Re: XSD: RDF and XSchema
Tim Bray wrote: > > This distinction seems questionable. I'd like (potentially) to be able to > issue a query along the lines of "find me elements in this repository > which have a creation-date prior to 1998 and which are of a type that > can have ProjectNumber as a child element." Here is how I understand Tim's argument: Just as the benefit of using XML as an encoding for XSchema is that code and even full applications that have never heard of XSchemas can do interesting things with XSchema documents, the benefit of using RDF as an encoding for XSchemas would be to allow RDF-smart code and even applications to do interesting things with XSchema documents without specifically knowing about XSchema. If this is the important argument, then the "correct" level of RDF use is the level at which this sort of "blind underlayer use" is practical. For instance it makes perfect sense to ask about which element types have a HasAttribute property with value "xml:link". It also makes perfect sense to ask about which documents have a ConformsTo property of "HTML 5.0". But when you get into trying to do queries on content models, you quickly run into a problem. It's easy to check the [element] ---CanContain--> [ProjectNumber] relationship. That's essentially just asking if ProjectNumber is anywhere in element's content model. But try checking that an element type can contain BOTH a ProjectNumber AND a ProjectDescription. That's easy with regular expression theory, but I don't think it can be expressed in RDF alone. The relationship is more complicated than a property/value relationship. This suggests to me that RDF breaks down at that level. I think that RDF should be used to: * describe the relationship between documents and schemata. * describe the relationship between elements and their attributes. But I can't see an intuitive RDF-compatible encoding for content model relationships. Some types of relationships are just outside of RDF's competency. RDF-philes, do you agree? Paul Prescod - http://itrc.uwaterloo.ca/~papresco Three things see no end: A loop with exit code done wrong A semaphore untested, and the change that comes along http://www.geezjan.org/humor/computers/threes.html 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/ 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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