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Re: Review of "Storing Data in Documents"

From: <noah_mendelsohn@us.ibm.com>
Date: Tue, 22 Mar 2005 14:47:10 -0500
To: Dan Connolly <connolly@w3.org>
Cc: Chris Lilley <chris@w3.org>, "Henry S. Thompson" <ht@inf.ed.ac.uk>, www-tag <www-tag@w3.org>
Message-ID: <OF3F0BB380.55A77F5D-ON85256FCC.006C25D5@lotus.com>

Dan Connolly writes:

> I have thought of it as implicit in the spec too,
> but it's clearly too implicit. I hope to clarify
> soon...

> There's a relevant section... in the editor's
> draft, at least...
>   http://www.w3.org/2004/01/rdxh/spec#ns-bind

Cool!  Am I right in suggesting that this is in part making good on the 
promise of Cambridge Communiqué which states [1]:

"The extension mechanism should be appropriate for use to incorporate 
declarations ("mapping declarations") to aid the construction of 
application-oriented data structures (e.g. ones implementing the RDF 
model) as part of the schema-validation and XML infoset construction 
process. This facility should not be exclusive to RDF, but should also be 
useable to guide the construction of data structures conforming to other 
data models, e.g. UML."

Actually, the Communiqué focussed quite a bit on putting the mapping hooks 
into the XML Schema for a namespace, and that seems to be exactly what's 
shown at [2].  So, it took 5 years, big deal!  Maybe Dan's historical 
review at [3] should mention the Communiqué, the hooks left in the XML 
schema design, and the exploitation of those hooks by GRDDL?

On a barely related subject:  I'm tempted to ask how central the .xsl 
document really should be in defining the transformation.  On the one 
hand, it obviously is.  On the other, it seems to me that XSL is in some 
ways too high overhead to use in some of the higher performance situations 
where you'll want to do these mappings.  Try to import 100,000 XML 
documents into and RDF database;  running XSL 100,000 times isn't going to 
help if all you're doing is extracting some simple metadata about authors 
and creation dates.

What I'm struggling to articulate is whether there should be some sense 
that the URI in the GRDDL should be for the transformation in the 
abstract, with the xsl viewed just as a representation of that 
transformation.  Thus, we might emphasis that it's not running the .xsl 
per-se that's mandated by GRDDL, but implementating the correct transform. 
 I don't know whether there are observable differences in these two views, 
but I think the philosphical implications are somewhat different.  For 
example, I could invent a transform URI and document it in English or 
French.  You or I could write C code to implement the transform.  Maybe or 
maybe not someone would go to the trouble of offering an XSL 
representation of the transform, retrievable at the URI, as well.  This 
idea seems closely related to but not quite the same as the Standard GRDDL 
library mentioned in Dan's note.  Does this make any sense? 

Anyway, now that I've finally grok'd GRDDL, it looks like really nice, and 
more to the point, I like Dan's note at [3].


[1] http://www.w3.org/TR/1999/NOTE-schema-arch-19991007#observations
[2] http://www.w3.org/2003/g/po-ex
[3] http://www.w3.org/2004/01/rdxh/specbg.html

Noah Mendelsohn 
IBM Corporation
One Rogers Street
Cambridge, MA 02142
Received on Tuesday, 22 March 2005 19:48:06 UTC

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