That thunder behind you is the REST bandwagon comin’ your way. Anne Thomas-Manes at the Burton Group has proclaimed that the future of SOA lies in REST. I’m not saying the Burton group is itself just jumping on a bandwagon – but their declaration is significant enough to convince others to take a leap. The REST dust-up is in such a very early phase and it’s far from clear whether the bandwagon is going to help me or hurt me. David thinks he might jump on, but let someone else do the driving. Nothing wrong with that strategy, but does it feels like history has come around a bit, eh David?
I think the REST bandwagon, the long-time Lords of the Web, and the WS-* camps are heading toward a colossal and rather fun collision. There will be friction between the stewards of HTTP and those who warp it to meet their RESTful needs. The REST camp likes to say HTTP is all you need – and I agree. But don’t be fooled into thinking that the foresight of the authors of RFC-2616 and RFC-2396 took all this into account. The RESTafarians probably won't want to see their momentum slowed by the standards trust. And then someone is going to say, “Hello! Is that an XML document you’re handing me? Care to sign it?” The WS-* folks are already figuring out how to chase that ambulance.
I’ve wasted a lot of cycles worrying that the Lords of the Web are going to tell me I’m perverting the Web’s majesty. For whatit's worth, here is my advice. First, it’s OK to say you are doing REST even if you haven’t read the dissertation. Personally, I think the magic is in the URIs and the links embedded in the payload. But that’s just me. Second, use the HTTP methods however you see fit. I use GET and POST exclusively myself. I use the occasional URN and I don’t think it’s an evil thing. Some people use the HTTP media-type to indicate what the payload contains. But RFC-2616 “discourages” the use of media-type values that are unregistered (section 3.7). Just use media-type if it helps you. When my payloads are XML, I have a namespace (a URN, BTW) to indicate what it is. For HTML, I haven’t really settled on anything yet.
No matter how far ahead of the REST bandwagon you think you are, it *will* overtake you. I’m sure our marketing department will snap up REST as fast as we did “web services”. I blinked one day and the word “SOA” appeared on the collateral. But you don’t need a REST toolkit – use the bits you have now. More importantly, don’t let the toolkit vendors say “just make objects – we’ll hide the REST part for you”. Good musicians learn to improvise by first knowing their scales. If you know the fundamentals of data modeling, URIs, and HTTP you shouldn’t need WADL, WCF, O’Reilly, or the bandwagon to be successful.