Copyright © 2016-2021 European Union. This document is licensed under a Creative Commons Attribution 4.0 License.

Abstract

This document describes the background and methodology for the design of the Schema.org profile of DCAT-AP (DCAT-AP-SDO), as well as the defined mappings.

Introduction

This document describes the background and methodology for the design of the Schema.org profile of DCAT-AP (DCAT-AP-SDO), as well as the defined mappings.

The motivation for investigating the possiblity of aligning DCAT-AP metadata with Schema.org is twofold:

  1. To identify how to create a DCAT-AP-compliant representation of Schema.org metadata, in order to enable their sharing across DCAT-AP-enabled data catalogues.
  2. To identify how to create a Schema.org-compliant representation of DCAT-AP metadata, in order to enhance their discoverability on the Web.

The following sections first illustrate the background () and methodology () for the design of DCAT-AP-SDO, followed by a summary of the mapping issues ().

The defined mappings are introduced in , and grouped as follows:

A formal definition of the proposed mappings, encoded in the form of SPARQL queries, is included in appendix ().

Background

The DCAT Application Profile for Data Portals in Europe (DCAT-AP)

DCAT-AP [[DCAT-AP]] is a metadata profile developed in the framework of the EU Programme Interoperability Solutions for European Public Administrations (ISA), and based on and compliant with the W3C Data Catalog vocabulary (DCAT) [[VOCAB-DCAT]] - currently, one of the most widely used Semantic Web vocabularies for describing datasets and data catalogues.

The purpose of DCAT-AP is to define a common interchange metadata format for data portals of the EU and of EU Member States. In order to achieve this, DCAT-AP defines a set of classes and properties, grouped into mandatory, recommended and optional. Such classes and properties correspond to information on datasets and data catalogues that are shared by many European data portals, aiding interoperability. Although DCAT-AP is designed to be independent from its actual implementation, RDF [[RDF-CONCEPTS]] and Linked Data [[LD-BOOK]] are the reference technologies.

Schema.org

Schema.org [[SCHEMA-ORG]] is an initiative promoted by Google, Microsoft, Yahoo and Yandex, aiming to develop and maintain metadata vocabularies for the description of Web resources, to be re-used by search engines to enhance online content indexing and discovery.

Since its launch in 2011, Schema.org has incrementally grown to cover a variety of domains, also through the re-use of existing popular vocabularies - as Dublin Core [[DCTERMS]], the Friend Of A Friend (FOAF) vocabulary [[FOAF]], vCard [[VCARD-RDF]], as well as DCAT [[VOCAB-DCAT]]. According to an estimation reported in [[GUHA-2015]], at the end of 2015 the adoption of Schema.org concerned around 12,000,000 Web sites.

Typically, Schema.org is used to embed metadata in Web pages, using mechanisms as Microdata [[MICRODATA]], RDFa [[HTML-RDFa]] and JSON-LD [[JSON-LD]]. The data model is based on and compliant with RDF.

Aligning DCAT-AP with Schema.org

The motivation for investigating the possiblity of aligning DCAT-AP metadata with Schema.org is twofold:

  1. To identify how to create a DCAT-AP-compliant representation of Schema.org metadata, in order to enable their sharing across DCAT-AP-enabled data catalogues.
  2. To identify how to create a Schema.org-compliant representation of DCAT-AP metadata, in order to enhance their discoverability on the Web.

In both cases, this analysis is not meant to provide a complete representation of all DCAT-AP metadata elements and those included in its thematic extensions (e.g., geospatial and statistical), but only of those supported by Schema.org.

Methodology

The reference DCAT-AP and Schema.org specifications used in this exercise are the following ones:

For the mappings, existing work has been taken into account concerning the mapping of Schema.org to other metadata standards. In particular:

DCAT-AP-SDO re-uses these specifications, and extends them to provide an as much as possible complete mapping of the metadata elements in [[DCAT-AP]], [[GeoDCAT-AP]], and [[StatDCAT-AP]].

Summary of alignment issues

A general issue is determined by the fact that Schema.org and DCAT-AP address different use cases. More precisely, the main purpose of Schema.org is to enhance discovery and indexing of online resources via search engines. As such, it is addressing more general objectives compared with DCAT-AP, that is instead meant to represent in detail information on datasets and data catalogues.

One of the main consequences is that some information that is relevant in DCAT-AP it is not described in Schema.org with specific terms. This results in a relevant amount of (a) "missing" and (b) "many-to-one" mappings - i.e., different metadata elements of DCAT-AP are mapped to the same element in Schema.org.

This is not necessarily a problem, since the objective of mapping DCAT-AP and Schema.org is to enhance discoverability of DCAT-AP metadata on the Web, which does not require a complete, 1-to-1 representation of DCAT-AP metadata. Actually, the result of this exercise can also include the identification of the subset of DCAT-AP metadata elements that is worth representing in a Schema.org-based description. On the other hand, this situation also implies that a reverse mapping (i.e., from Schema.org to DCAT-AP) may be problematic or not possible.

The following sections describe the DCAT-AP metadata elements posing mapping issues.

Categories and category schemes

This concerns classes skos:ConceptScheme and skos:Concept.

Only few of the categories and categories schemes used in DCAT-AP are supported in Schema.org. The re-use of "external" controlled vocabularies is allowed in Schema.org, but how this can be specified is unclear.

Based on the documentation found online [[WEBSCHEMAS-EE]], the approach seems to be based on the use of schema:Enumeration for skos:ConceptScheme, but it is unclear how to state that a given skos:Concept is in a given skos:ConceptScheme.

Another option could be to use schema:ItemList for skos:ConceptScheme's, and schema:ListItem for skos:Concept's, and to link the two with schema:itemListElement.

Resource "types"

This concerns properties denoting the "type" of a resource, by using a skos:Concept. In DCAT-AP, this is typically done by using property dct:type.

Schema.org has a generic property, namely schema:additionalType - defined as a sub-property of rdf:type, that is meant to be used to associate multiple types with the same resource. It is to be investigated whether it can be used for this purpose.

Resource status

This concerns properties denoting the status of a resource in its lifecycle, by using a skos:Concept. In DCAT-AP, this is done by using property adms:status.

Schema.org does not have properties for this purpose, and it seems there are no suitable candidates that can be used.

Rights

This concerns properties denoting the rights (as use and access conditions) applying to a resource. In DCAT-AP, this is specified by using property dct:rights, and its subproperties dct:accessRights and dct:license.

Schema.org only supports one of these properties, namely schema:license.

Versioning

This concerns properties denoting the different versions of a resource, as well as other versioning aspects - as the update frequency, version numbers, and version notes. In DCAT-AP, this is typically done by using properties dct:hasVersion, dct:isVersionOf, dct:accrualPeriodicity, owl:versionInfo, and adms:versionNotes.

Schema.org only supports one of these properties, namely schema:version, corresponding to owl:versionInfo.

Provenance

DCAT-AP uses property dct:provenance to specify "provenance statements" about datasets (typically, their lineage).

Schema.org does not have specific terms for this purpose, so a possible option is to use more generic ones, like schema:description.

Conformance

This concerns properties denoting the conformance of a resource with a standard. In DCAT-AP, this is typically done by using property dct:conformsTo, which is used in different contexts (namely, to express conformance with a metadata standard, with a data schema, with a reference system, with given quality criteria).

Schema.org does not have properties for this purpose, and it seems there are no suitable candidates that can be used. The only one currently available is schema:publishingPrinciples, which might be used to specify, e.g., data policies.

Data quality

This concerns properties used to specify quality aspects, as spatial and temporal resolution. DCAT-AP supports this with two specific properties: dcat:spatialResolutionInMeters and dcat:temporalResolution. In addition, [[GeoDCAT-AP]], following [[VOCAB-DCAT-2]] recommendations, makes use of property dqv:hasQualityMeasurement to specify the different types of spatial resolution.

Schema.org does not have properties for this purpose, and it seems there are no suitable candidates that can be used.

Checksum

DCAT-AP allows the specification of the checksum of a dataset distribution by using specific classes and properties from the Software Package Data Exchange (SDPX) vocabulary [[SPDX]].

Schema.org does not have terms for this purpose, and it seems there are no suitable candidates that can be used.

Licences, standards & al.

Resources as licences and standards are represented by specific classes and properties in DCAT-AP.

In Schema.org, there is a general "type", namely schema:CreativeWork, further refined with a number of "sub-types" (e.g., schema:Dataset is one of these sub-types). However, none of them is specifically denoting resources as, e.g., licences and standards.

Geometries

This concerns properties dcat:bbox, dcat:centroid, and locn:geometry.

Schema.org uses a specific representation for geometries, whereas dcat:bbox, dcat:centroid, and locn:geometry support any type of geometry encoding / representation.

The mapping of dcat:bbox, dcat:centroid, and locn:geometry to Schema.org may therefore require further processing to convert the original geometry encoding / representation to the target one.

For more details, see .

Dimensions and attributes

[[StatDCAT-AP]] defines properties stat:dimension and stat:attribute to specify, respectively, the dimensions an observation applies to (time, area, gender) and information needed to qualify and interpret the observed values (unit of measure, scaling factors, status of the observation).

Schema.org does not have properties for this purpose, and it seems there are no suitable candidates that can be used.

Mapping summary

The following sections summarise the alignments defined in DCAT-AP-SDO.

The alignments cover the metadata elements defined in the following specifications:

For each of the mapped elements and the reference controlled vocabularies, the relevant specification is referred to in the tables included in the following sections.

For Schema.org, the reference specification is Schema.org 12.0 () [[SCHEMA-ORG-20210308]].

The alignments are grouped as follows:

In the mapping tables included in the following sections, column "Obl." ("Obligation"), denotes whether the class / property is mandatory ("M"), recommended ("R"), or optional ("O").

Used namespaces

Prefix Namespace URI Schema & documentation
adms http://www.w3.org/ns/adms# [[VOCAB-ADMS]]
cnt http://www.w3.org/2011/content# [[Content-in-RDF]]
dcat http://www.w3.org/ns/dcat# [[VOCAB-DCAT]]
dcatap http://data.europa.eu/r5r/ [[DCAT-AP]]
dct http://purl.org/dc/terms/ [[DCTERMS]]
dqv http://www.w3.org/ns/dqv# [[VOCAB-DQV]]
foaf http://xmlns.com/foaf/0.1/ [[FOAF]]
geodcat http://data.europa.eu/930/ [[GeoDCAT-AP]]
gsp http://www.opengis.net/ont/geosparql# [[GeoSPARQL]]
locn http://www.w3.org/ns/locn# [[LOCN]]
oa http://www.w3.org/ns/oa# [[ANNOTATION-VOCAB]]
odrl http://www.w3.org/ns/odrl/2/ [[VOCAB-ODRL]]
org http://www.w3.org/ns/org# [[VOCAB-ORG]]
owl http://www.w3.org/2002/07/owl# [[OWL-REF]]
prov http://www.w3.org/ns/prov# [[PROV-O]]
rdf http://www.w3.org/1999/02/22-rdf-syntax-ns# [[RDF-CONCEPTS]]
rdfs http://www.w3.org/2000/01/rdf-schema# [[RDF-SCHEMA]]
schema http://schema.org/ [[SCHEMA-ORG]]
sdmx-attribute http://purl.org/linked-data/sdmx/2009/attribute# [[VOCAB-DATA-CUBE]]
skos http://www.w3.org/2004/02/skos/core# [[SKOS-REFERENCE]]
spdx http://spdx.org/rdf/terms# [[SPDX]]
stat http://data.europa.eu/m8g/ [[StatDCAT-AP]]
time http://www.w3.org/2006/time# [[OWL-TIME]]
vcard http://www.w3.org/2006/vcard/ns# [[VCARD-RDF]]
xsd http://www.w3.org/2001/XMLSchema# [[XMLSCHEMA11-2]]

Reference code lists for metadata elements

Specification Metadata elements Code list URI Code lists Status
[[DCAT-AP]] Catalogue record change type http://purl.org/adms/changetype ADMS Change Type controlled vocabulary [[ADMS-SKOS]] stable
[[GeoDCAT-AP]] Degree of conformity http://inspire.ec.europa.eu/metadata-codelist/DegreeOfConformity [[INSPIRE-DoC]] stable
[[DCAT-AP]] Distribution availability http://data.europa.eu/r5r/availability [[DCAT-AP-DA]] stable
[[DCAT-AP]] Distribution status http://purl.org/adms/status ADMS Status controlled vocabulary [[ADMS-SKOS]] stable
[[StatDCAT-AP]] Distribution type http://publications.europa.eu/resource/authority/distribution-type [[EUV-DT]] stable
[[DCAT-AP]] Format http://publications.europa.eu/resource/authority/file-type [[EUV-FT]] stable
[[GeoDCAT-AP]] INSPIRE spatial data themes http://inspire.ec.europa.eu/theme [[INSPIRE-THEMES]] stable
[[DCAT-AP]] Geographical names http://publications.europa.eu/resource/authority/continent [[EUV-CONT]] stable
http://publications.europa.eu/resource/authority/country [[EUV-COUNTRIES]] stable
http://publications.europa.eu/resource/authority/place [[EUV-PLACES]] stable
http://sws.geonames.org/ [[GEONAMES]] stable
[[DCAT-AP]] Language http://publications.europa.eu/resource/authority/language [[EUV-LANG]] stable
[[DCAT-AP]] Licence type http://purl.org/adms/licencetype ADMS Licence Type controlled vocabulary [[ADMS-SKOS]] stable
[[DCAT-AP]] Maintenance frequency (Maintenance information) http://publications.europa.eu/resource/authority/frequency [[EUV-FREQ]] stable
[[GeoDCAT-AP]] http://inspire.ec.europa.eu/metadata-codelist/MaintenanceFrequency [[INSPIRE-MF]]. stable
[[DCAT-AP]] EU Vocabularies Data themes http://publications.europa.eu/resource/authority/theme [[EUV-THEMES]] stable
[[DCAT-AP]] Media type http://www.iana.org/assignments/media-types [[IANA-MEDIA-TYPES]] stable
[[DCAT-AP]] Publisher http://publications.europa.eu/resource/authority/corporate-body [[EUV-CB]] stable
[[GeoDCAT-AP]] Reference system http://www.opengis.net/def/crs/EPSG/ [[OGC-EPSG]] stable
[[DCAT-AP]] Publisher type http://purl.org/adms/publishertype ADMS Publisher Type controlled vocabulary [[ADMS-SKOS]] stable
[[GeoDCAT-AP]] Reference system type http://inspire.ec.europa.eu/glossary/SpatialReferenceSystem [[INSPIRE-GLOSSARY]]. testing
http://inspire.ec.europa.eu/glossary/TemporalReferenceSystem
[[GeoDCAT-AP]] Resource type http://inspire.ec.europa.eu/metadata-codelist/ResourceType [[INSPIRE-RT]] stable
[[GeoDCAT-AP]] Service type http://inspire.ec.europa.eu/metadata-codelist/SpatialDataServiceType [[INSPIRE-SDST]] stable
[[GeoDCAT-AP]] Spatial data service categories http://inspire.ec.europa.eu/metadata-codelist/SpatialDataServiceCategory [[INSPIRE-SDSC]] stable
[[GeoDCAT-AP]] Spatial representation type http://inspire.ec.europa.eu/metadata-codelist/SpatialRepresentationType [[INSPIRE-SRT]] stable
[[GeoDCAT-AP]] Topic category http://inspire.ec.europa.eu/metadata-codelist/TopicCategory [[INSPIRE-TC]] stable

Classes

DCAT-AP Schema.org Comments
Specification Obl. Label QName
[[DCAT-AP]] M Agent foaf:Agent schema:Organization | schema:Person
[[DCAT-AP]] M Catalogue dcat:Catalog schema:DataCatalog
[[DCAT-AP]] M Dataset dcat:Dataset schema:Dataset
[[DCAT-AP]] R Category skos:Concept schema:Thing TBD
[[DCAT-AP]] R Category Scheme skos:ConceptScheme schema:Enumeration TBD
[[DCAT-AP]] R Distribution dcat:Distribution schema:DataDownload
[[DCAT-AP]] R Licence Document dct:LicenseDocument schema:CreativeWork | schema:URL TDB
[[GeoDCAT-AP]] O Address locn:Address schema:PostalAddress Used with class Agent, via property locn:address.
[[GeoDCAT-AP]] O vcard:Address Used with class Kind, via property vcard:hasAddress.
[[DCAT-AP]] O Catalogue Record dcat:CatalogRecord schema:ListItem
[[DCAT-AP]] O Checksum spdx:Checksum schema:Thing TBD
[[DCAT-AP]] O Data Service dcat:DataService schema:WebAPI
[[DCAT-AP]] O Document foaf:Document schema:CreativeWork | schema:URL TBD
[[DCAT-AP]] O Identifier adms:Identifier schema:PropertyValue schema:PropertyValue is the mechanism currently recommended in Schema.org to specify identifiers represented as structured objects.
[[DCAT-AP]] O Kind vcard:Kind schema:ContactPoint
[[DCAT-AP]] O Location dct:Location schema:Place
[[DCAT-AP]] O Media Type or Extent dct:MediaTypeOrExtent schema:Text | schema:URL TBD
[[DCAT-AP]] O Period of Time dct:PeriodOfTime schema:DateTime
[[DCAT-AP]] O Provenance Statement dct:ProvenanceStatement schema:CreativeWork | schema:URL TBD
[[GeoDCAT-AP]] O Quality Measurement dqv:QualityMeasurement schema:QuantitativeValue
[[DCAT-AP]] O Rights Statement dct:RightsStatement schema:CreativeWork | schema:URL TBD
[[DCAT-AP]] O Standard dct:Standard schema:CreativeWork | schema:URL TBD

Properties for mandatory classes

Agent

These properties should be used with schema:Organization or schema:Person (formal definition in ).

DCAT-AP Schema.org Comments
Specification Obl. Label QName
[[DCAT-AP]] M name foaf:name schema:name
[[DCAT-AP]] R type dct:type schema:?? TBD
[[GeoDCAT-AP]] O address locn:address schema:address See .
[[GeoDCAT-AP]] O affiliation org:memberOf schema:memberOf
[[GeoDCAT-AP]] O email foaf:mbox schema:email
[[GeoDCAT-AP]] O homepage foaf:workplaceHomepage schema:url
[[GeoDCAT-AP]] O phone foaf:phone schema:telephone

Catalogue

These properties should be used with schema:DataCatalog (formal definition in ).

DCAT-AP Schema.org Comments
Specification Obl. Label QName
[[DCAT-AP]] M dataset dcat:dataset schema:dataset
[[DCAT-AP]] M description dct:description schema:description
[[DCAT-AP]] M publisher dct:publisher schema:publisher
[[DCAT-AP]] M title dct:title schema:name
[[DCAT-AP]] R homepage foaf:homepage schema:url
[[DCAT-AP]] R language dct:language schema:inLanguage
[[DCAT-AP]] R licence dct:license schema:license
[[DCAT-AP]] R release date dct:issued schema:datePublished
[[DCAT-AP]] R spatial / geographic coverage dct:spatial schema:spatialCoverage
[[DCAT-AP]] R themes dcat:themeTaxonomy schema:?? TBD
[[DCAT-AP]] R update / modification date dct:modified schema:dateModified
[[GeoDCAT-AP]] O access rights dct:accessRights schema:?? TBD
[[DCAT-AP]] O catalogue dcat:catalog schema:hasPart
[[GeoDCAT-AP]] O conformance result / conformity (data quality) dct:conformsTo schema:?? TBD
[[GeoDCAT-AP]] O contact point dcat:contactPoint schema:contactPoint
[[GeoDCAT-AP]] O creation date dct:created schema:dateCreated
[[DCAT-AP]] O creator dct:creator schema:creator
[[DCAT-AP]] O has part dct:hasPart schema:hasPart
[[GeoDCAT-AP]] O identifier dct:identifier schema:identifier
[[DCAT-AP]] O is part of dct:isPartOf schema:isPartOf
[[GeoDCAT-AP]] O keyword dcat:keyword schema:keywords
[[DCAT-AP]] O record dcat:record schema:itemListElement
[[GeoDCAT-AP]] O reference system dct:conformsTo schema:?? TBD
[[DCAT-AP]] O rights dct:rights schema:?? TBD
[[GeoDCAT-AP]] O rights holder dct:rightsHolder schema:copyrightHolder
[[DCAT-AP]] O service dcat:service schema:hasPart
[[GeoDCAT-AP]] O temporal coverage dct:temporal schema:temporalCoverage
[[GeoDCAT-AP]] O theme / category dcat:theme schema:about
[[GeoDCAT-AP]] O topic category dct:subject schema:about
[[GeoDCAT-AP]] O custodian geodcat:custodian schema:?? TBD
[[GeoDCAT-AP]] O distributor geodcat:distributor schema:?? TBD
[[GeoDCAT-AP]] O originator geodcat:originator schema:?? TBD
[[GeoDCAT-AP]] O principal investigator geodcat:principalInvestigator schema:?? TBD
[[GeoDCAT-AP]] O processor geodcat:processor schema:?? TBD
[[GeoDCAT-AP]] O resource provider geodcat:resourceProvider schema:provider
[[GeoDCAT-AP]] O user geodcat:user schema:?? TBD

Dataset

These properties should be used with schema:Dataset (formal definition in ).

DCAT-AP Schema.org Comments
Specification Obl. Label QName
[[DCAT-AP]] M description dct:description schema:description
[[DCAT-AP]] M title dct:title schema:name
[[DCAT-AP]] R contact point dcat:contactPoint schema:contactPoint
[[DCAT-AP]] R dataset distribution dcat:distribution schema:distribution
[[DCAT-AP]] R keyword dcat:keyword schema:keywords
[[DCAT-AP]] R publisher dct:publisher schema:publisher
[[DCAT-AP]] R spatial / geographic coverage dct:spatial schema:spatialCoverage
[[DCAT-AP]] R temporal coverage dct:temporal schema:temporalCoverage
[[DCAT-AP]] R theme / category dcat:theme schema:about
[[DCAT-AP]] O access rights dct:accessRights schema:?? TBD
[[StatDCAT-AP]] O attribute stat:attribute schema:?? TBD
[[GeoDCAT-AP]] O conformance result / conformity (data quality) dct:conformsTo schema:?? TBD
[[DCAT-AP]] O conforms to dct:conformsTo schema:?? TBD
[[GeoDCAT-AP]] O creation date dct:created schema:dateCreated
[[DCAT-AP]] O creator dct:creator schema:creator
[[StatDCAT-AP]] O dimension stat:dimension schema:?? TBD
[[DCAT-AP]] O documentation foaf:page schema:mainEntityOfPage
[[DCAT-AP]] O frequency dct:accrualPeriodicity schema:?? TBD
[[DCAT-AP]] O has version dct:hasVersion schema:?? TBD
[[DCAT-AP]] O identifier dct:identifier schema:identifier
[[DCAT-AP]] O is referenced by dct:isReferencedBy schema:citation
[[DCAT-AP]] O is version of dct:isVersionOf schema:?? TBD
[[DCAT-AP]] O landing page dcat:landingPage schema:url
[[DCAT-AP]] O language dct:language schema:inLanguage
[[StatDCAT-AP]] O number of data series stat:numSeries schema:?? TBD
[[DCAT-AP]] O other identifier adms:identifier schema:identifier Schema.org does not currently provide a way to denote "other" identifiers.
[[DCAT-AP]] O provenance dct:provenance schema:?? TBD
[[StatDCAT-AP]] O quality annotation dqv:hasQualityAnnotation schema:review
[[GeoDCAT-AP]] O reference system dct:conformsTo schema:?? TBD
[[DCAT-AP]] O related resource dct:relation schema:mentions
[[DCAT-AP]] O release date dct:issued schema:datePublished
[[GeoDCAT-AP]] O rights holder dct:rightsHolder schema:copyrightHolder
[[DCAT-AP]] O sample adms:sample schema:?? TBD
[[DCAT-AP]] O source dct:source schema:isBasedOn
[[GeoDCAT-AP]] O spatial resolution dqv:hasQualityMeasurement schema:?? TBD
[[DCAT-AP]] O spatial resolution in metres dcat:spatialResolutionInMeters schema:?? TBD
[[GeoDCAT-AP]] O spatial resolution as text rdfs:comment schema:?? TBD
[[DCAT-AP]] O temporal resolution dcat:temporalResolution schema:?? TBD
[[GeoDCAT-AP]] O topic category dct:subject schema:about
[[DCAT-AP]] O type dct:type schema:?? TBD
[[StatDCAT-AP]] O unit of measurement stat:statUnitMeasure schema:?? TBD
[[DCAT-AP]] O update / modification date dct:modified schema:dateModified
[[DCAT-AP]] O version owl:versionInfo schema:version
[[DCAT-AP]] O version notes adms:versionNotes schema:?? TBD
[[GeoDCAT-AP]] O custodian geodcat:custodian schema:?? TBD
[[GeoDCAT-AP]] O distributor geodcat:distributor schema:?? TBD
[[GeoDCAT-AP]] O originator geodcat:originator schema:?? TBD
[[GeoDCAT-AP]] O principal investigator geodcat:principalInvestigator schema:?? TBD
[[GeoDCAT-AP]] O processor geodcat:processor schema:?? TBD
[[GeoDCAT-AP]] O resource provider geodcat:resourceProvider schema:provider
[[GeoDCAT-AP]] O user geodcat:user schema:?? TBD

Properties for optional classes

Address

These properties should be used with schema:PostalAddress (formal definition in ).

In the table, [[LOCN]] properties are used to specify the address of an Agent, via property locn:address, whereas [[VCARD-RDF]] properties are used to specify the address of a Kind, via property vcard:hasAddress. Their domains are, respectively, locn:Address and vcard:Address.

DCAT-AP Schema.org Comments
Specification Obl. Label QName
[[GeoDCAT-AP]] R administrative area locn:adminUnitL2 schema:addressRegion
[[GeoDCAT-AP]] R vcard:region
[[GeoDCAT-AP]] R city locn:postName schema:addressLocality
[[GeoDCAT-AP]] R vcard:locality
[[GeoDCAT-AP]] R country locn:adminUnitL1 schema:addressCountry
[[GeoDCAT-AP]] R vcard:country-name
[[GeoDCAT-AP]] R postal code locn:postCode schema:postalCode
[[GeoDCAT-AP]] R vcard:postal-code
[[GeoDCAT-AP]] R street address locn:thoroughfare schema:streetAddress
[[GeoDCAT-AP]] R vcard:street-address

Catalogue record

These properties should be used with schema:ListItem (formal definition in ).

DCAT-AP Schema.org Comments
Specification Obl. Label QName
[[DCAT-AP]] M primary topic foaf:primaryTopic schema:item
[[DCAT-AP]] M update / modification date dct:modified schema:dateModified
[[DCAT-AP]] R application profile dct:conformsTo schema:?? TBD
[[DCAT-AP]] R change type adms:status schema:?? TBD
[[DCAT-AP]] R listing date dct:issued schema:datePublished
[[GeoDCAT-AP]] O character encoding cnt:characterEncoding schema:?? TBD
[[GeoDCAT-AP]] O contact point dcat:contactPoint schema:contactPoint
[[GeoDCAT-AP]] O creation date dct:created schema:dateCreated
[[GeoDCAT-AP]] O creator dct:creator schema:creator
[[DCAT-AP]] O description dct:description schema:description
[[GeoDCAT-AP]] O identifier dct:identifier schema:identifier
[[DCAT-AP]] O language dct:language schema:inLanguage
[[GeoDCAT-AP]] O publisher dct:publisher schema:publisher
[[GeoDCAT-AP]] O rights holder dct:rightsHolder schema:copyrightHolder
[[DCAT-AP]] O source metadata dct:source schema:isBasedOn
[[DCAT-AP]] O title dct:title schema:name
[[GeoDCAT-AP]] O custodian geodcat:custodian schema:?? TBD
[[GeoDCAT-AP]] O distributor geodcat:distributor schema:?? TBD
[[GeoDCAT-AP]] O originator geodcat:originator schema:?? TBD
[[GeoDCAT-AP]] O principal investigator geodcat:principalInvestigator schema:?? TBD
[[GeoDCAT-AP]] O processor geodcat:processor schema:?? TBD
[[GeoDCAT-AP]] O resource provider geodcat:resourceProvider schema:provider
[[GeoDCAT-AP]] O user geodcat:user schema:?? TBD

Checksum

TBD (formal definition in ).

DCAT-AP Schema.org Comments
Specification Obl. Label QName
[[DCAT-AP]] M algorithm spdx:algorithm schema:?? TBD
[[DCAT-AP]] M checksum value spdx:checksumValue schema:?? TBD

Data Service

These properties should be used with schema:Service (formal definition in ).

DCAT-AP Schema.org Comments
Specification Obl. Label QName
[[DCAT-AP]] M endpoint URL dcat:endpointURL schema:url
[[DCAT-AP]] M title dct:title schema:name
[[DCAT-AP]] R endpoint description dcat:endpointDescription schema:mainEntityOfPage
[[DCAT-AP]] R serves dataset dcat:servesDataset schema:serviceOutput
[[DCAT-AP]] O access rights dct:accessRights schema:?? TBD
[[GeoDCAT-AP]] O conformance result / conformity (data quality) dct:conformsTo schema:?? TBD
[[GeoDCAT-AP]] O conforms to dct:conformsTo schema:?? TBD
[[GeoDCAT-AP]] O contact point dcat:contactPoint schema:contactPoint
[[GeoDCAT-AP]] O creation date dct:created schema:dateCreated
[[GeoDCAT-AP]] O creator dct:creator schema:creator
[[DCAT-AP]] O description dct:description schema:description
[[GeoDCAT-AP]] O identifier dct:identifier schema:identifier
[[GeoDCAT-AP]] O keyword (free text) dcat:keyword schema:keywords
[[GeoDCAT-AP]] O keyword (from a controlled vocabulary) dcat:theme schema:about
[[GeoDCAT-AP]] O language dct:language schema:inLanguage
[[DCAT-AP]] O licence dct:license schema:license
[[GeoDCAT-AP]] O publisher dct:publisher schema:publisher
[[GeoDCAT-AP]] O release date dct:issued schema:datePublished
[[GeoDCAT-AP]] O rights holder dct:rightsHolder schema:copyrightHolder
[[GeoDCAT-AP]] O spatial / geographic coverage dct:spatial schema:spatialCoverage
[[GeoDCAT-AP]] O spatial data service category dct:type schema:?? TBD
[[GeoDCAT-AP]] O spatial data service type dct:type schema:?? TBD
[[GeoDCAT-AP]] O spatial resolution dqv:hasQualityMeasurement schema:?? TBD
[[GeoDCAT-AP]] O spatial resolution in metres dcat:spatialResolutionInMeters schema:?? TBD
[[GeoDCAT-AP]] O spatial resolution as text rdfs:comment schema:?? TBD
[[GeoDCAT-AP]] O temporal coverage dct:temporal schema:temporalCoverage
[[GeoDCAT-AP]] O temporal resolution dcat:temporalResolution schema:?? TBD
[[GeoDCAT-AP]] O topic category dct:subject schema:about
[[GeoDCAT-AP]] O type dct:type schema:?? TBD
[[GeoDCAT-AP]] O update / modification date dct:modified schema:dateModified
[[GeoDCAT-AP]] O custodian geodcat:custodian schema:?? TBD
[[GeoDCAT-AP]] O distributor geodcat:distributor schema:?? TBD
[[GeoDCAT-AP]] O originator geodcat:originator schema:?? TBD
[[GeoDCAT-AP]] O principal investigator geodcat:principalInvestigator schema:?? TBD
[[GeoDCAT-AP]] O processor geodcat:processor schema:?? TBD
[[GeoDCAT-AP]] O resource provider geodcat:resourceProvider schema:provider
[[GeoDCAT-AP]] O user geodcat:user schema:?? TBD

Document

TBD (formal definition in ).

DCAT-AP Schema.org Comments
Specification Obl. Label QName
[[GeoDCAT-AP]] R description dct:description schema:description
[[GeoDCAT-AP]] R title dct:title schema:name

Identifier

These properties should be used with schema:PropertyValue (formal definition in ).

DCAT-AP Schema.org Comments
Specification Obl. Label QName
[[DCAT-AP]] M notation skos:notation schema:value The actual identifier string
[[DCAT-AP]] O notation skos:notation/@rdf:datatype schema:propertyID The type of identifier

Kind

These properties should be used with schema:ContactPoint (formal definition in ).

DCAT-AP Schema.org Comments
Specification Obl. Label QName
[[GeoDCAT-AP]] R name vcard:fn schema:name
[[DCAT-AP-IG]] R
[[GeoDCAT-AP]] R email vcard:hasEmail schema:email
[[DCAT-AP-IG]] R
[[GeoDCAT-AP]] R homepage vcard:hasURL schema:url
[[DCAT-AP-IG]] O
[[GeoDCAT-AP]] O address vcard:hasAddress schema:address See .
[[GeoDCAT-AP]] O affiliation vcard:organization-name schema:memberOf / schema:name
[[GeoDCAT-AP]] O telephone vcard:hasTelephone schema:telephone
[[DCAT-AP-IG]] O

Location

These properties should be used with schema:Place (formal definition in ).

DCAT-AP Schema.org Comments
Specification Obl. Label QName
[[DCAT-AP]] R bounding box dcat:bbox schema:box

Schema.org expects bounding boxes to be specified with a literal, consisting of two points (corresponding to the lower corner and the upper corner, respectively).

[[VOCAB-DCAT]] allows any type of geometry encoding.

As a consequence, the dcat:bbox mapping might require further processing to encode the geometry according to the Schema.org format.
[[DCAT-AP]] R centroid dcat:centroid schema:latitude + schema:longitude + schema:elevation

Schema.org expects point coordinates to be specified with distinct properties (latitude, longitude, and elevation).

[[VOCAB-DCAT]] uses instead a single property, and supports any type of geometry encoding.

As a consequence, the dcat:centroid mapping might require further processing to encode the geometry according to the Schema.org format.
[[GeoDCAT-AP]] O geographical identifier dct:identifier schema:identifier
[[GeoDCAT-AP]] O geographical identifier / name authority skos:inScheme schema:?? TBD. The "authority" denotes the reference register for the geographical name / identifier (typically, a gazetteer).
[[GeoDCAT-AP]] O geographical name skos:prefLabel schema:name
[[DCAT-AP]] O geometry locn:geometry schema:geo

Schema.org expects as value an instance of schema:GeoCoordinates (for points) or schema:GeoShape (for more complex geometries).

LOCN allows any type of geometry, and any type of geometry encoding / representation—including those supported by Schema.org.

As a consequence, the locn:geometry mapping might require further processing to encode the geometry according the encodings supported in Schema.org.

Media type or extent

TBD (formal definition in ).

DCAT-AP Schema.org Comments
Specification Obl. Label QName
[[GeoDCAT-AP]] R label rdfs:label schema:name

Period of time

These properties should be used with schema:DateTime (formal definition in ).

DCAT-AP Schema.org Comments
Specification Obl. Label QName
[[DCAT-AP]] R start date / time dcat:startDate schema:startDate
[[DCAT-AP]] R end date / time dcat:endDate schema:endDate
[[DCAT-AP]] O has beginning time:hasBeginning schema:startDate
[[DCAT-AP]] O has end time:hasEnd schema:endDate

Provenance statement

TBD (formal definition in ).

DCAT-AP Schema.org Comments
Specification Obl. Label QName
[[GeoDCAT-AP]] R name / description rdfs:label schema:?? TBD

Quality measurement

These properties should be used with schema:QuantitativeValue (formal definition in ).

DCAT-AP Schema.org Comments
Specification Obl. Label QName
[[GeoDCAT-AP]] R is measurement of dqv:isMeasurementOf schema:valueReference
[[GeoDCAT-AP]] R unit of measure sdmx-attribute:unitMeasure schema:unitCode
[[GeoDCAT-AP]] R is measurement of dqv:value schema:value

Rights statement

TBD (formal definition in ).

DCAT-AP Schema.org Comments
Specification Obl. Label QName
[[GeoDCAT-AP]] R name / description rdfs:label schema:?? TBD

Standard

TBD (formal definition in ).

DCAT-AP Schema.org Comments
Specification Obl. Label QName
[[GeoDCAT-AP]] R description dct:description schema:description
[[GeoDCAT-AP]] R identifier dct:identifier schema:identifier
[[GeoDCAT-AP]] R reference register skos:inScheme schema:?? TBD
[[GeoDCAT-AP]] R release date dct:issued schema:datePublished
[[GeoDCAT-AP]] R title dct:title schema:name
[[GeoDCAT-AP]] R type dct:type schema:?? TBD
[[GeoDCAT-AP]] R version owl:versionInfo schema:version
[[GeoDCAT-AP]] O creation date dct:created schema:dateCreated
[[GeoDCAT-AP]] O update / modification date dct:modified schema:dateModified

SPARQL implementation

This section illustrates a tentative implementation of the mappings defined in DCAT-AP-SDO, in the form of SPARQL CONSTRUCT queries.

The mappings have been defined in a modular way, with a separate SPARQL query for each of the DCAT-AP classes, and related properties. A complete representation of a given resource (e.g., a dataset) and related resource (e.g., distribution, licence, publisher) can be obtained by combining the relevant SPARQL queries.

The source SPARQL queries are maintained in the dedicated GitHub repository.

Agent

For the corresponding mapping table, see .










Catalogue



For the corresponding mapping table, see .












Dataset



For the corresponding mapping table, see .












Category



For the corresponding mapping table, see .













Category scheme



For the corresponding mapping table, see .












Distribution



For the corresponding mapping table, see .












Licence document



For the corresponding mapping table, see .












Address



For the corresponding mapping table, see .






Address (Agent)












Address (Kind)















Catalogue record



For the corresponding mapping table, see .












Checksum



For the corresponding mapping table, see .












Data Service



For the corresponding mapping table, see .












Document



For the corresponding mapping table, see .












Identifier



For the corresponding mapping table, see .












Kind



For the corresponding mapping table, see .












Location



For the corresponding mapping table, see .














Media type of extent



For the corresponding mapping table, see .












Period of time



For the corresponding mapping table, see .












Provenance statement



For the corresponding mapping table, see .












Quality measurement



For the corresponding mapping table, see .














Rights statement



For the corresponding mapping table, see .















Standard



For the corresponding mapping table, see .