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Merge pull request #295 from w3c/dcat-dataset-relations-simon
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Dataset -> resource/file relations
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@davebrowning
davebrowning committed Jul 26, 2018
2 parents 7ab290f + 3dd002c commit a8017b3
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161 changes: 139 additions & 22 deletions dcat/index.html
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Expand Up @@ -309,6 +309,68 @@ <h3>A dataset available as a download and behind some Web page</h3>
does not have to be defined as a separate dcat:Distribution instance.
</section>

<section id="bag-of-files">
<h3>Loosely structured catalog</h3>
<p>
In many legacy catalogues and repositories (e.g. CKAN), ‘datasets’ are ‘just a bag of files’. There is no distinction made between part/whole, distribution (representation), and other kinds of relationship (e.g. documentation, schema, supporting documents) from the dataset to each of the files.
</p>
<p>
If the nature of the relationships between a dataset and component resources in a catalogue, repository, or elsewhere are not known, <b>dct:relation</b> can be used:
</p>
<pre>
:d33937
dct:description "A set of RDF graphs representing the International [Chrono]stratigraphic Chart, ..." ;
dct:identifier "https://doi.org/10.25919/5b4d2b83cbf2d"^^xsd:anyURI ;
dct:relation <https://vocabs.ands.org.au/viewById/196> ;
dct:relation :ChronostratChart2017-02.pdf ;
dct:relation :ChronostratChart2017-02.jpg ;
dct:relation :timescale.zip ;
dct:relation :isc2017.jsonld ;
dct:relation :isc2017.nt ;
dct:relation :isc2017.rdf ;
dct:relation :isc2017.ttl ;
.
</pre>
<p>
If it is clear that any of these related resources is a proper <i>representation</i> of the dataset, dcat:distribution should be used.
</p>
<pre>
:d33937
rdf:type dcat:Dataset ;
dct:description "A set of RDF graphs representing the International [Chrono]stratigraphic Chart, ..." ;
dct:identifier "https://doi.org/10.25919/5b4d2b83cbf2d"^^xsd:anyURI ;
dct:relation <https://vocabs.ands.org.au/viewById/196> ;
dct:relation :ChronostratChart2017-02.pdf ;
dct:relation :ChronostratChart2017-02.jpg ;
dct:relation :timescale.zip ;
dcat:distribution [
rdf:type dcat:Distribution ;
dcat:downloadURL :isc2017.jsonld ;
dcat:byteSize "698039"^^xsd:decimal ;
dcat:mediaType <https://www.iana.org/assignments/media-types/application/ld+json> ;
] ;
dcat:distribution [
rdf:type dcat:Distribution ;
dcat:downloadURL :isc2017.nt ;
dcat:byteSize "2047874"^^xsd:decimal ;
dcat:mediaType <https://www.iana.org/assignments/media-types/application/n-triples> ;
] ;
dcat:distribution [
rdf:type dcat:Distribution ;
dcat:downloadURL :isc2017.rdf ;
dcat:byteSize "1600569"^^xsd:decimal ;
dcat:mediaType <https://www.iana.org/assignments/media-types/application/rdf+xml> ;
] ;
dcat:distribution [
rdf:type dcat:Distribution ;
dcat:downloadURL :isc2017.ttl ;
dcat:byteSize "531703"^^xsd:decimal ;
dcat:mediaType <https://www.iana.org/assignments/media-types/text/turtle> ;
] ;
.
</pre>
</section>

<section id="more-examples-needed">
<h3>More examples needed</h3>
<p class="note">
Expand Down Expand Up @@ -874,13 +936,10 @@ <h4>Property: access rights</h4>
<section id="class-dataset">
<h3>Class: Dataset</h3>
<p>In addition to the properties inherited from the super-class <a href="http://www.w3.org/ns/dcat#Resource">dcat:Resource</a>, the following properties are recommended for use on this class:
<a href="#Property:dataset_distribution">distribution</a>,
<!--
<a href="#Property:dataset_hasDatasetPart">hasDatasetPart</a>,
-->
<a href="#Property:dataset_frequency">frequency</a>,
<a href="#Property:dataset_spatial">spatial coverage</a>,
<a href="#Property:dataset_temporal">temporal coverage</a>,
<a href="#Property:dataset_distribution">distribution</a>,
<a href="#Property:dataset_frequency">frequency</a>,
<a href="#Property:dataset_spatial">spatial coverage</a>,
<a href="#Property:dataset_temporal">temporal coverage</a>
</p>

<p>
Expand Down Expand Up @@ -916,6 +975,10 @@ <h3>Class: Dataset</h3>
The need to be able to provide usage notes for a dataset or distribution has been identified as a requirement to be satisfied in the revision of DCAT.
</p>

<p class="issue" data-number="253">
The need to recommend a method for linking from a dataset to various kinds of resources to complement <i>Distributions</i> has been proposed as a requirement to be satisfied in this revision of DCAT.
</p>

<table class="definition">
<thead><tr><th>RDF Class:</th><th><a href="http://www.w3.org/ns/dcat#Dataset">dcat:Dataset</a></th></tr></thead>
<tbody>
Expand All @@ -937,29 +1000,36 @@ <h4>Property: dataset distribution</h4>
<thead><tr><th>RDF Property:</th><th><a href="http://www.w3.org/ns/dcat#distribution">dcat:distribution</a></th></tr></thead>
<tbody>
<tr><td class="prop">Definition:</td><td>Connects a dataset to its available distributions.</td></tr>
<tr><td class="prop">Sub property of:</td><td><a href="http://purl.org/dc/terms/relation">dct:relation</a></td></tr>
<tr><td class="prop">Domain:</td><td><a href="http://www.w3.org/ns/dcat#Dataset">dcat:Dataset</a></td></tr>
<tr><td class="prop">Range:</td><td><a href="http://www.w3.org/ns/dcat#Distribution">dcat:Distribution</a></td></tr>
</tbody>
</table>
</section>

<!--
<section id="Property:dataset_hasDatasetPart">
<h4>Property: has dataset part</h4>
<p class="note">
Property added in this revision of DCAT.
<p class="issue">
<a href="https://github.com/w3c/dxwg/issues/81">Issue #81</a> concerns the general need to describe relationships between datasets.
Guidance on the use of specializations of dct:relation is required in the context of dcat:Dataset.
</p>

<!--
<section id="Property:dataset_part">
<h4>Property: dataset part</h4>
<table class="definition">
<thead><tr><th>RDF Property:</th><th><a href="http://www.w3.org/ns/dcat#hasDatasetPart">dcat:hasDatasetPart</a></th></tr></thead>
<thead><tr><th>RDF Property:</th><th><a href="http://purl.org/dc/terms/hasPart">dct:hasPart</a></th></tr></thead>
<tbody>
<tr><td class="prop">Definition:</td><td>Link to a dataset which is a part of this one</td></tr>
<tr><td class="prop">Sub property of:</td><td><a href="http://purl.org/dc/terms/hasPart">dct:hasPart</a></td></tr>
<tr><td class="prop">Domain:</td><td><a href="http://www.w3.org/ns/dcat#Dataset">dcat:Dataset</a></td></tr>
<tr><td class="prop">Range:</td><td><a href="http://www.w3.org/ns/dcat#Dataset">dcat:Dataset</a></td></tr>
<tr><td class="prop">Definition:</td><td>A related resource that is a component of the described resource.</td></tr>
<tr><td class="prop">Sub property of:</td><td><a href="http://purl.org/dc/terms/relation">dct:relation</a></td></tr>
<tr><td class="prop">Range:</td><td><a href="http://www.w3.org/ns/dcat#Dataset">dcat:Dataset</a></td></tr>
<tr><td class="prop">Usage note:</td><td><a href="http://purl.org/dc/terms/hasPart">dct:hasPart</a> may be used for general whole-to-part relationships to other resources. The component may be a formal <a href="http://www.w3.org/ns/dcat#Dataset">dcat:Dataset</a> that is managed and catalogued in its own right, or may just be a resource (implicitly a dataset) that is packaged as part of a formal dataset in a catalog. </td></tr>
</tbody>
</table>
<p class="note">
Use of this Dublin Core Terms property in this context added in this revision of DCAT.
</p>
</section>
-->

Expand Down Expand Up @@ -1325,6 +1395,7 @@ <h3>Class: Catalogued resource</h3>
<a href="#Property:resource_keyword">keyword</a>,
<a href="#Property:resource_landingpage">landing page</a>,
<a href="#Property:resource_language">language</a>,
<a href="#Property:resource_relation">relation</a>,
<a href="#Property:resource_publisher">publisher</a>,
<a href="#Property:resource_release_date">release date</a>,
<a href="#Property:resource_theme">theme</a>,
Expand All @@ -1349,10 +1420,6 @@ <h3>Class: Catalogued resource</h3>
The need to be able to link a catalogued resource with the business or project context of its production has been identified as a requirement to be satisfied in the revision of DCAT.
</p>

<p class="issue" data-number="81">
The need describe relationships between catalogued resources has been identified as a requirement to be satisfied in the revision of DCAT.
</p>

<table class="definition">
<thead><tr><th>RDF Class:</th><th><a href="http://www.w3.org/ns/dcat#Resource">dcat:Resource</a></th></tr></thead>
<tbody>
Expand Down Expand Up @@ -1546,6 +1613,50 @@ <h4>Property: type/genre</h4>
</table>
</section>

<section id="Property:resource_relation">
<h4>Property: resource relation</h4>

<table class="definition">
<thead><tr><th>RDF Property:</th><th><a href="http://purl.org/dc/terms/relation">dct:relation</a></th></tr></thead>
<tbody>
<tr><td class="prop">Definition:</td><td>Connects a catalogued item to other resources related to it.</td></tr>
<tr><td class="prop">Usage note:</td><td><a href="http://purl.org/dc/terms/relation">dct:relation</a> <em title="SHOULD" class="rfc2119">SHOULD</em> be used where the nature of the relationship between a catalogued item and related resources is not known. A more specific sub-property <em title="SHOULD" class="rfc2119">SHOULD</em> be used if the nature of the relationship of the link is known.
The property <a href="http://www.w3.org/ns/dcat#distribution">dcat:distribution</a> <em title="SHOULD" class="rfc2119">SHOULD</em> be used to link from a <a href="http://www.w3.org/ns/dcat#Dataset">dcat:Dataset</a> to a representation of the dataset, described as a <a href="http://www.w3.org/ns/dcat#Distribution">dcat:Distribution</a></td></tr>
<tr><td class="prop">See also:</td><td>sub-properties of dct:relation in particular
<a href="http://www.w3.org/ns/dcat#distribution">dcat:distribution</a>,
<a href="http://purl.org/dc/terms/hasPart">dct:hasPart</a>,
<a href="http://purl.org/dc/terms/isPartOf">dct:isPartOf</a>,
<a href="http://purl.org/dc/terms/conformsTo">dct:conformsTo</a>,
<a href="http://purl.org/dc/terms/isFormatOf">dct:isFormatOf</a>,
<a href="http://purl.org/dc/terms/hasFormat">dct:hasFormat</a>,
<a href="http://purl.org/dc/terms/isVersionOf">dct:isVersionOf</a>,
<a href="http://purl.org/dc/terms/hasVersion">dct:hasVersion</a>,
<a href="http://purl.org/dc/terms/replaces">dct:replaces</a>,
<a href="http://purl.org/dc/terms/isReplacedBy">dct:isReplacedBy</a>,
<a href="http://purl.org/dc/terms/references">dct:references</a>,
<a href="http://purl.org/dc/terms/isReferencedBy">dct:isReferencedBy</a>,
<a href="http://purl.org/dc/terms/requires">dct:requires</a></td>,
<a href="http://purl.org/dc/terms/isRequiredBy">dct:isRequiredBy</a></td>
</tr>
</tbody>
</table>

<p>
Many existing and legacy catalogues do not distinguish between dataset components, representations, documentation, schemata and other resources that are lumped together as part of a dataset.
<a href="http://purl.org/dc/terms/relation">dct:relation</a> is a super-property of a number of more specific properties which express more precise relationships, so use of dct:relation is not inconsistent with a subsequent reclassification with more specific semantics, though the more specialized sub-properties <em title="SHOULD" class="rfc2119">SHOULD</em> be used to link a dataset to component and supplementary resources if possible.
</p>

<p class="issue" data-number="81">
The general need to describe relationships between datasets has been identified as a requirement to be satisfied in the revision of DCAT.
Guidance on the use of more specific relationship predicates is required, particularly in the context of dcat:Dataset sub-class.
</p>

<p class="note">
Use of this Dublin Core Terms property in this context added in this revision of DCAT.
</p>

</section>

<section id="Property:resource_conformsto">
<h4>Property: conforms to</h4>
<table class="definition">
Expand Down Expand Up @@ -2086,6 +2197,12 @@ <h3>Changes since the W3C Recommendation of 16 January 2014</h3>
<p>The document has undergone the following changes since the W3C Recommendation of 16 January 2014 [[VOCAB-DCAT-20140116]]:</p>

<ul>

<li>
<a href="#Property:resource_relation">Property: resource relation</a>: The property dct:relation is recommended for use in the context of a catalogued resource to capture general relationships, including the case where the package of resources associated with a catalogued item includes a mixture of representations, parts, documentation and other elements which are not strictly 'distributions' of a dataset - see <a href="https://github.com/w3c/dxwg/issues/253">Issue #253</a>.
</li>


<li>
<a href="#Property:distribution_media_type"></a>: The range of dcat:mediaType has been tightened from dct:MediaTypeOrExtent to dct:MediaType - see <a href="https://github.com/w3c/dxwg/issues/127">Issue #127</a>.
</li>
Expand Down
6 changes: 6 additions & 0 deletions dcat/rdf/dcat.ttl
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Expand Up @@ -233,6 +233,11 @@ dcat:DataDistributionService
rdf:type owl:Class ;
rdfs:comment "A site or end-point that provides access to datasets through distributions of the datasets" ;
rdfs:label "Data distribution service" ;
rdfs:subClassOf [
rdf:type owl:Restriction ;
owl:hasValue <https://inspire.ec.europa.eu/metadata-codelist/SpatialDataServiceType/download> ;
owl:onProperty dct:type ;
] ;
rdfs:subClassOf dcat:DataService ;
skos:changeNote "New class in this revision of DCAT" ;
skos:editorialNote "Status: Class accepted by DCAT revision team, but details of definition and constraints not yet resolved." ;
Expand Down Expand Up @@ -538,6 +543,7 @@ dcat:distribution
rdfs:label "データセット配信"@ja ;
rdfs:label "distribuce"@cs ;
rdfs:range dcat:Distribution ;
rdfs:subPropertyOf dct:relation ;
.
dcat:downloadURL
rdf:type rdf:Property ;
Expand Down

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