Ontologies

This package provides ontologies management utilities.

Features

• Manage ontologies with prefixes, OWL files and JSON-LD contexts
• Allow services to register the ontologies they need
• Allow to persist ontologies if they must be kept on server restart
• Allow to find ontologies prefixes through prefix.cc

Dependencies

• JsonLdService

Sub-services

• OntologiesRegistryService

Install

$ yarn add @semapps/ontologies

Usage

const { OntologiesService } = require('@semapps/ontologies');

module.exports = {
  mixins: [OntologiesService],
  settings: {
    ontologies: [
      {
        prefix: 'ont1',
        namespace: 'https://www.w3.org/ns/ontology1#',
        owl: 'https://www.w3.org/ns/ontology1.ttl',
        jsonldContext: 'https://www.w3.org/ns/ontology1.ttl', // Can also be a array or an object
        preserveContextUri: false // If true, the jsonldContext won't be merged in the local context file
      }
    ],
    persistRegistry: false,
    setingsDataset: 'settings'
  }
};

Persisting registry

Any services may call the register action to add new ontologies. That's how most core services register the ontologies they need.

By default, the ontologies registry is not persisted. It is kept in memory and so the register action must be called again on every restart.

If you wish ontologies to be persisted, you must set the persistRegistry setting to true.

By default, they will be persisted in a dataset named settings (the same used by the auth.account service). If you wish to use another dataset name, you can change the settingsDataset setting.

Settings

Property	Type	Default	Description
ontologies	[Array]		List of (custom) ontologies to be registered
persistRegistry	Boolean	false	If true, registered ontologies will be persisted in a dataset
settingsDataset	String	"settings"	The dataset where to persist ontologies (if persistRegistry is true )

Core ontologies

These ontologies can be imported individually using their prefixes, or as a whole with coreOntologies.

Prefix	Namespace
acl	http://www.w3.org/ns/auth/acl#
as	https://www.w3.org/ns/activitystreams#
dc	http://purl.org/dc/terms/
foaf	http://xmlns.com/foaf/0.1/
ldp	http://www.w3.org/ns/ldp#
rdf	http://www.w3.org/1999/02/22-rdf-syntax-ns#
rdfs	http://www.w3.org/2000/01/rdf-schema#
sec	https://w3id.org/security#
semapps	http://semapps.org/ns/core#
vcard	http://www.w3.org/2006/vcard/ns#
void	http://rdfs.org/ns/void#
xsd	http://www.w3.org/2001/XMLSchema#

Actions

The following service actions are available:

findPrefix

Fetch prefix.cc to find the prefix of the provided URI.

Parameters

Property	Type	Default	Description
uri	String	required	URI of the ontology or of a predicate

Return

The prefix, or null if no prefix was found.

findNamespace

Fetch prefix.cc to find the namespace associated with a prefix.

Parameters

Property	Type	Default	Description
prefix	String	required	Prefix of the ontology

Return

The namespace, or null if the prefix doesn't exist in prefix.cc.

get

Return a registered ontology by its prefix, namespace or URI.

Parameters

Property	Type	Default	Description
prefix	String		Prefix of the ontology
namespace	String		Namespace of the ontology
uri	String		URI to match with the namespace of the ontology

Return

The ontology, or null if no registered ontology was found.

getPrefixes

Return the registered prefixes as an object.

Return

An object with the prefix in keys, and the associated URLs in values.

getRdfPrefixes

Return the registered ontologies' prefixes as a string to be used in SPARQL queries.

Return

A string of type PREFIX ont1: <https://www.w3.org/ns/ontology1#>, split with new lines.

list

Return the registered ontologies

Return

An array of object, formatted as above.

register

Register a new ontology.

Parameters

Property	Type	Default	Description
prefix	String	required	Prefix of the ontology
namespace	String	required	Namespace of the ontology
owl	String		URL of the OWL file (used by the InferenceService)
jsonldContext	String, Array or Object		JSON-LD context associated with the ontology. Can be an URL, a array or an object
preserveContextUri	Boolean	false	If true, the jsonldContext will not be merged in the local context file. Works only if jsonldContext is an URL or an array of URLs.
overwrite	Boolean	false	If true, any existing ontology with the same prefix and URL will be overwritten