People often don't make a crucial distinction: Are you developing an API that happens to be accessible via HTTP or are you developing a Web Service. For an API

People often don't make a crucial distinction: Are you developing an API that happens to be accessible via HTTP or are you developing a Web Service. For an API where you control both the server and the client, you don't need to use REST. For a Web Service, where you don't control which clients are using, you are better off with a RESTful implementation supporting hypermedia. Especially if you are interested in keeping clients happy and not give them the middle-finger shaped like a incompatible-v2 version of your service.