ISO/CSDGM DCAT¶

FAQ - DCAT with ISO/CSDGM¶

This FAQ provides a method for linking to a geospatial record (ISO/CSDGM) in DCAT-US 1.1 or DCAT-US 3.0 metadata for publishing into GeoPlatform.

GeoPlatform supports the publishing of ISO 19139:2007 and Content Standard for Digital Geospatial Metadata (CSDGM) metadata records. GeoPlatform can additionally support the publishing of geospatial metadata records linked within a DCAT-US record using the Distribuition and conformsTo fields. The following examples show the process for linking to geospatial records.

For more information on the GeoPlatform’s harvesting see the Data Sources FAQ.

Geospatial Metadata Link Example¶

Data.gov Geospatial data.json examples

To link to the geospatial record add a Dataset Distribution Field and define the conformsTo field to specify the schema for the geospatial record.

GeoPlatform supported conformsTo fields:

https://www.isotc211.org/2005/gmd (for ISO 19115)
https://www.isotc211.org/2005/gmi (for ISO 19115-2)
https://standards.iso.org/iso/19115/-3/mdb/1.0 (for ISO 19115-1)
https://standards.iso.org/iso/19115/-3/mdb/2.0 (for ISO 19115-1)
https://www.fgdc.gov/schemas/metadata (for CSDGM)

In DCAT-US 3.0, conformsTo can be a Standard object instead of a URL. GeoPlatform reads the Standard’s @id, so use one of the URLs above as the @id.

In DCAT-US 1.1, the GeoPlatform harvester searches for an XML metadata file in the Distribution field. In DCAT-US 3.0, the harvester checks both the Distribution field and the metadataDistribution field. If no XML metadata file is found, the DCAT record is used as the source metadata record.

Multiple metadata records can be linked in a single DCAT file. If an ISO 19115-3 and ISO 19115 record are both linked in the DCAT file, the ISO 19115-3 record will be used. If an ISO (19115, 19115-2, or ISO 19115-3) and CSDGM record are both linked in the DCAT file, the ISO record takes precedence and will be used. If the DCAT file exclusively links to a CSDGM record, the CSDGM record will be utilized.

The conformsTo field identifies the metadata standard of the linked file. The file itself is downloaded from the downloadURL or accessURL of the same distribution. If that file is not a valid ISO or CSDGM XML file, no other distributions are checked and the DCAT record is used.

If no distribution has a supported conformsTo field with a downloadURL or accessURL, all distributions in the DCAT record are scanned in an attempt to identify an XML file.

When the DCAT record is scanned in an attempt to identify an XML file, the following preference is used:

The dcat:Distribution title and description fields will be scanned for the word ‘metadata’.
The dcat:Distribution mediaType field will be scanned for the following: ‘text/xml’, ‘application/xml’.
The dcat:Distribution format field will be scanned for the text ‘XML’.

The first XML distribution file that is found will be used as the metadata file. If that file is not a valid ISO or CSDGM XML file, no other distributions are checked and the DCAT record is used.

Best practice for creating the DCAT record includes:¶

Use the downloadURL field to point to the URL that provides a direct access link to the original source metadata file.
Include a mediaType and format (text/xml and XML, respectively).
Ensure that the DCAT record title and abstract are the same as the source metadata record.
Include the “geospatial” theme in the DCAT record so that your dataset is labeled as geospatial in Data.gov. GeoPlatform harvests all Data.gov records, so the theme is not required for GeoPlatform to find your dataset.

Example DCAT Snippet from “FINAL Critical Habitat for 135 plant and animal species” DCAT-US record.¶

Link to example DCAT-US record in Data.gov that points to an ISO geospatial metadata record.

{
    "@type": "dcat:Distribution",
    "conformsTo": "http://www.isotc211.org/2005/gmi",
    "description": "The metadata original source", "downloadURL": "https://data.doi.gov/harvest/object/212ebcce-557a-4031-9931-b21751b2d640",
    "format": "XML", "mediaType": "text/xml", "title": "Original Metadata"
}

Example DCAT Snippet from “LANDFIRE Forest Canopy Cover” DCAT-US record.¶

Link to example DCAT-US record in Data.gov that points to a CSDGM record.

{
    "@type": "dcat:Distribution",
    "conformsTo": "https://www.fgdc.gov/schemas/metadata/",
    "description": "The metadata original format", "downloadURL": "https://data.usgs.gov/datacatalog/metadata/USGS.64bead9bd34e70357a31c52a.xml",
    "format": "XML", "mediaType": "text/xml", "title": "Original Metadata"
}

More information¶

Data.gov Geospatial Metadata link data.json examples
Data.gov DCAT Validator
FAQ - GeoPlatform Data Sources
FAQ - Baseline of GeoPlatform Standards
Data.gov DCAT-US 1.1 metadata
Data.gov DCAT-US 3.0 metadata