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   Re: RE: [xml-dev] XQuery and DTD/Schema?

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At 01:27 PM 7/6/2002 -0400, Simon St.Laurent wrote:
>At 01:03 PM 7/6/2002 -0400, Jonathan Robie wrote:
>>I agree, but I do believe that XML should be able to express datatypes - 
>>and a lot of people seem to agree, including the designers of RELAX-NG 
>>and most other recent schema languages. I would like to be able to 
>>support these datatypes efficiently.
>I don't find support for those datatypes compelling for XML.  I find them 
>to be a distraction from the text-based functionality that makes XML so 
>useful at best, a distressing calamity at worst.  I'm starting to argue 
>that compromise even with the primitive types is a dangerous mistake.

I think that is a pretty clear statement that you are not our target audience.

A query language that does not correctly sort integers or do even basic 
type inference just doesn't meet the requirements for XQuery.

>>Are you asking us to drop support for types entirely? If so, is that 
>>because you want all processing to be done by converting XML into Java or 
>>relational data first, or because you think processing data does not 
>>require types? Or are you suggesting a different strategy for supporting 
>>types in XQuery? If the latter, could you please explain what approaches 
>>you favor?
>I'm saying that:
>* XML has a type system - it's called element types.
>* Applications are welcome to build whatever processing they want on that 
>* The "XML Core" should not recognize any type systems beyond those in XML 
>Too minimalist for many? Probably.  Layering solutions rather than piling 
>type systems into the core would take care of a lot of my 
>objections.  Sadly, XQuery seems intent on building on XML+WXS, not XML.

Layering works if you really do intend to physically move things through 
all those layers. If I am querying gigabytes of information, I really don't 
ever intend to ever physically realize that data and start doing operations 
on it. If we had to do that, XQuery could never work efficiently.

For data that is physically represented as XML, there already *is* a 
layering - XML text is parsed to create an Infoset, which is validated to 
create a PSVI, which is mapped into the XML Query data model. Do you 
suggest a different layering? What layering would you prefer, and how would 
this relate to the XML Query data model and typed operatoins?



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