REST api’s are being developed for more and more business function. For certain business function once and once only delivery of a message over a REST call is required. Enter Certified Http, an effort led by second life with participation by IBM. It is simple to understand, has a reference implementation in python and they have this to say about their main competition.
httpr and ws-reliable.
These tend to be thoroughly engineered protocol specifications which regrettably repeat the mistakes of the nearly defunct XMLRPC and the soon to join it SOAP — namely, treating services as a function call. This is a reasonable approach, and is probably the most obvious to the engineers working on the problem. The most obvious path, which is followed in both of the examples, is to package a traditional message queue body into an HTTP body sent via POST. Treating web services as function calls severely limits the expressive nature of HTTP and should be avoided.