W3C home > Mailing lists > Public > semantic-web@w3.org > September 2006

Re: "role" and inheriting "about"

From: Ben Adida <ben@adida.net>
Date: Sat, 09 Sep 2006 20:45:09 -0400
Message-ID: <45036015.1030305@adida.net>
To: Elias Torres <elias@torrez.us>
CC: Yoshio Fukushige <fukushige.yoshio@jp.panasonic.com>, semantic-web@w3.org, public-rdf-in-xhtml-tf@w3.org


Elias, Yoshio,

Good points and questions. Some clarifications below as to where things
*currently* stand. We're still very much open to comments, of course,
though hopefully this explanation will convince you that the current
mechanisms are okay.

> Yoshio Fukushige wrote:
>> Hi RDFa people,
>>
>> A question on RDFa "role" and inheriting "about."
>>
>> Per RDFa Primer 1.0 (2006-05-16 version) [1],
>> one can use "role" to introduce a new resource of a certain kind
>>
>> e.g.
>>
>> <p role="cal:Vevent">
>>  ...
>> </p>
>>
>> (cf. 2.2 Publishing An Event)

Yes, though you should think of ROLE as just a way of declaring a type
on that HTML element. Though, as Elias mentions below, this is *not*
finalized yet.

Elias Torres wrote:
>
> I believe role was added last minute to the primer but not to the syntax
> spec and it's definitely either not final or underspecified. We were
> discussing a couple meetings ago whether we would use @role or reuse
> @class. We did not reach a decision at the time, but it is one of our
> central issues right now.

+1. This isn't finalized.


>> My question is what if an RDFa browser finds a "role" attribute on its way 
>> climbing the tree.
> 
> [non-normative] Right now my Python parser follows the subject
> resolution mechanism ignoring the presence of a role attribute in the
> three[/non-normative]

Currently, "role" has no effect on the subject.

>> <p role="cal:Vevent">
>>   I'm giving 
>>   <span property="cal:summary"> a talk at the XTech conference </span>
>> </p>
>>
>> Does it stop climbing and set the resource introduced by the "role" attribute 
>> as the subject?

No, it currently doesn't, but it would if:

- you used <meta> instead of <span>, since <meta> applies to its
immediate parent (this is what the Primer uses), or if

- you set ID="event_1" and ABOUT="#event_1" attributes on the <P>

> From the primer, I'd assume that this is the intended case.

Note that the primer uses META. So no, we did not intend to imply that
role would change the subject inheritance. We should make that clearer,
though.

>> To me, it sounds more natural for the search to stop
>> when a "role" is found on its way.

The problem I see with this is that it doesn't scale well to other use
cases. It seems to work because ROLE is new and has no other uses right
now. However, we're currently talking about how ROLE is not really the
right way to declare a type: CLASS is probably better. This is
particularly true when RDFa is made to work with XHTML1, where ROLE does
not exist.

But then, you don't want CLASS to change the inheritance rule every
time, right? It's best if there's an explicit way to change the subject,
using the ABOUT attribute, for example.

[...]

>> Do I miss or misunderstand something? 
>> (or misdeduce?)
> 
> Not at all Yoshio, if anything we need to do a better job of being more
> explicit, but it's all a work in progress and thanks for your
> questions/feedback.

+1 +1 +1.

Please continue to ask these questions, as it helps us understand what
we didn't explain well, and also makes us think even more carefully
about the design decisions made along the way.

-Ben
Received on Sunday, 10 September 2006 00:45:18 UTC

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