Re: XML doesn't deserve its "X".
On Tue, 2002-03-05 at 02:53, Eric van der Vlist wrote: > Title says it all, the extensibility of XML is one of its myths... I'm not sure it had to be mythical, nor am I convinced that extensibility is lost to all of use at this point. > Technically, XML is based on trees which are not the most extensible > structures (compared to tables or triples). If you extend a tree you are > likely to break its structure (and existing applications). I would say > that trees grow but are not "extended". For some applications, you may be right, and different approaches like RDF probably make sense in those cases. Still, I have a very hard time imagining writing my data in triples, and a harder time imagining triples having anywhere near the transparency that relatively flat tree structures have. Extending trees isn't difficult so long as you haven't tightly bound yourself to a particular vision of how the tree must absolutely postively precisely be structured. If you're willing to accept that adding a new branch to a tree or reorganizing a branch doesn't automatically make it a diabolical mutant, there's a lot more flexibility. Extensibility scares people - while object-oriented programming, for instance, permits all kind of extensibility through class and interface structures, it also has best practices which strongly encourage encapsulation, hiding all of those details from other parts of the program. XML has a tougher challenge here, as it is both extensible and extremely open. I prefer to think of XML as a broad syntax containing all of its possible applications rather than as a toolkit for building specific vocabularies. This perspective seems to encourage rather different best practices than focusing on vocabulary-building. The document contents are the foundation of processing, not a particular schema, and the same contents need to be visible ("fully composed", as Tim Bray put it yesterday) to all comers, without any vocabulary-specific knowledge. Once we've got that document, we can (and should) go anywhere. Tools like schemas, stylesheets, RDDL, and code should let us explore and describe possibilities, not choke off anything that doesn't conform to a particular vocabulary. > This technical limitation has been strengthen by a community which has > become conservative and any evolution seems deamed to fail. I think the conservatism has always been there. As radical as XML is ("Hey folks! Create your own labeled structures for information!"), a lot of people have sold it short. Incessant talk about the need for firm contracts between parties, a fondness for expert committees, and the continuing desire to couple program logic and information as tightly as possible are constant themes. To some extent, it's reasonable. Hurling XML into the world without such restraints would likely have created (even more of) a backlash against these crazy anarchists. Programmers are pretty conservative when it comes to data structures, and I suspect most of them have learned firm lessons from the limitations of earlier systems. Tools vendors are out to make money selling tools, not extensibility. I'm can't say I'm very impressed with the "official" line of evolution right now. I suspect the W3C is (as it seems to have always been) mired in a notion of XML as vocabulary toolkit rather than a syntactical continuum, and their output seems to confirm that. Recent discussions on www-tag about how tightly to bind processing resources to namespace URIs aren't exactly encouraging, either. (On the other hand, I'll admit to liking some of the vocabularies they're building there.) > XML is now legacy. Its users community is screaming against any change > and its specification body seems paralysed by its structure and the > diverging interests of its members... I'm not sure that makes XML as a whole legacy. It certainly means that those of us who want to do things differently have to get our points across in both words and code. I don't see the W3C or the tools vendors doing it, and I don't see the people for whom XML is just a small part of their job doing it. > It's probably time to look for the next wave! I suspect the next wave will still be markup of some kind. There may be tuples or triples involved somewhere, but I can't see them being on the surface. It may be a good time to start making waves, while the vendors are all in a corner marveling at Web Services. -- Simon St.Laurent Ring around the content, a pocket full of brackets Errors, errors, all fall down! http://simonstl.com
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