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Re: Display values for RDFa object URLs

From: Ivan Herman <ivan@w3.org>
Date: Fri, 10 Aug 2007 14:13:33 +0200
Message-ID: <46BC566D.4090607@w3.org>
To: Mark Birbeck <mark.birbeck@formsPlayer.com>
CC: Manu Sporny <msporny@digitalbazaar.com>, RDFa mailing list <public-rdf-in-xhtml-tf@w3.org>
Hi Mark,

I swear I did not do it on purpose! But I just made a page where I've put:

package is also <a
href="http://dev.w3.org/2004/PythonLib-IH/pyRdfa/">available for

Yes, this is not RDFa but, had I wanted, I could have said something like

<a rel="namesp:code"
href="http://dev.w3.org/2004/PythonLib-IH/pyRdfa/">available for

The text of the link is, sort of, o.k. for the flow of the HTML text,
but I do not think it is o.k. for the label of
http://dev.w3.org/2004/PythonLib-IH/pyRdfa/. However, if I take your
approach, _I do not have a choice_, that _will_ be the rdfs:label. And
that is what I do not like: I've lost control.

By the way, one of the differences in our perceptions may come from your

we try to provide an *interpretation* of the mark-up in triple form,

which is not the way I look at it. We do not try to interpret the
mark-up; we give tools to the user to add 'metadata' (yey, I used the
m-word:-) to his/her own text in a specific mark-up.

I guess we can safely agree that we disagree on that:-) and let the
group vote on this...


Mark Birbeck wrote:
> Hi Ivan,
>> I understand the intention, I see the solution, but I am not convinced:-(.
> :)
>> I think we should keep such 'implicit' rules of triple generation to the
>> minimum. We try to second guess the author's intentions here and I am
>> not sure that is justified.
> We don't actually try to 'second guess' intentions at all; we try to
> provide an *interpretation* of the mark-up in triple form, that could
> be said to be legitimate based on the HTML spec. If I say @rel="x"
> then the HTML spec says that I'm establishing a relationship between
> one document and another, so we can legitimately use the contents of
> @rel as a predicate. Similary if I say <a href="x">y</a> then I have
> unavoidably provided text to label a link--there is no second guessing
> of the author's intentions going on there at all, since in fact the
> browser is obliged to use that label on the link.
>> There are a number of Web pages, for
>> example, that use the (absolutely horrible!) 'click here' or 'see here',
>> or similar content to <a>. Yes, it is a very bad design, but it is
>> there. Ie, we will get a bunch of meaningless rdfs:label-s...
> Now it's my turn to be not convinced...so what? :)
>> As you say, the construction:
>> <div about="#song" instanceof="hmedia:Audio">
>>  <a rel="hmedia:sample" href="http://www.bitmunk.com/sample/6011101">
>>        <span property="rdfs:label">A Sample</span>
>>  </a>
>> </div>
>> works, it makes it explicit what the user wants, and also gives him/her
>> to possibility to fine tune what should be a label and what shouldn't.
> But like I say, they have already said what should be a label--that's
> the contents of the <a>. I'd be interested to hear other points of
> view, but I don't see using the text as an rdfs:label as very
> controversial. The reason it hasn't been in the spec for so long--and
> I've had this pending action item to 'work it back in'--is because
> it's been difficult to come up with a simply rule that justifies
> attaching the label to the @href. Now we're dealing with chaining
> again, it seems more logical.
>> It also opens the flood gates to a bunch of other questions. Do you want
>> to introduce the same mechanism everywhere where one would use @href
>> (after all, we opened this particular flood gate by allowing @href
>> everywhere!)? What happens if I use @resource on <a> but no @href? What
>> happens if there is additional markup within <a>? All set of additional
>> issues that (1) has to be answered (2) has to be specified in the
>> syntax, thereby making it more complicated (3) has to be properly
>> explained in a primer document (4) has to be documented with test cases,
>> etc, etc. I just do not see that avoiding one additional <span>
>> justifies these costs...
> I don't see it as being so complicated. In my view this kind of thing
> makes things much simpler, because authors add less code, not more.
> In my version, the author simply creates a link using ordinary
> mark-up, in the way they are used to as an HTML author:
>   <a rel="p" href="o">label</a>
> Our RDFa rules then say that this link--which HTML defines as being a
> combination of a target document with some text to describe the
> navigation to it--will generate two triples (which reflects that
> combination). The first triple describes the relationship between the
> current document and the target, and the second describes the label
> used to refer to that target document.
> In the 'longhand' version though, the author has to add more mark-up
> to indicate that they want a label for the link, which is far more
> confusing, since most authors will rightly say, but haven't I already
> specified a label? This won't get done, since there is no particular
> reason that authors would think they need to do this, and then we have
> nothing in our parsed output that can be used to label the links.
> Regards,
> Mark


Ivan Herman, W3C Semantic Web Activity Lead
Home: http://www.w3.org/People/Ivan/
PGP Key: http://www.ivan-herman.net/pgpkey.html
FOAF: http://www.ivan-herman.net/foaf.rdf

Received on Friday, 10 August 2007 12:13:39 UTC

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