Progressive Disclosure is a concept in User Interface Design which advocates only presenting to the user the information they need when they need it. In many ways, the book you are reading right now is an example of this principle. In fact, it is quite likely that this book wouldn’t have “worked” a mere seven years ago.
For you see, the programming world was quite a different place when RESTful Web Services, the predecessor of this book, was written. At that time, the term “REST” was was rarely used. And when it was used it was often misapplied, and widely misunderstood.
This was the case despite the fact that the standards upon which REST is based, namely HTTP and HTML, were developed and became IETF and W3C standards in roughly their current form in the second half of the 1990s. Roy Fielding’s thesis paper in which he introduced the term REST and on which this book was based was itself published in 2000.
Leonard Richardson and I set out to correct this injustice. To do this, we focused primarily on the concepts underpinning HTTP, and we provided practical guidance on how to apply those concepts to applications.
I’d like to think that we helped kick a few pebbles loose that started the avalanche of support for REST that came forth since that time. REST rapidly took on a life of its own, and in the process has become a buzzword. In fact it now is pretty much the case that presenting a web interface and calling it REST is practically the default. We’ve definitely come a long way in a few short years.
Admittedly, REST as a term is often over applied, and not always correctly. But all things considered, I am very pleased that the concepts of resources and URIs have successfully managed to infiltrate their way into application interface design. The web, after all, is a resilient place, and these new interfaces, albeit imperfect, are leaps and bounds better than the ones that they replace.
But we can do better.
Now that those building blocks are in place, it is time to take a step back, survey the territory, and build on top of these concepts. The next logical step is to explore media types in general, and hypermedia formats in specific. While the first book focused almost exclusively on the correct application of HTTP, it is time to delve more deeply into the concepts behind hypertext media types like HTML—media types that aren’t tightly bound to a single application or even a single vendor.
HTML remains a prime example of a such a hypermedia format, and it continues to hold a special place in web architecture. In fact, my personal journey of discovery has been to take a deep dive into development of the W3C standard for HTML, now branded as HTML5. And while HTML does have a prominent place in this new book, there is so much more to cover on the topic of hypermedia. So while I have remained in touch, Leonard picked up a capable replacement for my role as coauthor in Mike Amundsen.
It has been a pleasure to watch this book be written, and in reading this book I’ve learned about a number of media types that I had not been exposed to by any other source. More importantly, this book shows what these types have in common, and how to differentiate them, as each has its own specialty.
Hopefully the pebbles that this book kicks loose will have the same effect as its predecessor did. Who knows, perhaps in another seven years it will be time to do this all over again, and highlight some other facet of Representational State Transfer that continues to be under-appreciated.