Presentation at ELAG 2018

1. SHACL
shortly

2. prepare
> wget https://www.dropbox.com/s/cddlq531xwqfohf/user-with-errors.data.ttl
> wget https://www.dropbox.com/s/d6d7iy5rzq4qqpj/user.data.ttl
> wget https://www.dropbox.com/s/j7b6w0olf75xk7d/user.shape.ttl

3. start with a success message
> shaclvalidate.sh -datafile user.data.ttl -shapesfile user.shape.ttl
[ a sh:ValidationReport ;
sh:conforms true
] .

4. an error message
> shaclvalidate.sh -datafile user-with-errors.data.ttl -shapesfile user.shape.ttl
[ a sh:ValidationReport ;
sh:conforms false ;
sh:result [
a sh:ValidationResult ;
sh:focusNode :frank ; #1
sh:resultMessage "Less than 1^^http://www.w3.org/2001/ #2
XMLSchema#integer values" ;
sh:resultPath schema:name ; #3
sh:resultSeverity sh:Violation ;
sh:sourceConstraintComponent sh:MinCountConstraintComponent ;
sh:sourceShape _:b0
] ;
] .
#1 the problematic statement
#2 explanation
#3 the problematic property

5. Check the data - missing schema:name
data:
:frank a :User ;
foaf:name "Frank" ;
schema:gender schema:Male
.
shape:
:UserShape a sh:NodeShape;
sh:targetClass :User ;
sh:property [
sh:path schema:name ;
sh:minCount 1;
sh:maxCount 1;
sh:datatype xsd:string ;
] ;
# …

6. rules: minCount, maxCount, datatype
sh:property [
sh:path schema:name ; #1
sh:minCount 1; #2
sh:maxCount 1; #3
sh:datatype xsd:string ; #4
] ;
#1 The qualified name of the property
#2 minimum number of instance
#3 maximum number of instance
#4 data type (use XML schema’s definition)

7. rules: or, in
sh:property [
sh:path schema:gender ;
sh:minCount 1;
sh:maxCount 1;
sh:or ( # 1
[ sh:in ( # 2
schema:Male
schema:Female
)
]
[ sh:datatype xsd:string]
)
] ;
#1 the value should be either X or Y
#2 the value should be one of a set
of values
Meaning: schema:gender property
should be schema:Male,
schema:Female or a string

8. rules: IRI, class
sh:property [
sh:path schema:knows ;
sh:nodeKind sh:IRI ; #1
sh:class :User ; #2
]
#1 the value must be an IRI
#2 the value must be an instance of
User
Meaning: schema:knows property
must be a reference to another user
BlankNode, IRI, Literal,
BlankNodeOrIRI, BlankNodeOrLiteral, IRIOrLiteral

9. Defining rules w/ blank nodes or w/ named nodes
Blank nodes:
:UserShape a sh:NodeShape;
sh:targetClass :User ;
sh:property [
sh:path schema:name ;
sh:minCount 1;
sh:maxCount 1;
sh:datatype xsd:string ;
] ;
# …
Named nodes:
:UserShape a sh:NodeShape;
sh:targetClass :User ;
sh:property :HasName;
# …
:HasName sh:path schema:name ;
sh:minCount 1;
sh:maxCount 1;
sh:datatype xsd:string .

10. Implicit target class
Blank nodes:
:UserShape a sh:NodeShape;
sh:targetClass :User ;
sh:property [
sh:path schema:name ;
sh:minCount 1;
sh:maxCount 1;
sh:datatype xsd:string ;
] ;
# …
Named nodes:
:User a sh:NodeShape, drfs:Class;
sh:property [
sh:path schema:name ;
sh:minCount 1;
sh:maxCount 1;
sh:datatype xsd:string
] ;

11. Core constraints
Cardinality minCount, maxCount
Types of values class, datatype, nodeKind
Values node, in, hasValue
Range of values minInclusive, maxInclusive, minExclusive, maxExclusive
String based minLength, maxLength, pattern, stem, uniqueLang
Logical constraints not, and, or, xone
Closed shapes closed, ignoredProperties
Property pair constraints equals, disjoint, lessThan, lessThanOrEquals
Non-validating constraints name, value, defaultValue
Qualified shapes qualifiedValueShape, qualifiedMinCount, qualifiedMaxCount

12. uniqueLang - one literal per language
Shape:
:Country a sh:NodeShape ;
sh:property [
sh:path schema:name ;
sh:uniqueLang true
] .
# …
Data:
:spain schema:name "Spain"@en,
"España"@es .
:france schema:name "France"@en,
"Francia"@es .
:usa schema:name "USA"@en,
"United States"@en.

13. Closed shapes
Shape:
:User a sh:NodeShape ;
sh:closed true ;
sh:ignoredProperties
( rdf:type );
sh:property [
sh:path schema:givenName;
];
sh:property [
sh:path schema:lastName ;
] .
Data:
:alice schema:givenName "Alice";
schema:lastName "Cooper" .
:carol schema:givenName "Carol";
schema:lastName "King" ;
rdfs:label "Carol" .

14. References
★ Shapes Constraint Language (SHACL) W3C Recommendation 20 July 2017
https://www.w3.org/TR/shacl/
★ Gayo—Prud’hommeaux—Solbrig—Boneva: SHACL by example
https://www.slideshare.net/jelabra/shacl-by-example
★ Gayo—Prud’hommeaux—Boneva—Kontokostas: Validating RDF Data.
(Morgan & Claypool, 2018) 328 p. /Synthesis Lectures on the Semantic Web:
Theory and Technology, Vol. 7, No. 1/) http://book.validatingrdf.com/