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At 6:58 PM +0100 5/7/02, Michael Kay wrote:
>The XPath 2.0 data model is based on the PSVI, not on the schema definition
>language. It's explicitly an aim that you can generate the PSVI by
>validation against a DTD, it should also be possible to generate it by
>validation against other schema languages.
>
On an unrelated matter, does XPath 2.0 bother to define how the PSVI
is actually constructed from a specific XML document or does it allow
processors to create whatever PSVI they want to whether or not that
PSVI has any relation to the original XML document at all? For
instance, is it acceptable for an XSLT2 processor to replace all
child elements with attributes or convert rectangle elements into
circle elements? or simply replace the entire input document with the
Gospel According to Bob?
Of course, such insane behavior would render a processor useless.
However, some people have claimed that XSLT 1.0 permits this. I
personally don't believe those assertions. I think they're based on
misreadings of the XSLT 1.0 spec. However, I would like to have XSLT2
rule out these possibilities very clearly, so we can stop having that
argument. Alternately, if the XSLT2 working group makes the wrong
decision and endorses such silliness, then everyone on the XSLT
conformance group can stop wasting their time, since clearly any
behavior could be made conformant.
Let me make a specific proposal here: the XSLT working draft should
require that:
1. When two conformant XML processors are presented with the same XML
document, whether as a stream, DOM Document, a sequence of SAX
events, or some other form that can reasonably express a XML
document; and
2. An XSLT stylesheet does not use any features explicitly marked as optional;
Then, both processors must be able to generate an XML document as a
sequence of bytes or characters, such that, when the two documents
are compared according to Canonical XML with comments, the two output
documents are identical.
The wording clearly needs work, but you get the drift. I want it
possible to be able to do conformance testing on XXSLT processors
without any weaseling about source tree construction. I want a clear
path from genuine XML document to PSVI to source tree.
--
+-----------------------+------------------------+-------------------+
| Elliotte Rusty Harold | elharo@metalab.unc.edu | Writer/Programmer |
+-----------------------+------------------------+-------------------+
| The XML Bible, 2nd Edition (Hungry Minds, 2001) |
| http://www.cafeconleche.org/books/bible2/ |
| http://www.amazon.com/exec/obidos/ISBN=0764547607/cafeaulaitA/ |
+----------------------------------+---------------------------------+
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