Post-Commit Web Hooks for Google Code Project Hosting (via) I really, really like web hooks (which I’ve been calling “callback APIs”, but it looks like “web hooks” is the term that’s sticking). I’m interested in their scaling challenges—I’ve heard XMPP advocates argue that a web hook style model simply won’t scale for really large sites.
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I think the challenges of scaling outgoing HTTP notifications and outgoing XMPP notifications have similar scaling characteristics. We ought to be able to re-use the thinking behind email notifications.
In all three cases the same thing is happening at a high level: connect to some foreign server and deliver a payload. The bits on the wire are a little different, but the principle is the same.
I was just thinking the other day that RSS could use an email-notification-style push component. If I comment on a six-month-old blog post, for example, I might want to know if anyone else comments, but there's no reason to be checking the RSS feed every day, even. It would be nice if you could request that a site ping your feed collector when the feed is updated.