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   Re: Didier's lab report

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  • From: Nikita Ogievetsky <nogievet@cogx.com>
  • To: Uche Ogbuji <uche.ogbuji@fourthought.com>, xml-dev@xml.org
  • Date: Wed, 13 Dec 2000 23:40:11 -0500

Hello Uche,

You said:

> Well, not to start a TM vs RDF holy war, but I hardly think of this as a
> reson to prefer TM.  You can do this as well in RDF: meta-meta-data is
> simply a matter of reified statements.

No doubt  it can be done in RDF.

> Nice thing about RDF is that you
> are free to extend your meta-meta-data as you wish.

Surprise - surprise, same is true about Topic Maps! :-)
(in the "scope" of my perception :-))

> You don't have to
> worry whether the RDF spec hard-codes in the idea of "conditional
> include" or whatever modifier you seek.

There is no notion of "conditional include" hardcoded into Topic Maps
Instead, notion of "conditional include" can be established by looking at
the scope of a referred resource (stylesheet in this case).
(i.e. by the subject of one of the scoping topics)
I believe that this is more intuitive
then going through aggregates of RDF triples.
But may be you can prove the opposite?

> IMO RDF's power is in its simplicity.
Damn it! this is what I always say about Topic Maps! :-))

Lets take this as an example:
> > In the scope of WML aware client use this stylesheet,
> > in the scope IE5 use another stylesheet
> > and in the scope of NC and IE4  and IE3 use yet  third stylesheet.
> > I used this approach a couple of months ago and quite successfully!.
> > Same thing applies to the values of XSLT parameters.

Here is XTM syntax for it (my $.02):

<topic id="abc">
<subjectIdentity><resourceRef xlink:href="abc.xml"/></subjectIdentity>
 <instanceOf><topicRef xlink:href="#xslt-stylesheet"/></instanceOf>
 <scope><topicRef xlink:href="#wml"/></scope>
 <resourceRef xlink:href="wml.xsl"/>
 <instanceOf><topicRef xlink:href="#xslt-stylesheet"/></instanceOf>
 <scope><topicRef xlink:href="#ie5"/></scope>
 <resourceRef xlink:href="ie5.xsl"/>
 <instanceOf><topicRef xlink:href="#xslt-stylesheet"/></instanceOf>
 <scope><topicRef xlink:href="#nc"/></scope>
 <resourceRef xlink:href="nc.xsl"/>

The "xslt-stylesheet" topic defined elsewhere specifies that this occurrence
is XSLT stylesheet
The "wml" scoping topic (theme) defined elsewhere specifies that "wml.xsl"
stylesheet should be used in the scope of WML aware browsers;
same goes for "ie5" and  "nc"

Note that this is a very RDF-like case because the subject of the topic is a
(XTM topic can also have a real-world subject, one that can not be addressed
In this case "the subject may be indicated through one or more resources
that describe the subject" -- xtm spec.)

In any case, could you give an equivalent to the above example that uses RDF
triples? Would you like to go for this exercise?



Nikita Ogievetsky, Cogitech Inc.
Consultant in XML/XSLT/Xlink/TopicMaps
Cogito Ergo XML


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