Web Things, by Mark Baker

James Strachan asks that if the method doesn’t go in the SOAP envelope, could it go in the URI or an HTTP header? My answer would be “No”, that in order to gain the benefits of REST, the only method you need should be the one in the HTTP request line, such as GET/PUT/POST. That’s not to say more methods can’t be defined, only that they should all have uniform semantics, and that when using HTTP, they should be HTTP methods.

Does that explain why HTTP is an application protocol, and not a transport protocol?