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   RE: [xml-dev] XPath 1.5? (was RE: [xml-dev] typing and markup)

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> -----Original Message-----
> From: Jonathan Robie 
> [mailto:jonathan.robie@datadirect-technologies.com] 
> Sent: Tuesday, May 07, 2002 12:52 PM
> To: Elliotte Rusty Harold; xml-dev@lists.xml.org
> Subject: RE: [xml-dev] XPath 1.5? (was RE: [xml-dev]
typing 
> and markup)
> 
> >Here's just one:
> >
> >         avg( input()//person/name )
> >
> >You say you want this to fail. I say I want it to
return NaN 
> if any of 
> >the
> >identified name elements contains a non-number and
the 
> actual average if 
> >they all do contain strings that can be parsed as
numbers. 
> Neither of us 
> >is right. Neither is wrong. We simply have
different needs 
> in our local 
> >environments. Tomorrow I may move to a different
local 
> environment with 
> >different needs.
> 
> If error handling is different in each environment,
then real 
> interoperability is very hard to achieve.
> 


I'll let you in one an Open Secret, Jonathan; XQuery
is not going to be interoperable. The XQuery WG set
out to create the SQL of the XML world and they have
succeeded. Interoperability between RDBMSs breaks down
beyond the simple cases with proprietary extensions
holding sway while lip service is paid to standards.
No one fully implements SQL92, SQL99 may as well be a
myth for all RDBMS vendors care about. 

From conversations with XQuery implementers both
within and outside MS, I am confident that this
situation is about to be replicated with XQuery
especially since a number of its requirements simply
cannot be efficiently implemented over certain data
repositories. Throw in the fact that everyone will
probably have their own homebrew update syntax, I
can't imagine why anyone would expect interoperability
between XQuery implementations. 

Then again, it's not like XQueries are data like XML
documents or XML schemas so interoperability is
probably shouldn't be a goal in any case. 

PS: If the XQuery WG is judicious in how they treat
conformance levels, XQuery may yet avoid becoming the
SQL of the XML world. 

DISCLAIMER: This is my personal opinion and does not
reflect the intentions, opinions, strategies or plans
of my employer. 

-- 
PITHY WORDS OF WISDOM 
Never put off until tomorrow what you can put off all
together. 
 
This posting is provided "AS IS" with no warranties,
and confers no rights. 
You assume all risk for your use.  2002 Microsoft
Corporation. All rights reserved.

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