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RE: Using urn:publicid: for namespaces

From: <Patrick.Stickler@nokia.com>
Date: Mon, 13 Aug 2001 10:23:21 +0300
Message-ID: <2BF0AD29BC31FE46B78877321144043114BF7E@trebe003.NOE.Nokia.com>
To: sean@mysterylights.com, scranefield@infoscience.otago.ac.nz, www-rdf-interest@w3.org



> -----Original Message-----
> From: ext Sean B. Palmer [mailto:sean@mysterylights.com]
> Sent: 11 August, 2001 04:00
> To: Stickler Patrick (NRC/Tampere); 
> scranefield@infoscience.otago.ac.nz;
> www-rdf-interest@w3.org
> Subject: Re: Using urn:publicid: for namespaces
> 
> 
> > *but* the QName to resource URI problem is a "show
> > stopper" (i.e. a critical problem that has to be fixed, and
> > soon).
> 
> Why can't you model a QName as an anonymous resource? I did send a
> letter about this to www-rdf-interest a short while ago; perhaps you
> missed it :-)

I must have. Can you send me a copy?
 
> Basically, the concept is that the QName:-
> 
>    {http://www.w3.org/1999/xhtml}title
> 
> as an element can be modelled as:-
> 
> [ :ns <http://www.w3.org/1999/xhtml>; :expEType "title" ] .
> 
> and so on. See the appendices of the XML Names specification for a
> detailed description of the grammar. It's a shame that it does not set
> out URIs for these terms, and it would be good if the W3C could do
> that.

Firstly, I don't see how the above is a valid URI. If we simply
mapped all QNames to some non-combined syntax such as {ns}name,
such that the result was a URI, that would be fine insofar as
QNames are concerned, but it doesn't address the fact that many
literal values in serialized RDF/XML instances really represent
resources that need explicit URIs rather than just being passed
through as literals. Also, whatever mapping is employed, it must
be the only allowed mapping and all conformant RDF parsers must
follow it (see below).

> > The following is a proposal for extensions/refinements of RDF
> > and RDF Schema with the aim of achieving modular, scalable and
> > generic interchange of knowledge for the Semantic Web.
> 
> Note that BSWL [1] contains some attributes that serve a similar
> function to your proposal (i.e. add XML QName referencing to the
> syntax rather than the model). I'm not sure whether I'd prefer to see
> it in the model (as I suggested above), or in the syntax (as you
> suggested, and as I added to BSWL).
> 
> [1] http://infomesh.net/2001/07/bswl/

Yes, but BSWL is "after the fact". Once we're in the realm of
triples, the current RDF/XML serialization encoding is irrelevant.

The problem I am focusing on in my proposal is getting from
RDF/XML instances to triples such that no matter what RDF parser
you are using, so long as it conforms to the standard, you will
get exactly the same set of triples with the exact same URIs
for resources, such that e.g. something like BSWL could be used
to pass triples between RDF engines without going back out to
RDF/XML (which IMO was really meant for humans anyway).

If one RDF parser gives you ns:name -> nsname and another
gives you ns:name -> ns#name and yet another gives you 
ns:name -> 'ns'name (a'la SWI Prolog + RDF) and yet another
gives you ns:name -> urn:qname:ns/name, etc. etc. then we
have IMO a broken standard and there is *no* possibility of interchange
of information between agents as presumed by BSWL.

IMO it is the underlying conceptual model of triples that is the
real value of RDF, and the serialization issues are entirely
secondary. They are a means to an end, to get the knowledge into
triples. They are necessary, since humans will be creating most
of that metadata, and humans need an approachable syntax with
minimal keystroke overhead -- but if the standard does not ensure
that *every* RDF parser produces *precisely* the same set of
triples, including the QName to URI mappings, then we will face
many unecessary and avoidable challenges in the future as we try to
achieve a truly global and interoperable semantic web.

Furthermore, since humans need a means of easy data entry, and
would prefer to enter 'en' for language rather than something
like "http://some.authority.com/languages/English", and since
we really want our SW Agents to deal with resources rather than
literals as much as possible, we need to map the literal 'en'
to the more informative and useful resource URI *and* in a way
specified by the standard so that, again, *every* RDF parser
maps it correctly and consistently.

Things like BSWL only become possible and useful *if* the QName
to URI mapping problem is solved within the RDF standard itself.

Cheers,

Patrick

--
Patrick Stickler                      Phone:  +358 3 356 0209
Senior Research Scientist             Mobile: +358 50 483 9453
Software Technology Laboratory        Fax:    +358 7180 35409
Nokia Research Center                 Video:  +358 3 356 0209 / 4227
Visiokatu 1, 33720 Tampere, Finland   Email:  patrick.stickler@nokia.com
 
Received on Monday, 13 August 2001 03:23:40 GMT

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