Subscribe and pull are pretty handy, but push (especially asynchronous) is just as useful, and often seems to be missing. So where is it at web level?
Let's say I have something named/identified with a URI, like myself, now everytime that's mentioned anywhere on the web I'd like to know about it (okay not all the time, but it should at least be possible) - insert multiple scenario's here, conclude that any notification solution needs to be as generalized as possible.
So, I simply propose 3 basic things:
NOTIFY - a new HTTP verb
Why a new verb? to prevent collisions with usage of POST and to leverage the already existing design of HTTP, especially things like Accept and OPTIONS. (will need to have properties similar to POST)
notify - a new link relation
To be used in html, and with the Link header, this allows resources to specify where notifications should be sent to.
x:notify - a URI identifying the new link relation
it's just the rel, but using a full URI for compatibility with the semantic web.
That's it, quite sure one can build a lot of things on top of that.
