Data Catalog Vocabulary (DCAT)

4.1 Basic Example

This section is non-normative.

This example provides a quick overview of how DCAT might be used to represent a government catalog and its datasets.

First, the catalog description:

   :catalog
       a dcat:Catalog ;
       dct:title "Imaginary Catalog" ;
       rdfs:label "Imaginary Catalog" ;
       foaf:homepage <http://example.org/catalog> ;
       dct:publisher :transparency-office ;
       dct:language <http://id.loc.gov/vocabulary/iso639-1/en>  ;
       dcat:dataset :dataset-001  , :dataset-002 , :dataset-003 ; 
       .

The publisher of the catalog has the relative URI :transparency-office. Further description of the publisher can be provided as in the following example:

   :transparency-office
       a foaf:Organization ;
       rdfs:label "Transparency Office" ;
       .

The catalog lists each of its datasets via dcat:dataset property. In the example above, an example dataset was mentioned with the relative URI :dataset-001. A possible description of it using DCAT is shown below:

   :dataset-001
       a dcat:Dataset ;
       dct:title "Imaginary dataset" ;
       dcat:keyword "accountability","transparency" ,"payments" ;
       dct:issued "2011-12-05"^^xsd:date ;
       dct:modified "2011-12-05"^^xsd:date ;
       dct:publisher :finance-ministry ;
       dct:language <http://id.loc.gov/vocabulary/iso639-1/en>  ;
       dct:accrualPeriodicity <http://purl.org/linked-data/sdmx/2009/code#freq-W>  ;
       dcat:distribution :dataset-001-csv ;
       .

In order to express frequency of update in the example above, we chose to use an instance from the Content-Oriented Guidelines developed as part of the W3C Data Cube Vocabulary efforts.

The dataset distribution :dataset-001-csv can be downloaded as a 5Kb CSV file. This information is represented via an RDF resource of type dcat:Distribution.

   :dataset-001-csv
       a dcat:Distribution ;
       dcat:downloadURL <http://www.example.org/files/001.csv> ;
       dct:title "CSV distribution of imaginary dataset 001" ;
       dcat:mediaType "text/csv" ;
       dcat:byteSize "5120"^^xsd:decimal ;
       .

4.2 Classifying datasets

The catalog classifies its datasets according to a set of domains represented by the relative URI :themes. SKOS can be used to describe the domains used:

   :catalog dcat:themeTaxonomy :themes .

   :themes
       a skos:ConceptScheme ;
       skos:prefLabel "A set of domains to classify documents" ;
       .

   :dataset-001 dcat:theme :accountability  .

Notice that this dataset is classified under the domain represented by the relative URI :accountability. It is recommended to define the concept as part of the concepts scheme identified by the URI :themes that was used to describe the catalog domains. An example SKOS description:

   :accountability 
       a skos:Concept ;
       skos:inScheme :themes ;
       skos:prefLabel "Accountability" ;
       .

4.3 Describing catalog records metadata

If the catalog publisher decides to keep metadata describing its records (i.e. the records containing metadata describing the datasets), dcat:CatalogRecord can be used. For example, while :dataset-001 was issued on 2011-12-05, its description on Imaginary Catalog was added on 2011-12-11. This can be represented by DCAT as in the following:

   :catalog  dcat:record :record-001  .

   :record-001
       a dcat:CatalogRecord ;
       foaf:primaryTopic :dataset-001 ;
       dct:issued "2011-12-11"^^xsd:date ;
       .  

4.4 A dataset available only behind some Web page

:dataset-002 is available as a CSV file. However :dataset-002 can only be obtained through some Web page where the user needs to click some links, provide some information and check some boxes before accessing the data

   :dataset-002 
       a dcat:Dataset ;
       dcat:landingPage <http://example.org/dataset-002.html> ;
       dcat:distribution :dataset-002-csv ;
       .
   :dataset-002-csv 
       a dcat:Distribution ;
       dcat:accessURL <http://example.org/dataset-002.html> ;
       dcat:mediaType "text/csv" ;
       .

4.5 A dataset available as download and behind some Web page

On the other hand, :dataset-003 can be obtained through some landing page but also can be downloaded from a known URL.

   :dataset-003 
       a dcat:Dataset ;
       dcat:landingPage <http://example.org/dataset-003.html> ;
       dcat:distribution :dataset-003-csv ;
       .
   :dataset-003-csv 
       a dcat:Distribution ;
       dcat:downloadURL <http://example.org/dataset-003.csv> .
       dcat:mediaType "text/csv" ;
       .