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Re: intertwined specs

• From: Eric van der Vlist <vdv@d...>
• To: xml-dev@l...
• Date: Mon, 19 Feb 2001 19:14:52 +0100

> Jonathan.Robie@S... wrote:
> 
> Simon wrote:
> 
> > Does the data model fit XPath as it currently exists?
> > Or will XPath need retrofitting?
> 
> XPath is based on four datatypes, and provides elaborate rules for
> converting any node or nodeset to each of these datatypes. These four
> datatypes do not exist in XML 1.0, and they are not the datatypes of
> XML Schema. I believe that XPath will have to adopt the XML Schema
> simple datatypes, define operations on these datatypes, and define
> consistent casting rules for these datatypes.

This is an interesting example...

W3C XML Schema is considering the string datatype (and all the types
derived from this type) as being unordered.

Does that mean that we should loose a sort order on string datatypes
when we use XSLT and/or XQuery to be consistent with W3C XML Schema
because these datatypes are not ordered?

A problem with intertwined specs is that if we don't want that they
become like a plate of spaghetti we need to define a clean layered
structure first and probably define a complete datatype system rather
than trying to reuse one that has been defined for what is IMHO a
specific purpose and has had to accept to drop many features to deliver
in a timely fashion.

Another problem is that we are creating a chain and that if we do so,
the strength of the chain will be the strength of its weakest link.

In other words, generalizing XPath would mean generalizing its implied
data model that is but a subset of the infoset just like generalizing
W3C XML Schema structures and/or W3C XML Schema datatypes would mean
generalizing their limitations.

These are decisions that have a significant impact.

My 0,02 Euros.

Eric
-- 
See you in Austin (Knowledge Technologies 2001)
              http://www.gca.org/attend/2001_conferences/kt_2001/mon.htm
------------------------------------------------------------------------
Eric van der Vlist       Dyomedea                    http://dyomedea.com
http://xmlfr.org         http://4xt.org              http://ducotede.com
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