This tutorial show how to use the Corese-library framework through simple examples of the main features. We assume a basic knowledge in Java programming and in semantic web.
The first part describes how to create, load and export a Graph. The second part show how to query a graph with SPARQL. The third part details how to validate a graph with the Shapes Constraint Language (SHACL). The fourth part shows how to transforme a graph with the extension language SPARQL Template Transformation Language (STTL). The fifth part details how to apply a set of rules on a graph using the SPARQL Rule extension language. Finally, the sixth part describes how to define and use functions with the LDScript extension language.
- Getting Started With Corese-library
Installations instructions are available on the Corese-Command GitHub repository.
This section describes how to create a graph manually, load a graph from file and serialize a graph to file.
It is also possible to use the RDF4J Model API to create and manipulate a graph.
The example shows how to create the RDF graph bellow:
graph LR;
classDef IRI fill:#FEAE65,stroke-width:0px
classDef DT fill:#FEFEFE,stroke-width:0px
iri:EdithPiaf(["ex:EdithPiaf"])
iri:Singer(["ex:Singer"])
dt:Edith["''Edith''"]
dt:Piaf["''Piaf''"]
class iri:EdithPiaf,iri:Singer IRI
class dt:Edith,dt:Piaf DT
iri:EdithPiaf--rdf:type-->iri:Singer;
iri:EdithPiaf--ex:firstName-->dt:Edith;
iri:EdithPiaf--ex:lastName-->dt:Piaf;
This graph represents three statements :
- Edith Piaf is a singer
- Edith Piaf's first name is Edith
- Edith Piaf's last name is Piaf
// Define the namespace ex
String ex = "http://example.org/";
// Create a new empty Graph
Graph graph = Graph.create();
// Create and add IRIs to Graph
Node edithPiafIRI = graph.addResource(ex + "EdithPiaf");
Node singerIRI = graph.addResource(ex + "Singer");
// Create and add properties to Graph
Node rdfTypeProperty = graph.addProperty(RDF.TYPE);
Node firstNameProperty = graph.addProperty(ex + "firstName");
Node lastNameProperty = graph.addProperty(ex + "lastName");
// Create and add datatypes to Graph
Node edithDatatype = graph.addLiteral("Edith");
Node piafDatatype = graph.addLiteral("Piaf");
// Add first statement : Edith Piaf is an Singer
graph.addEdge(edithPiafIRI, rdfTypeProperty, singerIRI);
// Add second statement : Edith Piaf's first name is Edith
graph.addEdge(edithPiafIRI, firstNameProperty, edithDatatype);
// Add third statement : Edith Piaf's last name is Piaf
graph.addEdge(edithPiafIRI, lastNameProperty, piafDatatype);This example shows how to load a graph from a file. Corese Loader can load formats :
- RDF/XML (.rdf)
- TURTLE (.ttl)
- TRIG (.trig)
- JSONLD (.jsonld)
- NTRIPLES (.nt)
- NQUADS (.nq)
- JSON-LD (.jsonld)
- RDFa (.html)
// Create a new empty Graph
Graph graph = Graph.create();
// Create loader and parse file
Load ld = Load.create(graph);
ld.parse("input graph file path");This example shows how to serialize a graph in file, here in TURTLE format.
// We assume that the 'graph' variable has been define previously
// Create exporter
ResultFormat exporter = ResultFormat.create(graph, ResultFormat.TURTLE_FORMAT);
String result = exporter.toString();
// Write result in file
FileWriter writer = new FileWriter("output file path");
writer.write(result);
writer.close();Corese Transformer can serialize graphs in different formats :
- RDF/XML
ResultFormat.RDF_XML_FORMAT - TURTLE
ResultFormat.TURTLE_FORMAT - TRIG
ResultFormat.TRIG_FORMAT - JSONLD
ResultFormat.JSONLD_FORMAT - NTRIPLES
ResultFormat.NTRIPLES_FORMAT - NQUADS
ResultFormat.NQUADS_FORMAT
This section describes how to query a graph with SPARQL in Corese.
This example shows how to execute a SPARQL SELECT query, print and export results.
// We assume that the 'graph' variable has been define previously
// Sparql query
QueryProcess exec = QueryProcess.create(graph);
Mappings map = exec.query("select * where { ?s ?p ?o }");Example of how to get a variable value in the results:
// Iterate on each result
for (Mapping m : map) {
// Get the value of the variable ?o
IDatatype dt = m.getValue("?o");
// Test and convert the value to java type
if (dt.isURI()) {
String uriLabel = dt.getLabel();
}
else if (dt.isBlank()) {
String BNLabel = dt.getLabel();
}
else {
if (dt.isBoolean()) {
boolean boolResult = dt.booleanValue();
}
else if (dt.isNumber()) {
int intResult = dt.intValue();
double doubleResult = dt.doubleValue();
float floatResult = dt.floatValue();
BigDecimal bigDecimalResult = dt.decimalValue();
long longResult = dt.longValue();
}
else {
String stringResult = dt.stringValue();
String stringLangResult = dt.getLang();
}
}
}Print list of variables in the result:
System.out.println(map.getSelect());
// Exemple: ["?s", "?p", "?o"]Print results:
for (Mapping m: map){
System.out.println(m);
}Export result in XML:
ResultFormat result_xml = ResultFormat.create(map);
result_xml.write("output file path");This example shows how to execute a SPARQL ASK query and print results.
// We assume that the 'graph' variable has been define previously
// Sparql query
QueryProcess exec = QueryProcess.create(graph);
Mappings map = exec.query("ask { ?person foaf:name ?name. }");Print results:
// if the mappings is empty then the result is false
// if the mappings is not empty then the result is true
system.out.println(!map.isEmpty());// We assume that the 'graph' variable has been define previously
// Sparql query
QueryProcess exec = QueryProcess.create(graph);
Mappings map = exec.query("""
prefix foaf: <http://xmlns.com/foaf/0.1/>
prefix vcard: <http://www.w3.org/2001/vcard-rdf/3.0#>
construct {
?person vcard:FN ?name
}
where {
?person foaf:name ?name.
}
"""
);Print graph result of a construct-where query :
Graph g = (Graph) map.getGraph();
Graph result_graph = (Graph) map.getGraph();
System.out.println(result_graph.display());Export result in XML:
// Export result in XML
ResultFormat result_xml = ResultFormat.create(map);
result_xml.write("output file path");// We assume that the 'graph' variable has been define previously
// Sparql query
QueryProcess exec = QueryProcess.create(graph);
exec.query("""
prefix foaf: <http://xmlns.com/foaf/0.1/>
prefix vcard: <http://www.w3.org/2001/vcard-rdf/3.0#>
insert {
?person vcard:FN ?name
}
where {
?person foaf:name ?name.
}
"""
);This section show how to validate a graph with the Shapes Constraint Language (SHACL) in Corese. The example below shows us how to load a shapes graph (SHACL file), check the validity of the data graph and finally print results.
// Load data graph
Graph dataGraph = Graph.create();
Load ld = Load.create(dataGraph);
ld.parse("input graph file path");
// Load shape graph
Graph shapeGraph = Graph.create();
ld = Load.create(shapeGraph);
ld.parse("input shape file path.ttl");
// Evaluation
Shacl shacl = new Shacl(dataGraph, shapeGraph);
Graph result = shacl.eval();
// print results
Transformer transformer = Transformer.create(result, Transformer.TURTLE);
System.out.println(transformer.toString());Input graph file path:
@prefix ex: <http://example.org/ns#> .
@prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> .
ex:Alice ex:ssn "987-65-4323" ;
ex:worksFor ex:Haribo, ex:KitKat ;
rdf:type ex:Person .
ex:Bob ex:ssn "124-35-6789" ;
ex:worksFor ex:Twitch ;
rdf:type ex:Person .
ex:Calvin ex:ssn "648-67-6545" ;
ex:worksFor ex:UntypedCompany ;
rdf:type ex:Person .
ex:Haribo rdf:type ex:Company .
ex:KitKat rdf:type ex:Company .
ex:Twitch rdf:type ex:Company .
ex:UntypedCompany rdf:type ex:Company .Input shape file path:
@prefix sh: <http://www.w3.org/ns/shacl#> .
@prefix xsd: <http://www.w3.org/2001/XMLSchema#> .
@prefix ex: <http://example.org/ns#> .
@prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> .
ex:PersonShape
a sh:NodeShape ;
sh:targetClass ex:Person ;
sh:property [
sh:path ex:ssn ;
sh:maxCount 1 ;
sh:datatype xsd:string ;
sh:pattern "^\\d{3}-\\d{2}-\\d{4}$" ;
] ;
sh:property [
sh:path ex:worksFor ;
sh:class ex:Company ;
sh:nodeKind sh:IRI ;
] ;
sh:closed true ;
sh:ignoredProperties ( rdf:type ) .Result:
@prefix xsh: <http://www.w3.org/ns/shacl#> .
@prefix sh: <http://www.w3.org/ns/shacl#> .
[a sh:ValidationReport ;
sh:conforms true] .This sections shows how to transforme a graph with a subset of the extension language SPARQL Template Transformation Language (STTL).
This example detail how load a data graph from a file, transforme it in a visual HTML format and export the result in a file.
// Open template file
Path path = Path.of("input template file path");
String sttl_query = Files.readString(path, StandardCharsets.UTF_8);
// Load data graph
Graph dataGraph = Graph.create();
Load ld = Load.create(dataGraph);
ld.parse("input graph file path");
// Apply STTL query
QueryProcess exec = QueryProcess.create(dataGraph);
Mappings map = exec.query(sttl_query);
// Export result
ResultFormat result_xml = ResultFormat.create(map);
result_xml.write("output file path");Input template file:
template {
format {
"<html>\n\n<body>\n\t<table>\n%s\t</table>\n</body>\n\n</html>"
group {
format {
"\t\t<tr>\n\t\t\t<td>%s</td>\n\t\t\t<td>%s</td>\n\t\t\t<td>%s</td>\n\t\t</tr>\n"
?s ?p ?o
}
}
}
}
where {
?s ?p ?o
}
order by ?s ?p ?oResult :
<html>
<body>
<table>
<tr>
<td>http://example.org/EdithPiaf</td>
<td>http://example.org/firstName</td>
<td>Edith</td>
</tr>
<tr>
<td>http://example.org/EdithPiaf</td>
<td>http://example.org/lastName</td>
<td>Piaf</td>
</tr>
<tr>
<td>http://example.org/EdithPiaf</td>
<td>http://www.w3.org/1999/02/22-rdf-syntax-ns#type</td>
<td>http://example.org/Singer</td>
</tr>
</table>
</body>
</html>This section details how to apply a set of rules on a graph using the SPARQL Rule extension language.
The example below shows the application of two rules (symmetry and transitivity) on a simple graph.
// Create and load data in a graph
Graph dataGraph = Graph.create();
Load dataLoader = Load.create(dataGraph);
dataLoader.parse("input graph file path");
// Create and load rules into a rules engine
RuleEngine ruleEngine = RuleEngine.create(dataGraph);
RuleLoad ruleLoader = RuleLoad.create(ruleEngine);
ruleLoader.parse("input rules file path.rul");
// Apply rules on graph
ruleEngine.process();Original graph:
graph LR;
classDef IRI fill:#FEAE65,stroke-width:0px
iri:alice(["ex:Alice"])
iri:bob(["ex:Bob"])
iri:camille(["ex:Camille"])
iri:daniel(["ex:Daniel"])
iri:elise(["ex:Elise"])
class iri:alice,iri:bob,iri:camille,iri:daniel,iri:elise IRI
iri:alice--ex:friend-->iri:bob;
iri:bob--ex:friend-->iri:camille;
iri:daniel--ex:isMarriedTo-->iri:elise;
Rules file:
- Symmetry :
if exist X➝Y then Y➝X - Transitivity :
if X➝Y➝Z then X➝Z
<?xml version="1.0"?>
<rdf:RDF
xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
xmlns="http://ns.inria.fr/corese/rule/">
<rule>
<body>
<![CDATA[
prefix owl: <http://www.w3.org/2002/07/owl#>
construct {
?x ?p ?z
}
where {
?p a owl:TransitiveProperty .
?x ?p ?y .
?y ?p ?z
}
]]>
</body>
</rule>
<rule>
<body>
<![CDATA[
prefix owl: <http://www.w3.org/2002/07/owl#>
construct {
?y ?p ?x
}
where {
?p a owl:SymmetricProperty .
?x ?p ?y .
}
]]>
</body>
</rule>
</rdf:RDF>
Result graph:
graph LR;
classDef IRI fill:#FEAE65,stroke-width:0px
iri:alice(["ex:Alice"])
iri:bob(["ex:Bob"])
iri:camille(["ex:Camille"])
iri:daniel(["ex:Daniel"])
iri:elise(["ex:Elise"])
class iri:alice,iri:bob,iri:camille,iri:daniel,iri:elise IRI
iri:alice--ex:friend-->iri:bob;
iri:bob--ex:friend-->iri:camille;
iri:alice-.ex:friend.->iri:camille;
iri:daniel--ex:isMarriedTo.->iri:elise;
iri:elise-.ex:isMarriedTo.->iri:daniel;
linkStyle 4,2 stroke:#a3ddcb,stroke-width:3px;
The example below shows the application of OWL RL rules.
// We assume that the 'graph' variable has been define previously
// Apply rules
RuleEngine engine = RuleEngine.create(graph);
engine.setProfile(RuleEngine.OWL_RL);
engine.process();This section describes how to define and use functions with the LDScript extension language.
This example shows how to define and compute the twelfth number of the Fibonnacci sequence.
// Open LDScript file
Path path = Path.of("input LDScript file path.rq");
String ldScript = Files.readString(path, StandardCharsets.UTF_8);
// Compile LDScript
QueryProcess exec = QueryProcess.create();
exec.compile(ldScript);
// Compute the twelfth number of the Fibonnacci sequence
String name = "http://ns.inria.fr/fibonacci";
IDatatype dt = exec.funcall(name, DatatypeMap.newInstance(25));
// Print result
System.out.println(dt);Input LDScript file path:
prefix fun: <http://ns.inria.fr/>
@public function fun:fibonacci(n) {
if (n < 0) {
error()
}
else if (n = 0) {
return(0)
}
else if (n = 1) {
return(1)
}
else {
return (fun:fibonacci(n - 1) + fun:fibonacci(n - 2))
}
}This example shows how to call an LDScript function from a SPARQL query.
String check_query = """
prefix ex: <http://example.com/city/>
prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
prefix fun: <http://ns.inria.fr/>
select ?name ?area
where {
?city rdf:type ex:city ;
ex:area ?area .
filter(?area > fun:toSquareKm(40))
}
# Convert square mile to square Kilometer
function fun:toSquareKm(squareMile) {
return (squareMile * 2.59)
}
""";
// Load graph
Graph graph = Graph.create();
Load ld = Load.create(graph);
ld.parse("input file path");
// Sparql query
QueryProcess exec = QueryProcess.create(graph);
Mappings map = exec.query(check_query);The java program below computes the percentage of people subscribed to social networks of city compared to its number of inhabitants. Data is collected from Wikidata.
// Open LDScript file
Path path = Path.of("input LDScript file path.rq");
String ldScript = Files.readString(path, StandardCharsets.UTF_8);
// Compile LDScript
QueryProcess exec = QueryProcess.create();
exec.compile(ldScript);
// Execute program
String name = "http://ns.inria.fr/main";
IDatatype dt = exec.funcall(name);
// Print result
System.out.println(dt);Input LDScript file path:
prefix fun: <http://ns.inria.fr/>
prefix wd: <http://www.wikidata.org/entity/>
prefix wdt: <http://www.wikidata.org/prop/direct/>
prefix wikibase: <http://wikiba.se/ontology#>
prefix bd: <http://www.bigdata.com/rdf#>
prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#>
@public
function fun:percentage(sub, total) {
return (sub / total * 100)
}
@public
function fun:citypopulationsocialmedia() {
query(
select ?city ?citylabel ?population ?socialmediafolower where {
service <https://query.wikidata.org/sparql> {
?city wdt:P31 wd:Q1549591;
wdt:P8687 ?socialmediafolower;
wdt:P1082 ?population.
optional {
?city rdfs:label ?citylabel
filter (lang(?citylabel) = "en").
}
}
}
order by desc (?socialmediafolower)
limit 100
)
}
@public
function fun:main() {
xt:sort(
maplist (
function(x) {
let ((citylabel population socialmediafolower) = x) {
return (xt:list(citylabel, fun:percentage(socialmediafolower, population)))
}
},
fun:citypopulationsocialmedia()
),
function(x,y) {
let ((x_name, x_value) = x, (y_name, y_value) = y) {
if (x_value < y_value, 1, if(x=y, o, -1))
}
}
)
}