Re: [topicmaps-comment] TMs & XTM [Was: skills to create topic maps]

[Murray Altheim <murray.altheim@sun.com>]

"Steven R. Newcomb" wrote:
[...]
> Topic Maps are essentially graphs.  There can be any
> number of syntaxes for interchanging these graphs.
> 
> The XTM 1.0 syntax is a really good syntax for
> interchanging topic map graphs: redundancy is
> minimized, and human readers of the XML instances can
> understand the topic maps that are represented by them
> pretty intuitively.  The XTM 1.0 syntax is also *very*
> good for introductory learning about what topic maps
> are and how they work.  For these reasons, and others,
> I believe the XTM 1.0 syntax is the best choice for the
> standardized interchange of topic maps.  It's a "market
> opening" syntax, and (thanks be to God) it's powerful
> enough to keep on working well for the foreseeable
> future.
> 
> It is impossible to design a syntax that meets *all*
> requirements; requirements conflict with one another.
> The requirement that redundancy be minimized is a
> perfectly valid requirement for interchange syntaxes,
> and XTM 1.0 respects this requirement.  XTM 1.0
> therefore does *not* meet the requirement that Tony
> implies in his comment, above, namely that DOM
> implementations be able to be used directly to gain
> access to the topic map graph.  For Tony and others
> like him, the good news is that it *is* possible to
> interchange topic maps by means of an XML syntax that
> accurately and directly reflects the topic map graph,
> so that DOM implementations can directly use the topic
> map without needing a Topic Map engine to translate the
> XML.  In other words, topic maps can be published in
> XML in a way that obviates the need for a topic map
> engine.  There's a price, though: the XML instances are
> necessarily chockfull of redundant information, and the
> tasks of creating and maintaining such instances cannot
> be accomplished by hand.  (The smallest tweak is very
> likely to render the instance inconsistent with
> itself.)
> 
> A syntax for Topic Maps that can meet Tony's
> requirement can be found at
> http://www.topicmaps.net/TMGraphAPI3.htm.  It's very
> redundant, but something like it could be used in the
> way that Tony wants.

IOW, a tool that could import and export XTM syntax for purposes of
authoring, but could also export TMGraphAPI-compliant documents (though
probably not stress importing) would allow interoperability, as well
as Web-based publishing of the product. The only real downside is that
we now need a new processor/interpretor for TMGraphAPI. Do you think
there's any way to express TMGraphAPI documents in XTM? The suggestion
sounds a bit *weird* I realize, but if you thought so we could attend 
to this idea in the PubSubs TC, developing a set of PSIs and Best 
Practices/documentation on how to generate and interpret such documents.

Myself, I'd prefer not having to deal with a second syntax, but would
rather add a layer of semantics on top of XTM if at all possible. 

Murray

...........................................................................
Murray Altheim, SGML/XML Grease Monkey  <mailto:murray.altheim&#64;sun.com>
Java and XML Software
Sun Microsystems, 1601 Willow Rd., MS UMPK17-102, Menlo Park, CA 94025

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