[erlang-questions] Twoorl: an open source Twitter clone

Dave Smith <>
Sat May 31 04:51:35 CEST 2008


On Fri, May 30, 2008 at 9:02 AM, Per Melin <> wrote:
> 2008/5/30 Joe Armstrong <>:
>>  - what is Twitter?
>
> It was launched as a "micro-blogging" service. Each post is limited to
> 140 characters (like an SMS).
>
> Users can follow what others post with RSS, SMS, instant messaging,
> desktop applications (through an API), email or on the Twitter
> website.
>
> Some users have tens of thousands of "followers" and some follow
> thousands of people.

Twitter is basically a large-scale notification problem -- N people
wanting to know most recent status of M other people, where the rate
of status change is high (multiple changes per minute) and the latency
of notification must be low. Furthermore, not all parties are
necessarily "online" at any given moment, so some sort of
store-and-forward must be present such that changes are not missed.

My understanding is that the reason they have such poor uptime is due
to the fact that they modeled the problem as a web-app instead of a
messaging system. Compounded on this poor design choice is that they
have achieved success and so are experiencing record growth every
month -- i.e. no time to recover from past success. :)

Certainly Erlang would be a great foundation for Twitter, but
honestly, the problem they have is not one of language choice so much
as correctly identifying the characteristics of the problem.  Along
these lines, twoorl repeats this mistake by modeling it as a web-app
instead of a messaging system, but again..just an opinion. :)

D.



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