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- To: "Dare Obasanjo" <dareo@microsoft.com>,"Rick Jelliffe" <ricko@allette.com.au>,<xml-dev@lists.xml.org>
- Subject: RE: [xml-dev] What are the characteristics of a good type system for XML?
- From: "Dare Obasanjo" <dareo@microsoft.com>
- Date: Wed, 14 May 2003 10:32:06 -0700
- Thread-index: AcMZ2YfKFygf9lptS0OeMTCbcakzoQAWuncwAAJ/KuA=
- Thread-topic: [xml-dev] 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@microsoft.com]
> Sent: Wednesday, May 14, 2003 9:46 AM
> To: Rick Jelliffe; xml-dev@lists.xml.org
>
> 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@allette.com.au]
> > Sent: Tuesday, May 13, 2003 10:30 PM
> > To: xml-dev@lists.xml.org
> >
> > From: "Dare Obasanjo" <dareo@microsoft.com>
> >
> > > 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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