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(unknown charset) Re: do XML Datatypes work for RDF?

From: (unknown charset) Dan Brickley <danbri@w3.org>
Date: Sat, 19 Feb 2000 12:44:54 -0500 (EST)
To: (unknown charset) www-rdf-interest@w3.org
Message-ID: <Pine.LNX.4.20.0002191230410.15923-100000@tux.w3.org>

RDF IG,

I'd like to set a deadline for RDF IG review comments on this topic, which
I'll then summarise, circulate here, and pass back to the XML Schema
folks. Can anyone with an interest in this please post a response to Dan's
message within the coming week. I'll then summarise over weekend of 2000-02-25. 

So:  review comments to the list please by 2000-02-24 (next friday)

As a rule for making progress, bear in mind that objections to specific
technical proposals are far more likely to be listened to if they're
accompanied by a positive proposal. That said, this shouldn't stop RDF IG
members pointing out possible technical difficulties simply because they
can't see how to fix the situation. We need to bear in mind that the
outcome of this review may ultimately feed into the TODO list of the XML
datatypes editors; consequently positive proposals should accompany any
critique of their existing specification.

Thanks for your careful attention on this topic. The RDF specs took care
to try to anticipate the XML datatypes work, but I feel we need input at
this point from RDF implementors to give a firm answer to Dan's questions.

Dan

--
RDF Interest Group chair
mailto:danbri@w3.org



On Wed, 16 Feb 2000, Dan Connolly wrote:

> Short version: the datatypes part of the XML Schema specs
> doesn't specify a URI for each primitive type (boolean,
> float, double, etc.) but only a URI for all these types.
> Is that good enough for RDF use cases?
> 
> Details:
> 
> The RDF schema WG had an issue(c21) about external type systems;
> part of that issue specifically regarded "IEEE floating point numbers,
> Integers, Boolean values, Dates and Times, etc". The
> issue was deffered, pending an XML-wide solution for such
> primitive datatypes. The spec sketches, in example 2, how
> this is expected to work:
> 
> <rdfs:range
> rdf:resource="http://www.datatypes.org/useful_types#FloatZeroToOne"/>
> 	-- http://www.w3.org/TR/1999/PR-rdf-schema-19990303/
> 
> In the XML Schema WG, we're preparing for last call, which
> is when we say "all the issues we can find are resolved;
> what do you think?" but it's also a time to say "we think
> we've met our requirements... do you agree?"
> 
> The XML Schema requirement that I proposed to represent
> the postponed RDF schema issue turned into:
> 
> "The XML schema language must define:
> 
> [...]
>    3.mechanism for URI reference to standard semantic understanding of a
>      construct; "
> 	-- http://www.w3.org/TR/1999/NOTE-xml-schema-req-19990215#Structural
> 
> The WG isn't exactly sure what that means... we agreed in Mar '99 to
> clarify it
> but we haven't come up with replacement wording since. I was thinking
> that it meant we would supply, explicitly, a URI for each of
> boolean, float, double, etc. If that's what it means, we haven't met
> it. But I need more clear wording to take to the XML Schema WG, along
> with use cases, in order to make the case.
> 
> I suppose we could use
> 	http://www.w3.org/TR/1999/WD-xmlschema-2-19991217/#boolean
> for the value of the rdf:range property, but that doesn't work
> for user-defined derived types.
> 
> The schema spec provides an answer of sorts:
> 
> "we observe that
> [XPointer] provides a mechanism which maps well onto our notion of
> symbol spaces.
> An fragment identifier of the form
> #xpointer(schema/element[@name="person"]) will
> uniquely identify the element declaration with name person, and similar
> fragment
> identifiers can obviously be constructed for the other top-level symbol
> spaces."
> http://www.w3.org/TR/1999/WD-xmlschema-1-19991217/#ref-schema
> 
> Is that good enough?
> 
> 
> The schema specs also include:
> 
> "RDF Schema 
>      XML Schema: Structures has not yet documented requirements or
>      dependencies. See [Cambridge Communiqué] for a clarification of the
>      relationship between the two, which includes requirements arising
> from web
>      architecture considerations. "
> 	http://www.w3.org/TR/1999/WD-xmlschema-1-19991217/#intro-relatedWork
> 
> but I don't see anything in the Cambridge Communiqué that's relevant.
> 
> The Cambridge Communiqué 
> W3C NOTE 7 October 1999 
> http://www.w3.org/TR/1999/NOTE-schema-arch-19991007
> 
> 
> -- 
> Dan Connolly
> http://www.w3.org/People/Connolly/
> 
Received on Saturday, 19 February 2000 12:44:54 GMT

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