[foaf-dev] Drupal user profiles in RDFa

Stephane Corlosquet scorlosquet at gmail.com
Tue Oct 13 21:17:44 CEST 2009


Hi,

Thank you all for your feedback, that's excellent! :)

On a side-note people still haven't agreed if the URIs of profile
> pages can be used as the URIs of the accounts but I wouldn't worry too
> much about that.
>

Yes, I asked the same question to Dan Brickley during DrupalCon Paris, and
he said it was ok to do that.That's also simpler to grasp for people with
little background in RDF.


Alternatively you could get rid of the span by just not declaring the
> name [...] and/or the type on this page.
> Instead you just link the maker with the appropriate property. The
> type can be inferred from the range of the property and the name could
> be supplied when dereferencing the profile. This is of course
> problematic with the case you describe below where the profile is not
> accessible.
>

That was also my first take on this, but I changed my mind as some plugins
or UI tool can take advantage of the typeof values. There exist plugins
which target specific attributes on RDFa pages and format them depending on
their value, e.g. sioc:User of a page in a special form (with a logo, popup
or whatever - I know Michael Hausenblas or Alexandre Passant have an example
for this). Relying on reasoning and dereferencing is too much to expect and
would slow down such interface.


I'd like to get more opinions on the 3 third case where anonymous visitor
can leave comments. I agree that using foaf:homepage here is inappropriate
due to the IFP, and since we do not control what URI people will put in
there we should be careful. Options suggested so far:
1. bnode typed sioc:User or foaf:Agent to cover the case where it's a link
to a company homepage.
2. link this bnode to the "homepage" URI with foaf:isPrimaryTopicOf,
foaf:page or rdfs:seeAlso.

foaf:isPrimaryTopicOf is also an IFP, so I think we should avoid it.
rdfs:seeAlso is good though somewhat generic. foaf:page seems the most
appropriate here and does not imply strong assumptions. What do you think?

Stephane.

On Mon, Oct 12, 2009 at 7:48 AM, Steven Pemberton
<Steven.Pemberton at cwi.nl>wrote:

> On Sun, 11 Oct 2009 17:09:52 +0200, Stephane Corlosquet <
> scorlosquet at gmail.com> wrote:
>
>  Hi all,
>>
>> I'm checking the RDFa markup we have chosen for Drupal 7 and want to make
>> sure it's optimal, given that it won't be able to change it after the code
>> freeze (which in one week!). In particular I'd like to discuss the case of
>> the user markup which is used to describe the author or a page or comment.
>>
>
> Thanks for the chance to feedback!
>
>  "User profile" in this email refers to the concept of sioc:User /
>> foaf:OnlineAccount. Drupal has 3 main cases which all have different
>> markup.
>>
>>
>> 1. If the administrator of the site decided to make the user profile pages
>> public, then the author will be a link to the author profile page
>> http://example.org/user/23. The original markup is:
>>
>> <a href="/user/23" title="View user profile." class="username">John</a>
>>
>> We have 2 options to add RDFa to this link which both return the same RDF
>> data:
>>
>> <a href="/user/1" rel="sioc:has_creator foaf:maker" title="View user
>> profile." class="username"><span resource="/user/1" typeof="sioc:User"
>> property="foaf:name">Henry</span></a>
>>
>> or
>>
>> <span rel="sioc:has_creator foaf:maker"><a href="/d7sprint/user/1"
>> typeof="sioc:User" property="foaf:name" title="View user profile."
>> class="username">Henry</a></span></span>
>>
>
> I'm assuming the /dsprint7 is a typo here, otherwise they wouldn't have the
> same triples.
>
> So the triples they produce are like:
>
>  <http://www.w3.org/basedoc.html> <http://sioc.org/has_creator> <
> http://www.w3.org/user/1> .
>  <http://www.w3.org/basedoc.html> <http://foaf.org/maker> <
> http://www.w3.org/user/1> .
>  <http://www.w3.org/user/1> <http://foaf.org/name> "Henry" .
>  <http://www.w3.org/user/1> <
> http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://sioc.org/User> .
>
> Of the two I slightly prefer the second, with the outer <span>, since the
> URI doesn't have to get repeated.
>
> If it weren't for the @typeof, you could do it all in one go:
>
> <a href="/user/3" rel="sioc:has_creator foaf:maker" title="View user
> profile." class="username" property="foaf:name">Steven</a>
>
> but of course the @typeof changes the subject.
>
>  Question for the RDFa ninjas reading this: is there a way to embed all
>> this
>> information without adding a span tag either inside or outside the a
>> existing a tag. I'm asking this because adding extra markup is frown upon
>> by
>> Drupal themers as it might break some CSS rules or have unintended
>> effects,
>> so if we can do without it it's best.
>>
>
> At the cost of repeating the URI, but with the advantage that it doesn't
> risk messing up your CSS, you don't have to nest the extra span:
>
> <a href="/user/1" rel="sioc:has_creator foaf:maker" title="View user
> profile." class="username" property="foaf:name">Henry</a>
> <span about="/user/1" typeof="sioc:User"></span>
>
> So this is a non-nested version of your first solution.
>
>
>  2. If the user profile pages are not accessible then only the name of the
>> author will be displayed and we are missing the URL of her profile page,
>> or rather I should say we can generate a URI for the user profile, but
>> resolving it would lead to a 403 Access denied. The default Drupal markup
>> in
>> this case is simply:
>> <span class="username">John</span>
>>
>> I see 3 alternatives to annotate this in RDFa:
>>
>>  2.1 Use a markup similar to the one above, but the cons is that the user
>> profile URI will not be dereferencable (and hereby breaking one of the
>> Linked Data principles). It will return a 403 Access denied.
>>
>> <span rel="sioc:has_creator foaf:maker" class="username"><span
>> resource="/user/1" typeof="sioc:User"
>> property="foaf:name">Henry</span></span>
>>
>>  2.2 Same as 2.1 but without the resource attribute hence generating a
>> bnode. I always try hard to avoid generating these, but if this is no work
>> around, then we'll have to use it.
>>
>> <span rel="sioc:has_creator foaf:maker" class="username"><span
>> resource="/user/1" typeof="sioc:User"
>> property="foaf:name">Henry</span></span>
>>
>>  2.3 We don't introduce the concept of user profile and simply link the
>> page to a name (literal).
>>
>> <span class="username" property="foaf:maker">Henry</span>
>>
>> I don't like 2.3 because it's not as meaningful from an RDF perspective.
>> Also, we don't have the same choices in the RDF properties we can use due
>> to
>> the domain which is now a literal, which would be a problem in the context
>> of Drupal since the page -> author relationship gets the same set of RDF
>> properties no matter what the case is (between 1, 2 or 3). So I'd rather
>> use
>> 2.1 or 2.2. but we've got to decide between the best of the two: a non
>> dereferencable URI or a bnode? I like the non referencable URI because we
>> can uniquely identify the author outside the scope of the page, but I
>> wonder
>> how the parsers will react when trying to resolve the URI.
>>
>
> I think you're worrying too much about the 403s. The triples are true,
> whether or not you try to dereference the URIs:
>
>  <http://www.w3.org/basedoc.html> <http://sioc.org/has_creator> <
> http://www.w3.org/user/1> .
>  <http://www.w3.org/basedoc.html> <http://foaf.org/maker> <
> http://www.w3.org/user/1> .
>  <http://www.w3.org/user/1> <
> http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://sioc.org/User> .
>  <http://www.w3.org/user/1> <http://foaf.org/name> "Henry" .
>
> What you may want to avoid is making them *easy* to dereference. Then I
> would use a span+ at resource instead of an a:
>
> <span resource="/user/1" rel="sioc:has_creator foaf:maker"
> title="Inaccessible user profile" class="username"
> property="foaf:name">Henry</a>
> <span about="/user/1" typeof="sioc:User"></span>
>
>  3. In the case of a non registered user leaving a comment, Drupal offers
>> to leave her name, homepage and email address (though the email address is
>> not displayed for privacy reasons). The default markup is:
>>
>> <a href="http://openspring.net/" rel="nofollow" class="username">Stephane
>> Corlosquet (not verified)</a>
>>
>> We don't have a user profile URI here, but a homepage which is usually
>> linked to a foaf:Person. Here we have multiple options again to describe
>> the author of a comment. I'm not sure we should directly link a page to a
>> foaf:Person, should we?
>>
>
> No.
>
>  Do we have to generate a foaf:OnlineAccount
>> /sioc:User URI here based on the homepage by adding #user to it? use a
>> bnode? opinions?
>>
>
> In the absence of other information I prefer to use
> rel="foaf:isPrimaryTopicOf" to identify a person from their homepage.
> (See http://www.w3.org/MarkUp/2009/rdfa-for-html-authors)
>
> Hope this helps.
>
> Best wishes,
>
> Steven Pemberton
>
>
>> Stephane.
>>
>
>
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