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Thoughts on @href/@resource completing hanging @rels

From: Manu Sporny <msporny@digitalbazaar.com>
Date: Mon, 21 Jan 2008 14:19:12 -0500
Message-ID: <4794F030.50102@digitalbazaar.com>
To: RDFa mailing list <public-rdf-in-xhtml-tf@w3.org>

Hi all,

I've been thinking about this quite actively for the past week or two
and have since come to the same conclusion that Mark has... in short, by
simply stating that @about completes hanging rels, but @resource
doesn't, we're making RDFa more complicated. I am arguing against that
added complexity because it doesn't really get us anything, IMHO.

My position currently, which has changed from what it was 3 weeks ago,
is that @href and @resource should complete hanging @rels.

The rest of this e-mail is loose reasoning and formalization.

------------------------- Loose Reasoning ---------------------------

My first concern was that by allowing @href-@rel-@href or
@resource-@rel-@resource constructs we would confuse current XHTML
authors. It certainly was confusing to me at first, but only because
this construct was a new way of thinking about the structure of an XHTML
document (to me, at least). Mark said a few things last week that
resonated, namely - that getting people to understand this approach is a
matter of education.

Spurious triples were another concern, but after considering a couple of
samples (based only on a sample of 20-30 websites - not many, I know), I
didn't see any that had a @href-@rel-@href approach. @resource doesn't
exist and neither does @about, so the ones that we really have to worry
about are @href-@rel-@src and @href-@rel-@href constructs. I was unable
to find any web pages that had the @href-@rel-@href construct. So, I
don't think that there would be an issue with spurious triples in legacy
pages.

As for spurious triples in newly created XHTML+RDFa pages, well, there
is no such thing. Either you are authoring an XHTML+RDFa page, or you
are not. If you are authoring an XHTML+RDFa page - you should know the
basic rules (which can be explained quite simply). Let us not forget
that there are very complex rules for authoring cross-browser
Javascript/XHTML and CSS. I wouldn't put the hanging @rel issue anywhere
in the same ballpark as issues that current web designers must go
through. In other words - if this is the most complicated thing to learn
about RDFa, then that's good news.

-------------------------- Formalization ----------------------------

Just to clarify further, this is my current position using Test Cases to
illustrate:

@about subject, no hanging @rels, @href completes triples.
-----------------------------------------------------------------
<div about="#me">
   <span rel="foaf:knows" href="#ivan">
   <span rel="foaf:knows" href="#shane">
</div>
--------
<#me> foaf:knows <#ivan> .
<#me> foaf:knows <#shane> .
-----------------------------------------------------------------

@about subject, hanging @rel, @href/@resource completes triples
-----------------------------------------------------------------
<div about="#me" rel="foaf:knows">
   <span href="#ivan">
   <span resource="#shane">
</div>
--------
<#me> foaf:knows <#ivan> .
<#me> foaf:knows <#shane> .
-----------------------------------------------------------------

@href subject, hanging @rel, @href/@resource completes triples
-----------------------------------------------------------------
<div href="#me" rel="foaf:knows">
   <span href="#ivan">
   <span resource="#shane">
</div>
--------
<#me> foaf:knows <#ivan> .
<#me> foaf:knows <#shane> .
-----------------------------------------------------------------

@resource subject, hanging @rel, @href/@resource completes triples
-----------------------------------------------------------------
<div resource="#me" rel="foaf:knows">
   <span href="#ivan">
   <span resource="#shane">
</div>
--------
<#me> foaf:knows <#ivan> .
<#me> foaf:knows <#shane> .
-----------------------------------------------------------------

-- manu

-- 
Manu Sporny
President/CEO - Digital Bazaar, Inc.
blog: Intro to the Semantic Web in 6 minutes (video)
http://blog.digitalbazaar.com/2007/12/26/semantic-web-intro
Received on Monday, 21 January 2008 19:19:22 GMT

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