ActionWebService out, ActiveResource in
It’ll probably come as no surprise that Rails has picked a side in the SOAP vs REST debate. Unless you absolutely have to use SOAP for integration purposes, we strongly discourage you from doing so. As a naturally extension of that, we’ve pulled ActionWebService from the default bundle. It’s only a gem install actionwebservice away, but it sends an important message none the less.
This is an interesting question: When do you have to use SOAP? or WSDL? The answer is that rarely do you "have" to use it. The two most common reasons for using it are
1. It's the corporate standard (someone tells you to)
2. You have some software that only speaks SOAP
I'm a fan of using the smallest amount of protocol to accomplish the job at hand. REST is about simplicity - simple to design, simple to consume. And simplicity introduces scalability of human consumers. That is, it doesn't require reading gobs of white papers on the subject to understand it.
The funny thing is I'm also a fan of protocol extensions. The big idea behind the WS-* stack was that it didn't require you to use all of the WS-* stuff at once; you were able to pick and choose the elements you needed. You could use the basic messaging stuff and throw in a bit of security. If you don't want security, don't use it. You need transactions, hell throw that in... What the REST approach seems to be telling the Web Services world is that even the light stack (WS-I Basic Profile) is too fat. And I agree.
Clearly, I'm not alone on this. Plenty of people have pointed figures at the WS-I and called them ugly names. However, I haven't picked up anything from the WS-I organization suggesting that they realize that their lightweight stack is too fat. Instead of working on an even slimmer profile (call it the WS-SuperLight Profile), they are adding new WS-Fat stuff to the mix. I can't make it any clearer than this: WS-* is dead unless they create a lighter weight protocol.
True RESTifarians will point out that REST isn't really about a 'lighter stack' but rather the genius of REST is in the tenets of the disertation. I mostly agree but I think that there are still variations of the tenets that need to be explored. For example, some might argue that if a new profile was created that Relax NG might be strongly considered as an element.
Regardless, it is clear to me that the WS-I is too fat and about to have a heart attack. But rather than going out and exercising, the leadership team seems devoted to going out and eating a couple pounds of cheese cake. WS-* will collapse if measures are not taken - and soon.