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Need input on new P3P data schema format!

From: Lorrie Cranor <lorrie@cs.cmu.edu>
Date: Wed, 23 Jun 2004 14:27:30 -0400
Message-Id: <FC770A56-C542-11D8-89A3-000A95DA3F5A@cs.cmu.edu>
To: public-p3p-spec <public-p3p-spec@w3.org>

We are almost ready to bring P3P 1.1 to last call, but we have one big 
issue left to resolve:

We have been discussing the possibility of including a new data schema 
format in P3P 1.1. Giles has come up with a proposal [1] that greatly 
improves on the P3P 1.0 format and should make things a lot easier for 
people who are trying to create custom data schema or build 
applications that use custom data schema. He has also come up with a 
tool to translate from the old format to the new format, but says it 
will be very difficult to translate in the other direction. Giles' 
proposal is to continue using the old syntax within a P3P policy to 
reference the base data elements and custom data elements, but to use 
the new syntax for declaring custom data schema. P3P 1.1 user agents 
would be required to be able to parse the new schema syntax but not the 
old (and they would continue being required to parse the old syntax for 
references to data elements).

The working group had previously adopted a set of backwards 
compatibility guidelines for P3P 1.1 [2]. Giles' proposal breaks 
backwards compatibility because

a) P3P 1.0 compliant web sites that use custom data schema could not be 
processed by P3P 1.1 user agents (and the only site we know about like 
this is ibm.com)

b) P3P 1.0 user agents would not be able to parse P3P1.1 sites that use 
custom data schema (but most P3P user agents don't actually parse the 
custom data schemas anyway, so this will only impact Privacy Bird and 
the JRC tool).

On the other hand, this improved syntax may help encourage people to 
use custom data schema and it may facilitate interactions with EPAL 
tools, semantic web tools, etc.

If it is feasible to create a tool to translate from new to old format, 
then we don't have any backwards compatibility problem -- we are 
looking into this, but there are some doubts about it.

We really need input from implementers (and anyone else with an 
opinion) on this. I would like to have more discussion on the mailing 
list so that we can make a FINAL decision on this on our July 21 call 
and proceed to last call shortly there after.


1. http://lists.w3.org/Archives/Public/public-p3p-spec/2004May/0014.html
2. http://www.w3.org/P3P/2003/05-backwards.html
Received on Wednesday, 23 June 2004 14:27:36 UTC

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