- From: Ivan Herman <ivan@w3.org>
- Date: Thu, 17 Nov 2011 09:37:19 +0100
- To: W3C RDFWA WG <public-rdfa-wg@w3.org>
Resending for the tracker Ivan Begin forwarded message: > Resent-From: public-html-data-tf@w3.org > From: Jeni Tennison <jeni@jenitennison.com> > Date: November 16, 2011 23:49:56 GMT+01:00 > To: Niklas Lindström <lindstream@gmail.com>, public-rdfa-wg <public-rdfa-wg@w3.org> > Cc: HTML Data Task Force WG <public-html-data-tf@w3.org>, Dan Brickley <danbri@danbri.org> > Subject: Re: Using @resource instead of @about in RDFa Lite > archived-at: <http://www.w3.org/mid/8B8B204A-13E9-4258-B678-057D3C17CA7B@jenitennison.com> > list-id: <public-html-data-tf.w3.org> > > > On 16 Nov 2011, at 21:19, Niklas Lindström wrote: >> Have we considered whether @resource would be preferable over @about >> in RDFa Lite? > > It's funny because I was just running into some issues that made me wish for @resource rather than @about. > > @danbri set me the challenge of creating a stylesheet to map microdata into RDFa 1.1 Lite in part to easily generate some RDFa 1.1 Lite examples using schema.org markup. > > The first document that I tried was http://www.imdb.com/title/tt0813715/. This contains the markup (much simplified here): > > <div itemscope itemtype="http://schema.org/TVSeries"> > <div itemprop="aggregateRating" > itemscope itemtype="http://schema.org/AggregateRating"> > Ratings: > <strong><span itemprop="ratingValue">7.2</span></strong> > <span class="mellow">/<span itemprop="bestRating">10</span></span> from > <a href="ratings" > title="23,201 IMDb users have given an average vote of 7.2/10"> > <span itemprop="ratingCount">23,201</span> users</a> > </div> > </div> > > which if you were to convert to RDF using the microdata/RDF mapping that Gregg's been working on, would generate something like: > > <> md:item [ > a schema:TVSeries; > schema:aggregateRating [ > a schema:AggregateRating; > schema:bestRating "10"; > schema:ratingCount "23,201"; > schema:ratingValue "7.2" > ] > ] . > > A simplistic mapping into RDFa 1.1 gives: > > <div vocab="http://schema.org/" typeof="TVSeries"> > <div property="aggregateRating" > vocab="http://schema.org/" typeof="AggregateRating"> > Ratings: > <strong><span property="ratingValue">7.2</span></strong> > <span class="mellow">/<span property="bestRating">10</span></span> from > <a href="ratings" > title="23,201 IMDb users have given an average vote of 7.2/10"> > <span property="ratingCount">23,201</span> users</a> > </div> > </div> > > If you run that through a RDFa parser, you get: > > [ > a schema:TVSeries; > schema:aggregateRating [ > a schema:AggregateRating; > schema:bestRating "10"; > schema:ratingValue "7.2" > ] > ] . > > <ratings> schema:ratingCount "23,201" . > > What's happened? The ratingCount property is nested within a link, and the @href of the link is creating a new scope for the statements within that link, so instead of belonging to the AggregateRating, the ratingCount is a property of <ratings> (the URI of the link). > > I can get around that in this case by adding a property="" to the link. However, if it had a @rel on it already, like this: > > <div vocab="http://schema.org/" typeof="TVSeries"> > <div property="aggregateRating" > vocab="http://schema.org/" typeof="AggregateRating"> > Ratings: > <strong><span property="ratingValue">7.2</span></strong> > <span class="mellow">/<span property="bestRating">10</span></span> from > <a href="ratings" rel="prefetch" > title="23,201 IMDb users have given an average vote of 7.2/10"> > <span property="ratingCount">23,201</span> users</a> > </div> > </div> > > then that wouldn't work. In that case, I need to make sure that the subject of the ratingCount property is the aggregate rating, rather than <ratings>. > > I could do that in two ways. One would be to add an @about attribute on both elements pointing to the same blank node, but in that case I'd need to create another nested <div> because if I put an @about attribute on the element with property="aggregateRating" then the subject of the triple generated by that property would be the @about. But then the property="aggregateRating" doesn't chain, so I'd have to use @rel: > > <div vocab="http://schema.org/" typeof="TVSeries"> > <div rel="aggregateRating"> > <div about="_:rating" vocab="http://schema.org/" typeof="AggregateRating"> > Ratings: > <strong><span property="ratingValue">7.2</span></strong> > <span class="mellow">/<span property="bestRating">10</span></span> from > <a href="ratings" rel="prefetch" > title="23,201 IMDb users have given an average vote of 7.2/10"> > <span about="_:rating" property="ratingCount">23,201</span> users</a> > </div> > </div> > </div> > > Or as Nicklas suggested I could use the @resource attribute. That works out a lot neater: > > <div vocab="http://schema.org/" typeof="TVSeries"> > <div property="aggregateRating" resource="_:rating" > vocab="http://schema.org/" typeof="AggregateRating"> > Ratings: > <strong><span property="ratingValue">7.2</span></strong> > <span class="mellow">/<span property="bestRating">10</span></span> from > <a href="ratings" rel="prefetch" resource="_:rating" > title="23,201 IMDb users have given an average vote of 7.2/10"> > <span property="ratingCount">23,201</span> users</a> > </div> > </div> > > Note that in neither case does the xhv:prefetch relationship make any sense whatsoever. Hopefully processors will ignore the bogus xhv:* properties. > > @resource also gives a lot better mapping for @itemid. Say the microdata had an @itemid on the inner <div> like this: > > <div itemscope itemtype="http://schema.org/TVSeries"> > <div itemprop="aggregateRating" > itemscope itemtype="http://schema.org/AggregateRating" > itemid="ratings"> > Ratings: > <strong><span itemprop="ratingValue">7.2</span></strong> > <span class="mellow">/<span itemprop="bestRating">10</span></span> from > <a href="ratings" > title="23,201 IMDb users have given an average vote of 7.2/10"> > <span itemprop="ratingCount">23,201</span> users</a> > </div> > </div> > > If @resource were allowed in RDFa 1.1 Lite then I could just map the @itemid to @resource really easily: > > <div vocab="http://schema.org/" typeof="TVSeries"> > <div property="aggregateRating" > vocab="http://schema.org/" typeof="AggregateRating" > resource="ratings"> > Ratings: > <strong><span property="ratingValue">7.2</span></strong> > <span class="mellow">/<span property="bestRating">10</span></span> from > <a href="ratings" > title="23,201 IMDb users have given an average vote of 7.2/10"> > <span property="ratingCount">23,201</span> users</a> > </div> > </div> > > So I strongly support Niklas' suggestion of using @resource rather than @about in RDFa 1.1 Lite. > > Cheers, > > Jeni > -- > Jeni Tennison > http://www.jenitennison.com > > ---- Ivan Herman, W3C Semantic Web Activity Lead Home: http://www.w3.org/People/Ivan/ mobile: +31-641044153 FOAF: http://www.ivan-herman.net/foaf.rdf
Received on Thursday, 17 November 2011 08:34:37 UTC