Subject: [Ecrit] Phone BCP: Default Location

From: Hannes Tschofenig <[email-masked]>
Date: Sun, 30 Mar 2008 22:55:28 +0300

"
   AN-23/SP-22 Default locations MUST be marked with method=Default and
   the proxy MUST be identfied in provided-by element of the PIDF-LO.
"

Someone should register the token "default". To my knowledge it is not 
registered.

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From: "Brian Rosen" <[email-masked]>
Date: Sun, 30 Mar 2008 16:18:30 -0400

Yes, I am aware of this.  I will prepare a draft.

-----Original Message-----
From: [email-masked] [mailto:[email-masked]] On Behalf Of
Hannes Tschofenig
Sent: Sunday, March 30, 2008 3:55 PM
To: [email-masked]
Subject: [Ecrit] Phone BCP: Default Location

"

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From: "Winterbottom, James" <[email-masked]>
Date: Sun, 30 Mar 2008 15:33:51 -0500

Actually this is a misuse of the method token.
The method token says how location was determined for inclusion in the PIDF-LO.
The intent I read from this requirement is that the method is attempting to say that the location doesn't represent where the end point is at all,
but is what they have registered as a default location.

I think you need a new element in the PIDF-LO to represent this.
Something like:
<defaultLocation>yes</defaultLocation>

or

<locationRepresents>default</locationRespresents>

Then it could have a value of "current" or "recent" or other kind of subjective things too.

Cheers
James

-----Original Message-----
From: [email-masked] on behalf of Hannes Tschofenig
Sent: Sun 3/30/2008 2:55 PM
To: [email-masked]
Subject: [Ecrit] Phone BCP: Default Location
 
"

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From: "Hannes Tschofenig" <[email-masked]>
Date: Mon, 31 Mar 2008 12:12:29 +0200

Hi Brian, 

I thought about the issue a bit more and I don't think that "default" for the <method> element is actually a good idea at all. 

The method element was supposed to be used for indicating which location determination technique was used to derive the location information. 

"Default" is not really a location determination technique. Instead, what you really want to say is "I have added location information but it is probably of dubious quality since I had nothing else available. Be careful."

Hence, I believe you want to have an indication of the quality of the data you provided. 

Ciao
Hannes

PS: Here is the text from RFC 4117. The usage of "dhcp" should be depricated from the registry since it is not a location determination technique either. Should be replaced by wiremap. Someone should talk to IANA todo that. 

2.2.3.  'method' Element

   The optional 'method' element describes the way that the location
   information was derived or discovered.  An example of this element
   (for a geographical position system) is:

          <method>gps</method>

   The possible values of the 'method' element are enumerated within an
   IANA registry.  Implementations MUST limit the use of this method to
   the values shepherded by IANA.  This document pre-populates the IANA
   registry with seven possible values; see Section 6.1 for more
   information.

   The 'method' element is useful, for example, when multiple sources
   are reporting location information for a given user, and some means
   of determining location might be considered more authoritative than
   others (i.e., a dynamic, real-time position system versus static
   provisioning associated with a target device).  However, note that
   inclusion of 'method' might reveal sensitive information when the
   generator is providing intentionally coarsened location information.
   For example, when a LO is transmitted with 'DHCP' as the 'method',
   but the location information indicates only the city in which the
   generator is located, the sender has good justification to suspect
   that some location information is being withheld.

Ciao
Hannes

-------- Original-Nachricht --------
> Datum: Sun, 30 Mar 2008 16:18:30 -0400
> Von: "Brian Rosen" <[email-masked]>
> An: "\'Hannes Tschofenig\'" <[email-masked]>, [email-masked]
> Betreff: RE: [Ecrit] Phone BCP: Default Location

---

From: "Brian Rosen" <[email-masked]>
Date: Mon, 31 Mar 2008 08:59:27 -0400

No, it represents the best available location of the user.

It was determined by some element who failed to get it by some other method,
and is using a default value which was predefined for that purpose.   The
best available location is the default value, and the method used to
determine it was the 'default' method.

I think it's appropriate as defined.

Brian

-----Original Message-----
From: [email-masked] [mailto:[email-masked]] On Behalf Of
Winterbottom, James
Sent: Sunday, March 30, 2008 4:34 PM
To: Hannes Tschofenig; [email-masked]
Subject: Re: [Ecrit] Phone BCP: Default Location

Actually this is a misuse of the method token.
The method token says how location was determined for inclusion in the
PIDF-LO.
The intent I read from this requirement is that the method is attempting to
say that the location doesn't represent where the end point is at all,
but is what they have registered as a default location.

or

Then it could have a value of "current" or "recent" or other kind of
subjective things too.

Cheers
James

-----Original Message-----
From: [email-masked] on behalf of Hannes Tschofenig
Sent: Sun 3/30/2008 2:55 PM
To: [email-masked]
Subject: [Ecrit] Phone BCP: Default Location
 
"

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From: "Roger Marshall" <[email-masked]>
Date: Mon, 31 Mar 2008 14:17:31 -0700

...Brian Rosen wrote on Monday, March 31, 2008 5:59 AM,

> It was determined by some element who failed to get it by 

I'm not sure I get it.  Are you saying "default", in the sense of
"manually provisioned" only?

Locations in their most basic form are either 
1. <given> (e.g., wiremap), 
2. <measured> (e.g., agps), or 
3. <derived> (e.g., geocoded)
  
Configuration mechanisms have been talked about, such as using a DHCP
server for location acquisition.  I just want to make sure folks don't
think that the answer as to what to put in the PIDF-LO's method element
would be something like <by_dhcp>.  If so, then any info relating to the
3 methods above is gone.  If not, then we need another value in PIDF-LO,
something like:

<configured_by>dhcp</configured_by>

Mostly though, the method value <default> doesn't tell me anything about
the how the location should be characterized.

-roger.

> From: [email-masked] [mailto:[email-masked]] 
> On Behalf Of Brian Rosen
> Sent: Monday, March 31, 2008 5:59 AM
> To: 'Winterbottom, James'; 'Hannes Tschofenig'; [email-masked]
> best available location is the default value, and the method 
> used to determine it was the 'default' method.
> 
> From: [email-masked] [mailto:[email-masked]] 
> On Behalf Of Winterbottom, James
> The intent I read from this requirement is that the method is 
> attempting to say that the location doesn't represent where 
> the end point is at all, but is what they have registered as 
> a default location.
> 
> Someone should register the token "default". To my knowledge 
> it is not registered.
> 

CONFIDENTIALITY NOTICE: The information contained in this message may be privileged and/or confidential. If you are not the intended recipient, or responsible for delivering this message to the intended recipient, any review, forwarding, dissemination, distribution or copying of this communication or any attachment(s) is strictly prohibited. If you have received this message in error, please notify the sender immediately, and delete it and all attachments from your computer and network.

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From: "Winterbottom, James" <[email-masked]>
Date: Mon, 31 Mar 2008 16:34:30 -0500

Hi Roger,

I think I agree with you, which is why I proposed what I did.
I certainly don't believe that the <method> tag should have a value of
default as is being suggested by the current text.

Cheers
James

> From: Roger Marshall [mailto:[email-masked]]
> Sent: Tuesday, 1 April 2008 8:18 AM
> To: Brian Rosen; Winterbottom, James; Hannes Tschofenig;
[email-masked]
> Subject: RE: [Ecrit] Phone BCP: Default Location
> 
> CONFIDENTIALITY NOTICE: The information contained in this message may
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From: "Brian Rosen" <[email-masked]>
Date: Mon, 31 Mar 2008 18:13:51 -0400

Well, maybe.  I don't want to limit default to manually provisioned, but
it's probably the most common way you get it.

The point is that every element that handles an emergency call has to be
prepared to supply a default value.  The closer the element is to the
endpoint, the more likely it is to have a good default value.  In your list,
in most cases, it's <given>.

DHCP is an LCP, not a method.  In most cases, a civic location is a wiremap
and a geo is measured by GPS or triangulated by APs.  It isn't always so,
but that's probably good enough.

Default is a method.  You got it some basic way (usually configured).  We
used an example of a CMTS area for a cable system.  If the LIS failed to
determine a location, or a proxy server needed to add location, using some
location in the CMTS service area may be a decent default location.  The
"some location" is configured.

When you have a default location, you don't have some other method.  If you
did, you would use it, and you wouldn't need a default.

Brian

-----Original Message-----
From: Roger Marshall [mailto:[email-masked]] 
Sent: Monday, March 31, 2008 5:18 PM
To: Brian Rosen; Winterbottom, James; Hannes Tschofenig; [email-masked]
Subject: RE: [Ecrit] Phone BCP: Default Location

  

-roger.

> Someone should register the token "default". To my knowledge 

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From: "Winterbottom, James" <[email-masked]>
Date: Mon, 31 Mar 2008 19:22:57 -0500

Let's agree to disagree on this.
I see method as a means of describing how the location of the Target was
determined. What is being described by a value of default is that the
location bears no perceivable relationship to the Target, but is being
provided because we want the call to be answered. This is a measure of
the quality of the location information, and this requires a separate
indicator.

If everybody disagrees me on this then I will let it drop, but I think
it is a slippery path to follow.

Cheers
James 

> From: Brian Rosen [mailto:[email-masked]]
> Sent: Tuesday, 1 April 2008 9:14 AM
> To: 'Roger Marshall'; Winterbottom, James; 'Hannes Tschofenig';
> [email-masked]
> When you have a default location, you don't have some other method.
If
> you
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or
and