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Re: Describing documents and their parts

From: Niklas Lindström <lindstream@gmail.com>
Date: Wed, 9 Jan 2008 23:06:31 +0100
Message-ID: <cf8107640801091406i6ccc6567v7dea0f4e89aaf0f1@mail.gmail.com>
To: RDFa <public-rdf-in-xhtml-tf@w3.org>

Hi,

I noticed a misleading thing in my examples, so just to be clear: I
don't really do <body about="..."> anywhere, but set the base URI --
so the @id thing works as expected. I can do that, or write out
@about="/publication#section-1" etc. of course.

(I wrote out the explicit "/publication" since otherwise my first
example with explicit reverse relations would look "misleadingly"
terse (@resource=""), and it isn't always the current document URI I
speak about -- especially not in "parts of parts" relations -- e.g.
<#chapter> ex:hasPart <#note>).

(.. Since we primarily indend to use XHTML2 (with <section> and other
goodies), I can also use @xml:base instead of <base>, which is quite
nice (I know I should use base URI:s with care though). But I digress.
;) )

Best regards,
Niklas



On Jan 9, 2008 6:20 PM, Niklas Lindström <lindstream@gmail.com> wrote:
> Hi all!
>
> I obviously got the current behaviour of @instanceof backwards (I'm
> afraid I've been out of the loop for about a month). It is clear to me
> now that it will *not* type a chained @resource, only the present
> @about or generated bnode. I don't dispute this (and am terribly sorry
> for speaking up before reading up on the more than month-old
> discussions).
>
>
> The cause of my concern is a use case in my current work, which I'd
> like to describe here for your advice. (Btw., this is the project
> mentioned in <http://rdfa.info/2007/10/02/rdfa-in-use-in-government/>.)
>
> We are using RDFa to describe legal documents (the real publications,
> not the xhtml information resources, which are representations *about*
> those) with properties and references, and *their parts* (chapters,
> articles) -- to be able to talk about, reference and analyze those in
> detail.
>
> I need to establish a relation between such a document and its parts
> (@id:d fragments). I will only talk about "top level parts" here, but
> parts within parts would follow this same logic as well (articles
> within chapters, advice sections within articles etc).
>
> These are the triples I want (I use a simplified made-up vocabulary
> here since ours is tightly bound to swedish legal concepts):
>
>     </publication> ex:section <#section-1> .
>     <#section-1> a ex:Section .
>     </publication> ex:appendix <#appendix-a> .
>     <#appendix-a> a ex:Appendix .
>
> Consider this skeleton example, with typed subjects in place but none
> of the needed composition relations:
>
>     <body about="/publication">
>         <div id="section-1" about="#section-1" instanceof="ex:Section">
>         </div>
>         <div id="appendix-a" about="#appendix-a" instanceof="ex:Appendix">
>         </div>
>     </body>
>
> Until I realized that @instanceof now only applies to the subject
> resource, I had been using this markup:
>
>     <body about="/publication">
>         <div id="section-1" rel="ex:section" resource="#section-1"
>              instanceof="ex:Section">
>         </div>
>         <div id="appendix-a" rel="ex:appendix" resource="#appendix-a"
>              instanceof="ex:Appendix">
>         </div>
>     </body>
>
> Since this no longer works, I can mainly think of three solutions,
> given here with some criticism of each:
>
>
> ------------------------------------------
> 1. Duplicated container relations
> ------------------------------------------
>
>     <body about="/publication">
>         <div id="section-1" about="#section-1" instanceof="ex:Section">
>             <span rev="ex:section" resource="/publication"/>
>         </div>
>         <div id="appendix-a" about="#appendix-a" instanceof="ex:Appendix">
>             <span rev="ex:appendix" resource="/publication"/>
>         </div>
>     </body>
>
> [+] short type declaration
> [+] quite clear semantics, id and about seem "correlated", the div is
> "about" its content
> [-] has to repeat the container resource when giving the relation to the part.
>
>
> ------------------------------------------
> 2. Verbose type (and possibly odd semantics)
> ------------------------------------------
>
>     <body about="/publication">
>         <div id="section-1" rel="ex:section" resource="#section-1">
>             <span rel="rdf:type" resource="ex:Section"/>
>         </div>
>         <div id="appendix-a" rel="ex:appendix" resource="#appendix-a">
>             <span rel="rdf:type" resource="ex:Appendix"/>
>         </div>
>     </body>
>
> [+] saves repetition of container resource
> [-] verbose type declaration (sacrificed type shorthand in favour of
> non-repeated container resource)
> [-] perhaps odd, since the identified div "carries the relation to itself".
>
>
> ------------------------------------------
> 3. Hanging rels, with artificial div:s
> ------------------------------------------
>
>     <body about="/publication">
>         <div rel="ex:section">
>             <div id="section-1" about="#section-1" instanceof="ex:Section">
>             </div>
>         </div>
>         <div rel="ex:appendix">
>             <div id="appendix-a" about="#appendix-a" instanceof="ex:Appendix">
>             </div>
>         </div>
>     </body>
>
> [+] saves repetition of container resource
> [-] artificial wrapping div ("div-itis"), may not work at all in some
> cases due to doctype or "conventional" restrictions, editing tools and
> similar.
>
>
> IMHO, neither of these are ideal. Perhaps hanging rels (#3) is "best",
> but it can cause problems due to the power of hanging (which is
> currently debated), and not the least due to the mentioned "divitis"
> which can become really messy. I would have preferred to describe
> parts of a document and their relations in a very compact way, since
> RDFa does it so well for descriptions of many other things. Granted,
> it's still readily possible of course, and there is obviously more
> than one way to achieve my need.
>
> I can imagine the next step for me could be something like hGRDDL
> instead (although it doesn't exist even in working draft form yet), to
> achieve the terseness and DRYness I desire.
>
>
> .. One crazy thought I had was to "kidnap" e.g. @role
> (<http://www.w3.org/TR/xhtml-role/>) for this, to establish both the
> relation between parent container and part, and while I'm at it
> perhaps also the repetition of the fragment id in @about (since @role
> is reasonably about the element itself (that fragment of the
> document), at least by default -- the "overloading" with @about
> *could* affect the semantics I suppose). It'd look like:
>
>     <body about="/publication">
>         <div id="section-1" role="ex:section" instanceof="ex:Section">
>         </div>
>         <div id="appendix-a" role="ex:section" instanceof="ex:Appendix">
>         </div>
>     </body>
>
> Admittedly, I *really* force the semantics of @role here to mean: "the
> role of an element is the relation from its container to it" and maybe
> I should just use a @class and hGRDDL). Apart from that, this solution
> would fit this specific case perfectly. :)
>
>
> But I wonder, aren't use-cases like this likely to be a common use for
> RDFa? I've always thought so (at least cases like <h1
> property="dc:title"> very much suggests it). Am I missing something?
> Or am I just trying to get too much of the RDFa goodness at the
> expense of its generality?
>
> What do you think?
>
> Best regards,
> Niklas
>
Received on Wednesday, 9 January 2008 22:06:42 GMT

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