WebSub or PubSubHubbub

I recently found James Cridland’s article, A Podcast Industry Guide to WebSub, or PubSubHubbub. It’s a good unpack of how the RSS-is-a-pull-service impediment to scaling is solved by creating aggregators that support pushing RSS update notifications.

…how does your podcast player notice that daily podcast is out, without polling the podcast’s RSS feed every minute?

I’ve added a link to Cridland’s article to my Deep Dive About Podcast Feeds.