Salvatore Loreto - Real-Time Communication with WebRTC: Peer-to-Peer in the Browser

Web Real-Time Communication (WebRTC) is a new standard that lets browsers communicate in real time using a peer-to-peer architecture. It is about secure, consent-based, audio/video (and data) peer-to-peer communication between HTML5 browsers. This is a disruptive evolution in the web applications world, since it enables, for the very first time, web developers to build real-time multimedia applications with no need for proprietary plug-ins.

WebRTC puts together two historically separated camps, associated, respectively, with telecommunications on one side and web development on the other. Those who do not come from the telecommunications world might be discouraged by the overwhelming quantity of information to be aware of in order to understand all of the nits and bits associated with real-time transmission over the Internet. On the other hand, for those who are not aware of the latest developments in the field of web programming (both client and server side), it might feel uncomfortable to move a legacy VoIP application to the browser.

The aim of this book is to facilitate both communities, by providing developers with a learn-by-example description of the WebRTC APIs sitting on top of the most advanced real-time communication protocols. It targets a heterogeneous readership, made not only of web programmers, but also of real-time applications architects who have some knowledge of the inner workings of the Internet protocols and communication paradigms. Different readers can enter the book at different points. They will be provided with both some theoretical explanation and a handy set of pre-tailored exercises they can properly modify and apply to their own projects.

We will first of all describe, at a high level of abstraction, the entire development cycle associated with WebRTC. Then, we will walk hand in hand with our readers and build a complete WebRTC application. We will first disregard all networking aspects related to the construction of a signaling channel between any pair of browser peers aiming to communicate. In this first phase, we will illustrate how you can write code to query (and gain access to) local multimedia resources like audio and video devices and render them within an HTML5 browser window. We will then discuss how the obtained media streams can be associated with a PeerConnection object representing an abstraction for a logical connection to a remote peer. During these first steps, no actual communication channel with a remote peer will be instantiated. All of the code samples will be run on a single node and will just help the programmer familiarize with the WebRTC APIs. Once done with this phase, we will briefly discuss the various choices related to the setup of a proper signaling channel allowing two peers to exchange (and negotiate) information about a real-time multimedia session between each other. For this second phase, we will unavoidably need to take a look at the server side. The running example will be purposely kept as simple as possible. It will basically represent a bare-bones piece of code focusing just on the WebRTC APIs and leave aside all stylistic aspects associated with the look and feel of the final application. We believe that readers will quickly learn how to develop their own use cases, starting from the sample code provided in the book.

The book is structured as follows: