Yoan Blanc’s weblog

After the Pain-in-the-a** issue of yesterday. I’ll try to be more practical today with a gentle introduction to ActiveRDF.

First, install it. You need Ruby and Ruby Gems (it’s just like the Pythonic eggs).

gem install activerdf
gem install activerdf_rdflite
gem install sqlite3-ruby

Now, pick up a RDF Schema somewhere (sucked from there) convert it into NTriples (with rapper).

Now create some datas.

<?xml version="1.0"?> 
<rdf:RDF
 xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
 xmlns:rdfs="http://www.w3.org/2000/01/rdf-schema#"
 xmlns:foaf="http://xmlns.org/foaf/0.1/"
 xmlns:simple="http://yoan.dosimple.ch/beta/simple.rdfs#"
 xml:base="http://yoan.dosimple.ch/beta/simple.rdf#">

 <simple:Teacher rdf:ID="professor">
  <simple:name>Professor</simple:name>
 </simple:Teacher>
 
 <simple:Course rdf:ID="rdf">
  <simple:name>RDF and
   RDF Schema</simple:name>
  <simple:teacher rdf:resource="#professor" />
  <simple:students>
   <rdf:Seq>
    <rdf:li rdf:resource="#yoan" />
    <rdf:li rdf:resource="#batiste" />
   </rdf:Seq>
  </simple:students>
 </simple:Course>
 
 <simple:Student rdf:ID="yoan">
  <simple:name>Yoan Blanc</simple:name>
  <foaf:weblog>http://yoan.dosimle.ch/blog/
   </foaf:weblog>
  <foaf:know rdf:resource="#batiste" />
 </simple:Student>
 
 <simple:Student rdf:ID="batiste">
  <simple:name>Batiste Bieler</simple:name>
  <foaf:weblog>http://batiste.dosimle.ch/blog/
   </foaf:weblog>
  <foaf:know rdf:resource="#yoan" />
 </simple:Student>
</rdf:RDF>

And do a Triple with it. The RDF Validator and Converter can help you.

So we can start.

$ irb

We are into the interactive ruby shell.

require 'active_rdf'

ActiveRDF is loaded

pool = ConnectionPool.add_data_source :type => :rdflite, \
 :location=> 'database.db', :keyword=>true

There is our pool, you can change to :redland if you prefer.

pool.load 'schema.nt'
pool.load 'data.nt'

Then our datas are loaded, in NTriple format, not RDF/XML.

Namespace.register :simple 'http://yoan.dosimple.ch/test/simple.rdfs#'
ObjectManager.construct_classes

Register our namespace (you’ll understand) and build the classes, like ActiveRecord do.

SIMPLE::Person.find_by_name("Professor")

Get a person.

SIMPLE::Person.find_by_name("Yoan Blanc").weblog

Yeah, we’ve got it. Of course, I helped myself with this article : “Getting Started Guide” from the ActiveRDF wiki.

Next step is to do some queries, it’s not very trivial, some I need some time to achieve this...