The most basic of everything is that REST assumes that you won't ever try to call an operation on the resource, apart maybe from creating or destroying it (and God forbid running an operation that is not tied to any resource at all, or works on multiple resources at the same time). So your REST service is basically a passive data store. Once you go outside of this realm (and more often than not you should do so), you have remote procedures, and REST, being a pattern instead of protocol and working on individual object, gives you nothing useful.