- From: John Cowan <jcowan@reutershealth.com>
- Date: Tue, 16 May 2000 15:10:35 -0400
- To: Tim Bray <tbray@textuality.com>, "xml-uri@w3.org" <xml-uri@w3.org>
Tim Bray wrote: > If we decree, now, that namespace names really are URLs, then I argue that > the simple design goal of dispatching software to markup based on its > universal name is grievously compromised. Here's why: I suppose you mean "dispatching markup to software"? > As we all know, the same URL can return different resources in successive > microseconds; It's a deep (3-beer) question whether in that case you are returning a different resource, or merely a different entity body (= interpreted sequence of bytes) for the same resource. > Given this, if a namespace name is really a URL in all its important > respects, then the actual contents of the string aren't important at all; > if I want to use it to dispatch to software in the intended way, I'd really > have to dispatch based on the contents of the resource that is yielded by > dereferencing it. > > So for the time being, I think we have to, for the purposes of software > dispatching, treat namespace names in the way the namespace spec specifies, > namely as literal strings. I don't see that your argument leads to your conclusion at all. Since changing a relative URI reference to absolute form does not involve the state-of-the-Web but is a purely syntactic action, what is affected is simply a question of namespace name identity. Is the namespace name "foo", declared in two different documents, the same namespace name or different ones? > Any attempt to be smart about this leads down > the slippery slope of having to dereference it and dispatching based on the > contents. What slippery slope? Absolutizing no more leads to dereferencing than marijuana .... (naaah) > Relative URI references have many virtues; but they do not include either > uniqueness or persistence. They do, however, have the "virtue" of actually existing within documents that are in being and in compliance with the Namespace Rec. > - say they're OK because namespace names really are URIs, and relative > references are well-proven and known to be good practice. The tactics > here also occupy a spectrum, ranging at the weak end from canonicalizing > away such usages as foo/././././bar through expanding them by applying > the BASE uri (if you happen to know it) to requiring that the resource be > retrieved and the dispatching based on it rather than its identifier. > For my money only the last of these is consistent. I think we are talking about RFC 2396, which includes the first and second tactics but not the third. > But in the here and now, those of us who build software for a living really > do need cheap, lightweight ways to name markup vocabularies. If we have to > dereference them to use them, we can't use them. Please don't take them > away from us. -Tim Dereferencing is a red herring. -- Schlingt dreifach einen Kreis um dies! || John Cowan <jcowan@reutershealth.com> Schliesst euer Aug vor heiliger Schau, || http://www.reutershealth.com Denn er genoss vom Honig-Tau, || http://www.ccil.org/~cowan Und trank die Milch vom Paradies. -- Coleridge (tr. Politzer)
Received on Tuesday, 16 May 2000 15:10:50 UTC