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

Re: Dedicated, Standardized URI Scheme for QNames?

From: Sean B. Palmer <sean@mysterylights.com>
Date: Tue, 21 Aug 2001 21:06:02 +0100
Message-ID: <003d01c12a7c$d7cf8fa0$c9d993c3@Palmer>
To: <Patrick.Stickler@nokia.com>
Cc: <www-rdf-interest@w3.org>
> [...] the following accomplishes the same, but in a more
> compact form:
>
>   <qn:title:http://www.w3.org/1999/xhtml>
>      a :ExpEName .

So, if I wanted to point to the ExpAType QName, I'd have to use the same
URI?

<qn:title:http://www.w3.org/1999/xhtml>
   a :ExpAType .

Well, that's not going to work... what if you want to refer to the ExpEName
and ExpAType (element and attribute QNames) in the same document (which is
more than likely)?

Doing it the other way is non-ambiguous:-

<http://www.w3.org/1999/xhtml#element_title>
   a :ExpEName;
   :namespace <http://www.w3.org/1999/xhtml>;
   :name "title" .

<http://www.w3.org/1999/xhtml#attribute_title>
   a :ExpAType;
   :namespace <http://www.w3.org/1999/xhtml>;
   :name "title" .

> Since you *have* to define the contextual distinction of
> element QName versus attribute QName, etc. explicitly
> in the RDF, I see no reason why it is the qn URI that has
> a problem. It offers no more nor less information in that
> regard than the directly concatenated URI.

Except that you don't have to directly concatenate it, e.g. in the example
above, so no. It's not only certain URIs that can be used to refer to
QNames of a given partition... it's any URI, as long as that URI isn't
already being used to identify something.

[...]
> I don't see how namespace partitions belong in the URI scheme,
> since the URI scheme only defines *QNames* not how they are
> used in any given model or instance.

As long as the information is in there somewhere, I don't care too much
(others may disagree with me here), but your scheme appears to still have
to use the same identifier for two totally separate resources. That's
forbidden.

You could only fix it by either adding the partition information to the URI
scheme (noting that you'd have to add element and attribute QName
information sometimes, per the XML Namespace specification), or by dropping
this diversion and using any suitable generic URI/URI-Reference that the
world has come up with to date.

> As far as I can tell, all you are doing is taking the existing
> (broken) mapping function and making statements about
> the derived URI.

Ugh, why do you keep getting stuck on that? I can use *any* URI that I have
the power to use! As long as it doesn't already identify something, is
using an appropriate scheme, etc.

> the elements
>
>   <foo:def xmlns:foo="urn:x:abc">
>   <bar:ef xmlns:bar="urn:x:abcd">
>
> gives us
>
>   <urn:x:abcdef>
>      a :ExpEName;
>      :namespace <urn:x:abc>;
>      :name "def" .

Not necessarily. I could invent any URI to refer to those QNames.

<http://urn.org/x/#abc_def>
   a :ExpEName;
   :namespace <urn:x:abc>;
   :name "def" .

<http://urn.org/x/#abcd_ef>
   a :ExpEName;
   :namespace <urn:x:abcd>;
   :name "ef" .

> [...] Who knows, maybe XTM will rule the SW...

I doubt it, but for some applications, XTM may be better. RDF and XTM each
have their own particular characteristics.

--
Kindest Regards,
Sean B. Palmer
@prefix : <http://webns.net/roughterms/> .
:Sean :hasHomepage <http://purl.org/net/sbp/> .
Received on Tuesday, 21 August 2001 16:05:59 GMT

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