[topicmapmail] XTM Datatypes [Was: Adding weigths to associations]

[Murray Altheim]

Kal Ahmed wrote:

 > Data-typing could also be addressed by extending XTM 1.0 to allow XML
 > fragments within resourceData elements. In this way, one could use W3C XML
 > Schema or your-choice-of-schema-language-with-datatypes to provide occurrence
 > values. In this way, you would be treating topic maps (and specifically XTM
 > interchange syntax) as a "layer" on top of existing datatyping mechanisms,
 > rather than reflecting those mechanisms in topic map terms.

Kal,

I'm strongly against extending XTM, since any extension would
basically destroy one of the principal reasons for having it:
namely, a standardized interchange language. And then every
different approach taken by every different person would have
to be taken into account. And this is only one possible extension
among the very many that are possible -- then we end up with
what's happened to XML: it's too complex to use, if you don't
ignore most of the plethora of "extension" specs (XML Namespaces,
XML Base, XML Include, XLink, XSLT, Associating Stylesheets with
XML (which could transform the document), XPointer, XPath (since
you need to do them in a transformation), CSS3/CSS Selectors,
XML Fragments, XML Events, XFrames, XML Schema, etc.). I think
you get my point. :-)

The idea of mixed namespaces may be considered acceptable to
many (particularly within the W3C), but absent a rather complex
schema establishing exactly how the mix occurs, this ups the
ante on expertise (not too many people can or want to write
XML Schemas) and processing complexity. You may need an XML
Schema engine, an RDF Schema engine, XSLT, who knows? By
comparison, the XTM DTD is quite simple, nicely simple.

I agree that some means of containing content in XTM elements
and characterizing such content is a good thing. But given that
a PSI for "boolean" can identify the contents of an element
within a topic map as well as in an external (ie., non-XTM, but
addressable) document, I think the PSI quite sufficient.

I'm hopefully going to be able to post some examples of this
with the PSI set, though I may hold off and just write up a
detailed description as a white paper of some sort.

Murray

......................................................................
Murray Altheim                  <http://kmi.open.ac.uk/people/murray/>
Knowledge Media Institute
The Open University, Milton Keynes, Bucks, MK7 6AA, UK

            If you're the first person in a new territory,
            you're likely to get shot at.
                                                     -- ma