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Re: Using @resource instead of @about in RDFa Lite (ISSUE-119)

From: Ivan Herman <ivan@w3.org>
Date: Thu, 17 Nov 2011 15:02:06 +0100
Cc: Jeni Tennison <jeni@jenitennison.com>, Niklas Lindström <lindstream@gmail.com>, public-rdfa-wg <public-rdfa-wg@w3.org>, HTML Data Task Force WG <public-html-data-tf@w3.org>, Dan Brickley <danbri@danbri.org>, Ben Adida <ben@adida.net>
Message-Id: <BD8CCBD9-EA0A-4BDE-BBA4-A48624D9B59E@w3.org>
To: Gregg Kellogg <gregg@kellogg-assoc.com>
I have added this as a formal issue, although I do not believe we can discuss and decide upon this today...

Ivan

On Nov 17, 2011, at 14:53 , Gregg Kellogg wrote:

> On Nov 17, 2011, at 12:32 AM, "Ivan Herman" <ivan@w3.org> wrote:
> 
>> I essentially agree. In fact, I realized a while ago, when I played with the new @property setting in RDFa 1.1, that @resource might really be missing[1]. I must admit I did not think of dropping @about although, thinking about it further, having them both might be a bit complicated for the constituency of RDFa Lite.
> 
> Another reason to at least include @resourse is that, in HTML5, the content model for @href/@src and other native resource types, is a URL, not an IRI; in the DOM API, IRIs are actually transformed into URLs. If you want to have IRI resources, you'd need @resource.
> 
> In any case, I think that @resource creates less confusion than @about.
> 
> Gregg
> 
>> I have cc-d Ben explicitly, to see if there were some technical issues discussed on this that we may not know about.
>> 
>> Ivan
>> 
>> [1] http://lists.w3.org/Archives/Public/public-rdfa-wg/2011Nov/0024.html
>> 
>> On Nov 16, 2011, at 23:49 , Jeni Tennison wrote:
>> 
>>> 
>>> 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
>> 
>> 
>> 
>> 
>> 
>> 


----
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 13:59:37 GMT

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