Designing Evolvable Web APIs with ASP.NET

Preface

Why Should You Read This Book?

Web API development is exploding. Companies are investing in droves to build systems that can be consumed by a range of clients over the Web. Think of your favorite website, and most likely there’s an API to talk to it. Creating an API that can talk over HTTP is very easy. The challenge comes after you deploy the first version. It turns out that the creators of HTTP thought a lot about this and how to design for evolvability. Both media types and hypermedia were central to the design for this reason. But many API authors don’t think or take advantage of this, deploying APIs that introduce a lot of coupling in the client and that don’t utilize HTTP as they should. This makes it very difficult to evolve the API without breaking the client. Why does this happen? Often because this is the easiest and most intuitive path from an engineering standpoint to get things done. However, it is counterintuitive in the long term and against the fundamental principles with which the Web itself was designed.

This is a book for people who want to design APIs that can adapt to change over time. Change is inevitable: the API you build today will evolve. Thus, the question is not if, it is how. The decisions (or nondecisions) you make early on can drastically influence the answer:

• Will adding a new feature break your existing clients, forcing them to be upgraded and redeployed, or can your existing clients continue to operate?
• How will you secure your API? Will ...