on the use of user@foo

[David Arnold]

following a lengthy ticker conversation this morning, i'd like to
comment on the usage of the domain portion of user names, and how its
use might be improved.

in ticker, the use of name at domain has evolved as an extremely useful
means of conveying the location of the sender.  for example,
"d at home" or "croy at work".  as an historical aside, i believe this
convention was initiated by Rik Taylor.

in the current (0.4.1) draft of the presence protocol, a user (or
presentity, to use the more specifc term) is identified by a _unique_
identifier formed from a combination of user and domain names.

in current usage, however, this is not occurring.  the convention of
using the domain portion of the user's name to convey location
information is carrying over.

i have two issues with this:

- it results in multiple presentities (at the protocol level) for a
  single person.

  when this is intentional (ie. you wish to present an alias), it's
  fine.  it's my impression however that most people are simply using
  this as a means of conveying their location rather than as an
  attempt to create an alternate persona.

- the use of common names like "home" or "work" for the domain portion
  of the identifier will cause collisions, leading to incorrect
  information about presentities.

  for example, David Arnold (DSTC) and David Parker (DSTO) are both
  current Presence-Protocol users.  if we were both to use
  "david at home" as our identifier, the protocol would present a
  meaningless combination of our statuses.


i'd like to propose two (really three) possible solutions to this problem:

1. since it appears (by observation, rather than interrogation ;-)
   that the main motivation for using different domain parts in users'
   identifiers is to convey their current location, perhaps we should
   add an explicit "Location" field to the Presence-Info notifications?

   clients would require users to specify their chosen _unique_ domain
   part (ie. a personally-owned domain, or their primary (maybe work?)
   domain) which would be used together with their user portion to
   form a unique name.  

   additionally, the clients should allow the user to specify a
   location (ie. "home", "work", "laptop", etc) which would be sent in
   the Location field, and displayed in user interfaces.

2. following the same motivations, we could retain the definition of
   the User field as being a unique identifier, but add a second field
   for the Display-Name.

   in this case, clients would be configured with a unique identifier
   for the user/presentity, most likely their primary email address.

   the text string displayed in user interfaces however would be
   free-form text.

   this would enable the use of unique names like "da947456 at yahoo.com"
   but would allow me to suggest a displayed name of "d at dstc", for
   example.

   it would also enable receiving clients to override the suggested
   display name, and have you see me as "ThatPickyBastard" if you
   wished.


ultimately, i think i prefer a combination of these approaches:

   User-Id: "da947456 at yahoo.com"
   Display-User: "d"
   Location: "monash"

which allows your client to override my display name, but still get my
location information.

comments?




d