19.5. Web services for the REST of us! SOAP is not without its critics, who argue that it doesn't do enough to warrant its complexity and attendant costs. They observe that in most SOAP services the HTTP Web protocol is doing the heavy work of moving data from place to place, and XML is describing the data that is being moved. Worse yet, they point out that SOAP doesn't use HTTP and XML in the way they were designed to be used. Instead of treating XML documents as persistent resources with Web addresses (URIs), SOAP treats them as transient messages sent to objects that are completely outside the Web or XML framework. A second generation of Web services is now being developed that is integrated with the architecture of the Web: Web URIs address XML documents that can be retrieved via the Web's HTTP. This architecture has been named REST. (You don't want to know why.)[6] It is also referred to as XML over HTTP. [6] Web pages are representations of resources. An application changes state as it traverses links to transfer from one page to another, hence Representational State Transfer (REST). We warned you that you didn't want to know why! Developers who use REST techniques say it is a more productive way to build Web Services because it builds on techniques that are known to work. Users seem to agree. The Amazon.com Web service is available in both the REST form that we discussed earlier and in a SOAP version. At the time of writing, Amazon reports that the REST service gets 85% of the use! | 
