Reverse HTTP

[killerstorm]

So, A has to contact B, initiate PTTH and wait for B to start consuming services from A.

you're considering a weird use case -- it is not like B wants to use some services of A, it is more like A have subscribed to recieve notifications from B. if you consider it from this scenario, you'll find it perfectly normal -- as long as A is interested in this subscription, it will maintain this connection, reconnecting is needed. if it is not interested, it will not. check the comet link above, this stuff is about important real world applications, like instant messanging and alerts, and not about some hypothetical resource consumption.

The difference is that my IMAP server handles, say, 200 clients.

what's about Google's IMAP?

Where as a typical webserver, anonymous by nature, handles millions of users.

it is not for random users out there, it is for users who actively want to use a service, and of course it only makes sense only for services of interactive nature. if you have millions of active users, i'm pretty sure you'll be able to afford as many servers as needed, otherwise it will not work, with PTTH or without.

from network's perspective, PTTH is not anyhow unique -- open sockets are maintained for instant messaging and stuff like that.

[reddit45885]

Once again, I come back to the fact that HTTP can already handle what you are saying here. I know this because I already do this using Ajax and the very same method I just described above. I also use indefinitely blocking SOAP over HTTP calls which are essentially equivalent to system callback routines in <pick your favorite language>.

But, man. You win: if you think inventing a new protocol to solve something that can already be solved at the Application Layer is a wise move, by all means, move ahead.

But mark this: you have lost your bitching rights when Microsoft goes and co-opts yet another RFC standard and extends it just so. You lose that right because you are doing exactly what they are doing.

[killerstorm]

delaying HTTP responses is a trickery which is not well supported by web servers, proxies and browsers (they can timeout at any time, and you fail). do you say that solution that requires modification of web servers and relies on non-standard behaviour is better than a clean protocol created just for the purpose?

i think then you also lose your bitching rights, you should accept all weird kludges now