- From: Peter F. Patel-Schneider <pfps@research.bell-labs.com>
- Date: Thu, 22 Aug 2002 08:27:48 -0400
- To: dave.beckett@bristol.ac.uk
- Cc: thabing@uiuc.edu, www-rdf-interest@w3.org
From: Dave Beckett <dave.beckett@bristol.ac.uk> Subject: Re: Using XMLSchema-instance attributes in RDF/XML Syntax Date: Thu, 22 Aug 2002 12:57:25 +0100 > >>>"Thomas G. Habing" said: > > > > 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." > > Since I'm the editor of the latter, I'll respond. > > Nobody has ever raised it as an issue, that's why it is not there. The issue of treating xsi:type specially in RDF/XML *has* been raised several times, including my message http://lists.w3.org/Archives/Public/www-rdf-comments/2002JulSep/0024.html xsi:type has been mentioned in at least 69 messages on the w3c-rdfcore-wg mailing list, including http://lists.w3.org/Archives/Public/w3c-rdf-core/2001Oct/0600.html and http://lists.w3.org/Archives/Public/w3c-rdf-core/2002Apr/0476.html > Using the W3C XML Schema language (henceforth WXS) to validate > RDF/XML is tricky but possible. It is? Where is the XML Schema schema document for RDF/XML then? I'm even interested in an XML Schema schema document for RDF/XML that only uses a fixed collection of properties. > I've never heard that there was an > insistence to scatter xsi:type attributes in RDF/XML data in order to > make WXS work. That sounds like a WXS problem, not RDF/XML's > although I'm surprised you can't separate the schema and the instance > data. I've managed to create such things for Dublin Core in RDF/XML > with WXS. I won't go into the other problems WXS has with RDF/XML here. Well, I think that it would be extraordinarily useful to be able to say in an RDF/XML document that a particular RDF literal had a particular XML Schema datatype. This has nothing to do with making XML Schema work, but has to do instead with providing typing for RDF/XML literals. > > 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. > > This seems a rather ugly solution to the problem with your schema. > Why should just that namespace be ignored? Perhaps because it is the XML Schema namespace? RDF/XML treats the XML namespace specially already. > What about future updates > that are bound to happen with WXS? That would be the reason to treat the entire namespace specially. > A good case could be made for > ignoring say XHTML's namespaces. And so on. Well, it might be reasonable to ignore XHTML's namespace, reserving it for decoration of the document. > Adding a single ignored namespace seems rather hacky. If namespace > ignoring was being added, it would make sense to add a general > rdf:ignoredNamespaces attribute off <rdf:RDF>. This is also ugly and > probably would get complaints from implementors. I'd complain, since > I'm one too ;) > Dave Peter F. Patel-Schneider Bell Labs Research
Received on Thursday, 22 August 2002 08:29:23 UTC