W3C home > Mailing lists > Public > www-rdf-interest@w3.org > May 2001

Re: QName Problem Isn't One

From: Aaron Swartz <aswartz@swartzfam.com>
Date: Tue, 08 May 2001 20:54:33 -0500
To: Jonathan Borden <jborden@mediaone.net>, "Sean B. Palmer" <sean@mysterylights.com>, RDF Interest <www-rdf-interest@w3.org>
Message-ID: <B71E0D87.B078%aswartz@swartzfam.com>
Jonathan Borden <jborden@mediaone.net> wrote:

> This discussion has become hopelessely confused. When such is the case it
> ought be a strong signal that problems exist, and people should be very
> hesistant to design systems with so much ambiguity.

I do not agree at all. Just because someone cannot understand a system, does
not necessarily mean it is flawed. It may mean that it is complicated, or
that the person trying to understand it has some issues to sort out. It is
not necessarily so that the system itself is at fault.

> I am sympathetic to the goal of using XML Schema datatypes in RDF, indeed

I too, wish to achieve this goal.

> using the simplified/strawman syntax that I and others have proposed (see
> http://www.openhealth.org/RDF/rdf_Syntax_and_Names.htm) several of the
> 'problems' with the DAML proposal to use XML Schema datatypes would vanish.
> So my criticism is not so much of the DAML proposal, as pointing out the
> need for the 'new RDF' to adopt these proposed changes [...]

All I am merely asking is what are these 'problems' that you speak of. You
propose a solution, but I want to know the problem it is solving first.

> A few points:

Points 1-3 seem true to me but are irrelevant. I don't see what they have to
do with the issue at hand.

> 4) If you aren't going to use the XML Schema QNames to refer to datatypes,
> the so called 'integration' is meaningless. Who really cares if the XML
> Schema URIs are the same if the namespace is different. All XML software
> works on namespace URIs (e.g. XSLT, SAX etc) and if you are going to change
> the namespace URI even by a single character, you mind as well define unique
> RDF datatypes.

I cannot think of any situations where I would want to use the same XSLT or
SAX thing on XML Schema documents as on RDF documents. Could you provide an
example of where this would be important?

> What is the benefit of using XML Schema URIs? Is this benefit
> realized when the namespace is different? What software do people expect
> will be able to work with this?

I think the idea is that we want to leverage the work of the XML Schema
group in a way that is as compatible as possible. By using the URIs for the
datatypes that they (and others schema-authors) define we save ourselves the
trouble of having to redo this work as well as sharing a common base of
types with the rest of XML. This way we can convert the PSVI into RDF and
convert RDF documents into XML Schema-based documents. I think this is very
useful.

What software would you like to see work with RDF?

> 5) If you insist on using a new namespace _DON'T_ use the "xsd" prefix, this
> is totally confusing to people who assume that "xsd" is bound to
> "http://www.w3.org/2001/XMLSchema", if you would simply bind the namespace
> "http://www.w3.org/2001/XMLSchema#" to the prefix "fubar" and refer to this
> as <fubar:decimal rdf:value="35.2"/> then there would be much less
> confusion.

Namespace prefixes are meaningless, but if you feel strongly about this then
you can use something like rxsd:decimal in your documents and as other to do
so. I, however, feel that xsd:decimal means the decimal datatype, and that
people shouldn't have to be confused about what rxsd:* means -- it means the
same thing as xsd:* -- it's just written in a slightly different way.

>>>> This is a tenuous area, I admit. RDF does not state the meaning
>>>> of the namespaces which it uses, but nor does XMLNS.
>>> Yep, and this is the crux of the matter. If XMLNS had clearly
>>> indicated the semantics behind XML namespaces, then we would not be in
>>> this mess.
>> 
>> Rather, I think the opposite. If it had indicated semantics, this
>> mess might
>> exists. As of now, it does not. Why do you think otherwise?
>> 
> 
> XML Schema clearly defines a datatype in terms of a QName. A "decimal" is
> refered to by the QName "xsd:decimal" (xsd bound to
> "http://www.w3.org/2001/XMLSchema")

But such QNames as used by XML Schema are different from those used in
normal XML Namespaces, you must admit. That is,

  <xsd:decimal>1</xsd:decimal>

is a rather different use of QNames than, say:

  <foo xsi:type="xsd:decimal">1</foo>


-- 
[ Aaron Swartz | me@aaronsw.com | http://www.aaronsw.com ]
Received on Tuesday, 8 May 2001 21:54:44 GMT

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