I don't know if they are still in use, but there are pub/sub services that can be used for notifications. This was created to avoid unnecessary polling of RSS/

I don't know if they are still in use, but there are pub/sub services that can be used for notifications. This was created to avoid unnecessary polling of RSS/Atom feeds: https://en.m.wikipedia.org/wiki/WebSub https://en.m.wikipedia.org/wiki/WebSub