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Re: Minimal RDDL [NamespaceDocument-8]

From: Martin Duerst <duerst@w3.org>
Date: Mon, 17 Feb 2003 15:03:01 -0500
Message-Id: <>
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] 
Received on Monday, 17 February 2003 19:54:32 UTC

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