Last call for feedback before Drupal 7 alpha release

Hi,

The first alpha release of Drupal 7 will be created next Friday Jan 15th.
We've already incorporated most of the feedback we received from the semweb
community so far, but I wanted to give the community a last chance to review
the RDFa markup and the default RDF mappings we use before it's too late. I
should emphasize that all the markup and default RDF mappings that we ship
in core will be pretty much set in stone after the stable release of Drupal
7, hence this call for feedback. Site administrators who care about
semantics will be able to alter these mappings by installing extra modules,
but many people (read several 10K sites) will just install Drupal and not
care about the semantics it generates. Therefore we want to make sure the
RDFa generated by Drupal out of the box is somewhat correct and does not
make folks from the semantic/pedantic web community angry :) - we've tried
to keep the semantics as generic as possible for that reason.

== RDF mappings ==

I've created a diagram [1] representing the default semantics of the core
data structure and we would appreciate feedback on the RDF terms we've used.
This schema was committed last week so if there is any change to be made we
should discuss it asap.


== RDFa markup ==

To make the RDFa markup review process easier, I've updated the usual
testing site at http://drupalrdf.openspring.net/. It features a blog post
[2] with some comments which represents a typical Drupal 7 page annotated
with RDFa. Some other pages have been randomly generated in order to test
the tracker [3] which acts as a very simple sitemap in RDFa.

Note that the URI for each resource of type node (foaf:Document), comment
(sioc:Post), term (skos:Concept) and user (sioc:User) is the same URI as the
page which describes it. This has been decided in order to keep things
simpler and after careful discussion with some members of the community.
Hash URIs for distinguishing thing from the page describing them can be
implemented quite easily but this case hasn't emerged in core (but will in
the modules people will build and use, and this will be taken care of by a
separate helper RDF module).

For those willing to install and try out the software, I've uploaded an
unstable version of Drupal 7 core at [4] which includes some of the RDF
patches which are still under review [5].

On a slightly different topic, all three RDFa parsers I've used for
debugging had each some different RDF output, which I believe are bugs (I've
reported most of them). Maybe there is some work to be done in improving
these RDFa parsing libraries: Ubiquity RDFa [6], Any23 [7], GetN3 [8] - I
feel uneasy when people ask "How can I see the RDFa?" and I can't give them
a compelling RDFa parser library which supports 100% of the RDFa markup we
output. I've also been unlucky at getting Yahoo! Search Monkey to generate
pretty search results from RDFa and I hear this service has been down in the
past weeks, which is an unfortunate timing.

Looking forward to your feedback on any of the above! There are several 100K
RDFa sites waiting to pop out on the Web, so we should make sure we do it
right before it gets too late.

regards,
Stéphane.

[1]
http://openspring.net/sites/openspring.net/files/drupal_core_RDFS_v3.5_core.png
[2]
http://drupalrdf.openspring.net/blog/2009/10/22/produce-and-consume-linked-data-with-drupal
[3] http://drupalrdf.openspring.net/tracker
[4] http://files.openspring.net/drupal/drupal7-unstable-rdf-20100110.tar.gz
[5]
http://drupal.org/project/issues/search/drupal?status[]=Open&issue_tags=RDF&version[]=7.x
[6] http://code.google.com/p/ubiquity-rdfa/
[7] http://code.google.com/p/any23/
[8] http://www.w3.org/2006/07/SWD/RDFa/impl/js/