PubSubHubBub & HTTP load Balancing
Dhaval Kolapkar (email@example.com)
I. Introduction to Scalability
Why does Facebook has a 5,000 user limit on the number of friends? Social Networking sites like Facebook, Twitter and wordpress use real time social graphs making scaling harder than the traditional websites. In order to provide such updated data to the earliest two technologies have changed the entire ball game- PubSubHubBub and HTTP load balancing.
How can the feed subscribers of a blog read the latest updates the moment they are published? This scalable and real time technology was not possible in the past until PubSubHubBub protocol was introduced by Google. Previously, when a content was published the feed aggregator would poll the site at regular interval and check for new content. If the new content is published, it will broadcast it to the subscribers else it will continue to poll. With this technology, it would take several hours for the content to be available for the RSS subscribers. PubSubHubBub changed the ball game and made everything realtime. So, the RSS subscribers can read the content as soon as it is published.
III. PubSubHubBub protocol in a Nutshell: PubSubHubBub is a publish/Subscribe protocol for distributed communication on the internet. It is an open webhook based server-to-server protocol. In the HTTP header, the resource URL/Topic declares its Hub servers. The Hub can be run by Google or by the subscriber