Subject: [Simple] Mobility of Buddy List

From: Vencour Marcel <[email-masked]>
Date: Tue, 19 Jun 2001 14:41:22 +0200

Hello everybody,

I have a problem concerning the buddy list used in a presence service: The
question is, where is the buddy list of the watcher stored when the watcher
goes offline? If it is stored in a file/database at the location of the
watcher, then it is bound to the watcher's client, i.e. it does not move
around with the watcher (here watcher means the person, not the client used
by that person) when he uses different machines to do his watching. Thus the
buddy list would have to be stored at the presence server/presence agent
(PS). But in this case how can the watcher go offline without deleting his
buddy list at the PS? If he goes offline without sending any unsubscribe
then the PS would continue to send notifications to the watcher which of
course is unnecessary overhead. On the other hand, if the watcher goes
offline and sends unsubscribes for all his buddies then the buddy list would
be removed from the PS.
The next question then is, what happens when the watcher goes online again?
How can he send a subscribe without giving a buddy in the request line (just
to tell that he is online and thus wants to receive notifications again)?

Thanks in advance for an answer, M. Vencour.

---

From: "Theodore Havinis" <[email-masked]>
Date: Thu, 21 Jun 2001 13:25:41 -0700

Hi Vencour,

I don't think we should mix the presence service and its services (provide
notification of state  changes) with the capabilities of a specific
application that helps you create a buddy-list and
potentially may also support 'reachability/mobility' capabilities which will
mean that you will beb able to access the 'buddy list' from any device.

To give you an example of what I mean, I don't believe that you need to have
presence service to have IM. Presence is an *enhancement* to IM.
Likewise, reachability/mobility is an *enhanacement* to IM. Thus, its the
application's capability to provide you with a reachability/mobility
*service* that helps you access your 'buddies' anywhere from any device and
*not* the presence service's responsibility.
(Please I want to avoid to get into mobility issues here ie whether it's
better
to handle it at application layer or lower layer...)

So, I tend to believe, that your question its a mobility/reachability issue
which means it should be addressed either at an IETF SIP/MobileIP group, but
also its a pure application issue ie how the particular application is
proposing to handle reachability/mobility and thus 3GPP/3GPP2 may also be
suitable since they are providing generic solutions.

Of course if 'buddy list' is an extension to IMPP then it should also be
addressed there.

Kind Rgrds,
Theo

TH>-----Original Message-----
TH>From: [email-masked]
TH>[mailto:[email-masked]]On Behalf Of Vencour Marcel
TH>Sent: Tuesday, June 19, 2001 5:41 AM
TH>To: [email-masked]'
TH>Cc: Mayerhofer Andreas A
TH>Subject: [Simple] Mobility of Buddy List
TH>
TH>
TH>Hello everybody,
TH>
TH>I have a problem concerning the buddy list used in a presence
TH>service: The
TH>question is, where is the buddy list of the watcher stored when
TH>the watcher
TH>goes offline? If it is stored in a file/database at the location of the
TH>watcher, then it is bound to the watcher's client, i.e. it does not move
TH>around with the watcher (here watcher means the person, not the
TH>client used
TH>by that person) when he uses different machines to do his
TH>watching. Thus the
TH>buddy list would have to be stored at the presence server/presence agent
TH>(PS). But in this case how can the watcher go offline without
TH>deleting his
TH>buddy list at the PS? If he goes offline without sending any unsubscribe
TH>then the PS would continue to send notifications to the watcher which of
TH>course is unnecessary overhead. On the other hand, if the watcher goes
TH>offline and sends unsubscribes for all his buddies then the
TH>buddy list would
TH>be removed from the PS.
TH>The next question then is, what happens when the watcher goes
TH>online again?
TH>How can he send a subscribe without giving a buddy in the
TH>request line (just
TH>to tell that he is online and thus wants to receive notifications again)?
TH>
TH>Thanks in advance for an answer, M. Vencour.
TH>
TH>_______________________________________________
TH>simple mailing list
TH>[email-masked]
TH>http://mailman.dynamicsoft.com/mailman/listinfo/simple
TH>