Configuring Apache Jena Fuseki 2.4.1 inference and reasoning support using SPARQL 1.1: Jena inference rules, RDFS Entailment Regimes and OWL reasoning

In this post, I will show you how to configure Apache Jena Fuseki 2.4.1 to enable inferece support using SPARQL 1.1. This is it what we will do:

Enable inference using Jena Rules reasoning.
Enable inference using RDFS Entailment Regimes reasoning
Enable inference using OWL reasoning.

Content:

Some useful links
Ontology files: model.ttl, data.ttl, myrules.rules
Apache Jena Fuseki 2.4.1 configuration: ElQuijote.ttl
Files
Citing this post

Some useful links:

Ontology files

I have the ontology files below. I will use these files to infer new knowledge using SPARQL 1.1 querys through reasoners. I will use two files: one for the data model model.ttl and another for the instances of the data model data.ttl

model.ttl

@prefix ns:   <http://www.example.org/ns#&gt> .
@prefix rdf:  <http://www.w3.org/1999/02/22-rdf-syntax-ns#> .
@prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> .
@prefix owl:  <http://www.w3.org/2002/07/owl#> .
@prefix xsd:  <http://www.w3.org/2001/XMLSchema#> .

ns:Person       rdf:type        owl:Class .
ns:Person       owl:unionOf     (ns:Man ns:Woman) .
ns:Man          rdf:type        owl:Class .
ns:Woman        rdf:type        owl:Class .
ns:knows        rdf:type        owl:SymmetricProperty .
ns:knows        rdfs:domain     ns:Person .
ns:knows        rdfs:range      ns:Person .
ns:Horse        rdf:type        owl:Class .

data.ttl

@prefix ns:   <http://www.example.org/ns#> .
@prefix rdf:  <http://www.w3.org/1999/02/22-rdf-syntax-ns#> .
@prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> .
@prefix owl:  <http://www.w3.org/2002/07/owl#> .
@prefix xsd:  <http://www.w3.org/2001/XMLSchema#> .

ns:Sancho       rdf:type    ns:Man .
ns:Don_Quijote  rdf:type    ns:Man .
ns:Don_Quijote  ns:knows    ns:Sancho .
ns:Rocinante    rdf:type    ns:Horse .
ns:Dulcinea     rdf:type    ns:Woman .

I will define some reasoner rules in the following file: myrules.rules

myrules.rules

@prefix ns:   <http://www.example.org/ns#> .
@prefix rdf:  <http://www.w3.org/1999/02/22-rdf-syntax-ns#> .
@prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> .
@prefix owl:  <http://www.w3.org/2002/07/owl#> .
@prefix xsd:  <http://www.w3.org/2001/XMLSchema#> .

[ruleKnows: (ns:knows rdf:type owl:SymmetricProperty) (?s ns:knows ?o) --> (?o ns:knows ?s)]

The rule file above defines a reasoning rules for the property ns:knows that declares:

IF ns:knows is a symmetric property AND exist a subject (?s) that ns:knows an object (?o), THEN, object (?o) ns:knows subject (?s) too.

Apache Jena Fuseki 2.4.1 configuration

Location of Apache Jena Fuseki installation (Windows) is in C:\apache-jena-fuseki-2.4.1\: please copy the ontology and rule files (model.ttl, data.ttl, myrules.rules) to C:\apache-jena-fuseki-2.4.1\run\databases\
Create a new file called ElQuijote.ttl (or whatever you like) in the location C:\apache-jena-fuseki-2.4.1\run\configuration\ with the following lines:

ElQuijote.ttl

@prefix :      <http://base/#> .
@prefix tdb:   <http://jena.hpl.hp.com/2008/tdb#> .
@prefix rdf:   <http://www.w3.org/1999/02/22-rdf-syntax-ns#> .
@prefix ja:    <http://jena.hpl.hp.com/2005/11/Assembler#> .
@prefix rdfs:  <http://www.w3.org/2000/01/rdf-schema#> .
@prefix fuseki: <http://jena.apache.org/fuseki#> .

#This line is a comment

:service1	a                         fuseki:Service ;
        fuseki:dataset                    :dataset ;
        fuseki:name                       "ElQuijote" ;
        fuseki:serviceQuery               "query" , "sparql" ;
        fuseki:serviceReadGraphStore      "get" ;
        fuseki:serviceReadWriteGraphStore "data" ;
        fuseki:serviceUpdate              "update" ;
        fuseki:serviceUpload              "upload" .

:dataset	rdf:type 	ja:RDFDataset ;
    rdfs:label "ElQuijote" ;
    ja:defaultGraph
      [ rdfs:label "ElQuijote" ;
        a ja:InfModel ;

        #Reference to model.ttl file
        ja:content [ja:externalContent <file:///C:/apache-jena-fuseki-2.4.1/run/databases/model.ttl> ] ;

        #Reference to data.ttl file
        ja:content [ja:externalContent <file:///C:/apache-jena-fuseki-2.4.1/run/databases/data.ttl> ] ;

        #Disable OWL-based reasoner
        #ja:reasoner [ja:reasonerURL <http://jena.hpl.hp.com/2003/OWLFBRuleReasoner>] ;

        #Disable RDFS-based reasoner
        #ja:reasoner [ja:reasonerURL <http://jena.hpl.hp.com/2003/RDFSExptRuleReasoner>] ;

        #Enable Jena Rules-based reasoner and we point the location of myrules.rules file
        ja:reasoner [
            ja:reasonerURL <http://jena.hpl.hp.com/2003/GenericRuleReasoner> ;
            ja:rulesFrom <file:///C:/apache-jena-fuseki-2.4.1/run/databases/myrules.rules> ;			
        ] ; 
      ] ;
     .

Start Apache Jena Fuseki server and execute the following SPARQL querys on "ElQuijote" dataset:

PREFIX ns:<http://www.example.org/ns#>

SELECT *
WHERE {
  ?s ns:knows ?o .
}

The following lines are the resultset of the query above. These lines are the result of the rules-based reasoner given myrules.rules file:

ns:Don_Quijote ns:knows   ns:Sancho      --> This relationship is declared in data.ttl
ns:Sancho      ns:knows   ns:Don_Quijote --> This relationship was inferred given the rule in myrules.rules file

The following query should return all persons defined in data.ttl (Don_Quijote, Sancho and Dulcinea), however, returns nothing (Why?)

PREFIX ns:<http://www.example.org/ns#>
PREFIX rdf:<http://www.w3.org/1999/02/22-rdf-syntax-ns#>

SELECT *
WHERE {
	?s rdf:type ns:Person .
}

It is required to add the following lines in myrules.rules to query returns all persons: ns:Don_Quijote, ns:Sancho and ns:Dulcinea:

Add the lines below to myrules.rules file:

[isPerson1: (?s rdf:type ns:Man) -> (?s rdf:type ns:Person)]
[isPerson2: (?s rdf:type ns:Woman) -> (?s rdf:type ns:Person)]

Previous rules indicates: IF a subject (?s) is ns:Man or ns:Woman, THEN that subject (?s) is a ns:Person.

To resolve this without add two rules above in myrules.rules, we can enable RDFS-based reasoner that is disabled in ElQuijote.ttl file, since ns:Person class is declared as the union (owl:unionOf) of ns:Man and ns:Woman classes, (see model.ttl file), and this fact is enough to infer on data model (model.ttl) and its instances (data.ttl), that ns:Don_Quijote, ns:Sancho and ns:Dulcinea are persons.

In the following lines from ElQuijote.ttl file (excerpt) I've disabled Jena Rules based reasoner and enabled RDFS based reasoner:

ElQuijote.ttl

	#Lines before the next ones remains untouchable:

	#Enable RDFS-based reasoner **<-- Changed below**
	ja:reasoner [ja:reasonerURL <http://jena.hpl.hp.com/2003/RDFSExptRuleReasoner>] ;

	#Disable Jena Rules-based reasoner and its rules file myrules.rules **<-- Changed below**
	#ja:reasoner [
	#    ja:reasonerURL <http://jena.hpl.hp.com/2003/GenericRuleReasoner> ;
	#    ja:rulesFrom <file:///C:/apache-jena-fuseki-2.4.1/run/databases/myrules.rules> ;			
	#] ; 
   ] ;
  .

In this configuration I've enabled RDFS-based reasoner (Entailment Regimes) and because of this, the last SPARQL query resultset is:

 ns:Don_Quijote
 ns:Sancho

And what happend with ns:Dulcinea? Why ns:Dulcinea does not included in the resultset?

Notice how ns:Don_Quijote and ns:Sancho are related through ns:knows symmetric property in data.ttl file. Notice how ns:knows property has a ns:Person class as a domain and range. If the domain of the ns:knows property is omitted (i.e, deleted), last SPARQL query obtains an empty resultset. This is because a limitation in the the OWL 2 RDF-Based semantics, since classes are treated as individuals that refer to elements of the domain. I suggest a reading of the following document: Entailments under the OWL 2 RDF-Based Semantics. In this case, ns:Dulcinea isn't realated with any other instance of the domain of the class ns:Person.

However, if I enable the OWL-based reasoner, the last SPARQL query resultset is not empty, I mean, I obtain the expected inferred instances: ns:Don_Quijote, ns:Sancho and ns:Dulcinea.

With OWL based reasoner, the first SPARQL query has the same resultset that we got with the rule ruleKnows in myrules.rules file. I mean:

ns:Don_Quijote ns:knows ns:Sancho      --> This relationship is declared in data.ttl 
ns:Sancho      ns:knows ns:Don_Quijote --> This relationship was inferred by the OWL based reasoner

Why the last resultset? Because ns:knows property is a symmetric property and OWL-based reasoner infers the second relationship in the resultset without using explit rules.

To enable OWL-based reasoner, disable the current RDFS based reasoner and enable the following lines in ElQuijote.ttl file:

ElQuijote.ttl(excerpt)

	#Lines before the next ones remains untouchable:

	#Enable OWL-based reasoner **<-- Changed below**
	ja:reasoner [ja:reasonerURL <http://jena.hpl.hp.com/2003/OWLFBRuleReasoner>] ;

	#Disable RDFS-based reasoner <-- Changed below
	#ja:reasoner [ja:reasonerURL <http://jena.hpl.hp.com/2003/RDFSExptRuleReasoner>] ;

	#Disable Jena Rules-based reasoner and its rules file myrules.rules
	#ja:reasoner [
	#    ja:reasonerURL <http://jena.hpl.hp.com/2003/GenericRuleReasoner> ;
	#    ja:rulesFrom <file:///C:/apache-jena-fuseki-2.4.1/run/databases/myrules.rules> ;			
	#] ;
   ] ;
  .

Conclusions

I show how to enable inference and reasoning in en Apache Jena Fuseki 2.4.1.
I show how to do inference with Apache Jena Fuseki using reasoning rules (Jena Rules). These rules can be very complex in expressiveness to infer any fact from the data model and its instances.
I show how to do inference in Apache Jena Fuseki using RDFS-based reasoning (Entailment Regimes). This reasoner is limited by features inherent to OWL 2 RDF-Based semantics and infers some facts from the data model.
I show you how to do complete inference in Apache Jena Fuseki using OWL-based reasoner (without Jena Rules).
According to the Jena documentation, it is possible to use a reasoner and inference rules file with reasoners, however, not all reasoners support inference rules.
Very poor official documentation on this topic we get, I mean, Apache Jena Fuseki inference/reasoning topic. There is a lot of documentation with Java examples using Apache Jena API, however, to enable inference/reasoning using Apache Jena Fuseki, the documentation is very poor in examples and explanations.
From what I have searched, reasoners available in Apache Jena Fuseki URIs, are:

For a complete inference support in Apache Jena, go to: Reasoners and rule engines: Jena inference support. This document describe reasoners capabilities and limitations. This document also describes Jena Rules.

Files

All files used in this document can be download from: Jena-Fuseki-Reasoner-Inference

Citing this post

Muñoz-Fernández, J. F. (2016, December 30). Configuring Apache Jena Fuseki 2.4.1 inference and reasoning support using SPARQL 1.1: Jena inference rules, RDFS Entailment Regimes and OWL reasoning. Retrieved <Month> <Day>, <Year>, from https://github.com/jfmunozf/Jena-Fuseki-Reasoner-Inference/wiki/Configuring-Apache-Jena-Fuseki-2.4.1-inference-and-reasoning-support-using-SPARQL-1.1:-Jena-inference-rules,-RDFS-Entailment-Regimes-and-OWL-reasoning

Thank you!

Juan Felipe Muñoz Fernández

CHANGELOG:

17-04-2020: Post migrated to markwdown. HTML was awful for this post.

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

Configuring Apache Jena Fuseki 2.4.1 inference and reasoning support using SPARQL 1.1: Jena inference rules, RDFS Entailment Regimes and OWL reasoning

Clone this wiki locally