April 24, 2006

Pubsub .vs. polling - again

This is a great read from Bob Wyman on Dave Winer's comments about polling compared to notification :
From As I May Think...: Dave Winer: Show me that mathematical proof!

Dave's lack of understanding of the issues related to scaling can be seen in the history of the weblogs.com site that he struggled to build and maintain for so long. That site takes "pings" from blogs and then consolidates them into tremendous "change lists" which must be polled. Essentially, this site converts an efficient push-based update notification system (pinging) into an inefficient polling based system. Weblogs.com, as Dave built it, didn't even support common methods like eTags or RFC3229+feed to improve polling efficiency and scaling. The result was that it simply didn't scale and was frequently incapable of providing the service levels that people expected. Only now that Verisign has taken over the site and dedicated much better engineering staff and much more hardware, has the weblogs.com service begun to be somewhat useful again. However, since weblogs.com is still based on the terribly inefficient polling of change-lists that Dave supports, it is still a far cry from being what it might be.

Ouch. But I did like the nod to KnowNow and mod-pubsub. Not sure if mod-pubsub is still alive and kicking though.

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