[topicmapmail] This is weird modeling, but is it valid XTM ?

[Murray Altheim]

Bernard Vatant wrote:
 > I'm currently checking a file sent by a "beginner" in XTM, and I stumble on
 > the following weird thing I'd never seen nor even thought of before. Maybe
 > some of you have already dealt with that kind of stuff.
 >
 > <topic id="foo"/>
 > ...
 > <topic id="bar">
 > 	<occurrence>
 >       	<instanceOf>
 >             	<subjectIndicatorRef xlink:href="bla"/>
 >       	</instanceOf>
 >       	<resourceRef xlink:href="#foo"/>
 > 	</occurrence>
 > </topic>
 >
 > IOW the <topic> element "foo" is declared as an occurrence of the topic
 > "bar". In the original file, it was actually a modeling mistake, confusing
 > an occurrence type with an association type. But supposing it makes sense
 > in some situation, would this be valid XTM? Is it correct to address a
 > <topic> element using <resourceRef>? It is valid syntax, but somehow I find
 > it quite weird, and certainly it would be likely to wreak havoc in some TM
 > applications, but I can't find in the specification any definitive argument
 > against it, other than "this is bad modeling". After all a <topic> element
 > is a resource ...

Unless I'm not understanding either the question or the problem, the
interpretation is that one is talking about the <topic> element "foo".
If the subject of topic "bar" was "XTM <topic> elements", say, one was
discussing an XTM document or XTM itself, then this (to me) makes good
sense. There are times when people talk about syntax, like right now.

So long as one uses a <resourceRef>, I see no problems with this either
from a modeling or functional standpoint. While topic maps typically
represent information "outside" the topic map, if one wanted to talk
about an XTM document as a bunch of resources, this would be the way to
do it.

This kind of thing bears a lot of resemblance to RDF, so I'm surprised
it's considered "weird". Though to my way of thinking, some of the
things that go on in RDF are weird. We do this when we point to a
<resourceData> element by ID, too, which is where XTM is RDF-like.

Murray

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

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