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Re: [RDFa] ISSUE-8: RDF containers in RDFa

From: Ivan Herman <ivan@w3.org>
Date: Thu, 12 Jul 2007 12:47:41 +0200
Message-ID: <469606CD.1070805@w3.org>
To: Ben Adida <ben@adida.net>
Cc: RDFa <public-rdf-in-xhtml-tf@w3.org>, SWD WG <public-swd-wg@w3.org>

Unfortunately, your proposal of 2006 has two major deficiencies:

- it was written with XHML2 in mind, ie, with the <nl> element
available. That is not the case for HTML4/XHTML1.1:-(
- there is no reference to collections, only containers. From my
predominantly RDF point of view:-), I would give a higher priority to
lists/containers than to collections... (see also my reply to Michael[1])

In any case, I would like to have a relatively easy way of expressing
lists in RDFa (I am not yet sure what exactly that should be), and
possibly leaving the containers aside for a moment. Here are my reasons

- Expressing Seq/Alt/Bag in a 'pedestrian' way, ie, spelling out the
structure manually, is not a huge deal. After all, the RDF/XML syntactic
sugars are really not big deals, just sparing an rdf:type with an extra
node, plus some trick with the rdf:li. Doing a, say, Seq in RDFa would mean:

<ul the-attribute-you-shall-not-name="rdf:Seq">
  <li property="rdf:_1">bla bla bla</li>
  <li property="rdf:_2">bla bla bla</li>

referring back to the various issues we discussed in the past few days.
I simply do not believe it is worth the trouble in RDFa to introduce
syntactic sugar for this...

- Expressing collections is, in terms of triples, _much_ nastier,
unfortunately, though much cleaner in terms of RDF (see[1]). In other
words, giving a helping hand for RDFa authors in that respect would
really be good. Unfortunately, the _only_ solution I see at the moment
is the introduction of a new attribute, much like RDF/XML parseType; ie,
having something like

<ul parseType="collection">
  <li property="rdf:_1">bla bla bla</li>
  <li property="rdf:_2">bla bla bla</li>

could then generate a blank node being a list with the <li>-s as
constituents. _I know_ it is a pain in the butt, but I do not see any
other solution...



Ben Adida wrote:
> Hi all,
> There's one syntax issue we haven't talked about n a while that we
> should probably address in *some* form: how to express RDF containers
> and/or lists. In particular, how do we indicate a list of creators, or a
> list of licenses, or a list of authors in a paper.
> I wrote a proposal on RDFa containers a while ago:
> http://www.w3.org/2001/sw/BestPractices/HTML/2006-rdfa-containers
> but that assumed we would do RDF Bags and Sequences. I don't know yet if
> that's what we should support, or if we should just focus on lists,
> denoted [a,b,c] in Turtle.
> Input from anyone, in particular the SWD WG, would be very helpful! I
> think for XHTML1.1+RDFa, we should do the simplest thing that doesn't
> completely prevent us from encoding lists of some kind.
> In terms of implementation, the right direction is likely something
> using UL, OL, and LI, possibly involving @href/@resource on the LI, as
> we had expected @href everywhere in the original XHTML2-based proposal.
> -Ben


Ivan Herman, W3C Semantic Web Activity Lead
URL: http://www.w3.org/People/Ivan/
PGP Key: http://www.cwi.nl/%7Eivan/AboutMe/pgpkey.html
FOAF: http://www.ivan-herman.net/foaf.rdf

Received on Thursday, 12 July 2007 10:47:38 UTC

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