Austin - Web Performance: The Definitive Guide (Early Release)

This book is written specifically for people working on Web experiences. Since performance is a design-time activity I want especially to reach the people who are involved in the design and development process. But a good Web experience on a desktop, a mobile device or some other Web client involves a lot more than just good design. Once the design is ready, then its the developers turn, and then after your Web experience goes live, its the operational aspects of the system that drive the quality of the user experience, and I want to write my book so that its useful to everyone involved. If you are into building coolstuff on the Web, and want to make it faster, please read this book.

Heres a partial list of roles performed by people involved inperformance work that Id like to reach with my book.

This book is intended to get you started thinking about Web performance, and provide you with the knowledge and skills required to tackle performance problems and optimize your Web experiences. So Ill start from the beginning, and try to give you a real overview of the performance domain. Ive tried to organize the book to provide a good mixture of both theory and practice, only introducing enough math to support our analysis and trying to focus on whats really happening.

One of the big challenges in writing this book has been to decide what to leave out, rather than what to include, and theres any number of topics that might have been included, but were not, in the name of staying focused. I havent covered, for example, every possible edge case, and as a friend said to me in the course of writing this book, Theres an exception to everything on the Web. Its true, but here well try to cover the most likely scenarios, under the sorts of circumstance that ordinary users face in their lives.

Another challenge is introducing a lot of technical words and ideas, some of which may be unfamiliar to readers, in a few short pages. Ive made a point of making sure that everything is explained as we go along, and not to make any assumptions. My goal is to make sure that you are as interested and excited about performance as I am, and that Im communicating what are often complex ideas so that everyone has a shared understanding.

Test it yourself is another big theme and as we go through the book Ive added several hands-on sections and suggested tests for you to try for yourself. Ive found that people grasp and retain information far more easily if they are able to actually perform the work themselves. Theres an element of personal knowledge involved in Web performance work, and engaging with real numbers and data is the best way to get a feel for performance problem solving. I hope you enjoy these exercises as much as I enjoyed putting them together.

I want to start off by explaining what Web performance is, in Chapter 1, and explain how performance fits into the bigger picture of the entire system, the systemic qualities, and the trade-offs involved from a high-level. Then well zoom in on performance and look at some of the factors involved in the End-to-End response time (E2E).

One important topic well cover in Chapter 1 is How fast is fast enough? This will introduce another important idea - that users are the most important component on the Web, and fast enough depends on them, not on clients, networks, or servers.

In chapters 2-7 well be talking specifically about the response time of the HTTP request/response cycle, and covering it in detail will lead us to the Multiple Parallel Persistent Connections (MPPC) model, which gives us a framework for understanding what happens under the covers when we surf the Web, starting with an overview in Chapter 2.

Ill go over each of the MPPC time segments (more on this later) in chapters 3-6, and describing whats actually happening in the client, network, and server(s), as well as how to identify problems and optimize the different contributions to the E2E. Along the way well find opportunities to test and measure various aspects of Web response time in the hands-on exercises, intended to give you a concrete sense of whats happening. Chapter 7 will tie it all together, bringing all the different aspects of our model into focus.