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Re: PROPOSAL: Using @resource to define objects that are resources

From: José Manuel Cantera Fonseca <jmcf@tid.es>
Date: Thu, 24 May 2007 17:38:23 +0200
To: RDFa <public-rdf-in-xhtml-tf@w3.org>
Message-id: <4655B16F.1090800@tid.es>

It is CDATA, but due to the fact that the datatype attribute is set to 
rdf:resource it is interpreted as a URI by the processor

Best regards

Shane McCarron escribió:
> Just to be clear, are you suggesting that @content now be a URI type 
> instead of a CDATA type?  To date content has been a way of specifying 
> content for a property when you do not want to use the actual content 
> of the element in question.  I think, anyway.
>
> José Manuel Cantera Fonseca wrote:
>>
>> Hello,
>>
>> I'm suggesting the following counterproposal which sounds more 
>> orthogonal to me and avoids introducing a new attribute:
>>
>> <div about="http://joost.com/some-film">
>>   <div property="dc:title">A film</div>
>>   <div property="dc:description">
>>     Some notes on the film
>>   </div>
>>   <span property="dc:subject" content="http://film-vocab/horror" 
>> datatype="rdf:resource">Category:
>> Horror</span>
>> </div>
>>
>> Best wishes
>>
>> Mark Birbeck escribió:
>>>
>>> This is a proposal for the requirement at:
>>>
>>>  <http://lists.w3.org/Archives/Public/public-rdf-in-xhtml-tf/2007May/0018.html> 
>>>
>>>
>>> Any discussion about whether this is a legitimate thing to try to do
>>> should be added to that thread. This thread is for a possible solution
>>> that meets the perceived need.
>>>
>>>
>>> CURRENT SYNTAX
>>>
>>> There are two current technique for specifying an object that is a
>>> resource. They are to use @href on elements that are not anchor tags,
>>> and the second is to use a link element.
>>>
>>> The first, using '@href everywhere':
>>>
>>>  <div about="http://joost.com/some-film">
>>>    <div property="dc:title">A film</div>
>>>    <div property="dc:description">
>>>      Some notes on the film
>>>    </div>
>>>    <span rel="dc:subject" href="http://film-vocab/horror">Category:
>>> Horror</span>
>>>  </div>
>>>
>>> There has been some pushback on this technique.
>>>
>>> The second is to use a link element:
>>>
>>>  <div about="http://joost.com/some-film">
>>>    <link rel="dc:subject" href="http://film-vocab/horror" />
>>>    <div property="dc:title">A film</div>
>>>    <div property="dc:description">
>>>      Some notes on the film
>>>    </div>
>>>    <span>Category: Horror</span>
>>>  </div>
>>>
>>> In terms of use in current browsers, we're finding that context
>>> information is lost when using 'link' in the body of the document, so
>>> this doesn't look like it will work. Obviously the elements could be
>>> added to <head> with an @about, but that makes things quite difficult
>>> to manage.
>>>
>>>
>>> @HREF EVERYWHERE
>>>
>>> In my view the idea that authors will be confused by having '@href
>>> everywhere' is not as big a problem as has been posed. However, I'm
>>> always of the view that if we can find an alternative solution that
>>> does as good a job as a solution that people aren't comfortable with,
>>> why not just use it. In this case, I think there is an alternative
>>> solution that is in some ways better than '@href everywhere'.
>>>
>>>
>>> A SHORT HISTORY OF @RESOURCE
>>>
>>> In my earliest drafts of RDFa I used attributes for subject, predicate
>>> and objects, and the one for objects that were resources was
>>> @resource. However, this was never satisfactory, because it meant that
>>> information would often be duplicated--once for a clickable link, and
>>> once for a statement--and it was the big thing that Ben Adida insisted
>>> we should solve. So, after a great deal of juggling things around, I
>>> stumbled upon the fact that @rel and @rev could be used on anchor
>>> tags--maybe I was the only one who didn't, but I had not known that
>>> that--and so it became pretty clear that HTML already gave us what we
>>> needed and we could use @href instead of @resource. This seemed to
>>> meet Ben's crucial requirement that we should only have to express the
>>> URI once, and so 'bridge the clickable and semantic webs'. :)
>>>
>>> Now, since XHTML 2 had previously added a new feature that @href could
>>> be used on any element in a document, to create a navigable link, it
>>> seemed obvious that all we had to do was drop @resource, and replace
>>> it with @href.
>>>
>>> However, non-XHTML 2 browsers actually have a tough time turning @href
>>> on a span into a clickable link, and although it can be done with some
>>> script, we don't get that out of the box. This means that we can have
>>> @href attributes in a document that are not clickable links, and there
>>> has been some argument that using @href on non-anchor elements could
>>> confuse people.
>>>
>>>
>>> PROPOSAL
>>>
>>> My proposal would therefore be to still _allow_ @href anywhere, but to
>>> play this feature down, and point people towards @resource. I feel
>>> that an RDFa parser should still process @href as an object that is a
>>> resource, wherever it finds it, so that if it encounters an XHTML 2
>>> document, it will still work.
>>>
>>> But whilst we still _support_ that feature, in our example code,
>>> tutorials, and so on, we should instead use the resource attribute to
>>> express an object that is a resource. Hopefully this way things will
>>> be clearer to authors.
>>>
>>> One way that we could understand this is that @resource is a core RDFa
>>> attribute, whilst @href is not. When we come to use RDFa in a 'host
>>> language' we add further rules, and in the case of the host language
>>> being HTML or XHTML we can say that @href is given the 'RDFa meaning'
>>> of being equivalent to @resource.
>>>
>>>
>>> SYNTAX
>>>
>>> Our previous example would now become:
>>>
>>>  <div about="http://joost.com/some-film">
>>>    <div property="dc:title">A film</div>
>>>    <div property="dc:description">
>>>      Some notes on the film
>>>    </div>
>>>    <span rel="dc:subject" resource="http://film-vocab/horror">
>>>      Category: Horror
>>>    </span>
>>>  </div>
>>>
>>> (I'll leave how the predicate is expressed out of this, but there are
>>> good arguments for using @property here. I'll start a new thread for
>>> that.)
>>>
>>> Regards,
>>>
>>> Mark
>>>
>>
>>
>>
>
Received on Thursday, 24 May 2007 15:43:43 GMT

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