WebRTC Book Update: Revised TOC and Some More Legroom

  • 31 May 2021

It’s the end of May, and I’m now about ten weeks into the contracted part of this project for Pragmatic Programmers. And in the last week, the book has grown from its original proposed 6 chapters at 150 pages to 8 chapters that will weigh in at around 250 pages. That gives me a lot more room to work and should prevent anything vital from having to be cut.

As I put the finishing touches this week on the work for my first major milestone—the three-chapter publisher’s review, which I’d originally planned for mid-June—the table of contents its looking like this, minus an introductory setup chapter that’ll be part of the frontmatter and an appendix showing a signaling channel written in pure WebSockets (the book itself uses Socket.IO in its recently released version 4):

  1. Working with a Signaling Channel. Readers set up an interface in HTML, CSS, and JavaScript to manage a basic video-chat app and wire up a pre-built signaling channel and its callbacks. A high-level description of WebRTC contextualizes the signaling channel’s purpose and limited features.
  2. Establishing a Peer-to-Peer Connection. Picking up right where the last chapter left off, readers learn to request permissions for camera/mic access and display the resulting stream. They then go on to create a peer connection using the “perfect negotiation” pattern described in the WebRTC specification and build out the rest of the basic video-chat app.
  3. Handling Data Channels. Media streaming is WebRTC’s most famous feature, but it’s data channels that really open up the possibilities for all kinds of real-time, peer-to-peer apps. Readers add a video-filter function to the app built over the first two chapters and then build a complete text-chat feature.
  4. Streaming Complex Data. Data channels can handle more than simple strings. This chapter opens with building fallbacks into the perfect-negotiation code so they can more confidently test their work, including especially with data channels, on browsers that have poorer implementations of WebRTC (ahem, Safari). Readers work with sending and receiving JSON strings to build out the chat feature further, and then turn to streaming binary data—as either Blobs or ArrayBuffers, using some clever feature-detection—to share images in the chat. Readers build a standalone peer-to-peer file-sharing app to close out the chapter.
  5. Building Peer-to-Peer Interfaces. The first four chapters cover all the fundamentals of WebRTC. This chapter looks more closely at real-time, peer-to-peer interface design—all framed by accessibility. Readers learn to build interfaces that take advantage of semantic HTML and ARIA attributes, while also giving users greater control over real-time interfaces, such as arranging interface elements in relation to their cameras.
  6. Managing Multi-Peer Connections. This chapter moves from one-to-one to many-to-many WebRTC apps. Sticking to the browser-based focus of the book, it introduces a mesh-network architecture for connecting three or more peers in a single call. Readers also learn the practical and theoretical upper limits to the number of simultaneous peer connections, and begin to work with the RTCPeerConnection.getStats() interface.
  7. Optimizing Media Streaming. Readers take a deep dive on different media APIs in this chapter, and learn to optimize streaming media based on local and remote statistics and even the simple appearance of media streams in the browser (how big does that video stream need to be? how small can it get?). The chapter also looks at current and forthcoming methods for optimizing images sent over data channels, including the exciting but currently not universally supported self.createImageBitmap() method.
  8. Deploying WebRTC Apps to Production. This final chapter of the book looks at what it takes to deploy a WebRTC app into production. Readers learn about using public STUN servers as well as setting up a private STUN/TURN server, with the TURN component as a fallback for when a direct peer-to-peer connection cannot be established.

There are a lot of topics packed into chapters six, seven, and eight especially. So I wouldn’t be surprised to discover a topic that deserves its own chapter—either on my own as I write or from feedback that’ll come in from the technical and beta reviews later in the summer.

The first three chapters are draft complete, apart from some intro and outro work that I need to do today. And I’ve got good chunks of the fourth and sixth chapters coming along, in addition to a growing number of topics for the fifth chapter, on interfaces and accessibility.

Put another way, this is starting to feel more like a book to me—and not just a collection of stuff I’ve written. Considering that the spring semester just ended for me a little over two weeks ago, I’m pretty happy with where I am. But I’m hoping to pick up the pace as I recover from this weird academic year and settle into the summer.