphone, thus allowing you to create all kinds of cool real-time video conferencing, collaboration, tutoring, and other live-presence use-cases.

The SkylinkJS library

WebRTC is still a rather low-level browser API and requires you to do significant work around solving signaling issues and resolving differences in implementation between web browsers. We, at Temasys, are part of the WebRTC working group at the W3C at the W3C, and create solutions with and around WebRTC for more than a year, now. We know this part of the puzzle inside and out, and that is why we have created SkylinkJS. We want to solve the connectivity and implementation headaches for you and let you focus on building the cool stuff.

App keys, rooms, and peers

When you use SkylinkJS in your website or app, you can invite users (we call them peers) to join a shared space in which they can exchange data privately with each other. We call this space a room. Every peer that wants to join a room needs to know its’ unique identifier, like a secure, generated token or a simple name. We leave it up to you on how you come up with these room IDs and how you inform peers about them. One of our primary goals in SkylinkJS was to not interfere with your application logic or UX. We recommend generating UUIDs as a best-practice here, for making the identifiers difficult to guess, reasonably unique and providing an additional layer of privacy of your users during room sessions.

In order to start using the Skylink, you would need to create an Application using our Developer Console or REST API. Every application creates a new realm in which your rooms can exist. You can now create unique App Keys under the application you have created. These keys are then used to help you identify yourself to the Skylink Infrastructure. Every App key for the Web platform will only work on your specified CORS domain name. If you want to have different websites or applications on different platforms(such as android/ios) to access the same realm and therefore the same rooms, you can create multiple keys under the same application – one for each platform. This extends the scope of the realm to other domain or applications.

Read more about creating a new application here.

Compatibility and Performance

Only Google Chrome and Mozilla Firefox support the technology natively in their current versions. We thought that wasn’t good enough and therefore created plugins for Mac and Windows, to upgrade Safari and Internet Explorer to support the current WebRTC standard as well. They’re available to download for free.

It’s still early days for WebRTC, but assuming a modern multi-core processor and broadband internet connection, you can reasonably expect to achieve 8-10 peers in an audio/video conference.

Chrome for Android supports WebRTC as well, but however due to the less powerful CPUs found in many mobile devices, one can expect around three peers or less, to be supported. Latest devices with hardware VP8 acceleration would be more likely to support additional peers. Users on iOS and other mobile OS browsers will still have to wait a bit longer for support.

To see it in action, try it out yourself in with our tech-demo at on your Android smartphone or tablet in a WebRTC enabled browser.

How do I get started building cool stuff with SkylinkJS myself?

Step 1: Get an App key

To identify yourself against our API, you’ll need to sign up through our Developer Console and get an App key. During our current beta phase, the usage of our platform is free, however, once we are out of beta, there is going to be a very affordable charge for our infrastructure services. In any case, newly created primary App keys come with a substantial allotment of free use to allow you to build, experiment, and test without up-front costs.

Step 2: Include SkylinkJS into your website

    <title>WebRTC with SkylinkJS</title>

<span class="nt">&lt;script </span><span class="na">src=</span><span class="s">"//"</span><span class="nt">&gt;&lt;/script&gt;</span>

</head> <body>

<video id="myvideo" style="transform: rotateY(-180deg);" autoplay muted></video>

</body> </html>

Here you have the choice to use our “Complete” version with all dependencies or if you want to do dependency management yourself with e.g. RequireJS or other client-side package managers, the “Library” version. Here is an overview of these files.

In our simple example above, we just include the complete version in a script tag in the header. The body itself only contains a video tag to show your own camera picture later. We used a CSS transform to mirror the image so it feels more natural and muted the audio, so you don’t hear yourself speaking. The autoplay attribute is needed in some browsers where you’d otherwise only see a picture of yourself.

Step 3: Instantiate Skylink and subscribe events

var skylink = new Skylink();

Create a new Skylink object and subscribe events using the on() function. Here are the most basic ones you'll need for a simple audio/video conference.

skylink.on('peerJoined', function(peerId, peerInfo, isSelf) {
  if(isSelf) return; // We already have a video element for our video and don't need to create a new one.
  var vid = document.createElement('video');
  vid.autoplay = true;
  vid.muted = true; // Added to avoid feedback when testing locally = peerId;

peerJoined: informs you that a peer has joined the room and shares their peerID and peerInfo a with you. In the example we create a new video element for this peer and use the peerId to identify this element in the DOM of our website.

skylink.on('incomingStream', function(peerId, stream, isSelf) {
  if(isSelf) return;
  var vid = document.getElementById(peerId);
  attachMediaStream(vid, stream);

incomingStream: This event is fired after peerJoined when SkylinkJS starts receiving the audio and video streams from that peer. This peer could be yourself in which case the event is fired when the user grants access to his microphone and/or camera and has joined a room successfully. In the example we use the attachMediaStream() function of our enhanced AdapterJS library to feed this stream into our previously created video tag. Why do we use this function? The different browser vendors have slightly different ways to do this and attachMediaStream() enables us to abstract this.

skylink.on('peerLeft', function(peerId, peerInfo, isSelf) {
  var vid = document.getElementById(peerId);

peerLeft: informs you that a peer has left the room. In our example, we look in the DOM for the video element with the events peerId and remove it.

skylink.on('mediaAccessSuccess', function(stream) {
  var vid = document.getElementById('myvideo');
  attachMediaStream(vid, stream);

mediaAccessSuccess: The user needs to authorize his browser to allow your website access to their camera, microphone or both. Once the user clicks "Allow" in his browser, this event fires and give us access to the audio/video stream. As you'd guess mediaAccessError will be triggered if the user declines.

Step 4: Initialize and joinRoom

  apiKey: 'Your App key',
  defaultRoom: 'Pick a room name'
}, function() {
    audio: true,
    video: true

By calling init SkylinkJS starts establishing a signaling connection with our servers and requires your App key as a parameter. This connection introduces new peers and sends control messages as required for the connection and handshake process between peers. You can also pass a defaultRoom parameter.

joinRoom then tells our servers that you now want to inform the other peers in the room, that you're joining and you are able to specify the features that you want to have enabled. In this case we establish both audio and video streams. You don't need to pass anything if you just want to send chat messages or data streams.

Step 5: Profit

You've created a simple video conference. Easy, right? You can find an overview of all the methods and events Skylink offers (like lockRoom, disableAudio or disableVideo, etc...) in our API doc.

Have fun, share this and let us know if you run into any issues!