Scalable Web

Chapter 0

Elements of Scalable Web Applications#

In this brief book, I discuss the elements behind scalable web applications. The book contains three projects (construct, reconstruct, and deconstruct) for you to complete that each illustrate a facet of scalability. By completing this book, you should understand different ways to build web applications while appreciating the problems that emerge when these applications have to scale. It is not only infrastructure that we have to consider but also the way we build applications. Therefore, scalability is not only a technical concern but also a social one. It has to do with how teams develop and maintain applications while requirements, constraints, and operating conditions change.

0.1 Why should you read this book#

By its nature, the book is more on the academic side and I have included references in each chapter for further study. I have tried to keep each chapter to the point, and the additional resources provide a fuller view of each topic. Together, the book and the projects give the concepts a concrete shape and deepen your understanding.

I wrote this book to capture my understanding of how to develop scalable web applications. Although the book is oriented toward the web, several principles discussed here apply more broadly. Even if you are not a web practitioner, you can likely still gain something from reading it.

In the age of AI-driven development, understanding the concepts behind scalability is perhaps more important than ever. For this reason, I focus more on concepts than on specific technical details, which tend to change over time. Through this book and the surrounding course, you will also learn how to use AI technologies critically so they support development while preserving attention to design quality, maintainability, and system constraints.

0.2 Structure of the book#

The course book is built around the three course projects: construct, reconstruct, and deconstruct. Across these projects, you build a baseline, change it under new constraints, and finally measure and critique the result. The purpose of this book is to support you as you complete these projects. With this goal in mind, I have structured the book as follows:

  1. How to develop in a scalable manner? -- How do the latest improvements to development techniques affect the way we develop? How can we get set with our development efforts the right way?
  2. What is scalability? -- How do we define scalability in the first place?
  3. What is the architecture of the web? -- How was the web built and what kind of constraints does that give to our designs? How do the constraints of the web shape API design?
  4. What happens when systems face reality? -- What kind of problems might we encounter as our systems face reality and real users? How can we scale beyond a single machine?
  5. How to benchmark web applications? -- Why is benchmarking important? How to benchmark effectively?
  6. How to evolve web applications? -- How to evolve API contracts over time? How to consider evolvability in our designs?
  7. How to scale web applications? -- What to consider when scaling our web applications? What kind of scaling techniques exist at a technical level? How does latency caused by physical constraints affect our designs?
  8. What is observability? -- What is observability and how does that contrast with monitoring? How to consider security in our designs? How to apply isolation in design?
  9. Why are architectural decisions easier to make in hindsight? -- What have we learned? Why do architectural constraints become apparent only in hindsight? What kind of additional constraints (ethical, sustainability) might we have to consider?