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Re: [Feedback on schema.org] why is the expected type for "image" not an "ImageObject"?

From: Dan Brickley <danbri@danbri.org>
Date: Fri, 6 Jan 2012 18:16:00 +0100
Message-ID: <CAFNgM+acBbAR6pNoKhjxB=e3kA=WEzvvb6944tRcrvu55CyBWA@mail.gmail.com>
To: Martin Hepp <martin.hepp@ebusiness-unibw.org>, Alexander Shubin <ajax@yandex-team.ru>, Fran├žois Daoust <francois@joshfire.com>, "public-vocabs@w3.org" <public-vocabs@w3.org>
2011/12/20 Martin Hepp <martin.hepp@ebusiness-unibw.org>:
> I think the best would be to say that the range for the respective properties is the union of URL and ImageObject.

I think that captures the intent, but there is also something a little
strange about 'URL'. In some ways it is a piece of machinery that
lives at another level of abstraction from classes like 'ImageObject'
(or Actor or Place or Document or whatever).  URLs (and URIs) are our
general machinery for referencing entities of all these types.
Sometimes it's true we want to describe these identifiers as
things-in-themselves, but I don't think that's a particular goal with
'image'. In RDF, these identifiers have special status and
representation within the abstract data model, rather than being just
certain kinds of string value. What we want to say about 'image',
colloquially, is that the value of the image is an ImageObject; but we
expect those values to be expressed in markup using an URL reference.
This isn't the kind of thing that RDFS directly express, since it
mixes vocabulary ("what can we say") with more document-format rules
("what should we say").

While we could try to represent these nuances more carefully, it's
unlikely that mainstream Web developers and publishers would put a lot
of thought thinking through the distinctions. I think URL works for
now...

cheers,

Dan

> On Dec 16, 2011, at 4:20 PM, Alexander Shubin wrote:
>
>> Hi Francois, Martin,
>>
>> I agree with Martin about keeping Thing as simple as possible. But 'thumbnail' and 'thumbnailUrl' is another issue so I raised it in our tracker (https://www.w3.org/2011/webschema/track/issues/8).
>>
>> About fallback mechanism. I think you may use it every time you want to keep you markup simple :)
Received on Friday, 6 January 2012 17:16:29 GMT

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