Subject: RE: [Geopriv] coming to terms on location by reference

From: "Roger Marshall" <[email-masked]>
Date: Tue, 12 Sep 2006 08:53:12 -0700

The method of handling a location, "by-reference", is supported in the
current ECRIT requirements draft as follows:

   Lo2.  Location delivery by-value: The mapping protocol MUST support
      the delivery of location information using a by-value method,
      though it MAY also support de-referencing a URL that references a
      location object.

      Motivation:  The mapping protocol is not required to support the
      ability to de-reference specific location references.

Roger Marshall.

>-----Original Message-----
>From: Andrew Newton [mailto:[email-masked]] 
>Sent: Tuesday, September 12, 2006 8:18 AM
>To: [email-masked]
>Subject: [Geopriv] coming to terms on location by reference
>
>
>As John Schnizlein has noted in a message 
>(http://www.ecotroph.net/~anewton/hypermail/geopriv/0607/2717.h
tml), we have not truly come to consensus on location by >reference
within this working group.  The GEOPRIV working 
>group has been presented with many individual submissions for 
>both architectural considerations and concrete solutions. 
>Additionally, this working group has discussed 
>location-by-reference with regard to its component uses in 
>location configuration protocols, location dereference 
>protocols, and location conveyance protocols. As a working 
>group, we are much further along in our understanding of 
>location-by-reference than we were just 1 year ago. And as it 
>stands, there are many who feel it is valuable, many who feel 
>it is not, and many who have not given their opinions.  But it 
>is now time for us to determine how we should move forward on 
>location-by-reference, either accepting it as a whole, 
>accepting it in limited form, or rejecting it entirely.
>
>To that end, I offer the following inexhaustive list of 
>observations on this
>topic:
>
>1) Location-by-reference offers better efficiency where 
>location of a target is not determined by the target and when 
>the target wishes to convey its location.  It is more 
>efficient because the target does not have to first retrieve 
>the location in order to convey it.
>
>2) Location measurement and determination (sighting) of a 
>target by another element is of limited scope as 
>self-determination methods such as GPS may offer greater accuracy.
>
>3) Authentication of the dereferencer may have unintended 
>consequences.  For example, a referent host may require 
>authentication that could cause the failure of emergency call 
>routing.  Therefore, location-by-reference may not appropriate 
>or could even be harmful for certain use cases.
>
>To further this discussion so that we may come to resolution 
>on this topic, I welcome comments regarding the above as well 
>as further observations.
>
>-andy
>
>
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---

From: "Dawson, Martin" <[email-masked]>
Date: Tue, 12 Sep 2006 10:59:21 -0500

It's also documented in the current SIP conveyance draft. I thought the
same but assumed Andy was confining it to the concerns of the Geopriv
group? Not sure of the theory here - perhaps consistency with other
working groups should not impinge on the processes of the WG. Is that
the story Andy?

Cheers,
Martin

> From: Roger Marshall [mailto:[email-masked]]
> Sent: Wednesday, 13 September 2006 1:53 AM
> To: Andrew Newton; [email-masked]
> Subject: RE: [Geopriv] coming to terms on location by reference
> 

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From: Andrew Newton <[email-masked]>
Date: Tue, 12 Sep 2006 13:15:45 -0400

> working groups should not impinge on the processes of the WG. Is that

The SIP conveyance document started life as a GEOPRIV milestone.  It is a 
SIP document because the IETF requires all extensions to SIP to go through 
the SIP working group.

With regard to the ECRIT requirement mentioned by Roger, I think it is 
important to note that the quoted requirement is about the mapping protocol 
and not about conveyance itself (not to mention that location-by-reference 
requirement is a MAY and not a MUST).

-andy

---

From: "Dawson, Martin" <[email-masked]>
Date: Tue, 12 Sep 2006 17:21:24 -0500

Thanks Andy. What is the relationship, then, between the SIP conveyance
having started as a Geopriv milestone and the current discussion? Does
the former anticipate the latter in any case? That is, does it not
indicate acceptance of location by reference already? Or is the
discussion now focused directly on how the reference is "discovered" by
the device and in particular whether it's a function of the location
acquisition protocol?

Cheers,
Martin

> Sent: Wednesday, 13 September 2006 3:16 AM
> To: Dawson, Martin
> Cc: Roger Marshall; [email-masked]
> Subject: Re: [Geopriv] coming to terms on location by reference
> 
> Dawson, Martin wrote:

---

From: Andrew Newton <[email-masked]>
Date: Tue, 12 Sep 2006 21:01:56 -0400

On Sep 12, 2006, at 6:21 PM, Dawson, Martin wrote:

> indicate acceptance of location by reference already?

I would not consider location-by-reference for conveyance a settled  
matter.

> Or is the

If by acquisition and discovery you mean what we have been calling a  
location configuration protocol, then the two are not necessarily  
directly coupled.  It is possible to have an LCP with references that  
requires the UAC to dereference its location so that it may convey  
that location.

-andy

---

From: "Dawson, Martin" <[email-masked]>
Date: Tue, 12 Sep 2006 20:23:54 -0500

Agreed - but I guess it's still not clear to me where you'd like the
current discussion to go. Since location-by-reference is established in
a number of places, what WG deliverable would the current discussion
(i.e. this thread) have a bearing on?

Cheers,

Martin

________________________________

From: Andrew Newton [mailto:[email-masked]] 
Sent: Wednesday, 13 September 2006 11:02 AM
To: Dawson, Martin
Cc: Roger Marshall; [email-masked]
Subject: Re: [Geopriv] coming to terms on location by reference

Or is the

acquisition protocol?

If by acquisition and discovery you mean what we have been calling a
location configuration protocol, then the two are not necessarily
directly coupled.  It is possible to have an LCP with references that
requires the UAC to dereference its location so that it may convey that
location.

-andy

---

From: Andrew Newton <[email-masked]>
Date: Tue, 12 Sep 2006 21:34:26 -0400

On Sep 12, 2006, at 9:23 PM, Dawson, Martin wrote:

> Agreed – but I guess it’s still not clear to me where you’d like  
> the current discussion to go. Since location-by-reference is  
> established in a number of places, what WG deliverable would the  
> current discussion (i.e. this thread) have a bearing on?
It could have consequences for both conveyance and configuration, one  
or the other, or neither.

-andy