how does webRTC functionally work?

Question

Is all the work for the webRTC functionality being done on a webRTC server ? For example, in the rtc data channel from simpl.info you can just copy the html for the input text box and out text box as well as the JavaScript and copy it to your local computer and it works perfectly. When the JavaScript file is inspected closer, there are a lot of calls which are coming from webRTC libraries without having them on my local computer. I.E.

window.localPeerConnection = new webkitRTCPeerConnection(servers,
{optional: [{RtpDataChannels: true}]});

at first I thought to get these methods to work I would have to download webRTC to the local machine that will be hosting the pages and then I can call them that way. But that does not seem to be the case, I have tried most of the examples and they all work without having webRTC locally.

I have watched the webRTC intro video it goes over a lot of the features but it doesnt explain this particular question. Another aspect that confuses me as well, is the fact when you go to the official webrtc.org getting started tutorial, it gives step by step instructions for download the webRTC libraries, which I did. But what is the purpose of that if you don't need to them to create webRTC apps and the work is being done in an outside server ?

I saw another question where the title is almost identical, how does webRTC work?, but after reading the accepted response and the question its different, OP wanted to know how the peer to peer connection worked and they explained to him ICE works and TURN servers, which I kinda understood from the intro video, my question is more are these turn servers, ICE, etc being hosted by Google or can we host them locally. And if its something Google hosts etc, isn't it unsafer than being able to host locally?

Answer 1

WebRTC is a very complex synergy of many components and protocols. Luckily, from a webdeveloper point of view, all of this is encapsulated by three main JavaScript API's: getUserMedia, RTCPeerConnection and RTCDataChannel. These API's are defined by the W3C and are part of the browser that support WebRTC. You can find an overview of the current support here:

• getUserMedia
• RTCPeerConnection
• RTCDataChannel

This means that you do not have to "download" WebRTC to use it, if the browser supports it, it's already there.

To answer your second question about STUN and TURN servers: There are publicly available servers. However, these are mostly for testing purposes. You can deploy your own TURN server, rfc5766-turn-server is such one and documentation is found here