[issue-dbooth-3] Identity transformation

I am still working on specific, normative text changes to submit as a
proposed solution to issue-dbooth-3 (ambiguity), and in trying to figure
out what the least cost solution might be I have benefitted greatly from
many private discussions with working group members that I have been
able to reach by phone.  However, today I stumbled upon another
illustration of the problem that I thought might help to clarify one
aspect of this issue more succintly.

In issue-dbooth-3, I picked on indeterminate XInclude processing as a
convenient *example* of the problem that can occur if the GRDDL
transformation author is not permitted to indicate what processing
should occur in producing the XPath Node tree from a given
representation.  Lest anyone think that this problem is limited to
XInclude, here is an illustration of it in a very general but simple
form.

IDENTITY TRANSFORMATION PROBLEM
As a GRDDL transformation author, I wish to write an unambiguous
identity transformation, such that for any given representation R,
served from URI U, the GRDDL result of the transformation is a single
RDF assertion of the form:

	U myns:says R.

At present, the GRDDL spec does not permit me to write such a
transformation to produce correct results without ambiguity, because a
GRDDL transformation is currently defined to take an XPath Node tree as
its input, and does not permit my GRDDL transformation to indicate how
the representation should be parsed into that XPath Node tree.

OBSERVATION
This aspect of issue-dbooth-3 would be relatively simple to fix by
changing the definition of "GRDDL transformation" to take the
representation as its input instead of an XPath Node tree.  This would
completely side-step the faithful-infoset issue (by leaving the choice
of infoset up to the GRDDL transformation author), and would also allow
GRDDL transformation authors to benefit from the XProc spec when it is
finished, and benefit from any TAG decision on the xmlfunctions-34 issue
when that is resolved.


David Booth, Ph.D.
HP Software
+1 617 629 8881 office  |  dbooth@hp.com
http://www.hp.com/go/software

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Received on Tuesday, 12 June 2007 18:56:19 UTC