IBM have released HTTPR, a specification for ensuring the reliable delivery of payloads with HTTP between server and client.

Releasing the specification to the public in order to "stimulate public discussion on reliable message delivery on the Internet," IBM have also published an HTTPR primer on their developerWorks site.

IBM's proposal, which would see two new URI protocol schemes HTTPR and an SSL-enabled HTTPSR, uses HTTP 1.1 as its base. Whereas HTTP is stateless, HTTPR also offers session-based and pipelined modes of operation. HTTPR sessions look essentially similar to HTTP POST requests, but with an extra set of headers in the HTTP body that encapsulate the HTTPR request, which can involve GET-RESPONDER-INFO, PUSH, PULL, EXCHANGE, REPORT, or RESOLVE verbs.

It will be intriguing to see how this proposal is received from the protocols community at large, riding as it does somewhat awkwardly on HTTP 1.1. Its main rival would seem to be the BEEP specification, which specifies a protocol framework on top of which such reliable messaging services could be defined. Initial feedback from seasoned protocol critic Mark Baker suggests that IBM may have some rethinking to do. Discussion is also ongoing on the W3C's web services mailing list.

Running unfortunately (and sadly predictably) counter to web culture, the specification is available only in PDF format. Feedback is encouraged to the discussion forum on IBM's developerWorks site.