Application Development - eWeek

Application Development: Google Fashioning PubSubHubbub as RSS on Steroids


Google programmers have begun propelling PubSubHubbub, a new feed protocol that allows programmers to turn existing Atom and RSS feeds into near real-time data streams. This enables new content or updates to existing content to show up in RSS and Atom feeds really fast. Google programmers Brett Slatkin and Brad Fitzpatrick launched PubSubHubbub last month and have been busy rolling it out to existing Google Web services, including Google Feedburner, Google Blogger, Google Reader shared items and Google Alerts. Google has open-sourced PubSubHubbub and provided instructions for programmers to add the technology to their own applications. In this slideshow eWEEK shows how the technology works, with the instructions courtesy of Google.
 
  • Google Fashioning PubSubHubbub as RSS on Steroids
    by Clint Boulton
  • PubSubHubbub
    The PubSubHubbub protocol has its own colorful logo. Check out the ensuing flow chart for how it works.
  • A Subscriber
    A subscriber polls a publisher's feed. The feed contains a forward link to the Hub.
  • The Subscriber
    The subscriber posts a subscription request to the Hub. The request contains the URL where the Hub should post new updates.
  • The Hub
    The Hub posts to the endpoint URL to verify the request was authentic. The subscriber then responds with confirmation to the Hub.
  • The Publisher
    The publisher notifies the Hub about updates by posting feed URLs to the Hub. The Hub pulls the feed again to find new entries.
  • When the Publisher Does not Tell the Hub About Updates
    If the publisher does not inform the Hub, the Hub will periodically poll the Publisher's feed for new updates.
  • Receiving Feed Updates
    When the Hub receives a new update to a feed, it posts the update to the Subscriber's endpoint URL.
  • What if There Are Multiple Subscribers?
    If feed X has multiple subscribers, the Hub sends updates to all of them.
  • The Distribution
    The future is distributed: There will be big hubs, many small hubs and tons of publishers and subscribers. Publishers, subscribers and hubs may play multiple roles.
  • PubSubHubbub Requirements
    This is what publishers, subscribers and hubs need for the protocol to work.
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