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RE: Using XMLSchema-instance attributes in RDF/XML Syntax (fwd)

From: <Patrick.Stickler@nokia.com>
Date: Thu, 22 Aug 2002 22:13:27 +0300
Message-ID: <A03E60B17132A84F9B4BB5EEDE57957B5FBA9C@trebe006.europe.nokia.com>
To: <thabing@uiuc.edu>
Cc: <danbri@w3.org>, <w3c-rdfcore-wg@w3.org>


Thomas,

Could you please have a look at

http://lists.w3.org/Archives/Public/w3c-rdfcore-wg/2002Aug/0187.html

Would the use of inlined datatype elements be a suitable representation 
for validating datatyped literals with an XML Schema validator?

Thanks,

Patrick

> -----Original Message-----
> From: ext Thomas G. Habing [mailto:thabing@uiuc.edu]
> Sent: 21 August, 2002 20:51
> To: Stickler Patrick (NRC/Tampere)
> Cc: ext Dan Brickley; w3c-rdfcore-wg@w3.org
> Subject: Re: Using XMLSchema-instance attributes in RDF/XML 
> Syntax (fwd)
> 
> 
> Hi Patrick,
> 
> I appreciate the reply, even if it isn't what I wanted to 
> hear :-)  If I
> understand correctly, you are saying that, for various 
> reasons, it is not
> appropriate to ever expect to be able to validate an RDF/XML 
> instance using
> XML Schema (except possibly through some non-standard means such as
> transforming some hybrid RDF/XML into different forms 
> depending on whether
> RDF or XML Schema processing is desired).  This seems 
> unfortunate since my
> vision of the two is complimentary instead of competing.
> 
> I can appreciate the desire to unify RDF and XML Schema, but 
> I would suggest
> that at least for the short term that the unification can be 
> very modest --
> something akin to my original suggestion :-) or some variation such as
> http://lists.w3.org/Archives/Public/www-rdf-interest/2002Aug/0
> 124.html. 
> Then at least it will be possible to create a valid RDF/XML 
> that can be
> validated with XML Schema.  If the grand unification of RDF 
> and XML Schema
> is closer than I think it is, that would be great and you can 
> skip this
> short term step, but I suspect it will be a while before I see an RDF
> datatyping spec which unifies the two, much less widely supported,
> non-experimental tools that support everything that XML 
> Schema currently
> supports, such as regular expressions patterns, unions of datatypes,
> extension and restriction of datatypes based on facets, etc.  
> (I just now
> scanned some of the OWL specs, and they look promising, but I 
> am sticking to
> my current convictions for the moment :-)
> 
> I have also interspersed some additional comments below.
> 
> Respectfully submitted,
> 	Tom Habing
> 
> Patrick Stickler wrote:
> > 
> > Thanks for the pointer Dan. I was about to reply
> > directly to Thomas on this.
> > 
> > I can very much appreciate the utility that would be
> > afforded XML Schema users in being able to express
> > local datatyping using xsi:type, but there remain several
> > questions about its use that have not been clarified:
> > 
> > 1. Must the datatype identified by xsi:type conform to
> > the XML Schema specification? Some preliminary
> > research I've done to determine this shows a strong
> > perception that this is true. Yet RDF datatyping should
> > work equally well for any arbitrary datatype which
> > conforms to the minimal characteristics defined by
> > RDF, including but not limited to  XML Schema datatypes.
> 
> My answer to this is, of course xsi:type should conform to 
> the XML Schema
> specification; that's the whole point.  Why can't RDF 
> datatyping and XML
> Schema datatyping coexist?
> 
> > 2. Will the XML Schema WG/community have a problem
> > with RDF adopting xsi:type as a key term in its own
> > vocabulary if that  means extending
> > or interpreting its semantics to apply to datatypes not
> > bound by the XML Schema specs. I suspect not.
> 
> Because I want to see RDF and XML Schema peacefully coexists, 
> I disagree. 
> Based on the above, the whole purpose of xsi:type is to 
> indicate that some
> part of a document should conform to some type defined in an 
> XML Schema. 
> Therefore, I believe this is the only way that xsi:type should ever be
> used.  RDF should never use xsi:type (except to ignore it) 
> unless it can
> also be used in the way expected by XML Schema.
> 
> > 
> > 3. Is introducing this co-dependency between the two
> > standards absolutely necessary? One could easily
> > construct a generic tool that incorporates an XML
> > Schema validator and which validates typed literals
> > in RDF/XML instances without parsing the RDF/XML
> > into a graph.
> 
> This may just be semantics, but I wouldn't necessarily call 
> what I suggested
> creating a co-dependency between RDF and XML Schema.  It is more like
> defining a dividing line between RDF and XML Schema -- 
> simply, any attribute
> in the XML Schema Instance (xsi) namespace is within the sole 
> purview of XML
> Schema, and RDF processors should keep their hands off.  Note, I am
> referring only to the XML Schema _Instance_ namespace, not 
> the XML Schema
> namespace (xsd).  I like the idea of using things like <xsd:Integer
> rdf:value='1234'/> and having that interpreted as valid RDF.
> 
> > 
> > Given the other aspects of RDF validation, as well as
> > those of upper layers such as OWL, I expect that in the
> > long term, validation will be performed on the graph,
> > not on the XML, and so any utility derived from adopting
> > xsi:type would be limited and short lived.
> 
> Even so, why can't we have both, if desired, especially for 
> the short term?
> 
> > 
> > While I'm very sympathetic to easy validation of RDF/XML
> > containing XML Schema datatyped literals, I don't think
> > it is advisable to employ xsi:type, for the reasons outlined
> > above.
> > 
> > Cheers,
> > 
> > Patrick
> > 
> > _____________Original message ____________
> > Subject:        Using XMLSchema-instance attributes in 
> RDF/XML Syntax (fwd)
> > Sender: ext Dan Brickley <danbri@w3.org>
> > Date:           Wed, 21 Aug 2002 09:52:49 +0300
> > 
> > of interest re datatyping options...
> > 
> > dan
> > 
> > ---------- Forwarded message ----------
> > Date: Tue, 20 Aug 2002 16:20:31 -0500
> > From: Thomas G. Habing <thabing@uiuc.edu>
> > To: www-rdf-interest@w3.org
> > Subject: Using XMLSchema-instance attributes in RDF/XML Syntax
> > Resent-Date: Tue, 20 Aug 2002 17:20:35 -0400 (EDT)
> > Resent-From: www-rdf-interest@w3.org
> > 
> > Hi all,
> > 
> > I posted the following to www-rdf-comments recently, but it 
> didn't generate
> > any comments or followup, so I am posting here to see what 
> happens :-).
> > Does what I am proposing make sense, is it too simplistic, 
> or am I just
> > missing something?
> > 
> > ---
> > 
> > I have been trying to figure out how I can use the various
> > XMLSchema-instance attributes (especially xsi:type, but 
> also xsi:nil,
> > xsi:schemaLocation, etc.) in an RDF/XML document.  I want 
> to create valid
> > RDF/XML, but at the same time I want to be able to validate at least
> > portions of the RDF/XML using XML Schema.  Some of my XML 
> Schemas require
> > the use of the xsi:type attribute in the instance documents 
> in order to
> > validate.  However, RDF insists on treating these 
> xsi:attributes as RDF
> > property attributes which causes the RDF to be invalid.
> > 
> > I can understand this in the original RDF M&S since it 
> predates XML Schema
> > by a year or so, but I am surprised to see no mention of 
> this issue in the
> > newest "RDF/XML Syntax Specification."
> > 
> > I have seen some of the discussions in the various lists of 
> using xsi:type
> > for data typing in RDF.  I don't claim to understand most 
> of the issues
> > associated with this, but I would like to humbly suggest 
> that at the very
> > least there should be some language in the "RDF/XML Syntax 
> Specification" to
> > the effect that attributes in the XMLSchema-instance 
> namespace should be
> > ignored by RDF parsers, similar to what is done with the 
> xml* attributes.
> > 
> > Thanks,
> >         Tom
> > --
> > Thomas Habing
> > Research Programmer, Digital Library Projects
> > University of Illinois at Urbana-Champaign
> > 155 Grainger Engineering Library Information Center, MC-274
> > thabing@uiuc.edu, (217) 244-4425
> > http://dli.grainger.uiuc.edu
> 
> -- 
> Thomas Habing
> Research Programmer, Digital Library Projects
> University of Illinois at Urbana-Champaign
> 155 Grainger Engineering Library Information Center, MC-274
> thabing@uiuc.edu, (217) 244-4425
> http://dli.grainger.uiuc.edu
> 
Received on Thursday, 22 August 2002 15:14:52 EDT

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