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Re: XPath 1.5? (was RE: typing and markup)

• To: <xml-dev@l...>
• Subject: Re: XPath 1.5? (was RE: typing and markup)
• From: "Rick Jelliffe" <ricko@a...>
• Date: Wed, 8 May 2002 19:21:52 +1000
• References: < <5.1.0.14.0.20020507100109.04decec0@n...> <5.1.0.14.0.20020507100109.04decec0@n...> <5.1.0.14.0.20020507112929.04dfc880@n...>

From: "Jonathan Robie" <jonathan.robie@d...>
 
> >The idea that a query system can optimise away, or generate errors on,
> >queries like aaa/bbb if the schema specifies that aaa has no bbb children
> >is also very worrying.
> 
> Indeed.
> 
> Whether or not that is an error is currently an open issue in XQuery. My 
> own view is that it should be neither a static nor a dynamic error, but 
> that it should evaluate to an empty sequence.

Is that right? There is no way to say "Tell me what is in the document"
if some schema has deemed something impossible.  How the hell can 
anyone validate documents-in-progress (which may well be invalid)
using that?
 
> >How could one write schematron in Xpath2 if it
> >needs to find exactly such cases and report errors? Xpath1 was designed
> >to work on documents that specified a DTD but were invalid, not only
> >well formed documents that did not specify a DTD. Is the same really
> >true of Xpath2 wrt schema?
> 
> This question has not been answered, it is an open issue. My own view is 
> that if the validation fails, XPath 2.0 and XQuery 1.0 should have 
> undefined behavior.

So you are saying an XPath 2.0 can never be used to positively locate errors?
What happened to the basic well-formedness versus valid distinction which
allows manipulation and rectification of XML even when it is not valid
using the same tools as when it is valid?  

I am sure the thousands of Schematron users (based on my logs) would
be interested in this. I certainly would: I don't want to waste my time
bringing in Schematron as part of ISO DSDL if the rug is being pulled
from under it by eager beaver DBMS vendors with sales problems 
on W3C committees and their pals,  who presumably have a vested interest 
in reducing the workability of simple structured-data files sitting on file systems. 

Would this extend to XSLT 2 as well? That we could not
use XSLT2 to repair a document that was not valid (or that
we would have to create some schema for the invalid document
first...yikes)?  

Startled
Rick Jelliffe

 

• Follow-Ups:
  • Re: XPath 1.5? (was RE: typing and markup)
    • From: Jonathan Robie <jonathan.robie@d...>
  • Re: XPath 1.5? (was RE: typing and markup)
    • From: "Jonathan Borden" <jborden@a...>

• References:
  • RE: XPath 1.5? (was RE: typing and markup)
    • From: Jonathan Robie <jonathan.robie@d...>
  • Re: XPath 1.5? (was RE: typing and markup)
    • From: Jonathan Robie <jonathan.robie@d...>

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