Hello, I have complex SPARQL queries, which I would like to divide into several parts (like function definitions), in order to reuse these parts among different SPARQL queries and in order to make a single SPARQL query easier to understand. What are my options to achieve this?
I had a look at Jenas built in functionality to support user defined function definitions. The problem with them is that it seems that they can be used only for simple functionality like calculating the max of two integers. But I have quite complex functionality, which I don't want to rewrite in Java. Example: ------------------------------------------------------------------------------------------------ select * where { ?s a ?tpe . filter not exists { ?sub rdfs:subClassOf ?tpe . filter (?sub != ?tpe) } } ------------------------------------------------------------------------------------------------ It would be great if that could be separated into: ------------------------------------------------------------------------------------------------ public class MyFunc extends FunctionBase1 { public NodeValue exec(NodeValue v) { return NodeValue.fromSparql("filter not exists {" + " ?sub rdfs:subClassOf ?tpe ." + " filter (?sub != ?tpe)" + "}") ; } } // and then later FunctionRegistry.get().put("http://example.org/function#myFunc", MyFunc.class) ; ------------------------------------------------------------------------------------------------ and then: ------------------------------------------------------------------------------------------------ prefix fun:<http://example.org/function#> select * where { ?s a ?tpe . filter(fun:myFunc(?tpe)) } ------------------------------------------------------------------------------------------------ Basically I'm looking for a way to call a SPARQL query from within a SPARQL query. Is that possible?