Hi Camilo,
REST is a description of how the World Wide Web works (from a software/platform perspective). The REST constraints provide high-level guidelines for Web API design. However, they leave some "wiggle room" in terms of the design of a REST API's resource model (e.g. URI paths and HTTP interactions) and its representations (e.g. JSON or XML).
The book attempts to motivate some particular choices that I believe are best practices. These include some very commonly held ideas, like the role of GET, and some not so established
patterns, like hypermedia links in JSON. The book has a few code examples but it is really not an implementation guide for RESTful web services.
This book asserts that REST API designs should only be as different as they really
need to be. Design differences for difference sake just makes things harder on our API clients and certainly don't help us advance toward the vision of a uniformly programmable Web. Personally, I like the idea of a World Wide Wiki - where all of the world's information is available via REST APIs that are similar enough (or provide enough metadata) that client programs can "digitally surf" (and even edit) this machine web in order to extract and mashup disparate data sets in interesting ways. Even more than that I like the idea of a
open standard REST API design approach with enough inertia that we can all invest in building a set of common tools and frameworks to make programming modern web applications much easier and more fun. Lastly, I'd like us all to be able to standardize on our web application interactions without converging to a common programming language - because I don't see that happening any time soon. These ideas and goals are the motivations behind the
WRML (http://www.wrml.org) open source project.
Thanks for your interest,
-Mark