X API for RDF

RDF Terms

Factory Object

During the execution of the custom code, the SHACL engine provides a Factory Object that can be used to create X Objects for RDF terms. The Object provides the following three functions:

literal(lex, languageOrDatatype)
namedNode(uri)
blankNode(id) or blankNode()

The RDF terms objects can be created using the following Factory Object:

JavaScriptPython

TermFactory

py_tf

Terms

Node Kind	Factory Function	Test Function
Literals	`literal(lex, languageOrDatatype)`	`isLiteral()`
IRIs	`namedNode(uri)`	`isURI()`
Blank Nodes	`blankNode(id)` or `blankNode()`	`isBlankNode()`

Literals

A literal is represented by an X Literal Object where isLiteral() returns true while isURI() and isBlankNode() return false. The lexical form of the literal is accessible through getLex(), e.g. "Switzerland" for the RDF node "Switzerland"^^xsd:string. The language value is accessible through getLanguage() and is a lowercase BCP-47 string (for example, "en", "de"), or an empty string if the literal has no language. The literal datatype is accessible through getDatatype(), and is a NamedNode representing the datatype IRI of the literal. Note that this datatype is never undefined, and language-tagged strings have rdf:langString as their datatype.

IRIs

An IRI is represented by an X NamedNode Object where isURI() returns true while isBlankNode() and isLiteral() return false. The value of IRI string is accessible through the getUri().

Blank Nodes

A blank node is represented by an X BlankNode Object where isBlankNode() returns true while isURI() and isLiteral() return false. The blank node identifier is a string accessible through getId(). That string must be consistent for the same RDF node for the duration of a SHACL validation and processing of validation results.

Example: Term creation using the Factory Object

JavaScriptPython

// Literals

// when the languageOrDatatype is a string it is considered as the language
TermFactory.literal("Switzerland", "en")    // "Switzerland"@en
TermFactory.literal("Schweiz", "de")        // "Schweiz"@de

// when the languageOrDatatype is a NamedNode it is considered as the dataype
let intType = TermFactory.namedNode("http://www.w3.org/2001/XMLSchema#integer")
TermFactory.literal(10, intType)            // "10"^^http://www.w3.org/2001/XMLSchema#integer

let stringType = TermFactory.namedNode("http://www.w3.org/2001/XMLSchema#string")
TermFactory.literal(10, stringType)         // "10"

// IRIs
TermFactory.namedNode("http://example.org/ns#germanLabel")

// Blank Nodes
TermFactory.blankNode()                     // a random id will be generated
TermFactory.blankNode("1298eaa4-61b3")

# Literals

# when the languageOrDatatype is a string it is considered as the language
py_tf.literal("Switzerland", "en")    # "Switzerland"@en
py_tf.literal("Schweiz", "de")        # "Schweiz"@de

# when the languageOrDatatype is a NamedNode it is considered as the dataype
int_type = py_tf.namedNode("http://www.w3.org/2001/XMLSchema#integer")
py_tf.literal(10, int_type)            # "10"^^http://www.w3.org/2001/XMLSchema#integer

string_type = py_tf.namedNode("http://www.w3.org/2001/XMLSchema#string")
py_tf.literal(10, string_type)         # "10"

# IRIs
py_tf.namedNode("http://example.org/ns#germanLabel")

# Blank Nodes
py_tf.blankNode()                     # a random id will be generated
py_tf.blankNode("1298eaa4-61b3")

Triples

An RDF triple is represented by a Triple Object.

Attribute	Function
subject	`getSubject()`
predicate	`getPredicate()`
object	`getObject()`

Graphs

Accessing the Data Graph

During a validation process, a variable points at the Graph Object representing the SHACL data graph.

JavaScriptPython

$data

_data

Accessing the Shapes Graph

During a validation process, a variable points at the Graph Object representing the SHACL shapes graph.

JavaScriptPython

$shapes

_shapes

Example

JavaScriptPython