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Re: RDFa 1.1 Lite

From: Jason Douglas <jasondouglas@google.com>
Date: Sat, 22 Oct 2011 10:18:40 -0700
Message-ID: <CAEiKvUD6BwEOPtocj+=n=okHBaVbsXZKbNafVvSkR1RqM-w0-g@mail.gmail.com>
To: Manu Sporny <msporny@digitalbazaar.com>
Cc: W3C Vocabularies <public-vocabs@w3.org>
On Fri, Oct 21, 2011 at 7:16 PM, Manu Sporny <msporny@digitalbazaar.com>wrote:

> On 10/21/2011 01:08 PM, Jason Douglas wrote:
>> There's a lot to like here.
> Glad to hear that. Jason, apologies for the late-joining on my part - but
> are you actively involved with the Rich Snippets stuff at Google, or just
> interested in it from a design perspective?

I'll wait to follow-up on everything else on the new threads Guha is
spinning off, but I figure I should still introduce myself here:  I came to
Google from the Metaweb acquisition and now, in addition to Freebase, my
work includes parts of Google's infrastructure for processing structured
markup.  I also contributed bits and pieces to the initial
schema.orgvocabularies.  So I'm interested from all angles.  :-)


 However, the two biggest issues raised in
>> the discussion at the workshop seem unaddressed / unacknowledged to me
>> by this document:
> Just to clarify - the document was meant to be a quick and dirty
> introduction - not a complete specification. So, there were many things that
> were left unsaid/unexplained.
>  1/ Why both property and rel?  There was concern expressed that
>> implementers wouldn't understand the difference (honestly, I'm not sure
>> I do) and it wasn't made clear why having both is necessary. If the
>> distinction is literal value vs. url, why not use value precedence (like
>> itemprop in microdata)?
> You could say that the distinction is "literal value vs. URL", but that's a
> bit of an over-generalization. @rel exists for a number of reasons:
> 1. It has always been the mechanism used in HTML to specify relevance
>   (aka: relationship information) to links on the Web.
> 2. We found that often people want to create a link relationship and
>   express a literal value at the same time, on the same element.
>   Having @rel and @property allows them to do that without having
>   to change their document structure.
> 3. The use was re-inforced in the Microformats community after
>   extensive study of usage patterns and it seems like people
>   were getting its usage correct.
> 4. Creative Commons supports the usage of @rel and many of their
>   implementers get it.
> In the 3 years since RDFa 1.0 has been in the field, we see very little
> abuse of @rel. In fact, we see far more examples of correct @rel usage in
> RDFa 1.0 than we do incorrect usage. So, while I do understand the concern,
> is there any publicly available study or data to back up the concern?
> The reason we didn't go with value precedence is for the reasons listed
> above. Value precedence also doesn't work when you really want to express a
> literal, but there just happens to be an @href on the element. We had
> considered this during the design of RDFa 1.0, but found it to not be
> adequate for the use cases we were considering for RDFa.
> Is the existence of @rel a deal-break for anyone? If so, why?
>  2/ Layer-ability on existing markup.  That's probably too abstract a
>> label... basically, implementers have found the itemref feature of
>> microdata to be useful in layering vocabulary on top of existing pages.
> I have a hard time believing this claim. I've found @itemref to be one of
> the most difficult parts of Microdata to use, and have not really found it
> to be that helpful in most documents. Do you have any numbers on the number
> of documents that use @itemref, or the frequency in which it is used on the
> Web?
>   For example, if the name of a product is in one part of the DOM tree,
>> but it's properties are in an entirely different one, how do you combine
>> them?
> Use @about.
>  If both the about URI and the markup
>> with the about attribute have RDFa in them, how are those properties and
>> types combined?
> Like this:
> <div about="#jason" typeof="schema:Person">
>   <span property="schema:name">Jason Douglas</span>
>   ... other stuff about Jason ...
> </div>
> ... Lots and lots of HTML ...
> <span about=#jason" property="schema:jobTitle">**Product Manager</span>
> Any time that you want to talk about the same subject again - you just use
> the same @about value. Make sense?
> -- manu
> --
> Manu Sporny (skype: msporny, twitter: manusporny)
> Founder/CEO - Digital Bazaar, Inc.
> blog: Standardizing Payment Links - Why Online Tipping has Failed
> http://manu.sporny.org/2011/**payment-links/<http://manu.sporny.org/2011/payment-links/>
Received on Saturday, 22 October 2011 17:19:17 UTC

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