Subject: [Geopriv] Re: [Simple] xcap/geopriv alignment issue 5: permission data type s

From: Jonathan Rosenberg <[email-masked]>
Date: Thu, 04 Dec 2003 01:23:09 -0500

inline.

Tschofenig Hannes wrote:

> hi jonathan, 
> 
> ~~ snip~~ 
> 
>>I did look at the slides, but I dont see or understand the problem. 
>>WHy is the result counter-intuitive? It says that the civil location 
>>that gets distributed is at the city level, and the D flag is TRUE. 
>>Seems OK to me... maybe I am missing something...
> 
> 
> the result is perfectly fine from the perspective of the permission
> combining algorithm. 
> 
> let me consider the example again: 
> 
> i want to disclose location information at a coarse granularity (in this
> case country) for everyone (and additionally allow them to further
> distribute this location information). 
> additionally i specify a second rule which says that one particular person
> is allowed to see my detailed location (city in this case) but i do not want
> to allow the distribution of this information (= D-flag set to false). 
> 
> usually someone would assume that the outcome is that allison requesting
> location information would not be allowed to further distribute information.
> however, based on the rule combining algorithm this is not the case. 
> 
> you can easily extend this example to other attributes (e.g., encryption). 
> 
> don't you think that this is counter-intuitive?

I can see how it may not be the result you might want, but I dont 
think its counter-intuitive. Its a natural consequence of the two key 
properties here - orthogonality of permissions and additivity of 
permissions. The problem is that you don't want the D flag to really 
be orthogonal to the transformation applied to the data. Rather, you 
want it to be more of an integer, like the location granularity 
itself, that specifies the maximum level of detail which is allowed to 
be distributed.

Using this model, your two rules would be:

<applies-to>
   <any/>
</applies-to>

<civil>country</civil>
<distribute-up-to>country</distribute-up-to>

and

<applies-to>
   <uri>sip:[email-masked]</uri>
</applies-to>

<civil>city</civil>

For Allison, she would get city information, but she, like everyone 
else, is only allowed to distribute inforamtion about my country. By 
structuring the "D flag" in this way, it can once again be orthogonal 
to the other permissions.

This is becoming more of a geopriv discussion, so I am cc'ing geopriv. 
I know folks dont like cross-posting, but I suspect there are enough 
folks on geopriv and not simple that it is probably the right thing here.

-Jonathan R.

-- 
Jonathan D. Rosenberg, Ph.D.                600 Lanidex Plaza
Chief Technology Officer                    Parsippany, NJ 07054-2711
dynamicsoft
[email-masked]                     FAX:   (973) 952-5050
http://www.jdrosen.net                      PHONE: (973) 952-5000
http://www.dynamicsoft.com

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