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Re: RDF-ISSUE-80 (rdf:PlainLiteral): Ask OWL and RIF WGs to update the rdf:PlainLiteral spec [RDF General]

From: Sandro Hawke <sandro@w3.org>
Date: Fri, 18 Nov 2011 09:01:07 -0500
To: Andy Seaborne <andy.seaborne@epimorphics.com>
Cc: public-rdf-wg@w3.org
Message-ID: <1321624867.15001.65.camel@waldron>
On Fri, 2011-11-18 at 13:29 +0000, Andy Seaborne wrote:
> 
> On 17/11/11 21:27, Sandro Hawke wrote:
> > On Thu, 2011-11-17 at 20:32 +0000, Richard Cyganiak wrote:
> >> On 17 Nov 2011, at 19:33, Sandro Hawke wrote:
> >>> I think it should actually be this group which does the revision,
> >>> though.
> >>
> >> Why?
> >
> > Because RDF should be the common data model.
> >
> > rdf:PlainLiteral was invented because a group of people trying to build
> > on top of RDF found the data model just too broken to work with.   (They
> > needed something simple and consistent enough on which to build
> > additional logics.)  So, together with everyone who was willing to help,
> > we came up with something that isn't pretty but that does work.
> >
> >> The rdf:PlainLiteral spec defines a datatype that's defined as being usable only *outside* of RDF graphs.
> >
> > That's not a design goal, it's just an aspect of how we had to define it
> > to not break anything existing.    Given RDF 1.1 is willing to make some
> > changes to existing things, it wouldn't necessarily have to be done that
> > way any more.
> 
> s/break/change/

I don't quite see the difference in this case.

> rdf:PlainLiteral appear very late in the OWL/RIF WG cycle.

It was called rif:text for a long time.  It wasn't until the OWL 2 WG
decided it wanted something similar that we started trying to come up
with a shareable name for it. 

> >
> >>   It defines facets for that datatype. It defines XPath functions. None of these things are directly useful for RDF. They all make sense for, and are motivated by, RIF and OWL.
> >
> > If you're going to actually define a useful XML datatype, it makes sense
> > to define facets and XPath functions for it.   The fact that OWL 2 can
> > use the facets and RIF can use the XPath functions helped motivate it,
> > but it seemed like one would want these things anyway.  I mean, if you
> > have a language tagged string, don't you want to be able to constrain
> > and/or act upon the language tag?   So we defined a way to do that which
> > happens to fit neatly into the existing XML datatype mechanisms.   They
> > are in no way just for RIF or OWL -- they are for anyone who wants to
> > use strings with language tags in RDF, using machinery from the XML
> > world.
> >
> > Maybe XML is dead, so this doesn't matter any more?
> 
> XML treats language tag as an orthogonal to datatype
> through xml:lang and through schema datatyping.
> 
> In that sense, RDF-2004 reflected XML quite accurately.

Perhaps, but having another orthogonal component has significant cost.

My point was that *if* you're going to make a datatype that embeds the
language tag into the value, *then* in the XML world it makes sense to
provide facets and functions to get at the text and the language tag.
 
> rdf:PlainLiteral uses a 1-D lexical space for a 2-D value space.  The 
> lang tag does not have the same status as the datatype,
> 
> 	Andy

So, I'm not quite sure what you're arguing here.  I think the issue at
hand is what role the RDF WG should take in updating the
rdf:PlainLiteral spec.   I think we could reasonably do anything on the
spectrum from (1) mention to the other groups they might want to do
something to (10) update the spec ourselves.   I lean closer to (10) but
not strongly enough to take on the work myself.  Mostly I'm happy to
have it done however it's most likely to get done.

   -- Sandro
Received on Friday, 18 November 2011 14:01:21 GMT

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