RE: Expressing XLink concepts in XML Schema
On Sat, 31 Jul 1999, Didier PH Martin wrote: > This is because some are stretching too much the utility of RDF. At its > origin, RDF has been designed as a metadata encoding tool. And XML was designed for structured document interchange, but that's not stopped people having all sorts of unanticipated fun with it... (and can anyone remember what the Internet itself was originally for? ;-) It may well be that RDF is in some quarters being stretched beyond current capabilities. It certainly hasn't suffered the dangerous hype currently afflicting XML, and I personally hope it never does. Appeals to origins don't help much here: is better to argue on technical capabilities. There are certainly many things now missing from RDF which hinder our use of it for Web database-oriented applications. Data aggregation for example turns out to be difficult (even though URI-based graphs provide a solid foundation...) given the modest constraint mechanisms in the proposed Schema 1.0 system. Because we have no notion of cardinality/occurance in 1.0, aggregating overlapping data is hard without having hard-coded additional knowledge of the vocabualries/applicatiosn concerned. This has nothing to do with the origins of RDF, of XML, or of the Internet. It's just an interesting fact about what's currently feasible given the specs on the table. > a) rdf for metadata - to add information to existing resources > b) xlink for resource linkage - to link resources > > This said, we'll have more and more similarities because: > a) all these languages are XML based, > b) we start to see now some common sub languages used across different tools No - the similarity it because RDF describes resources in terms of their relationships with other resources (conceptual and concrete) as well as ascribing simpler flat attributes to those resources. Xlink allows for links to be expressed between document-like resources, and for those knowledge of those relationships to be stored outside the resources concerned. These are clearly overlapping pieces of the same larger puzzle. For my money the XArc proposal goes some way towards addressing potential overlaps here. > like for instance XPath and XPointer (re-united) and the string based > pointer language used in other XML based languages. > > James said: > Also between XML Schemas and RDF Schemas. > > Didier says: > Yes and this is good news because having a single schema language is more > intelligent than having to still live in the Babel tower. I'd rather have a single data model and a family of schema languages built to a common approach... Dan -- Daniel.Brickley@b... Institute for Learning and Research Technology http://www.ilrt.bris.ac.uk/ University of Bristol, Bristol BS8 1TN, UK. phone:+44(0)117-9287096 xml-dev: A list for W3C XML Developers. To post, mailto:xml-dev@i... Archived as: http://www.lists.ic.ac.uk/hypermail/xml-dev/ and on CD-ROM/ISBN 981-02-3594-1 To (un)subscribe, mailto:majordomo@i... the following message; (un)subscribe xml-dev To subscribe to the digests, mailto:majordomo@i... the following message; subscribe xml-dev-digest List coordinator, Henry Rzepa (mailto:rzepa@i...)
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