W3C home > Mailing lists > Public > public-rdf-in-xhtml-tf@w3.org > August 2007

Re: Display values for RDFa object URLs

From: Niklas Lindström <lindstream@gmail.com>
Date: Wed, 8 Aug 2007 11:24:59 +0200
Message-ID: <cf8107640708080224oa5aa64n2f7ea8125c2d46ba@mail.gmail.com>
To: "Manu Sporny" <msporny@digitalbazaar.com>
Cc: "RDFa mailing list" <public-rdf-in-xhtml-tf@w3.org>


> something like this:
> <div instanceof="hmedia:Audio" about="#song">
>    <a href="http://www.bitmunk.com/sample/6011101"
>       rel="hmedia:sample" about="#HREF" property="dc:title">
>       A Sample
>    </a>
> </div>
> or in other words, we'd like the following (N3):
> <#song> rdf:type hmedia:Audio;
>         hmedia:sample <http://www.bitmunk.com/sample/6011101> .
> <http://www.bitmunk.com/sample/6011101> dc:title "A Sample" .

Absolutely, you can get that (verified with Ivan's pyRdfa) from this:

   <div about="#song" instanceof="hmedia:Audio">
       <a rel="hmedia:sample"
           <span property="dc:title">A Sample</span>

> Niklas, apologies, as it seems that I didn't state the problem very well
> the first time around :) - we'd like something a bit more terse than
> what you proposed (even though it did solve the problem I had previously
> stated).
> Apologies if this makes no sense, as I'm still coming up to speed with
> what is/isn't possible via chaining in RDFa. Can we get the above N3
> without having to use a hmedia:Sample class?

NP, I mostly focused on syntactic stuff, not the terseness. As seen in
the last example, it's a little more succinct. The extra span doesn't
cost much IMHO.

First, just a note. You don't need @instanceof really (which is not
final yet AFAIK), it is mostly just syntactic sugar for an rdf:type
statement. It comes in handy in some places as it also affects
chaining (mainly when you want a bnode), but can in general be
replaced by a more explicit regular @rel="rdf:type" + resource
reference (in a nested element - if used in the same, chaining makes
the *type* the chained subject). Also, @class has been voted off - it
will not (for now) mean anything in the RDFa sense (which is a good
thing in my opinion).

Now, the example you give is something that crossed my mind earlier
when Ivan mentioned that @property isn't affected by the chaining if
on the same element (see
and Ben's reply). This was as it has been, so it was just an
observation. However, your example here illustrates that it *may* be
more intuitive if the rules where changed so that @property has the
"corresponding RDF identity" as its subject. I am not at all sure
about that though, it definitely could invalidate a lot of other
examples/uses. So I recommend the use of a nested span with @property
to be certain of getting it right (as right as can be pending
recommendation that is).

Do any others have thoughts about this?

Best regards,
Received on Wednesday, 8 August 2007 09:25:08 UTC

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