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Re: @rel syntax in RDFa (relevant to ISSUE-60 discussion), was: Using XMLNS in link/@rel

From: Ben Adida <ben@adida.net>
Date: Wed, 04 Mar 2009 16:26:54 -0800
Message-ID: <49AF1C4E.4050106@adida.net>
To: "Roy T. Fielding" <fielding@gbiv.com>
CC: "www-tag@w3.org WG" <www-tag@w3.org>
Roy T. Fielding wrote:
> It has been discussed periodically ever since 1996, when pre-RDF
> discussions concluded that properties had to be URIs.  It has been
> specified in the only relevant standard to be completed since 1999,
> namely Atom.

Atom is not HTML. I agree that @rel being a URI semantically in both
HTML and Atom is desirable, but I don't see why the syntax needs to be
common between the two.

> I know what the syntax issues are and the history of the specs.
> For example, look at
> <http://ksi.cpsc.ucalgary.ca/archives/HTML-WG/html-wg-95q1.messages/0794.html>
> 
> or
> <http://www.w3.org/mid/B87388E5-FDB3-471E-8E2A-4E9000C973F6@gbiv.com>

I don't see how these pointers imply that @rel is a syntactic URI. But
maybe I've missed it, do you have a more specific pointer, maybe to a spec?

> The URI, for those that need one, is defined relative
> to the registry (wherever that may be), and thus ":" already has
> a defined meaning within rel values to indicate "this is an absolute
> URI".

Based on what specification? I think this might be after-the-fact
rationalization for how one might put URIs in @rel, but is this really a
common practice in *HTML*? Is it spec'ed anywhere?

> The rel values are *not* specific to media types.

Agreed, the semantic values should not be specific to media types. A
CURIE is just a shorthand for a URI. Just like a link-type is a
shorthand, via a registry, for a URI.

> That makes no sense.  A syntax that wouldn't interfere with the existing
> ad-hoc uses would be dc.title

I think that would interfere more because dc.title is assumed to always
mean Dublin Core title, but what if a publisher redefines the "dc."
prefix? Then we have to hard-wire the existing prefixes, but those tend
to change over time (e.g. openid is relatively recent.)

So, the "prefix." approach is not really an extensible namespace when
there's no coordination and no URI anchoring.

Also, let's be clear about the context. @rel has *not* been specified to
be a URI, to my knowledge, and I don't see any extensive use of that on
the web today, in HTML. In fact, the "prefix.*" notation is far more
used, which indicates that going with "prefix:suffix" is actually less
prone to misinterpretation.

> In fact, the only possible way
> to screw with the state of the universe in link relations as decided
> by past W3C and IETF working groups is to introduce something insanely
> stupid like CURIEs.

I'm more than happy to field civil, objective criticism. But I'm not
okay with subjective personal attacks. Please refrain from those in
future conversations.

-Ben
Received on Thursday, 5 March 2009 00:27:34 GMT

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