Hello there. First of all I want to thank you for the work you are contributing to the Drupal community and for Semantic Web-related stuff specifically!
I am trying to build a specific solution for my company using a mix of different anguages, and therefore your evoc module is a boon :)
I am not sure if I should file this as a bug report, but here goes:

Trying to import the skos-xl extension for skos (http://www.w3.org/2008/05/skos-xl#), it just imported the namspace and not the properties.

Do you have any idea what might have caused this ?

Comments

scor’s picture

scor commented
Title: Importing skos-xl » use a local SPARQL endpoint for retrieving RDF vocabularies

I've also noticed that sometimes the distant SPARQL endpoint seem to fail for some reason independent from this module. I'm planning to be using a local SPARQL endpoint (via ARC) once I have time to integrate it. It does not seem to be available in the current version of the SPARQL module

I was able to retrieve all the terms of skos-xl using a local jena SPARQL endpoint for example. not sure why this is happening but I will definitely look into it.

minimalismore’s picture

minimalismore commented

Thank you for you swift reply :)
Well, since I still am in an initial process of figuring out the ontology I need, I will just populate the evoc_rdf_properties table by hand.
I would love to contribute in any way to help you, but I am afraid my knowledge of the technicalities behind RDF and parsing it with PHP still is on a fairly basic level.
I do come from the Topic Map communit though, and I would be very interesteded in participating, aven contributing to the evolving semantic functionalitites in Drupal. SO if you need any help at all, do not hesitate to get in touch :)

I want to ask you another question since the channel is already open ;)

Am I mistaken when believeing that using your evoc-module to import languagegs, and then mapping classes and properties to cck-fields, as well as mapping RDF-classes to content types, will make it possible for me to query them with SPARQL ?

I have done so, and cannot manage to get a listing of content from a specific field being mapped to lets say skos:altLabel...

ex:

prefix rdf:
prefix skos:
select *
where {
?class rdf:type skos:Concept.
}

What I find when I look at the fields created is

rdf_property for RDF property
while looking at "Manage RDF mappings", the correct skos-properties are listed..

Have I done somehting wrong maybe ??

Greetings from Norway

scor’s picture

scor commented

Well, since I still am in an initial process of figuring out the ontology I need, I will just populate the evoc_rdf_properties table by hand.

if your ontology is published online, I would strongly advice you to import it instead, it's much quicker and less error prone! Remember that evoc caches the terms, so you don't have to use them all, and they won't be used unless you specify them in the RDF CCK mapping page.

You can contribute a lot by just giving feedback like you are doing now ;)

Yes, SPARQL is something you can do, though not out of the box at the moment. I'm planning to index all the nodes in RDF so that you can query your site. In the meantime this is already possible by using an external store and crawling the RDF of your site.

minimalismore’s picture

minimalismore commented

Hi again!
Can you tell me if there are specific things I have to look out for when creating an ontology for import in order to import it with you module ?
I just created this ontology : http://webtest.teria.no/rdf/begrep.rdf and it seems that the module cannot parse it.

scor’s picture

scor commented

yes, evoc filters out the terms which don't belong to the URI you provide. Its API supports specifying a namespace different than the location of the vocabulary, and Neologism already use that feature, but I need to add this field on the evoc import form :)

Ideally you would want your classes and properties to be dereferencable. http://webtest.teria.no/rdf/ndlaontologi# returns 404, that's bad practice :(

minimalismore’s picture

minimalismore commented

Ahh but of course, did not see that :) Just copied links from my other ontology without updating them :/

Will I be able to query the imported classes and properties using SPARQL ?

minimalismore’s picture

minimalismore commented

So I ensured that all classes and properties dereferences http://webtest.teria.no/rdf/begrep#.
But still no import..
Any ideas ?
maybe the same problem as with skos-xl?

Also tried doing it on a local web server, with no luck. But maybe your local jena server does something special that makes it work ?

scor’s picture

scor commented

I have found the virtuoso SPARQL endpoint to be buggy at times. I was able to import using http://jena.hpl.hp.com:2020/sparql (you need to edit evoc.module).

febbraro’s picture

febbraro commented

Should we just make the endpoint a variable to use with variable_set/get? it can default to the jena hp endpoint if not set. We can also add a special variable and if set will try the local (if we ever implement it) endpoint?

scor’s picture

scor commented

good point. In the meantime I have switched to another endpoint in the dev release. I will implement the variable soon. (patches always welcome, obviously :)).