1.5. 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.

1.5.1. RESTful, Resource-Oriented Architectures

The main topic of this book is the web service architectures which can be considered RESTful: those which get a good score when judged on the criteria set forth in Roy Fielding’s dissertation. Now, lots of architectures are technically RESTful,^[7]but I want to focus on the architectures that are best for web services. So when I talk about RESTful web services, I mean services that look like the Web. I’m calling this kind of service resource-oriented. In Chapter 3 I’ll introduce the basic concepts of resource-oriented REST, in the context of a real web service: Amazon’s Simple Storage Service. Starting in Chapter 4, I’ll talk you through the defining characteristics of REST, and define a good architecture for RESTful web services: the Resource-Oriented Architecture.

^[7] More than you’d think. The Google SOAP API for web search technically has a RESTful architecture. So do many other read-only SOAP and XML-RPC services. But these are bad architectures for web services, because they look nothing like the Web.