Leonard Richardson, Sam Ruby

2008년 저작이라서 좀 오래됐음.

Contents

  1. Chapter 1. The Programmable Web and Its Inhabitants

Chapter 1. The Programmable Web and Its Inhabitants

Kinds of Things on the Programmable Web

The programmable web is based on HTTP and XML. Some parts of it serve HTML, JavaScript Object Notation (JSON), plain text, or binary documents, but most parts use XML. And it’s all based on HTTP: if you don’t use HTTP, you’re not on the web.

Imagine the programmable web as an ecosystem, like the ocean, containing many kinds of strange creatures. Ancient scientists and sailors classified sea creatures by their superficial appearance: whales were lumped in with the fish. Modern scientists classify animals according to their position in the evolutionary tree of all life: whales are now grouped with the other mammals. There are two analogous ways of classifying the services that inhabit the programmable web: by the technologies they use (URIs, SOAP, XML-RPC, and so on), or by the underlying architectures and design philosophies.

When it comes to classifying the programmable web, most of today’s terminology sorts services by their superficial appearances: the technologies they use. These classifications work in most cases, but they’re conceptually lacking and they lead to whale-fish mistakes. I’m going to present a taxonomy based on architecture, which shows how technology choices follow from underlying design principles. I’m exposing divisions I’ll come back to throughout the book, but my main purpose is to zoom in on the parts of the programmable web that can reasonably be associated with the term “REST.”

HTTP: Documents in Envelopes

Method Information

Scoping Information

The Competing Architectures

Now that I’ve identified the two main questions that web services answer differently, I can group web services by their answers to the questions. In my studies I’ve identified three common web service architectures: RESTful resource-oriented, RPC-style, and REST-RPC hybrid. I’ll cover each in turn.

RESTful, Resource-Oriented Architectures

A few well-known examples of RESTful, resource-oriented web services include:

Whenever I cover unRESTful architectures, as well as architectures that aren’t resource-oriented, I do it with some ulterior motive. In this chapter, I want to put RESTful web services into perspective, against the larger backdrop of the programmable web. In Chapter 2, I’m widening the book’s coverage of real web services, and showing that you can use the same client tools whether or not a service exactly fits my preferred architecture. In Chapter 10, I’m making an argument in a long-running debate about what the programmable web should look like.

RPC-Style Architectures

A few well-known examples of RPC-style web services:

REST-RPC Hybrid Architectures

This is a term I made up for describing web services that fit somewhere in between the RESTful web services and the purely RPC-style services. These services are often created by programmers who know a lot about real-world web applications, but not much about the theory of REST.

The Human Web Is on the Programmable Web

In the previous sections I claimed that all static web sites are RESTful. I claimed that web applications fall into one of the three categories, the majority being REST-RPC hybrids. Since the human web is made entirely of static web sites and web applications, this means that the entire human web is also on the programmable web! By now this should not be surprising to you. A web browser is a software program that makes HTTP requests and processes the responses somehow (by showing them to a human). That’s exactly what a web service client is. If it’s on the Web, it’s a web service.

My goal in this book is not to make the programmable web bigger. That’s almost impossible: the programmable web already encompasses nearly everything with an HTTP interface. My goal is to help make the programmable web better: more uniform, better-structured, and using the features of HTTP to greatest advantage.