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Re: [RDFa] ISSUE-28: following your nose to the RDFa specification

From: Keith Alexander <k.j.w.alexander@gmail.com>
Date: Sun, 01 Jul 2007 01:28:31 +0100
To: mark.birbeck@x-port.net, "Dan Connolly" <connolly@w3.org>
Cc: "Ben Adida" <ben@adida.net>, RDFa <public-rdf-in-xhtml-tf@w3.org>, "SWD WG" <public-swd-wg@w3.org>
Message-ID: <op.turfltf763ayaz@keith-alexanders-computer.local>

Hi,

I asked this question in another thread, but didn't really get an answer:  
what is the disadvantage in aligning RDFa completely with GRDDL ?

If an author has control over the DOCTYPE, s/he also has control over the  
@profile. So why not?

On Sat, 30 Jun 2007 20:49:11 +0100, Mark Birbeck <mark.birbeck@x-port.net>  
wrote:

>
> Hi Dan,
>
> I agree with Ben's comments in reply to this post, but would like to
> add some more.
>
>> This issue is about the case where you do find an RDFa
>> attribute (about/resource/etc); how do
>> you know that the author meant it in the RDFa sense?
>
> You don't. But I'm sure you'll agree that the chances of false
> positives are *enormously* smaller than the situation with
> microformats.

I disagree. It's true that it is unlikely you would do so accidentally,  
but GRDDL ought to enable me to define my own RDF-in-HTML syntax based on,  
or incorporating parts of, RDFa. If you don't let authors say "this is not  
RDFa" you shut down options and risk confusion about exactly what triples  
should be generated from documents. In my opinion this would hamper  
innovation, reliability, and the usefulness of RDF-in-HTML in general.

> XHTML. So you'd need an author to add one or more of @about, @content,
> @datatype, or @property. I've not come across anyone doing this so
> far, and believe it to be very unlikely. I'm not ruling it out, I'm
> just saying that given the way most HTML/XHTML authors currently work,
> it is an order of magnitude less likely than overloading @class
> values. And as RDFa becomes more well known, the chances of such false
> positives *decrease*. (Since it's less likely that someone devising
> their own language based on HTML would re-use these attributes.)

This is basically the same argument that microformats use isn't it? Choose  
some obscure strings to squat, and raise awareness that you are squatting  
on them?

Can you tell me about XHTML 2 and RDFa? XHTML 2 has those attributes built  
in doesn't it? So presumably won't need a different DOCTYPE? How, if at  
all, can an author use XHTML 2 without implying RDFa?


> Whether the author intended triples or not, doesn't matter; it
> may not have occurred to me that my documents would be spoken to a
> blind user, but that doesn't make it wrong for a voice browser to
> process and 'interpret' my documents in a different way. So too with
> an RDFa parser.

There is a big difference between a user being able to ignore the author's  
intention (or lack of stated intention), and an author being unable to  
clearly state their intention. Bad data can have serious consequences. So  
it needs to at least be clear from the specification, if there is bad  
data, who is to blame: the user (for interpreting it badly), or the author  
(for publishing it badly)?

I think if you really want to limit the possibilities of GRDDL, you need  
to at least be clear and up front about it so that GRDDL (and XHTML 2)  
authors are aware they need to avoid using RDFa-like syntax.

>
> I'm intrigued to know what you mean by 'hold the author to'. This
> isn't a concept I've come across in RDF in a sense that is independent
> of some other 'meta level' dealing with trust relationships. My
> reading of RDF is in fact the opposite; since "anyone can say anything
> about anything", I am perfectly entitled to generate any triples I
> like from your documents.

I'm not sure about 'entitled' precisely. You can certainly screenscrape  
any triples you like, but unless those triples actually reflect the  
author's intended meaning, they won't be much use. It comes down to  
accountability and responsibility. If I publish several items of content  
on a page under different copyright licenses (for example), and you  
interpret the semantics differently than I intended, and use my content in  
ways I didn't intend, it needs to be clear who is at fault.

Yours,

Keith

ps: Apologies (Mark and Dan) for responding to the remarks Mark addressed  
to Dan. I hope it didn't seem too much like butting in.

pps: Ben, does using hGRDDL imply "this is not RDFa", or only that the  
result of the transformation will be RDFa? (I wonder, could you use GRDDL  
on RDF/XML to generate, eg, reified RDF/XML ?)

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Received on Sunday, 1 July 2007 00:28:28 GMT

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