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[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message] patterns vs. identifiers
 I've spent too much time lately thinking about why I'm generally unhappy with the direction that a lot of markup work is headed at present, and about why things like XHTML 2.0 or RELAX NG make me much happier than things like RDF or WXS. The general answer - though one that I recognize probably isn't perfect - is that I'm far more comfortable working with patterns than working with identifiers. That's not to say I don't want to use identifiers - names and labels are a critical part of the patterns I find useful, but I tend to find them useful in context. Single identifers are easy to fit into patterns, especially if (as with URLs) there's a clear use pattern that makes it easier to make them concrete, but layers of identifiers quickly become a barrier. I don't find notions of abstract identifiers meaningful or particularly useful. I suspect that a fondness for such identifiers is a key factor in distinguishing high-end programmers, logicians, and mathematicians from the general public, and that those communities eventually lose track of the fact that what is easy for them is not necessarily easy for the rest of us. (How long does it take for the average person to figure out passing-by-reference vs. passing-by-value? It took me a couple of years to be genuinely comfortable with it.) My suspicion, after working with Ool [1] and out-of-line markup, is that markup works because it lets people describe patterns (labeled structures) in their content directly. They can see the patterns they create directly, with no need to keep a mental list of which pointer goes where. Containment is explicit, not controlled by a separate table of pointers that requires maintenance. Some markup technologies have taken advantage of this pattern-nature to create useful tools that are reasonably accessible. XPath does this, at least in its simpler forms. RELAX NG, especially in its non-XML form, is also very easy to read as a set of patterns. Other markup technologies seem to have gone toward the identifier-style approach. Namespaces in XML uses both abstract identifiers (URIs) and a scoped mapping approach that requires people working with documents to keep track of which identifier they're using when. W3C XML Schema supports the creation of - and extension and restriction of - types (separate from the concrete element/attribute vocabulary) which require a lot of tracking to get right. RDF appears to go furthest with this, to the point that I'm not really sure how to use RDF to apply metadata to a concrete representation of a resource rather than the abstract resource itself - but it may just be that I can't follow the long chain of identifiers. QNames are another catastrophe in this ongoing saga. I've been worried for a long time that the W3C is badly tilted toward developing specs that work on formal models of identifiers rather than with patterns. This is a lot of why I talk about things like the W3C and RDF inflicting "URI-poisoning" on XML or programmers causing as many problems as they solve because of a dangerously different perspective on information. The continuing dominance of those groups in markup technologies is why I presently see little hope for improvement in XML as maintained by the W3C. (At this point, I wouldn't be averse to shutting down the XML activity in order to prevent additional damage.) (The groups focused on maintaining and creating specific vocabularies seem to do better, fortunately, though they have an awful lot to cope with.) [1] - http://simonstl.com/projects/ool/ ------------- Simon St.Laurent - SSL is my TLA http://simonstl.com may be my URI http://monasticxml.org may be my ascetic URI urn:oid:1.3.6.1.4.1.6320 is another possibility altogether 
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