Cart
|
[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message] Iceberg development (was Re: maps)
 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 
|
PURCHASE STYLUS STUDIO ONLINE TODAY!Purchasing Stylus Studio from our online shop is Easy, Secure and Value Priced! 
Download The World's Best XML IDE!Accelerate XML development with our award-winning XML IDE - Download a free trial today! Subscribe in XML format
|
|||||||||
