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RE: Trouble with data schema

From: Giles Hogben <giles.hogben@jrc.it>
Date: Wed, 06 Jul 2005 12:03:33 +0200
To: "'Rigo Wenning'" <rigo@w3.org>
Cc: "'Lorrie Cranor'" <lorrie@cs.cmu.edu>, public-p3p-spec@w3.org
Message-id: <004401c58211$f7ff0f30$5f2abf8b@cs.jrc.it>

Hmmmm - I didn't mean that you can't keep using the old categories. I just
mean to simplify the syntax, let's forbid them in future. The point is that
in any new schema, broad categories could simply be expressed as e.g. :

<navigation><cookie/></navigation>

OR

<demographic><vehicle><color/></vehicle></demographic>

One possibility would be to offer them as elements in the new XSD BDS so
that the weird syntax string based ones disappear completely in new schemas
and you just use the element to hook new data elements onto.

We could even turn the XSD schema up on its head and get rid of the string
based categories so that the XSD defines the categories as elements with the
category would then be at the top level in the data element and details
would be hooked on below.

E.g.

<navigation><cookie/></navigation>

You could also write them without categories unless they were dynamic

<user><online><uri/></online></user></navigation>

Agents would match elements like <navigation/> to all the allowed
subelements of <navigation>

This would mean quite a lot of rewriting the transforms etc... I estimate 2
weeks extra work. It may also have nasty implications for APPEL. Any
thoughts.


-----Original Message-----
From: public-p3p-spec-request@w3.org [mailto:public-p3p-spec-request@w3.org]
On Behalf Of Rigo Wenning
Sent: Wednesday, July 06, 2005 11:28
To: Giles Hogben
Cc: 'Lorrie Cranor'; public-p3p-spec@w3.org
Subject: Re: Trouble with data schema


Am Wednesday 06 July 2005 09:27 verlautbarte Giles Hogben :
> I would like to propose a simplification which there is still time to 
> put in the spec. We include categories in the Base Data Schema for 
> backward compatibility - but we disallow them in custom schemas from 
> now on.

I don't get you here. One of the features of the category system was, 
that new custom data elements could be attached to the existing broad 
categories thus giving the custom elements some meaning. This meaning 
would then be easier to understand for user agents.

***There is nothing to stop you doing that.

> If you want to put in broad categories, there's nothing stopping you
> - you just have to make them into data elements which subsume the 
> narrower categories. There's no need for a completely different and 
> confusing syntax.

Can you give an example how this would look like?

> Yes it's because of XSD. Basically because each
> data element takes a subset of categories from a global set, this is
> only possible with a custom data type (or at least that's the only
> way we could find to do it and we consulted some XML lists)...

Can we say that we don't allow for NEW categories? Because in your 
example in the Spec, you say:

<element minoccurs="0" maxoccurs="1" name="musical-preference">
  <element minoccurs="0" maxoccurs="1" ref="classicalmusic-preference"/>
    <annotation>
      <documentation>
        Musical Preferences
      </documentation>
    </annotation>
    <element ref="CATEGORY" minoccurs="0" maxoccurs="*" 
             type="allCategories"/>
  </element>

So if you wanted new <category> - Elements, you would have to make them 
available in a custom XML Schema? How would that fit in our framework?

Best, 

Rigo
Received on Wednesday, 6 July 2005 10:04:03 GMT

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