DBpedia reconciliation not working?

[raja kumar dash]

Greetings,

At the suggestion of user "magdmartin" on Stackoverflow, I'm posting my OpenRefine-related question here as well. I'm summarizing.

It seems DBpedia reconciliation is not functioning as of late. I'm trying to reconcile a list of American universities/colleges. I have previously been successful several times -- the most recent being probably two months ago. Nothing on my end has changed since then, so I'm wondering what's happened.

A user on StackOverflow suggested trying the Spanish DBpedia SPARQL endpoint. I added it to my OpenRefine installation and it does appear to find the right ontologies -- the way the English service used to but no longer does. It seems to be slower than I recall the English service being, but that could because I have English institution names? (Matching success also seems reduced.)

Any ideas what happened to the English DBpedia reconciliation service?

I'm running "Google Refine Version 2.5" -- probably installed in early 2014, I think, though I can't recall, and added reconciliation services around the same time.

[Tom Morris]

I'm guessing that you're using the DERI RDF extension, but it would
help to be explicit about that and also state what version.
Additionally, there are several DBpedia SPARQL endpoints around, so it
would help to be explicit about which you're using.

I'm not very familiar with the RDF extension, so can't easily help,
but those who can will probably want the above information.

Does anyone who's been using the RDF extension recently have any other
hints that would help here?

Tom

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[raja kumar dash]

I don't know, re version or extension. I'm using V2.5 of OpenRefine. It's been so long since installation that I don't remember what I did -- probably added a reconciliation service based on a SPARQL endpoint -- namely the English non-https version, http://dbpedia.org/sparql (I think)

Someone else reported (on Stackoverflow) that the English version of DBpedia reconciliation is no longer working for him either. The Spanish version is working on some of my data, but it is having intermittent problems as well. I solved my problem a different, long-winded way with a SPARQL query, but instead of taking a couple of hours using reconciliation, I had to waste close to 24 hours essentially accomplishing the same functionality from scratch.

[Owen Stephens]

I tested the DBPedia SPARQL endpoint at http://dbpedia.org/sparql when you first reported this problem and found the same issue as you.

I've now tested again and it works for me fine. Nothing has changed at my end between the two tests. The most likely explanation (to me anyway) is the issue was caused be either a temporary or intermittent issue with the DBPedia SPARQL endpoint.

Owen

[Tom Morris]

Raja/Owen - was any error reported by the RDF extension when the
DBpedia SPARQL server was misbehaving or did it just silently fail in
some way?

Tom

[raja kumar dash]

Hi Tom,

When I clicked reconcile and selected DBpedia extension, it would take a while but come back saying it didn't recognize any ontology (not the exact message, but the essence). When the RDF extension works, with DBpedia, of course, you get a radio button list of all the schema choices. This was not happening during that period of problems. 

[Owen Stephens]

Hi Tom - I'm afraid I didn't make any further notes on the issue - but it definitely failed at the point where it was trying to retrieve the list of entity types to reconcile against

Owen

[Owen Stephens]

Hi Tom,

Via Filip Radulovic (@filiprd on Twitter) I got pointed at this Virtuoso Open Source (VOS) issue https://github.com/openlink/virtuoso-opensource/issues/405

It looks VOS started using XML 1.1 for SPARQL results, and this got rolled out to the DBPedia SPARQL endpoint at http://dbpedia.org/sparql. Unfortunately this seems to have caused issues for Jena/Xerces which couldn't parse the XML 1.1 (I'm just going by the comments in the VOS issue, not checked this). This would explain why the RDF Refine Extension had problems I guess.

Owen

[Tom Morris]

Thanks Owen. That certainly sounds like a plausible explanation. If
it ever becomes an issue again, there are some workarounds here:
https://issues.apache.org/jira/browse/JENA-942

Tom

[Thad Guidry]

​At Ericsson, switching to SAX based parsing has helped us with other issues in the past as well, such as Schema validation issues among others.

Thad

+ThadGuidry