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Re: telecon Thursday, 1600 UTC

From: Ivan Herman <ivan@w3.org>
Date: Mon, 24 Dec 2007 11:10:57 +0100
Message-ID: <476F85B1.4020700@w3.org>
To: Ben Adida <ben@adida.net>
CC: Mark Birbeck <mark.birbeck@formsPlayer.com>, Manu Sporny <msporny@digitalbazaar.com>, RDFa <public-rdf-in-xhtml-tf@w3.org>
Hi Ben,

(You always seem to find the good arguments: my happiness and the points
when I am actually the faulty one:-)

O.k. I think I get finally the point, sorry it took so long. My mind is
getting too old. So, thanks for the XMas present:-).

(It is more timely than you think; whereas in the anglo-saxon countries
the presents arrive on boxing day, ie, on the 25th, in Germanic
cultures, ie, in Hungary, too, presents arrives on the 'szenteste'
(meaning the 'Saint evening'), ie, the 24th in the evening. And that is
today:-)

I have actually changed my implementation (on my local disk only for
now, I still should test it properly) as well as the foaf.html file
(also locally). Obviously, the implementation part of all this was not
the complicated issue (well, I have implemented the new chaining rules
for a while, so the only thing I had to do was to add instanceof...).

Thanks!

Ivan

Ben Adida wrote:
> Ivan,
> 
> First let me solve your example, then get back to the reason why this
> makes sense.
> 
>> <http:://www.ivan-herman.net/Ivan_Herman>
>>    foaf:holdsAccount
>>       <http://www.facebook.com/p/Ivan_Herman/555188827>;
>>    foaf:foaf:publications
>>       <http://www.ivan-herman.net/professional/CV/publist.rdf>.
>>
>> <http://www.facebook.com/p/Ivan_Herman/555188827>
>>    rdf:type foaf:OnlineAccount;
>>    foaf:accountServiceHomepage <http://www.facebook.com>
>>    foaf:accountName "555188827".
> 
> 
> This is actually a great example to show off Mark's chaining rules.
> 
> First, write your Facebook account information:
> 
>   <div about="http://www.facebook.com/p/Ivan_Herman/555188827"
>        instanceof="foaf:OnlineAccount">
>      a <a rel="foaf:accountServiceHomePage">facebook account</a>
>      with name <span property="foaf:accountName">555188827</span>.
>   </div>
> 
> Let's call that block <<ACCOUNT>>.
> 
> Now, let's go back to your first triples:
> 
>   <div about="http://www.ivan-herman.net/Ian_Herman">
> 
>      <div rel="foaf:holdsAccount">
>         <<ACCOUNT>>
>      </div>
> 
>      and some
> 
>      <a rel="foaf:publications" href="/professional/CV/publist.rdf">
>         publications
>      </a>
>   </div>
> 
> 
> Now, you can literally substitute the first block of HTML+RDFa for
> <<ACCOUNT>>, and it all works out nicely. The @about completes the
> hanging @rel, and you're done. The beauty of this approach is that you
> can literally take whole blocks of HTML+RDFa and move them into the
> "object" of a hanging @rel without modification.
> 
> Now, to get back to your earlier comment:
> 
>> - but... why? I mean: why is it necessary to introduce an extra rule?
> 
> It's partly the fault of microformats, and, actually, it's partly your
> fault. Oh okay, and it's also partially mine. ;)
> 
> From the microformats community, we have the following general approach:
> 
>   <div class="hCal">
>     ...
>   </div>
> 
> where you can declare a calendar event without naming it. We wanted the
> same ease of use. To achieve it, we need to be able to declare a blank
> calendar event without explicitly naming it. Thus
> 
>   <div instanceof="cal:Vevent">
> 
> has the same "feel" to it as
> 
>   <div class="hCal">
> 
> It declare a new "thing", even if you don't give it a name.
> 
> Then, there's also the use case you brought up: a bibtex entry with
> multiple authors where one does not need to give the author a URI or
> even a bnode ID. With the @instanceof construct creating a new bnode, we
> get the following extremely pleasant approach:
> 
>   <div about="#paper">
>     <span property="dc:title">RDFa Primer</span>
> 
>     <div rel="dc:creator">
> 
>        <span instanceof="foaf:Person"
>              property="foaf:name">Ben Adida</span>
> 
>        <span instanceof="foaf:Person"
>              property="foaf:name">Mark Birbeck</span>
> 
>        ... more authors ...
> 
>     </div>
>   </div>
> 
> Now, we *could* force a new @rel="dc:creator" every time, but given the
> beauty of the chaining rules, doesn't that seem like a missed
> opportunity to have extremely clean markup?
> 
> There's a final argument that's more about how @instanceof feels to the
> publisher. When I see two <div>'s, each with @instanceof, that implies
> two instances to me. I think it would end up being counter-intuitive,
> from an HTML publisher perspective, if the following:
> 
>   <div instanceof="foo:bar">
>      ...
>   </div>
> 
>   <div instanceof="foo:baz">
>      ...
>   </div>
> 
> somehow referred to the same item with two different types. If you
> really wanted that, you would do:
> 
>   <div instanceof="foo:bar foo:baz">
>     ...
>   </div>
> 
> 
> I won't claim that my search has been exhaustive, but I did spend a good
> week trying to discredit Mark's chaining rules given the @instanceof
> rules, and I didn't find any good counter-examples :) I think this
> @instanceof approach combined with Mark's chaining rules form a strict
> superset of other approaches in terms of expressive capability. Plus,
> it's more pleasing to the eye, especially when you take all the history
> out of the equation and take a fresh look at the above bibtex markup
> example. Isn't it nice?
> 
> -Ben

-- 

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 Monday, 24 December 2007 10:11:23 GMT

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