[topicmapmail] Fragmented XTM for web metadata, and some ontology?

[Kal Ahmed]

On Sun, 2003-06-29 at 12:52, Murray Altheim wrote:
> Kal Ahmed wrote:
> > On Sun, 2003-06-29 at 05:59, Robert Barta wrote:
> > 
> >>On Fri, Jun 27, 2003 at 05:36:39PM +0100, Kal Ahmed wrote:
> >>
> >>>>So I think that we shoul NOT depricate resourceData.  Instead, we should
> >>>>strengthen it so it can specify the type of the literal data it holds.
> >>>
> >>>Absolutely. Though I go one step further. I don't want a reinvention of
> >>>data typing. I just want to be able to include XML from namespaces other
> >>>than the XTM one inside the resourceData element. Then I can use
> >>>MyFavouriteSchemaLanguage to do not only datatyping but to express other
> >>>constraints on the content. Then all I want after that is the ability in
> >>>TMCL to restrict occurrences of particular types to having resourceData
> >>>content from particular namespaces. Then I would be happy.
> >>
> >>Kal,
> >>
> >>Duly noted. But then I would assume that someone might also want to
> >>check constraints on the data INSIDE the XML fragment as well.
> >>
> >>This cannot/should not be done within TMCL but would have to be handed
> >>off to the XML constraint language of the author's choice.
> > 
> > Yes, absolutely. IMHO that separation of concerns is an advantage with
> > this proposal over the proposal to include datatypes as part of SAM/XTM.
> 
> I suppose this really depends on what one considers as a definition of
> the term "datatype". XSD is a constraint language. We can look at the
> "Datatypes in XTM" proposal in different lights: first, as a method of
> *labeling* (typing) the interpretation of a literal value (e.g., as a
> date, a time, a URI, a boolean, etc.); secondly as a method of attaching
> a constraint. But it's possible to do both at the same time.
> 
> I've not attempted to provide a constraint language (as there are others
> spending far more time and effort than I'd ever on this problem), I'm
> concentrating on labeling/typing, which is a necessity in its own right.
> If if one can label a literal value with an XSD primitive, by extension
> there's no reason why one couldn't use the same approach to "label" it
> with a custom datatype, where the PSI points to a bit of XML Schema markup
> that actually provides that constraint, so *if* an application wished to,
> it could retrieve that markup and actually perform the constraint checking.
> 

Yes, that is true and what you suggest would make a good way to solve
the problem of validating XML content from an XML namespace other than
the XTM 1.0 namespace. However, the issue for the XTM syntax is the
PCDATA content model of resourceData which prohibits XML content for the
element.

Cheers,

Kal