Here’s an interesting ‘pre-draft’ of HTTPLR, an ‘application protocol for reliable transmission of messages using HTTP’ (via the author’s blog). It doesn’t require throwing away already built out infrastructure. There are, however, a few wrinkes:
It uses the DELETE method (rather than the POST) to communicate client knowledge of message transfer (section 8.3, 9.3). I’m not sure how I feel about that, as it seems to be mis-using that method.
Other than that, I like the idea. It seems really well thought out, but it would be nice to see some sample code.