Metadata Registry: dbpedia, wikidata / Help needed

[Marcel J.]

Hello everybody,

I am new here (hi!) and to vocbench in general. My goal is to model a thesaurus in SKOS and link my concepts to dbpedia and wikidata resources.

In short, I am failing to set up the registry for dbpedia and wikidata. You can read about my efforts, so far, below.

(Also new to google groups, I am reposting this because my screenshots were not displayed properly...)

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I set up the Metadata Registry for DBpedia using "Discover Dataset" and pasting this OWL Ontology for dbpedia, which I found here: https://archivo.dbpedia.org/info?o=http%3A//dbpedia.org/ontology/ --- > http://dief.tools.dbpedia.org/server/ontology/dbpedia.owl

This is accepted by vocbench; using http://dbpedia.org/ontology/ as input yields an error.

Maybe this is already cause of my struggles, since this seems to be the DEV version of the ontology. Anyhow, I added the SPARQL endpoint for dbpedia; "Assess Lexicalization Model" works and yields a bunch of results, so it seems to work in general.

Then, I added skos:exactMatch to my concept. But unlike in the video, vocbench does not pull metadata from the registry when I doubleclick the entry. It seems to always stay in "local access mode".

Using the "Align with external resouce" feature never finds any results.

Im really not sure what's going wrong, could it be that the lexicalization for DBpedia is RDFS and I am using SKOS for my thesaurus? Wrong registry config? Wrong URI? ...

Vocbench 9.1.0 (Docker)

local Repository

admin user

Thanks in advance for your input

[Manuel Fiorelli]

Hi Marcel,

I have not attempted to reproduce your issue yet. However, I've noticed a potential "problem": you set up http://dbpedia.org/ontology/ as the namespace (which is the namespace of the DBpedia ontology), while you are working with Dbpedia resources in the http://dbpedia.org/resource/ namespace. So, try to change the value of the namespace in metadata registry.

I also suggest you to check "no aggregation" alongside the SPARQL endpoint of DBpedia inside the metadata registry.

Regards

Manuel

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Manuel Fiorelli

[Marcel J.]

Thank you, I tried this suggestion with no success, as well as different combinations of "Dereferenciation System" / "Aggregation" settings.

It's still like the program tries to resolve the link only locally and doesn't want to go resolve the resource on the web / with sparql. Access Mode on double click always stays "local".

You don't need to create a "remote" project for DBpedia in order for this to work, or do you?

Thanks,

Marcel

[Manuel Fiorelli]

Hi Marcel,

I've noticed that in the screenshot with a Dbpedia resource shown as local, its resource view is not empty, rather it contains a triple with the predicate skos:exactMatch (seemingly the symmetric of the triple with the same predicate having your local resource as subject). SO, it seems that your repository contains at least a triple having the remote resource as subject: this would make VB believe that this resource is local.

Have you enabled trivial inference that materialized symmetric triples? If yes, I think that this should be the root cause of your problem.

Regards

Manuel

To view this discussion on the web visit https://groups.google.com/d/msgid/vocbench-user/dc638604-b17a-459e-b5db-35abbf664b7en%40googlegroups.com.

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Manuel Fiorelli

[Marcel J.]

Yes, you are correct, trivial inference was enabled and that was the cause.

Thank you very much for looking into it!

This is a step forward, however as usual there is always a next error ...

Regards

Marcel

[Marcel J.]

Finally got DBPedia to work,  configuration is attached.

The initial way I used to obtain the configuration (first post) has proven to be viable.

Even tho not using the http://dbpedia.org/resource/  as namespace seemed wrong and counter-intuitive, http://dbpedia.org/ontology/ seems to be the way to go.

Wikidata is not working still. I am using the configuration shown briefly in the video.

It's erroring either about "Empty Label" or not finding RDF, depending on settings.

Regards

Marcel