You are viewing a plain text version of this content. The canonical link for it is here.

Posted to users@jena.apache.org by Marc Agate <ag...@gmail.com> on 2017/12/26 14:34:15 UTC

Custom ARQ function not working with fuseki endpoint

Hi !

I successfully implemented sparql queries using custom ARQ functions
using the following (custom function code):

****************
public class LevenshteinFilter extends FunctionBase2 {

    public LevenshteinFilter() { super() ; }

    public NodeValue exec(NodeValue value1, NodeValue value2){
        LevenshteinDistance LD=new LevenshteinDistance();
        int i = LD.apply(value1.asString(), value2.asString()); 
        return NodeValue.makeInteger(i); 
    }
}
***************

it works fine when I query against a Model loaded from a turtle file,
like this:

***************
InputStream input =
QueryProcessor.class.getClassLoader().getResourceAsStream("full.ttl");
            model =
ModelFactory.createMemModelMaker().createModel("default");
            model.read(input,null,"TURTLE"); // null base URI, since
model URIs are absolute
            input.close();
***************

with the query being sent like this :

***************
String functionUri = "http://www.example1.org/LevenshteinFunction"; 
        FunctionRegistry.get().put(functionUri ,
LevenshteinFilter.class);

        String s = "whatever you want";
        String sparql = prefixes+" SELECT DISTINCT ?l WHERE { ?x
rdfs:label ?l . " +  "FILTER(fct:LevenshteinFunction(?l, \"" + s + "\")
< 4) }";                                              
        Query query = QueryFactory.create(sparql);
        QueryExecution qexec = QueryExecutionFactory.create(query,
model); 
        ResultSet rs = qexec.execSelect();
***************

However, if i use a working fuseki endpoint for the same dataset
(full.ttl) like this :

***************
fusekiUrl="http://localhost:3030/ds/query";
***************

sending the query like this (using
QueryExecutionFactory.sparqlService(fusekiUrl,query) instead of
QueryExecutionFactory.create(query,model) ):

***************
String functionUri = "http://www.example1.org/LevenshteinFunction"; 
        FunctionRegistry.get().put(functionUri ,
LevenshteinFilter.class);

        String s = "whatever you want";
        String sparql = prefixes+" SELECT DISTINCT ?l WHERE { ?x
rdfs:label ?l . " + "FILTER(fct:LevenshteinFunction(?l, \"" + s + "\")
< 4) }";                                       
        Query query = QueryFactory.create(sparql);
        QueryExecution qexec =
QueryExecutionFactory.sparqlService(fusekiUrl,query); 
        ResultSet rs = qexec.execSelect();
***************

Then I don't get any results back. In both cases I printed out the
FunctionRegistry and they contain exactly the same entries, especially
:

key=http://www.example1.org/LevenshteinFunction value:
org.apache.jena.sparql.function.FunctionFactoryAuto@5a45133e

Any clue ?

Thanks