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

From: Elias Torres <elias@torrez.us>
Date: Wed, 23 May 2007 19:08:08 -0400
Message-ID: <4654C958.8080404@torrez.us>
To: mark.birbeck@x-port.net
CC: RDFa <public-rdf-in-xhtml-tf@w3.org>

I like @resource much better than @href any/everywhere.

... and yes, I'd like that to be @property instead of @rel.

-Elias

Mark Birbeck wrote:
> 
> 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 Wednesday, 23 May 2007 23:08:24 GMT

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