[ticker-dev] Multiple presence clients for a single user

[Phillips, Matthew]

> <Matthew.Phillips at dsto.defence.gov.au> writes:
> 
>   Matthew> There are 2 solutions to this that don't involve a third
>   Matthew> party 1) my home 'online' client notices the contradiction
>   Matthew> and sends a counter-update to set everyone straight or 2)
>   Matthew> other clients notice the conflict between my two clients
>   Matthew> and handle it by accepting the 'most available' status.
> 
> i'm wondering about a potential third method, which involves a few
> other changes as well.  i've been trying to clarify the semantics in
> my head, and i keep getting the urge to simplify ...
> 
> what if:
> <...>

One key point is that the 'unavailable?' status is special because it gets
set automatically, and is not necessarily triggered by a user.  The other
events are user-triggered and imply that the person is really present - they
are more 'positive' in that respect.  However, even though accepting that
the last positive event is authoritative most of the time, it can be broken
fairly easily.  Say I'm moving back and forth between two hosts and two
clients, both of which (correctly) list me as online.  I log out of one
host, setting my status to 'unavailable' as I do so.  I start using host 2,
which already thinks my status is 'online' and does not generate an update -
all clients now think I'm unavailable until I force client 2 to generate
what is, for it, a redundant update.

I also really want to have automatic 'unavailable?' as standard in
full-featured clients because we tend to forget about setting our status.  I
found that, until I added this feature to Sticker, presence status was
fairly useless: I'd dial in on a weekend and find that everyone was 'online'
;)

I absolutely agree with keeping things simple, even at the cost of losing
some cool features. I'd say the spec is too complex if an average hacker
can't put together a halfway useful presence implementation in an hour or
two - I don't think we've crossed that line yet.

Cheers,

Matthew.