Web Hooks ≈ callback URLs

WTF is a Web Hook?:

"In short, a web hook, or "http callback" allows you to subscribe to another website's events with a URL. You tell a website, "Hey, when some event happens, send some information about it to this URL". Why? It doesn't matter, it's up to the developer to decide what to do with that information."

(low-lumen) Enlightenment

I begin to see how to apply component-oriented techniques to distributed/federated web application development. Thanks to John Herren (bwo Tim O'Reilly) for the clue.