Subject: Re: Notes from Non-meeting

From: Ricardo Cuellar <[email-masked]>
Date: Thu, 21 Mar 2002 01:49:08 +0100

Brian wrote:
> One of the things that keeps getting us "wrapped around the
> axle" is that we can't seem to separate four different aspects
> of this work:

<snip>

> 4. The cryptographic operations needed to protect the object
> when it is transported, and possibly as part of the implementation
> of the policy.

I am missing the main point of the charter:
"assess authorization, integrity and privacy requirements to transfer or authorize via policies the release of location information, for different applications, in different layers, mandatory for implementation of location-aware protocols"

This is NOT choosing the crypto operations needed.

<snip>

> We had a really short discussion on terminology. The discussion
> centered around the word "target". The basic confusion is
> whether the target is an object like a cell phone, a collection
> of objects like a cell phone a pager and a PDA, or a person
> carrying all of the above.

> Henning observed that we should use "object oriented" language,
> and thus talk about the person object inheriting location from
> the cell phone object. The set of objects (cell/pager/PDA) problem
> was observed to be a case of multiple inheritance but unlike in
> computer science, not an inherently hard problem to solve :)

The problem with this solution is the dynamics of the "inheritance".
If you use a certain laptop (or cell phone) and logon entering
your password, then your location is now linked to the location
of the device. Now the important point is that the person
who decides the policies for the location information changes.

I do not see why the special case of a "target" being a "device"
makes life easier. The more general case is indeed needed
in many scenarios (like the multi-user PC).

Best regards,

Jorge

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From: Henning Schulzrinne <[email-masked]>
Date: Thu, 21 Mar 2002 07:56:42 -0600

Location information in a protocol only makes sense if it is associated
with some identifier. Thus, I don't think that general discussion about
the location of a cellphone vs. a person is sufficiently precise. It
makes sense to say "identifier X in protocol Y has location property Z,
where Y can be a location-specific protocol or a protocol whose primary
purpose is something other than conveying location. It's users who then
make associations with people, buses, taxis or other objects. We don't
have intrinsic identifiers for these objects, certainly not a single
one.

---

From: "James M. Polk" <[email-masked]>
Date: Thu, 21 Mar 2002 09:13:59 -0600

At 07:56 AM 3/21/2002 -0600, Henning Schulzrinne wrote:
> It's users who then

Until we're each implanted with something   ;-)

Otherwise, I agree with Henning here. People can make whatever associations
they want of two or more *things* that are related (temporarily) but not
physically joined as one. Today and for the past several decades it has been
true that I am associated with my home phone number (of which the choice to
list publicly or not has been *mine*). Today, if you call me there, I won't
answer because I'm not there. The association isn't dynamic enough to move that
association to the phone in my hotel room. My solution is my cellphone that I
carry with me (that works in North America only which is another issue). People
know that if they call me on my cellphone they will get me or *my* VM service
which is personal and associated with me. If I put my cellphone down and leave
it (hopefully temporarily) - any call goes to VM; but I can't make an emergency
call at that point either when it isn't with me. Until that device is
implanted, it's the best association with me and technology associated with me
-- so it's a fair association IMO that I will choose to maintain.

The idea of inheritance makes a great amount of sense when the human (target)
has some mechanism of control over that association (in a Location Server
interface I configure the rules of, for example). If I carry a pager too, but
you don't know the difference from a target label point of view, I'm still the
target you wish to get to through my cellphone. 

Inheritance puts the burden on me to choose which appropriate device represents
*me* to a Location Service, if I choose anything at all (which might be me
temporarily getting away from it all). The requester shouldn't have to keep up
with what I'm carrying at that moment, just that *something* is with me, and
you can get to me through it (if I allow you at that moment if ever).

*************************************
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James M. Polk
Consulting Engineer
Office of the CTO

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