SPARQL Jena iterative to get results about more subjects - sparql

Question

I'm trying to get information about some concepts on DBpedia. I found out how to get 1, but for more it fails. I've been told filtering should help, but the processing time is too long and i get timeouts.
The thing i can't do is VALUES ?s { dbpedia:Facebook dbpedia:Google }
So I've looked for an alternative way, but it still isn;t working. Here's where I'm now:
public static String concepts[] = { "Facebook", "Google" };
public static String getQuery(String concept) {
return "prefix dbpediaowl: <http://dbpedia.org/ontology/>"
+ " prefix dbpedia: <http://dbpedia.org/resource/>"
+ " prefix owl: <http://www.w3.org/2002/07/owl#>"
+ " prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> "
+ " PREFIX dbpprop: <http://dbpedia.org/property/>"
+ " prefix dbpedia-owl: <http://dbpedia.org/ontology/>"
+ " select ?s ?p ?o where { "
+ " values ?web { dbpedia:"
+ "Facebook"
+ " } "
+ " { ?web ?p ?o bind( ?web as ?s ) } " + " union "
+ " { ?s ?p ?web bind( ?web as ?o ) } " + " filter( ?p in ( "
+ "dbpprop:available, " + "dbpprop:company, "
+ "dbpprop:inventor, " + "dbpedia-owl:foundedBy, "
+ "dbpedia-owl:subsidiary, " + "dbpprop:foundation, "
+ "dbpprop:founder, " + "dbpprop:industry, "
+ "dbpprop:programmingLanguage, " + "dbpedia-owl:successor )) ";
}
public static void main(String[] args) {
OutputStream os;
PrintStream printStream;
try {
os = new FileOutputStream("C:/Users/alex/Desktop/data.txt");
printStream = new PrintStream(os);
printStream.println("am scris");
for (int i = 0; i < concepts.length; i++) {
printStream.println(i+ " concept");
Query query = QueryFactory.create(getQuery(concepts[i]));
QueryExecution qExe = QueryExecutionFactory.sparqlService(
"http://lod.openlinksw.com/sparql", query);
ResultSet results = qExe.execSelect();
while (results.hasNext()) {
printStream.println(results.nextSolution().toString());
}
}
printStream.close();
os.close();
} catch (Exception e) {
e.printStackTrace();
System.out.println(e.getCause());
}
}
For one concept at a time, in the SPARQL it works fine, but I need to call about 50 of them. So I need to know how i can do it programatically. Also, it would be great if you could help me select the predicates as well ( without the filtering ) because I also need to allow about 30-40 of them.
Thanks a lot! Hope you can help.

Answer 1

I thought we'd solved the problem with VALUES ?s { dbpedia:Facebook dbpedia:Google } in your previous question, Sparql about dbpedia:World_Wide_Web. Instead of doing values ?s { dbpedia:Facebook dbpedia:Google }, you can use filter( ?s in (dbpedia:Facebook, dbpedia:Google) }. This works just fine for subjects and properties. E.g., if you wanted to get the English abstracts and labels for Google and Facebook, you could use a query like this:
select ?s ?p ?o where {
?s ?p ?o
filter( ?s in (dbpedia:Google, dbpedia:Facebook) )
filter( ?p in (rdfs:label, dbpedia-owl:abstract) )
filter( !isLiteral(?o) || langMatches(lang(?o),"en") )
}
SPARQL results
Now, if you can get rid of that union (which you might be able to do, if you're really just looking for the values of certain properties from certain subjects), then you actually can use the values blocks in the way that you'd like to. (Really, I think the problematic behavior seen in your other question is due to a DBpedia bug; I think you should be able to use values and union together.) That is, to select non-literals, and literals with an English language tag for some specified properties, you can do:
select ?s ?p ?o where {
values ?s { dbpedia:Google dbpedia:Facebook }
values ?p { rdfs:label dbpedia-owl:abstract }
?s ?p ?o
filter( !isLiteral(?o) || langMatches(lang(?o),"en") )
}
SPARQL results