- From: Martin Duerst <duerst@w3.org>
- Date: Mon, 17 Feb 2003 15:03:01 -0500
- To: Tim Bray <tbray@textuality.com>, WWW-Tag <www-tag@w3.org>
Hello Tim, Does rddl contain a way for an RDDL document to say, in machine-readable form, "I'm a document about namespace X"? For example, the RDDL spec at http://www.rddl.org/ says: "This document describes the syntax and semantics of the Resource Directory Description Language 1.0, and also serves as a Resource Directory Description for the namespace http://www.rddl.org/." This is in prose, but is there an equivalent in machine readable form? Syntactically, this would probably be rather easy, by just defining a nature or purpose of http://www.w3.org/TR/REC-xml-names/ (the Namespace REC) to stand for 'this rddl document is a description of the namespace given as the link target'. Identifying the actual namespace described is important because one can always get to the same document in different ways (compare http://www.rddl.org and http://www.rddl.org/ and http://www.rddl.org/index.html; which one is the rddl namespace?). Regards, Martin. At 14:33 03/02/14 -0800, Tim Bray wrote: >I have an action item, working with Paul Cotton, to produce a draft of >RDDL based on the discussion we've had around the TAG. I reviewed the >input, talked to Paul, and co-author Jonathan Borden, and got to > > http://www.textuality.com/xml/rddl3.html > >Here's how. The original RDDL draft from Borden and me was XHTML plus a >new element <rddl:resource> with a bunch of ordinary attributes like title >and description, plus two special ones "nature" (namespace name or mime >type) and "purpose" (what you want to use this for). Both nature and >purpose were going to be URIs; RDDL was going to provide a bunch of useful >pre-cooked purposes. > >People coming from the Semantic Web direction (including co-author >Jonathan Borden) argued in favor of several different RDF representations, >but they all had significant overhead, and furthermore IMHO failed to >achieve their semantic-web objective while simultaneously making RDDL >uglier less useful in terms of its original goal. I just don't think the >community will buy into any of those alternatives. > >Next, Sandro Hawke suggested just using the existing <xhtml:a> element, >which has little-used attributes rel= and type= which fit pretty well >perfectly onto "nature" and "purpose". See >http://lists.w3.org/Archives/Public/www-tag/2002Dec/0232.html. Turns out >there are two problems with this. First of all, how do you know that some >particular <html:a> is pointing to related-resources, rather than just >being a human-oriented hyperlink right there in the text? Second, it turns >out that rel= and type= come preloaded with a bunch of fuzzy >semantics, I've appended a private email from Sandro. Having read it, it >seemed likely impossible to cleanly reuse rel= and type=. > >So, in conclusion, the above is a RDDL proposal using <html:a> >elements, not trying to re-use the "rel" and "rev" attributes, but rather >introducing just two new attributes, rddl:nature and rddl:purpose. The >element has tons of other useful attributes like "title" and "longdesc" >and so on already, people can use those if they want to and occasionally >browsers will even do something useful with them. Bear in mind that *all* >these RDDL proposals are more or less isomorphic in that you could turn >pretty well any of them into pretty well any of the others with an XSLT >script. -Tim Sandro's note >============================================== >> 1. The TAG seems to have >consensus that we should move forward toward >> something to fill the RDDL >hole, and I have part of the job of producing >> a first-cut WD. I would >like to base it on your suggestion using the >> existing attributes of > >http://lists.w3.org/Archives/Public/www-tag/2002Dec/0232.html), just >> >because it seems like the simplest possible way to proceed. Someone >> >piped up and said that your proposal was invalid per some HTML rule or >> >another but I never took the trouble to figure out whether this was >> >right or not. Is there a problem and does your proposal need >> >modification to work around this? I discussed the problem in a followup >[1] and then offered an amended proposal [2] which should be valid in all >HTMLs. It's a vaguely unpleasant situation with XHTML 1.1. The document >linked in [2] contains the amended rddl challenge text, or see [3]. One >could also do the imports using LINK in the HEAD, I suppose, if one wanted >them to be invisible. >> Also, another question... does the profile= >attribute in the > element mean that for all > the RDDL semantics? Or is >there a case to be made for some other >> syntactic mechanism to >distinguish > opposed to generic links? I think profiles allow you to >define additional link types (values for rel=), but not change existing >ones [4]. I'm thinking these RDDL semantics for type are the same as the >existing semantics (a hint as to what Content-Type you'll get if you do a >GET), so there's no issue there. This kind of relies on the TAG view that >Content-Type values should be viewed as URIs. It's hard to find an example >of profile= which doesn't have Dan Connolly's name on it. :-) [1] >http://lists.w3.org/Archives/Public/www-tag/2002Dec/0234.html [2] >http://lists.w3.org/Archives/Public/www-tag/2002Dec/0236.html [3] >http://www.w3.org/2002/12/ns/rddl-challenge.html [4] >http://www.w3.org/TR/html401/types.html#type-links >=========================================================================
Received on Monday, 17 February 2003 19:54:32 UTC