PubSubHubbub

A brief overview of the PubSubHubbub protocol.

For the past few months, my blog has been participating in something called PubSubHubbub. Other than “something with a cool name,” what is PubHubSubbub? It is “a simple, open, server-to-server publish/subscribe protocol as an extension to Atom and RSS.” Using the protocol, servers are able to get near-instant notification of feed updates (feeds are used by blogs and other sites to notify subscribers of new content). Using traditional technology, feed consumers (such as feed readers) periodically poll servers (such as a blog’s web server) for feed updates. This process works, but it wastes bandwidth and other resources since checking is done whether or not updates are available, while also causing delayed notification since polling occurs infrequently. PubSubHubbub fixes this by allowing feed consumers to receive near-instant notification of feed updates. It turns the traditionally-pull-based feed technology into a push technology, so that bandwidth and other resources are only used when actual updates are available and subscribers receive updates almost immediately. PubSubHubbub is a distributed system that is free and decentralized, meaning that no company is at the center of controlling it and anyone can run a “hub,” the component that sits between publishers (such as servers running blogs) and subscribers (such as Google Reader). As you can see in the demo below, this technology enables services to provide a greater level of real-time notification.