[topicmapmail] Fragmented XTM for web metadata, and some ontology?
Murray Altheim
m.altheim@open.ac.uk
Thu, 26 Jun 2003 14:29:20 +0100
Alexander Johannesen wrote:
>
> Hi Murray,
>
> ( And sorry for the long post )
No apologies necessary -- I'm often as longwinded as a politician.
> I'm trying to understand it all, but my feeble brain don't seem
> to be able to grok it; let me know where you think I'm missing
> the point. :)
Well, we're all on new territory to some extent, either that or trying
to combine older ideas from different sources in new ways, so it's all
a bit of a guess as to what the "point" is.
> I've been thinking of creating a simple XTM with PSI's based on DC 1.1,
> where you have for the DC element "type" ;
>
> <rdf:Property rdf:about="http://purl.org/dc/elements/1.1/type">
>
> which has got
>
> <rdfs:isDefinedBy rdf:resource="http://purl.org/dc/elements/1.1/"/>
>
> for a given element that would satisfy most for a PSIs, as defined as
> such for the DC "type" ;
>
> <topic id="dc:type">
> <subjectIdentity>
> <subjectIndicatorRef
> xlink:href="http://purl.org/dc/elements/1.1/type" />
> </subjectIdentity>
> </topic>
>
> ( id-attributes follow the DC recomended guideline for DC in XML )
I'm not sure when the guidelines were written, but the colon is prohibited
as a name character nowadays, in accordance with the XML Namespaces 1.1
Recommendation:
http://www.w3.org/TR/xml-names11/#Conformance
The reason it was allowed as a Name character was to allow experimentation;
in the end I believe it was decided that "namespaced IDs" didn't make much
sense. Thank God for that.
> I had some problems groking the associative DC metadata in Jan's
> document, but that might be because I don't understand why
> they should be expressed that way. Maybe my thinking is very
> slow, but I'd like an ontology (called FXTM for now) ;
>
[example elided...]
> My thinking says that for a given page, you have the following XTM;
>
> <!-- root node is the fragmented XTM's resource -->
>
> <topic id="root">
> <instanceOf>
> <topicRef xlink:href="#fxtm:page"/>
> </instanceOf>
> <occurrence>
> <instanceOf>
> <topicRef xlink:href="#dc:title" />
> </instanceOf>
> <resourceData>Some title</resourceData>
> </occurrence>
> <occurrence>
> <instanceOf>
> <topicRef xlink:href="#dc:date:publish" />
> </instanceOf>
> <resourceData>[Some date]</resourceData>
> </occurrence>
> </topic>
>
> Where the TMs for FXTM and DC are implicit part of the
> namespaces used (and merged in according to the FXTM
> spec?).
I don't think it's appropriate semantically to include properties
of a given topic as occurrences of that topic -- it's just not
sensible, doesn't "read" right to me. You yourself stated the sentence:
"here is the resources"
which is essentially saying "here are the untyped values". Since we
want to both name and type our values, and because occurrences don't
have names, each facet is a topic.
> I don't know. Maybe I'm mixing things up too much, or
> maybe I'm missing the incredible power of making the
> occurrences topics instead with associations binding them, but I feel
> that becomes more of an application specific way than a general "here
> is the resources" way;
>
> <topic id="murray">
> <instanceOf>
> <topicRef xlink:href="#fxtm:person"/>
> </instanceOf>
> <name>Murray Altheim</name>
> </topic>
>
> <topic id="murrays-site">
> <instanceOf>
> <topicRef xlink:href="#fxtm:site"/>
> </instanceOf>
> <occurrence>
> <instanceOf xlink:href="#dc:identifier" />
> <resourceData>[Some URL]</resourceData>
> </occurrence>
> <occurrence>
> <instanceOf xlink:href="#dc:title" />
> <resourceData>Some title</resourceData>
> </occurrence>
> </topic>
>
> <association>
> <instanceOf>
> <topicRef xlink:href="#fxtm:link"/>
> </instanceOf>
> <member>
> <roleSpec>
> <topicRef xlink:href="#fxtm:linked"/>
> </roleSpec>
> <topicRef xlink:href="#murray"/>
> </member>
> <member>
> <roleSpec>
> <topicRef xlink:href="#fxtm:linked-ref"/>
> </roleSpec>
> <topicRef xlink:href="#murrays-site"/>
> </member>
> <member>
> <roleSpec>
> <topicRef xlink:href="#fxtm:linker"/>
> </roleSpec>
> <topicRef xlink:href="#root"/>
> </member>
> </association>
>
> Basically, what I want is a PSI set for the FXTM set
> (both roles and types), and a set of PSIs for DC. The
> latter is the easy part. Where should I turn for the former? Is there
> anyone looking into a loose web browsing ontology?
You might look at the "topic map-based" XFML, at http://xfml.org/
which I believe is designed to solve either the same or a similar
problem (depending on how I understand your question).
By some coincidence, I happen to be working up a short specification
for doing facets in XTM, with the idea that you can associate a
name-value pair to a given topic.
BTW, Kal Ahmed has a PSI set for faceted classification (FC), and
we're discussing various aspects of it right now. I'm looking at the
description of facets in ISO 13250 as well as how FC works, as while
the use of "facet" is the same, there are some differences (as might
be imagined from terms coming from different communities). I'm
particularly interested in the overlap, for my own work.
I hope to publish the "Facets in XTM" draft within a week or so. If
I haven't by July 10th, it'll probably be in two weeks after that
(as I'm out of town and probably disconnected). I'll be updating my
"Datatypes in XTM" document at that time as well, as it is used in
typing the facet values, e.g.
"Birthday" has type "dateTime" and value "1961-07-04T20:00:00Z"
"Birthday" has type "date" and value "1961-07-04"
I have had a DC topic map for about two years now, unpublished. Since
that might be useful with the facet TM, if I have time I'll also put
that online.
Since the term "facet" also occurs in XML Schema datatypes, I'm
starting to feel a bit surrounded by the damn things, like some
kind of bad drug trip...
Murray
[1] http://www.techquila.com/tmsinia5.html
......................................................................
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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