Stephen Bussey - Real-Time Phoenix (for steve)

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The book youre reading is in beta. This means that we update itfrequently. Here is the list of the major changes that have been madeat each beta release of the book, with the most recent change first.

• We added a new chapter: Chapter 9,

• Addressed errata. Thanks for all of your help and keep them coming!

• We added a new chapter: Chapter 8,

• Addressed errata. Thanks for all of your help and keep them coming!

• Initial beta release.

I remember working on the first production-facing Elixir application I wroteit was a real-time application todrive an innovative new feature for our platform. Excitement, curiosity, and a goodbit of nervousness led me through that project. It was a trial by fire as the applicationwould receive more requests per minute than any other part of our platform. It still stands todaywithout much involvement needed over the past years.

I have gotten to work on many other real-time applications since that first project. Thelessons I learned were sometimes hard to come bya critical piece of the application wouldfail, applications would overuse resources like CPU and RAM, or I would code something in a non-optimal way.However, I was able to leverage the strong foundations of Elixir and Phoenix to solve any problem that appeared. Thisbook aims to collect the experience that I have gained working with Elixir and Phoenix Channelsover the last several years and distill it into the parts that matter most.

Elixir has changed the way that I think about, design, and code applications. The creators,community, and libraries empower me to think about code with a fresh perspective. My time withElixir has been filled with enthusiasm, to say the least. Throughout this book, I hope to share thatenthusiasm with you.

Do you work on modern web applications? Do you want to build applications that are different than the traditional web model ofrequest-in response-out? Have you started working on Elixir or Phoenix projects and want to dive deeper into the ecosystem?

If any of these questions ring a bell for you, then you will probably have a good experience with this book. If not, youwill still find an interesting approach to modern applications in these pages.

This book is targeted at intermediate to advanced developers. There will be Elixir code snippets throughouteach chapter, but you will be guided through each of them in order to have working examples locally.This book will not teach you Elixirthere are other books out there that are suited for that task. However,you will quickly catch on if you have a small amount of existing Elixir or Phoenix knowledge. You will walkaway with a deep understanding of the real-time Phoenix stack.

The three parts of this book build on each other to teach you about WebSockets, Phoenix Channels,and real-time application design. Part I focuses on the most important part of the real-time stack inElixirPhoenix Channels, WebSockets, and GenStage. Well cover a lot of ground in these chapters and youwill gain the foundations necessary to build real-time applications.

You will leverage the foundations from Part I when we work on a real-time application in Part II. You willadd real-time features to an e-commerce application that serves many users simultaneously. You will also getto work with some of the more advanced features of Phoenix, such as Phoenix Tracker.

Part III finishes the book with guidance on running real-time applications in production. The battle is onlybeginning when you write an application. You have to then keep it healthy and happy in production.

Elixir is required for this book, although setup is a bit outside of this books focus. I recommend usinga version manager like asdf in order to get Phoenix setup.