OASIS Mailing List ArchivesView the OASIS mailing list archive below
or browse/search using MarkMail.

 


Help: OASIS Mailing Lists Help | MarkMail Help

 


 

   Iceberg development (was Re: [xml-dev] maps)

[ Lists Home | Date Index | Thread Index ]

At 10:00 PM 8/4/2002 -0600, Uche Ogbuji wrote:
>And so the Titanic lumbers on.  Nought but the iceberg itself will alter its
>course.

Then perhaps we should be thinking about how to make icebergs. So...

> > I think that XML Schema part 2 should not have been a collection of
> > types and facets, but a language for the creation of datatype libraries,
> > and ideally a mechanism for registering those datatype libraries as
> > well.  But I've ranted on the topic, at rather more length, elsewhere
> > (see xml.com, if you're interested).
>
>Absolutely!  But don't think ranting will do the trick.  James Clark outlined
>the problems with blessed types in his XML 2001 keynote.  I've railed against
>them and wished for more generic facilities for constraint expression rather
>than a monolithic type-library-by-committee.  I used irrational numbers as my
>example, picking a purposefully tricky case.  Simon has brought up the more
>practical geospatial example.  But the folks who could clean up this mess
>mostly just take in all the warnings and blithely respond "sorry we had to
>satisfy OO and relational data type needs from our chartered requirements".

I'm wondering if we may actually already have the parts to solve a lot of 
this.  (Irrational numbers, being infinite and non-repeating, are pretty 
difficult, admittedly.)

It seems like regular expressions and RELAX NG provide most of the key 
pieces we need. Regular expressions provide a mechanism for parsing a wide 
range of lexical expressions and for breaking them down into smaller 
pieces.  RELAX NG provides a powerful vocabulary for describing constraints 
which I think could serve as the basis for describing the constraints 
inside such values.  (Schematron is also a likely contender in this 
space.)  Rather than creating a declarative system with an abstract PSVI, 
this work could be an explicit painting process, a (reversible?) 
transformation between the original XML and the result XML.

There are still some likely obstacles, as attributes are tough to break 
into smaller pieces, especially if there are multiple attributes of the 
same type.  On the other hand, breaking attributes out into child elements 
might not be all bad.  The kinds of constraints RELAX NG provides may not 
presently be enough for this, but I think its basic foundation is the right 
place to start.

A set of tools like this seems likely to represent a far greater set of 
lexical-value mappings than the current WXS approach.  I'm not sure that it 
could represent everything people want without getting ridiculous, but I 
think there may be an 80/20 in there somewhere.  Typing as labeled 
structures seems to fit pretty well with what markup does.

Just an idea, but something to think about this week at Extreme.  (I also 
think Eric van der Vlist has a lot of the parts in xvif[1], but he's on 
vacation.)

[1] - http://downloads.xmlschemata.org/python/xvif/

Simon St.Laurent
"Every day in every way I'm getting better and better." - Emile Coue





 

News | XML in Industry | Calendar | XML Registry
Marketplace | Resources | MyXML.org | Sponsors | Privacy Statement

Copyright 2001 XML.org. This site is hosted by OASIS