Guzzle Ayup! is a PubSubHubbub Hub. Publishers can notify the Guzzle Ayup! hub that new content is available on their feeds, in turn Guzzle Ayup! hub will notify all Subscribers that the feeds they subscribed to just got updated, by directly pushing the new entries to them.
Users can notify Guzzle Ayup! that new content is available on their feed by sending a POST request. Responses are formatted in XML.
PubSubHubbub has become the standard protocol for real-time RSS and Atom feed subscription and delivery. But not everybody wants to host their own PubSubHubbub hub in the same way that hardly anybody hosts their own website, and why cloud services in general have become so popular. Guzzle Ayup has entered the market to offer a hosted PubSubHubbub hub service.