It seems there is a lot of buzz about Representational State Transfer (REST) in blogs recently. First there was a post by Damien Katz, which got a response by Dare Obasanjo that I would like to mention first. He pointed out that REST was coined by Roy Fielding who was one of the HTTP 1.1 specification authors. SOAP on the other hand came from the Microsoft camp with people like Don Box. SOAP was then pushed by the W3C. It was of interest so that people could package old enterprise techniques such as COBRA into new buzzwords.Obasanjo continued that REST is specifically for the client server architecture. The statelessness feature of REST contributes to increased scalability and reliability. REST is a characteristic of the web. A resource is anything that can be named on the web. Regarding PUT and POST, PUT is idempotent. POST is not idempotent. In other words, you can PUT many times, and the outcome is the same. This is not true with POST. I liked the phrase that “session state is evil”. That does not mean that this architectural outlook is correct. In addition, Obasanjo lobbied for developers to not fight against the web.
In the same regard, I read a REST Questions blog post. The most interesting part of it were the comments from readers. REST says that application state is not supposed to be kept by the server. It is acceptable and desired for the client to keep application state. REST is not necessarily good at communicating errors back to the client. There is definitely a lack of good tools out there for REST. PUT and DELETE are not supported in browsers, causing a limitation to REST.
More REST Questions comments included one that the envelope/wrapper idea from SOAP is not a bad one. However making the envelope be in XML format is the problem. REST may indeed be simple to understand at a high level. However that does not mean it is easy to implement. There is still some confusion out there as to what REST is exactly. For example there is no REST RFC.
I expect the discussion to continue since REST is still one of those hot buzz words. We shall see what technology wins when all the dust settles. Last year I recall SOA being the buzzword of choice. And before that it was Ajax. Time will tell.
