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

[Per Melin]

2008/6/1 Paul Stanley <pstanley1970@REDACTED>:
> The alternative is to process outgoing messages at once, delivering
> copies to each "follower".

Twitter has features that makes it different from any other messaging
service I can think of. Some examples:

Anyone can go to a users page and see all their posts. So everyone
needs a special follower called "everyone else". Unless the user has
checked the "protect my updates" box in the settings, in which case
only approved followers can view the posts.

And even if *my* posts are public, one of them may be a reply to a
non-public post from someone else, and I believe that in this case
Twitter filters out even the public reply. Unless of course you're
logged in when you're viewing my posts and are also approved to view
the protected post that I was replying to.

I can put @paul in a message to show that it's directed to you. Users
have the option to filter out @-messages that are directed to people
they themselves are not following. If Joe is following me, but not
you, he may or may be shown a post from me with @paul in it.

So at some point in the chain, probably every time you show a post,
you need to pass through several filters, some of which may require
that you examine the settings of other users (which in a distributed
system may live on another node).

Disclaimer: I'm guilty of some speculation here, since I've only
lurked on Twitter, and don't fully know the ins and outs of the
functionality it offers. That will change now. I'll start posting, at
least for a while. My page: http://twitter.com/pmelin