W3C home > Mailing lists > Public > public-rdf-in-xhtml-tf@w3.org > June 2007

Re: Blank nodes & classes

From: CÚdric Mesnage <cedric.mesnage@lu.unisi.ch>
Date: Fri, 22 Jun 2007 12:54:21 +0200
Message-Id: <7164AAB1-34EF-45B6-B506-B89F6124E3C7@lu.unisi.ch>
To: public-rdf-in-xhtml-tf@w3.org
Hi Ben, Mark, all,

First of all, thank you for your answers, I used Ben's practice to  
solve the problem.

I am strongly against using URIs to identify resources, one should  
use URLs where you can get more info... so I'll use http://amazon.com/ 
ISBN:0091808189 instead of urn:ISBN:0091808189 even if amazon do not  
provide this service yet...

according to your example, to get the rdfs:label triple, the right  
markup would be:

<span about="http://amazon.com/ISBN:0091808189" property="rdfs:label">
	Canteen Cuisine
</span>

The question seems not to be what is the minimum markup that should  
give a triple but more :

	what is the minimum markup to generate the maximum triples...

Can we have :

<span about="http://amazon.com/ISBN:0091808189" property="rdfs:label"  
class="bib:book">
	Canteen Cuisine
</span>

which would give:

<http://amazon.com/ISBN:0091808189> rdf:type bib:book.
<http://amazon.com/ISBN:0091808189> rdfs:label "Canteen Cuisine".

and to go back to my example with Ben's solution:

<div class="foaf:Person" rel="rdf:li">
	some things about the person
</div>

which gives the triples :

<> rdf:li _:whatever.
_:whatever rdf:type foaf:Person.

Can we go further than that and do :

<div class="foaf:Person" rel="rdf:li" property="foaf:name">
	CÚdric Mesnage
</div>

or even :

<div class="foaf:Person" rel="rdf:li" property="foaf:name"  
content="CÚdric Mesnage"/>

and get:

<> rdf:li _:whatever.
_:whatever rdf:type foaf:Person.
_:whatever foaf:name "CÚdric Mesnage".


---
CÚdric Mesnage
PhD Student
cedric.mesnage@lu.unisi.ch
http://www.cedricmesnage.org
http://blog.cedricmesnage.org/


On Jun 21, 2007, at 12:10 PM, Mark Birbeck wrote:

> Hi Ben/CÚdric,
>
> [I'm not proposing a resolution to this question in this version of
> RDFa, but I think it's useful to collect use-cases.]
>
> I had a use-case the other day that is related to the ones you are
> describing. Essentially the question we all seem to be converging on
> is what is the minimum amount of mark-up that should give us a triple?
>
> So, the following feels quite natural, as a way of marking up the
> mention of something like a book in my blog:
>
>  Today I bought a copy of
>  <span about="urn:ISBN:0091808189" class="bib:book">
>    Canteen Cuisine
>  </span>
>  from my local bookshop.
>
> Since my system uses the URI to retrieve some data about the book from
> a book site like Amazon, I don't actually need any further triples
> like title, price, publisher, author, or whatever. But there is a an
> interesting question as to whether the following should be enough to
> get an entry in the triple store:
>
>  <span about="urn:ISBN:0091808189">
>    Canteen Cuisine
>  </span>
>
> The system could still do the same thing, and retrieve additional
> triples based on the resource, but the question is what are the
> parsing rules that get from this mark-up to a triple?
>
> The only way I can think of to achieve this from the mark-up I've
> shown is be automatically generate labels from the content of
> elements. The mark-up would therefore generate this:
>
>  <urn:ISBN:0091808189> rdfs:label "Canteen Cuisine" .
>
> and we would now have the URI for the book in our triple-store, and
> can make use of it to retrieve further information.
>
> Regards,
>
> Mark
>
> On 13/06/07, Ben Adida <ben@adida.net> wrote:
>>
>>
>> Cedric,
>>
>> This is an interesting question. I had to deal with this with the  
>> RDFa
>> clipboard [1], and I chose to use the predicate rel="rdf:li" on any
>> bnode I wanted to appear on the page, effectively saying "this  
>> bnode is
>> an item of the current page." For example, in your code below:
>>
>> <span class="foaf:Person" rel="rdf:li">
>> some things about the person
>> </span>
>>
>> which yields:
>>
>> <> rdf:li
>>      [a foaf:Person; ...things about the person...]
>>
>> I'm pretty sure this is not a "best practice", but it's the work- 
>> around
>> I came up with for precisely this issue, and it's not all that  
>> wrong in
>> terms of semantics: after all, that *is* an item on the page.
>>
>> -Ben
>>
>> CÚdric Mesnage wrote:
>> > Hi all,
>> >
>> > I have a question regarding blank nodes in RDFa, I don't know if  
>> the
>> > issue has been raised already and I apologize if it has. In the  
>> RDFa
>> > Primer I saw that you can create unnamed blank nodes using the  
>> 'rel'
>> > attribute as in the example:
>> >
>> > <dl class="foaf:Person" about="#card" id="card">
>> > ...
>> >  <dt>Address</dt>
>> >  <dd rel="foaf:address">
>> >   <span property="foaf:address_line_1">77 Massachusetts Ave.</ 
>> span><br />
>> >     <span property="foaf:address_line_2">MIT Room 32-G524</ 
>> span><br />
>> >   <span property="foaf:city">Cambridge</span> MA 02139<br />
>> >   <span property="foaf:country">USA</span>
>> >  </dd>
>> > ...
>> > </dl>
>> >
>> > This works for predicates layered in an instance definition, do  
>> you plan
>> > having a similar principle for classes? I'd like to have:
>> >
>> > <span class="foaf:Person" >
>> > some things about the person
>> > </span>
>> >
>> > to be considered as a blank node, currently in RDFa On
>> > Rails(http://rdfa.rubyforge.org/) I generate blank node names  
>> this way:
>> >
>> > <span class="foaf:Person" about="#BNode1">
>> > some things about the person
>> > </span>
>> >
>> > incrementing the number through the page generation, but this is  
>> ugly.
>> > The other solution is that I can just forbidden the use of  
>> classes if no
>> > uri or explicit blank node name is given.
>> >
>> > Hope this does make some sense and look forward to get you point  
>> of view.
>> >
>> > Best Regards!
>> > ---
>> > CÚdric Mesnage
>> > PhD Student
>> > cedric.mesnage@lu.unisi.ch <mailto:cedric.mesnage@lu.unisi.ch>
>> > http://www.inf.unisi.ch/phd/mesnage/
>> > http://myunderstanding.wordpress.com/
>> >
>> >
>>
>>
>>
>>
>
>
> -- 
>  Mark Birbeck, formsPlayer
>
>  mark.birbeck@x-port.net | +44 (0) 20 7689 9232
>  http://www.formsPlayer.com | http://internet-apps.blogspot.com
>
>  standards. innovation.
Received on Friday, 22 June 2007 10:52:33 UTC

This archive was generated by hypermail 2.3.1 : Tuesday, 6 January 2015 21:50:23 UTC