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RE: What are the characteristics of a good type system for XML

• To: "Dare Obasanjo" <dareo@m...>,"Rick Jelliffe" <ricko@a...>,<xml-dev@l...>
• Subject: RE: What are the characteristics of a good type system for XML?
• From: "Dare Obasanjo" <dareo@m...>
• Date: Wed, 14 May 2003 10:32:06 -0700
• Thread-index: AcMZ2YfKFygf9lptS0OeMTCbcakzoQAWuncwAAJ/KuA=
• Thread-topic: What are the characteristics of a good type system for XML?

I should point out that I simplified the cases in my geralizations. Many
sophisticated users of validation do want more than regexes and strings
when ensuring that a document satisfies its contract. They want to
ensure values fall within certain ranges and ensure that various
interdependencies are enforced. 

There that's it. My $0.02 

-- 
PITHY WORDS OF WISDOM 
Any simple theory will be worded in the most complicated way.


This posting is provided "AS IS" with no warranties, and confers no
rights. 

>  
>  
> -----Original Message-----
> From: Dare Obasanjo [mailto:dareo@m...] 
> Sent: Wednesday, May 14, 2003 9:46 AM
> To: Rick Jelliffe; xml-dev@l...
> 
> I've seen two broad classes of users of W3C XML Schema. Those 
> who want to perform document validation to ensure that the 
> contents of a document satisfy some pretedetermined contract 
> and those who want type augmented infosets. The people in the 
> former camp map to users of the XmlValidatingReader in the 
> .NET Framework and the latter folks are users of the DataSet, 
> .NET Framework XML Serialization and the SQLXML Managed classes. 
> 
> Those that want validation can be satisfied with a "type 
> system" where the simple types are either strings or [named] 
> regular expressions that restrict the lexical space of a 
> particular string. Those that want type augmented infosets 
> want them so that they can perform operations on values 
> depening on what types they are. They want to add numbers, 
> sort dates, concatenate strings, compare equivalence of 
> values, substitute
> and promote types,   etc. 
> 
> The failing of XML Schema is that they started doing the 
> latter then it seems like whenever they came across a problem 
> they just pretended they were doing the former. This gives us 
> things like (xs:float & xs:double & xs:decimal not being 
> comparable), indeterminate sorting problems with xs:duration, 
> the (a + b) + c !=  a + (b + c) problem if a is an xs:date 
> and b and c are durations, lack of comparability of 
> xs:hexBinary & xs:base64Binary, types like xs:QName with no 
> canonical form, and a host of other issues. 
> 
> Amelia's proposal and the current discussion seems just as 
> narrowly focused, hence the train wreck analogy.  ;) 
> 
> --
> PITHY WORDS OF WISDOM
> Any simple theory will be worded in the most complicated way.
> 
> 
> This posting is provided "AS IS" with no warranties, and 
> confers no rights. 
> 
> >  
> >  
> > -----Original Message-----
> > From: Rick Jelliffe [mailto:ricko@a...]
> > Sent: Tuesday, May 13, 2003 10:30 PM
> > To: xml-dev@l...
> > 
> > From: "Dare Obasanjo" <dareo@m...>
> > 
> > > Defining a type system via the narrow lens of validation is
> > partly the
> > > cause of what many term the "brokenness" of W3C XML 
> Schema and why 
> > > some of our devs and testers (of which I used to be one)
> > have had some
> > > issues with the XQuery type system.
> > 
> > What fun: I have never heard anyone say XML Schemas pays too much 
> > attention to validation (compared to issues related to configuring 
> > DBMS and middleware!) Indeed, one of the points with DSDL, RELAX, 
> > Schematron etc is that WXS does not meet the mark for document 
> > validation, by providing to few bangs for too many bucks.
> > 
> > Dare, what is the brokeness of WXS as you see it, especially that 
> > broken lens?
> > 
> > Cheers
> > Rick
> > 
> > 
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