How to make complex SPARQL queries reusable?

[Simon Schäfer <ma...@antoras.de>]

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?

Re: How to make complex SPARQL queries reusable?

["Lorenz B." <bu...@informatik.uni-leipzig.de>]

I don't think that this is possible with the current implementation
since a Function is supposed to return a single value and you'd need
something that returns a set of values resp. bindings.

Have you checked SPARQL SPIN [1]? Maybe this is something you could use.

[1] http://spinrdf.org/

> 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?
>
>
-- 
Lorenz Bühmann
AKSW group, University of Leipzig
Group: http://aksw.org - semantic web research center