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Re: Markup questions: html/body, datatype="", double predicates

From: Ivan Herman <ivan@w3.org>
Date: Wed, 10 Dec 2008 13:49:24 +0100
Message-ID: <493FBAD4.4070406@w3.org>
To: Richard Cyganiak <richard@cyganiak.de>
CC: public-rdfa@w3.org, W3C RDFa task force <public-rdf-in-xhtml-tf@w3.org>
Hi Richard,

because the distiller is a piece of software, and was written by me,
therefore distiller has bugs:-) That is part of the ABox:-)

Caveat: I am on a trip right now, I am not sure when I can handle this.
Please, bear with me...

Richard Cyganiak wrote:
[snip]
> 
> 
> 1. Behaviour of RDFa markup on <html> and <body> elements. Let's say my
> file contains these markup bits (doctype, namespace declarations etc
> omitted):
> 
> <html rel="foaf:maker" rev="foaf:homepage">
>   <body about="#me">
>     ...
> 
> I expect this to generate these triples:
> 
> <> foaf:maker <#me> .
> <#me> foaf:homepage <> .
> 
> But what I get from the RDFa Distiller:
> 
> <> foaf:maker <#me> .
> <#me> foaf:homepage <> .
> <> foaf:maker <> .
> <> foaf:homepage <> .
> 
> Why is this?
> 

At first glance, this does look like a bug. I will have to check that.

Actually, there might be a slight issue in the spec, though: the spec
explicitly says "if the element is the head or body element then act as
if there is an empty @about present" but it does not say anything about
the html element...

> 
> 2. Behaviour of datatype="" when the content includes *RDFa* markup.
> Let's say I have this in my HTML:
> 
> <p about="#me" property="bio:olb">
>   I work at
>   <a rel="foaf:workplaceHomepage" href="http://www.deri.ie/">DERI
>   Galway</a>.
> </p>
> 
> This works as expected, it creates two triples, a bio:olb triple whose
> value is an rdf:XMLLiteral, and a foaf:workplaceHomepage triple whose
> value is the DERI URL.
> 

???  I have put up your test file on the web by removing the @datatype:

http://www.ivan-herman.net/Misc/2008/cyg-test.html

and what I get via the distiller is:

<http://www.ivan-herman.net/Misc/2008/cyg-test.html#me> bio:olb "I work
at <a href=\"http://www.deri.ie/\" rel=\"foaf:workplaceHomepage\"
xml:lang=\"en\" xmlns=\"http://www.w3.org/1999/xhtml\">DERI
Galway</a>."^^rdf:XMLLiteral.

Ie, the foaf:workplaceHomepage triple is _not_ generated.

And that is correct! As Toby said in his reply, if a property is found
and a literal is generated, all processing should stop at that point...
I remember that we had lots of discussion on that issue in the group,
but that is indeed the final conclusion.

> Now I want the bio:olb as a plain literal, so I add datatype="" to the
> <p> tag. This creates the expected plain literal, but the
> foaf:workplaceHomepage triple disappears. Annoying! Is this the correct
> result? I sort of hope that it's a bug in the RDFa Distiller...
> 

Again, this behaviour is actually the right one. Labelling a subtree as
a @property means that this subtree is, sort of, removed from the RDFa
processing.


> 
> 3. Double predicates. Just to confirm, is it always allowed to have
> multiple CURIEs in the CURIE-accepting properties?
> 
> rel="foo:prop1 bar:prop2"
> rev="foo:prop1 bar:prop2"
> property="foo:prop1 bar:prop2"
> typeof="foo:prop1 bar:prop2"
> 
> I assume that all of these are legal and will result in two triples
> instead of one?
> 

Yes.

> 
> That's all for now. Finally, in case that some of the folks who
> influenced the design of RDFa on this list: Let me say that I'm
> impressed with the result. 

Thank you!

Ivan


>                             Obviously a lot of thought went into every
> detail of the language and the result is pleasing and elegant. Finally,
> here's an RDF syntax that does not suck and makes RDF publishing fun!
> 
> Cheers,
> Richard
> 

-- 

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 Wednesday, 10 December 2008 12:50:06 GMT

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