Data Catalog Vocabulary (dcat) | DERI Vocabularies

Data Catalog Vocabulary (dcat)

Authors:

Richard Cyganiak (Digital Enterprise Research Institute, NUI Galway) (Email)

Fadi Maali (DERI, NUI Galway) (Email)

Last update:

03 May 2012

Namespace URI:

http://www.w3.org/ns/dcat#

Abstract

Work on DCAT has moved to W3C. This document is now deprecated in favour of the W3C version.

This document defines an RDF vocabulary for the exchange of data catalogs. Its primary purpose is the expression of government data catalogs, such as data.gov or data.gov.uk, in RDF. It is being produced by the W3C eGovernment Interest Group. This is an early draft. We welcome feedback and discussion.

All terms at a glance

Classes: Catalog | CatalogRecord | Dataset | Distribution | Download | Feed | WebService

Properties: accessURL | bytes | dataDictionary | dataQuality | dataset | distribution | granularity | keyword | record | size | theme | themeTaxonomy

Overview diagram

Recent changes:

remove downloadURL property (has Distribution as its domain)
add Download class as subclass of Distribution
change the domain of accessURL from Dataset to Distribution

Questions:

should there be a relation between dcat:bytes and dcat:size? dcat:keyword and dcat:theme?
should the domain of dcat:size be defined as dcat:Dataset or left undefined?
Do we need to define a maintainer property (reuse from doap)?
FOAF also has theme property but marked as archaic

Classes

Class: dcat:Catalog

Catalog – A collection of datasets

URI:: http://www.w3.org/ns/dcat#Catalog
Properties include:: dcat:themeTaxonomy, dcat:dataset, dcat:record

Class: dcat:CatalogRecord

Catalog Record – Represents a description of a single dataset in the catalog

URI:: http://www.w3.org/ns/dcat#CatalogRecord
Used with:: dcat:record

Catalog Record represents a dataset in the context of a specific catalog and allows a catalog to provide details (e.g. quality, dates) regarding its description of the dataset. As the same dataset might be listed in different catalogs, each catalog will have its description regarding the dataset. Agents might utilize Catalog Record(s) to choose a specific catalog description of a dataset when multiple are available. E.g. choose the more recently updated record.

Class: dcat:Dataset

Dataset – A published collection of data

URI:: http://www.w3.org/ns/dcat#Dataset
Properties include:: dcat:distribution, dcat:dataQuality, dcat:dataDictionary, dcat:granularity
Used with:: dcat:dataset
Superclass:: dctype:Dataset

Class: dcat:Distribution

Distribution – Represents a specific available form of a dataset. Each dataset might be available in different forms, these forms might represent different formats of the dataset, different endpoints,... Examples of Distribution include a downloadable CSV file, an XLS file representing the dataset, an RSS endpoint that enables access to the dataset.

URI:: http://www.w3.org/ns/dcat#Distribution
Properties include:: dcat:size, dcat:bytes
Used with:: dcat:distribution
Subclasses:: dcat:Feed, dcat:WebService, dcat:Download

Class: dcat:Download

Download – represents a downloadable distribution of a dataset. Use accessURL to point to the downloadable file (should be a direct download link, use Distribution if not)

URI:: http://www.w3.org/ns/dcat#Download
Superclass:: dcat:Distribution

Class: dcat:Feed

Feed – represent a feed endpoint that enables access to the data of a dataset

URI:: http://www.w3.org/ns/dcat#Feed
Superclass:: dcat:Distribution

Class: dcat:WebService

Web Service – represents a web service that enables access to the data of a dataset

URI:: http://www.w3.org/ns/dcat#WebService
Superclass:: dcat:Distribution

Properties

Property: dcat:accessURL

access URL – describes availability of a dataset. This can be a direct download link, an HTML page containing a link to the actual data, Feed, Web Service etc. the semantic is determined by its domain (Distribution, Feed, WebService, Download).

URI:: http://www.w3.org/ns/dcat#accessURL

Property: dcat:bytes

size in bytes – describe size of resource in bytes

URI:: http://www.w3.org/ns/dcat#bytes
Domain:: dcat:Distribution
Range:: xsd:integer

Property: dcat:dataDictionary

data dictionary – links a dataset to a dictionary that helps interpreting the data.

URI:: http://www.w3.org/ns/dcat#dataDictionary
Domain:: dcat:Dataset

the value can be a URL, free text or a resource

Property: dcat:dataQuality

data quality – describes the quality of data e.g. precision. This should not be used to describe the data collection characteristics, other more specialized statistical properties can be used instead.

URI:: http://www.w3.org/ns/dcat#dataQuality
Domain:: dcat:Dataset

Property: dcat:dataset

dataset – Connects a catalog to datasets it describes.

URI:: http://www.w3.org/ns/dcat#dataset
Domain:: dcat:Catalog
Range:: dcat:Dataset

Property: dcat:distribution

distribution – connects a dataset to one of its available distributions

URI:: http://www.w3.org/ns/dcat#distribution
Domain:: dcat:Dataset
Range:: dcat:Distribution

Property: dcat:granularity

granularity – Describes the level of granularity of data in a dataset. The granularity can be in time, place etc

URI:: http://www.w3.org/ns/dcat#granularity
Domain:: dcat:Dataset

Property: dcat:keyword

keyword – refers to a tag or keyword describing the dataset

URI:: http://www.w3.org/ns/dcat#keyword
Superproperty:: dct:subject

have a free text value

Property: dcat:record

record – links a catalog to its records

URI:: http://www.w3.org/ns/dcat#record
Domain:: dcat:Catalog
Range:: dcat:CatalogRecord

Property: dcat:size

size – describe data size e.g. file size

URI:: http://www.w3.org/ns/dcat#size
Domain:: dcat:Distribution
Superproperty:: dct:extent

can have a free text value, however it is recommended to be used in conjunction with dcat:bytes to describe the precise size in bytes

Property: dcat:theme

theme – links a dataset to its theme i.e to its main category. a dataset can have multiple themes.

URI:: http://www.w3.org/ns/dcat#theme
Range:: skos:Concept
Superproperty:: dct:subject

Property: dcat:themeTaxonomy

theme taxonomy – the knowledge oraganization schema describing themes of datasets within the catalog.

URI:: http://www.w3.org/ns/dcat#themeTaxonomy
Domain:: dcat:Catalog
Range:: skos:ConceptScheme