I forgot to mention that according to
https://jena.apache.org/documentation/query/java-uri.html
I tried for testing purpose to set a PREFIX f:
<java:io.bdrc.ldsearch.query.functions.CustomARQFunctions.>and added
the following to fuseki config :
ja:loadClass "io.bdrc.ldsearch.query.functions.CustomARQFunctions" .
where CustomARQFunctions is :
public class CustomARQFunctions { public static
NodeValue myFilter(NodeValue value1){ int i =
value1.asString().length(); return
NodeValue.makeInteger(i); }
}
since according to
https://jena.apache.org/documentation/query/writing_functions.html
using the java:URI scheme "dynamically loads the code, which must be on
the Java classpath. With this scheme, the function URI gives the class
name. There is automatic registration of a wrapper into the function
registry. This way, no explicit registration step is needed by the
application and queries issues with the command line tools can load
custom functions."
but no luck: I keep getting the following exception:
Exception in thread "main" HttpException: 404 at
org.apache.jena.sparql.engine.http.HttpQuery.execGet(HttpQuery.java:328
) at
org.apache.jena.sparql.engine.http.HttpQuery.exec(HttpQuery.java:288)
at
org.apache.jena.sparql.engine.http.QueryEngineHTTP.execResultSetInner(Q
ueryEngineHTTP.java:348) at
org.apache.jena.sparql.engine.http.QueryEngineHTTP.execSelect(QueryEngi
neHTTP.java:340)
I am stuck !
Marc
Le mardi 26 décembre 2017 à 18:56 +0100, Marc Agate a écrit :
> Hi,
> Adam's gave me the right direction.
> I managed to load my function class in fuseki config using
> ja:loadClass
> but now remains the following issue (the function is not
> registered)seefuseki logs :
> [2017-12-26 16:10:13] exec WARN URI <http://purl.bdrc.io/funct
> ions#MyFilterFunction> has no registered function factory
> How can I register this function now that I have the code available
> onthe endpoint side ?
> Thanks for helping
> Marc.
>
> Le mardi 26 décembre 2017 à 17:43 +0000, Andy Seaborne a écrit :
> > As well s Adam's point (and all the libraries your function
> > needs, transitively)
> > What is in the Fuseki log file?How was the data loaded into Fuseki?
> > >> I printed out the >> FunctionRegistry
> > And
> > On 26/12/17 14:51, ajs6f wrote:
> > > I'm not as familiar with the extension points of ARQ as I
> > > wouldlike to be, but as I understand what you are doing, you
> > > areregistering a new function with your _local_ registry, then
> > > firinga query at a _remote_ endpoint (which has a completely
> > > independentregistry in a different JVM in a different process,
> > > potentially ina different _system_).
> > > The query is getting interpreted and executed by that
> > > remoteservice, not locally. So you need to register the function
> > > _there_.
> > > Take a look at this thread:
> > > https://lists.apache.org/thread.html/1cda23332af4264883e88697d994
> > > 605770edcde2f93ddea51240e4b8@%3Cusers.jena.apache.org%3E
> > > It should get you started as to how to register
> > > extensionfunctionality 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
> > > > .t
> > > > tl");
> > > > 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/LevenshteinFuncti
> > > > on
> > > > ";
> > > > 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/LevenshteinFuncti
> > > > on
> > > > ";
> > > > 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
