Another option is to express the query logic in standard rule notation, such as RIF, and translate to sparql. This approach is especially indicated if the sparql queries represent actual business rules.
Regards, --Paul > On Apr 24, 2017, at 06:22, Andy Seaborne <a...@apache.org> wrote: > > Simon, > > 1/ SpinRDF provides ways of defining custom functions and property functions > in SPARQL. > > http://spinrdf.org/ > > There'll probably be something in the SHACL-sphere (not in the standard, but > in the same general area/style/framework) soon. > > 2/ There are methods in ExprUtils to parse expressions in SPARQL syntax. > > You could build a general helper. > > That does not enable syntax replacement but does cover (?) your MyFunc > example. > > Andy > >> On 24/04/17 01:02, Simon Schäfer wrote: >> 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? >> >>
