[ticker-dev] presence protocol publication

[Phillips, Matthew]

> but, in summary, Status seems to have elements of multiple different
> properties munged into a single field.  for example
> 
> - activity / idleness ("online" / "unavailable?")
> - one time notification of client shutdown ("offline")
> - specific activity ("coffee")
> - explicit statement of unavailability ("unavailable")
> 
> i hadn't ever proposed something i was happy with (from memory), but
> it still troubles me.

I feel the need to defend this ;)

The "Status" field of the user is intended to convey the status of the user
in regard to *online communication* (ticker messaging is assumed):

"online" = user says they are online for communication.

"unavailable" = user says they are not available for communication now, but
ARE still running a client. ie there might be some point in sending a
personal message if you really need to talk.

"unavailable?" = client has guessed that the user is probably unavailable,
but it might be worth trying anyway

"coffee" = the same as "unavailable". It's a standard value so that presence
can be used to subsume coffeebiff, ie so that clients can watch for people
who are on coffee break. I suppose other values could also be used for
specific purposes (eg "meeting" might be interpreted specially by some
clients), but I think it's safest for general clients to conservatively
treat unspecified values as meaning "unavailable".

"offline" = Not available at all, don't bother sending anything, they aren't
going to receive it. This will usually be because the client has exited, but
that's just the most common cause of "offlineness".

Yes, in retrospect "Status" might have been better named
"Communication-Status" or something, but I am beginning to think that
getting too anal about field naming is one way to madness ;)

Cheers,

Matt.