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Fwd: [goodrelations] Google bug: foaf:page and Google Rich Snippets

From: Martin Hepp <martin.hepp@ebusiness-unibw.org>
Date: Wed, 15 Jun 2011 21:49:00 +0200
To: public-lod@w3.org, semantic-web@w3.org
Message-Id: <8BE3B4E0-7590-4E17-A9BE-B926DDA90282@ebusiness-unibw.org>
I thought this might also be relevant for subscribers of these lists.

Begin forwarded message:

> From: Martin Hepp <martin.hepp@ebusiness-unibw.org>
> Date: June 15, 2011 9:44:49 PM GMT+02:00
> To: goodrelations-list <goodrelations@ebusiness-unibw.org>
> Subject: [goodrelations] Google bug: foaf:page and Google Rich Snippets
> 
> Hi all:
> 
> I just found out that the Google Rich Snippets Testing tool rejects all RDFa markup for products if the data contains foaf:page (a link to the HTML page) with a value that is NOT from within the domain name space of the actual file location.
> 
> Example:
> 
> If you have the following markup in the page available from http://www.domain.com/example.html, then
> 
> a) an empty foaf:page value will work
> 
> <div typeof="gr:Offering" about="#offering" >
>      <div property="gr:name" content="ACME Anvil" xml:lang="en"></div>
>      <div rel="foaf:page" resource=""></div>
> 
> b) foaf:page with the actual page URI will work
> 
> <div typeof="gr:Offering" about="#offering" >
>      <div property="gr:name" content="ACME Anvil" xml:lang="en"></div>
>      <div rel="foaf:page" resource="http://www.domain.com/example.html"></div>
> 
> c) foaf:page with a URI from the same domain name space as the actual page URI will also work:
> 
> <div typeof="gr:Offering" about="#offering" >
>      <div property="gr:name" content="ACME Anvil" xml:lang="en"></div>
>      <div rel="foaf:page" resource="http://www.domain.com/canonical/example.html"></div>
> 
> BUT:
> 
> c) foaf:page with a URI from another domain name space than the actual page URI will NOT work:
> 
> <div typeof="gr:Offering" about="#offering" >
>      <div property="gr:name" content="ACME Anvil" xml:lang="en"></div>
>      <div rel="foaf:page" resource="http://www.some_other_domain.com/example.html"></div>
> 
> 
> Unfortunately, the testing tool gives the very uninformative error message
> 
> "Insufficient data to generate the preview.
> ... 
> Warning: In order to generate a preview, either price or review or availability needs to be present."
> 
> It is natural that Google does not like foaf:page pointers to external domain name spaces, but this unexpected behavior costed me almost a day.
> 
> So watch out!
> 
> Option b) is the recommended practice, because it works in any scenario, but it requires that you know the URI of the final publishing destination at markup-time (or the template has access to the deep URI as a variable).
> 
> Option a) is handier, because the URI of the current page will be automatically used as the value for foaf:page, but it 
> fails, if the document sets the base URI of all product item pages to the main shop page, e.g. via
> 
> 	<base href="http://shop.com/home/" />
> 
> because then all offers would point to the same base page and deep links would be lost.
> 
> Best wishes
> 
> Martin Hepp
> 
> 
> 
> 
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Received on Wednesday, 15 June 2011 19:49:26 UTC

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