News You Can Bruise for 2006 November 3

(5) Fri Nov 03 2006 17:31 REST Web Services: I'm writing a new book and it's called REST Web Services. It will be be the only book of its kind, and everyone should buy it who writes computer programs that work over the web.

There are lots of books about Big Web Services: complex distributed-object systems that reproduce the mechanics of method calls over HTTP. The problem is 1) these systems are way too big for what they do, and 2) they're on the web but they aren't of the web. They don't use any of the web's features, or interact with anything else on the web. They just use HTTP as a transport protocol. They could just as easily run over TCP and get better performance.

These un-weblike systems were able to take the name "Web Services" away from the competition because the competition is... the web. Just writing programs that interact with the web. Sounds pretty sketchy! The web may be all right as a platform for serving movies, or selling books, or trading stocks, or democratizing publishing, or coordinating huge volunteer projects, or searching much of the information currently in existence, but there's no way it's up to the task of managing Accounts Payable! For that you need... Web Services!

As Big Web Services gathered steam, the pro-web forces rallied behind the banner of REST: a name for the design philosophy that made the human-visible web so successful. They preached simplicity, addressability, statelessness and the uniform interface of HTTP. They also got into lots of heated arguments about what REST really meant.

Some organizations created services that claimed to be RESTful, and others critiqued those services and said they weren't RESTful really, and is "RESTful" even a word? Meanwhile the world's programmers started finding options in their IDEs that generated code for Big Web Service clients and servers, so they wouldn't have to do so much programming.

I got the idea for a REST book when I started seriously trying to figure out what was and wasn't REST. I noticed that though certain best practices showed up repeatedly in REST folklore, they never really progressed beyond that point. I decided to write a book that would set down the folklore and hopefully create some new canon, some common ground. I got Sam Ruby to agree to do the hard parts. And when I started work on the book I discovered a basic rule of thumb, a framing device that really focuses on what's important about REST, and makes it easy to tell what's RESTful and what's not.

We call this framing device the Resource-Oriented Architecture (we're not the first, but the other uses are compatible with ours), and I'm going to be writing about it a lot more in NYCB. It's too good to keep hidden in a book along with a bunch of implementation details.

Some people might say, "Leonard, why are you guys even writing this book? There already are lots of books about the web, and REST is just the web, right? That's the whole point! We wrote those books back in the 90s."

To them I say: "Some people, think about Ajax for a bit. Ajax, as a technology, is only about two years old, but it's composed entirely of technologies that are much older, like Javascript and XMLHttpRequest and the browser DOM. So why are there all these books about Ajax? (Including Christian Gross's Ajax and REST Recipes, coming out later this month and seemingly the only other book to mention REST in the title.) Why does Ajax excite people when DHTML was a big yawn? Because Ajax is a way of framing these old technologies so that people can do awesome things.

"There's nothing on the market that explains what REST really means and how to make it work for you. Nothing about programming the web in a way that's more structured than screen-scraping without falling into the pit of Big Web Services. This is a way of framing preexisting technologies that lets people do awesome things."

Then I add, "Speaking of Ajax, did you know that an Ajax application is basically a REST web service client that runs in your web browser? That's why Christian Gross's book is called what it is, and that's just one of the amazing reality-twisting facts you'll learn from my new book, Jon." Because I'm talking to Jon Stewart! I'm on The Daily Show, plugging my new REST book! It's a dream come true! But wait--I'm not actually on The Daily Show! I'm just on a clip from The Daily Show that someone uploaded to YouTube! And now someone is sending a DELETE request to my URI! I can see the Authorization request header, its value is "DMCA Takedown Notice", and nooooooooooo

Then I wake up. Whew! It was just a regular dream, not a dream come true. I get up and go back to work on my REST book.

Ruby is awesome and the Ruby Cookbook was a lot of fun to write, but it wasn't my idea. It's part of a high-profile O'Reilly series. There was destined to be a Ruby Cookbook, written by somebody, from the moment Rails strapped an E motor to Ruby and hit the igniter. This book was my idea, and Sam and I are driving it. In the coming months I'll be writing a lot more on this topic. There's a lot of work we need to do in the real world, in addition to writing stuff down in a book.

PS: I say this on the homepage for the book, but in case you haven't clicked through and you're interested in REST, please email me or Sam. We'd love to have you help us with the folklore and best practices, and we need lots of reviewers.