Subject: [Simple] immediate notify issue

From: Jonathan Rosenberg <[email-masked]>
Date: Tue, 27 Feb 2001 02:36:17 -0500

Folks,

I've encountered a privacy issue surrounding the current methodology of
immediately generating a NOTIFY on a successful subscription.

We have agreed that a SUBSCRIBE will pretty much always result in a 202
whether its accepted or not. This way, the subscriber cannot obtain any
information about whether the presentity is online or offline, based on the
response code or delays in receiving the response. We have also agreed that
the presence data is not included in the response to subscribe, and rather,
in an immediate notify. This was for aligment with CPIM.

However, there is now a problem with the notify. A client could determine
whether the PUA was online, or whether its subscription was accepted, based
on when a NOTIFY arrives (a slightly delayed one indicates they are online
and authorized the subscription; one that never arrives likely means they
are offline or the subscription was rejected).

To handle this, we may need to mandate that the presence agent generate an
immediate NOTIFY, containing the current state of the presentity. In all
cases, the presence document in this message contain a valid state for the
presentity. If a subscription was pending or rejected, the state would
indicate that the presentity was unavailable. If a subscription was
accepted, it would indicate the actual state, which could also be
unavailable. The key is that the presence document returned in the case of a
pending subscription be a valid one that can't be distinguished from one I
might get if my subscription were accepted.

Thoughts?

-Jonathan R.

---
Jonathan D. Rosenberg                       72 Eagle Rock Ave.
Chief Scientist                             First Floor
dynamicsoft                                 East Hanover, NJ 07936
[email-masked]                     FAX:   (973) 952-5050
http://www.cs.columbia.edu/~jdrosen         PHONE: (973) 952-5000
http://www.dynamicsoft.com

---

From: Nicolas Dramais <[email-masked]>
Date: Tue, 27 Feb 2001 11:14:38 +0100

> in an immediate notify. This was for aligment with CPIM.

My thought is that a NOTIFY shall be used only to signify a *change* in a
presentity's communication status.
I find it somehow misleading to use it to transport a current, unmodified
communications status as answer to a SUBSCRIBE.
I'd rather prefer to specify in CPIM that setting the current presence info in a
response to a SUBSCRIBE is optional and that when done (e.g. for IM independent
Presence service) it eliminates the need for an immediate NOTIFY.

> indicate that the presentity was unavailable.

My thought is if a subscription is rejected or pending, no presence info at all
should be provided and no NOTIFY should be wasted just to say so.
This is again somehow misleading.
Again, it could be solved in the CPIM by specifying presence info in responses
as optional.

> If a subscription was
> _______________________________________________
> simple mailing list
> [email-masked]
> http://mailman.dynamicsoft.com/mailman/listinfo/simple

--
Nicolas DRAMAIS
Communications Software Engineering
Indigo Software
"We join the dots"
~~~~~~~~~~~~~~~~~~~~~~
50, rue Wiertz
1050 Brussels
Belgium
tel.: +3222350952
fax:  +3222802676
mailto:[email-masked]
~~~~~~~~~~~~~~~~~~~~~~
http://www.indigosw.com

---

From: James Undery <[email-masked]>
Date: Tue, 27 Feb 2001 13:07:24 +0000

> Presence service) it eliminates the need for an immediate NOTIFY.

The CPIM document doesn't say that a response must contain any info, but it does
specify that an immediate notify follows a successful response to a subscription.

> > might get if my subscription were accepted.

I agree with Jonathan here, although I think the IMPP WG should be informed of this
problem as it will affect any WGs that comply with CPIM.. (I haven't cross posted as
I'll have to check the IMPP mail achive to see if this has been mentioned).

James Undery

---

From: "Adam B. Roach" <[email-masked]>
Date: Tue, 27 Feb 2001 09:50:10 -0600 (CST)

>might get if my subscription were accepted.

This seems like a sound solution to me. And it's applicable to
events in general, not just presence...  I'll include a discussion
of this in the next SUB/NOT draft.

-- 
Adam Roach, Ericsson Inc. |  Ph: +1 972 583 7594 | 1010 E. Arapaho, MS L-04
[email-masked]   | Fax: +1 972 669 0154 | Richardson, TX 75081 USA

---

From: hammer michael <[email-masked]>
Date: Tue, 27 Feb 2001 13:01:13 -0800

What is the primary purpose of the Subscribe and Notify?

Is the intent to make information available to the subscriber, or are you 
trying to create some gray area in between?

Also, if there is an always-on terminal, is the semantic to indicate the 
presence of the terminal or the user?
Likewise, if the user is always there, but does or does not want to 
communicate?

I would assume that the event being subscribed would be specific and either 
accepted or rejected, no gray areas.

Mike

---

From: "Hisham Khartabil" <[email-masked]>
Date: Fri, 16 Mar 2001 15:01:18 +0200

Hi,

What about when the Presence Agent is located at the client (ie: Presence
Client).  If I subscribe directly to that presence client, and that client
is off line, then I know because I don't even get a response to my
subscribe.  I guess nothing could be done about that besides motivate the
need for a presence server (Is that what we are trying to motivate, or are
we trying to motivate pushing login to peripherals?)

Regards,

Hisham Khartabil
Hotsip Finland
www.hotsip.com

-----Original Message-----
From: [email-masked]
[mailto:[email-masked]]On Behalf Of Jonathan Rosenberg
Sent: Tuesday, 27 February 2001 9:36 AM
To: [email-masked]'
Subject: [Simple] immediate notify issue

Folks,

Thoughts?

-Jonathan R.

---