- From: Andy Seaborne <andy.seaborne@epimorphics.com>
- Date: Fri, 18 Nov 2011 13:29:06 +0000
- To: public-rdf-wg@w3.org
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/ rdf:PlainLiteral appear very late in the OWL/RIF WG cycle. > >> 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. 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
Received on Friday, 18 November 2011 13:29:34 UTC