Class Node

A Class Node is used as a potential range for a Property Node.

It is represented by an object with "@type": "sh:NodeShape" that is wrapped by the term sh:node. This NodeShape is used to express all the characteristics and constraints of the Class Node. The most important constraint is sh:class, which constraints the class(es) that the target entity must have. For sh:class arrays are allowed, which are supposed to represent multi-typed entities (MTE).

The @id of a Class Node is used to reference it in other parts of the Domain Specification, and so reuse already defined constraints for a specific Class. Details below.

1. Example

{
  "sh:node": {
    "@id": "https://semantify.it/ds/OBbzsh4_B#DpruH",
    "@type": "sh:NodeShape",
    "sh:class": [
      "schema:Airport"
    ],
    "rdfs:label": [
      {
        "@language": "en",
        "@value": "Airport"
      },
      {
        "@language": "de",
        "@value": "Flughafen"
      }
    ],
    "rdfs:comment": [
      {
        "@language": "en",
        "@value": "An international Airport that is identified by its ICAO identifier."
      }
    ],
    "sh:closed": true,
    "ds:propertyDisplayOrder": [
      "schema:name",
      "schema:icaoCode",
      "schema:url"
    ],
    "sh:property": [
      ...
    ]
  }
}

2. Key-value Table

The following table lists all possible terms that can be used by a Class Node. The order in the table reflects the recommended order of these terms within a Class Node (optional).

key	required	value type	description	related error
@id	true	IRI	The IRI of the Class Node, which is based on the DS IRI it is in
@type	true	"sh:NodeShape"	The fixed type for a Class Node
sh:class	true	[ IRI ]	The IRI(s) of the Class(es) that the entity must have	Non-conform range
rdfs:label	false	List of Language tagged String	The label for this Class
rdfs:comment	false	List of Language tagged String	The description for this Class
sh:closed	false	Boolean	Specifies if additional properties are allowed or not	Non-conform property
ds:propertyDisplayOrder	false	List of IRI	A list of property IRIs that reflect the order of the properties for this Class. If this property is used, it replaces the order given by sh:order of the property nodes in question.
sh:property	false	List of PropertyNode	A list of property nodes that apply to the entity	Missing Property, Non-conform Property

3. Semantics

3.1. Class-Matching

See SHACL specification.

A Class Node includes sh:class to specify the class(es) that the verified entity MUST match. Domain Specifications use custom semantics for class matching.

Examples:

"sh:class": [
  "schema:LodgingBusiness",
  "schema:Restaurant"
]

"sh:class": [
  "schema:Article"
]

3.2. Properties

The terms sh:property and sh:closed are used in a Class Node to give further restrictions on the properties of the corresponding entity. Such a Class Node with property restrictions is also called Restricted Class Node. A Class Node without further property restrictions is called a Standard Class Node.

3.2.1. sh:property

See SHACL specification.

The term sh:property lists the property shapes that the target entity must comply with. For every property, there is a corresponding Property Node in this list.

Example:

"sh:property": [
  {
    "@type": "sh:PropertyShape",
    "sh:order": 0,
    "sh:path": "schema:identifier"
    "sh:maxCount": 1,
    "sh:or": [
      {
        "sh:datatype": "xsd:string",
      }
    ]
  },
  {
    "@type": "sh:PropertyShape",
    "sh:order": 1,
    "sh:path": "schema:alternateName"
    "sh:maxCount": 1,
    "sh:or": [
      {
       "sh:datatype": "xsd:string",
      }
    ]
  }
]

3.2.2. sh:closed

See SHACL specification.

The term sh:closed can be used to specify if additional properties (other than the properties allowed by sh:property) are allowed or not. In the past, Domain Specifications had "sh:closed": true implicitly in all NodeShapes. Now the DS creator should specify the wished behaviour.

Example:

"sh:closed": true

3.2.3. ds:propertyDisplayOrder

The term ds:propertyDisplayOrder provides a list of property IRIs that reflect a wished order of the properties for display purposes. Details about this term can be found in DomainSpecification.md.

3.3. Metadata

Following terms represent metadata about the given class. These terms do not have any effects on the verification result; They have only informational character.

3.3.1. rdfs:label

The term rdfs:label CAN be used to give the class a label (in different languages). The value for this term is a language-tagged string. The standard label for a class term is usually provided by its vocabulary itself, rdfs:label can be used to overwrite that standard label or provide a single label for multi-class entities (a class that has multiple sh:class entries).

Example:

{
  "@id": "https://semantify.it/ds/OBbzsh4_B#DpruH",
  "@type": "sh:NodeShape",
  "sh:class": [
    "schema:LodgingBusiness",
    "schema:Restaurant"
  ],
  "rdfs:label": [
    {
      "@language": "en",
      "@value":"Hotel and Restaurant"
    }
  ],
  ...
}

3.3.2. rdfs:comment

The term rdfs:comment CAN be used to describe the class (in different languages). The value for this term is a language-tagged string. The standard description for a class term is usually provided by its vocabulary itself, rdfs:comment can be used to overwrite that standard description or provide a single description for multi-class entities (a class that has multiple sh:class entries).

Example:

{
  "@id": "https://semantify.it/ds/OBbzsh4_B#DpruH",
  "@type": "sh:NodeShape",
  "sh:class": [
    "schema:LodgingBusiness",
    "schema:Restaurant"
  ],
  "rdfs:comment": [
    {
      "@language": "en",
      "@value":"A business that offers rooms and has a restaurant in the same building."
    }
  ],
  ...
}