I'm not as familiar with the extension points of ARQ as I would like to be, but as I understand what you are doing, you are registering a new function with your _local_ registry, then firing a query at a _remote_ endpoint (which has a completely independent registry in a different JVM in a different process, potentially in a different _system_).
The query is getting interpreted and executed by that remote service, not locally. So you need to register the function _there_. Take a look at this thread: https://lists.apache.org/thread.html/1cda23332af4264883e88697d994605770edcde2f93ddea51240e4b8@%3Cusers.jena.apache.org%3E It should get you started as to how to register extension functionality in Fuseki. Adam Soroka > On Dec 26, 2017, at 9:34 AM, Marc Agate <[email protected]> wrote: > > 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
