The attribute registry

Hello,


How exactly does the attribute registry work?

Once a resource has registered itself to the 
registry, what happens then ?
I read somewhere that it keeps them in a database in
the server? Is this true?
So you could use the registry as a sort of a DBMS?

When is this registry cleaned and by whom?


Sorry for all these registry questions, but it seems
like an intresting feature, so I like to know more
about it ;-)

Koen Van Exem