Subject: RE: [Simple] PIDF-LO and the presence data model

From: "Brok, Jacco (Jacco)" <[email-masked]>
Date: Thu, 14 Jul 2005 10:01:30 +0200

Hi,

I would prefer to allow it both under device and under person, but not tuple.

Justification for device: when the location is mesured by device equipment,
such as GPS, Wi-Fi etc. Mostly relevant for PUBLISH. Interestingly, a user
 may have multiple devices which are likely not at the same location.

Justification for person: when the location comes from manual input by the
user, and of course when device belongs to the presentity. Mostly revelant
for SUBSCRIBE/NOTIFY.

Regards,
Jacco

-----Original Message-----
From: [email-masked] [mailto:[email-masked]]On Behalf
Of Henning Schulzrinne
Sent: donderdag 14 juli 2005 4:23
To: [email-masked]; GEOPRIV
Subject: [Simple] PIDF-LO and the presence data model

There doesn't seem to be any real specification indicating how exactly 
PIDF-LO and the SIMPLE presence data model interact.

draft-ietf-geopriv-pidf-lo-03 just gives an example, putting it in 
<status> within <tuple>. From the perspective of the data model, that's 
probably the least-liekly place - tuples represent services and seem the 
least related to one one location, compared to devices (presumably 
always have exactly one location) and persons (one true location, 
despite attempts by people to be in two places at the same time).

If a user has multiple service (tuples), it seems odd to have one random 
one indicate a location, or, worse, two conflicting ones.

RFC 4079 describes general architecture, not really protocol bits.

So far, the Data Model draft doesn't mention PIDF-LO.

Did I miss a precise specification anywhere?

Maybe the data model should address this; I'm also happy to add this to 
RPID, but that seems more of a stretch.

Henning

_______________________________________________
Simple mailing list
[email-masked]
https://www1.ietf.org/mailman/listinfo/simple

_______________________________________________
Simple mailing list
[email-masked]
https://www1.ietf.org/mailman/listinfo/simple

---

From: Henning Schulzrinne <[email-masked]>
Date: Thu, 14 Jul 2005 13:40:58 -0400

This agrees with my suggestion below, I believe. I'd like to add a 
wrinkle: there are cases when location information isn't directly 
related to a communication device. For example, we locally use RFID 
(user-activated swipe) and UWB (badges) to determine indoor location. 
These would not be devices you'd include in a presence document.

There doesn't seem to be much disagreement (yet), but we do need a spec 
home for this before everybody does it their own way.

---

From: Paul Kyzivat <[email-masked]>
Date: Thu, 14 Jul 2005 18:16:58 -0400

> These would not be devices you'd include in a presence document.

They may be stupid devices, but these are still devices in my book. When 
this basic raw information is being published to a Presence server that 
will be doing composition, I think it is quite right for the incoming 
presence document containing a <device> entitity containing the PIDF-LO 
stuff, together with perhaps a small amount of stuff indicating that 
this is indeed the kind of device it is - enough to provide context for 
composition.

The composer may well take this info, fold it into a <person> element, 
and drop the <device> element. So the <device> may never be seen by 
watchers. But it is still there, in the background.

Alternatively, the publisher could instead publish take that same 
PIDF-LO data and publish it as <person> data. But that seems less 
desirable to me - it gives the composer less context to work from. If 
there are competing sources of location information, having the raw data 
of where it came from could help to decide which to trust.

	Paul

---

From: Henning Schulzrinne <[email-masked]>
Date: Thu, 14 Jul 2005 20:14:38 -0400

> presence document containing a <device> entitity containing the PIDF-LO 
[snip]

This requires at least some adjustment in the presence data model, since 
devices are said there to support services. Here, there would be 
"dangling" devices, with no service pointing to them. I don't think this 
is a major issue, but probably worth clearing up.

Henning

---

From: Jonathan Rosenberg <[email-masked]>
Date: Sun, 17 Jul 2005 23:54:58 -0400

I think two things are needed here.

Firstly, the data model should make vague reference to how location 
information is sensible as an example of a characteristic of a person or 
device. Thats it.

Next, a spec needs to be formally written which does something akin to 
RPID but for pidf-lo, and defines how it gets used in the presence data 
model. This would properly define the pidf-lo elements as valid children 
of person and device, and discuss any other considerations around its 
usage with the data model, if any. Probably it can be a short draft.

However, I am cautious about feature creep in either the data model or 
rpid, and I don't think the details of the usage of pidf-lo in the data 
model belong in either.

-Jonathan R.

-- 
Jonathan D. Rosenberg, Ph.D.                   600 Lanidex Plaza
Director, Service Provider VoIP Architecture   Parsippany, NJ 07054-2711
Cisco Systems
[email-masked]                              FAX:   (973) 952-5050
http://www.jdrosen.net                         PHONE: (973) 952-5000
http://www.cisco.com