pubsubhubbub — I’m not kidding — is an actual existing thing. Yeah, I too would have killed to be a fly on the wall when they decided to call it that, but there you go. So let’s dissect this piece of art of a name:
pubsub, i.e. pub/sub, i.e. publish/subscribe, which is a common pattern in, well, the world, where multiple parties subscribe to one or more publishers, to receive notifications on updates.