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On the last couple of years, open government and the use of open data has increased exponentially. There are new platforms highly focused on open data like CKAN. In that movement people focus on lean standards (DCAT). To solve the geometry usecase they looked for similar lean standards and embraced geojson.
The ease of use of these protocols (and availability of free data) has gathered a large group of users willing to use and develop around this environment. This process has popularized multiple applications based on open data.
GeoNetwork could profit from these developments and could implement some of their spin-offs (leafletjs/D3js). But also we should not abandon our xml users (OGC/Inspire). The challenge is to be lean where possible, and complient in other parts.
For example EU recently released a DCAT profile for open government data. It would be good to have it available as a schema plugin, but might be integrated in other parts of geonetwork also (harvester, csw-format)
In the open data movement some new catalogues are set up (for example in git). Some new harvesters could be made to retrieve metadata from those kind of repositories.
Another development is the increased interest for linked data (also within inspire).
Also there are currently limited ways to link to the actual data. One could imagine a component that uses a combination of iso19139 and feature-catalog metadata or WFS XSD to create RDF from WFS data.
DCAT support in GeoNetwork
GeoNetwork provides some features related to the linked data domain:
- search service returning response using RDF (eg. http://sdi.eea.europa.eu/catalogue/srv/eng/rdf.search?any=DEM)
- metadata export to RDF - ISO19139, dublin core mapping to DCAT/RDF are implemented (eg. http://sdi.eea.europa.eu/catalogue/srv/eng/rdf.metadata.get?uuid=7b0b89e3-055e-4d74-a98b-02a788b3a481).
- Sitemap use XML file that uses the Semantic Crawling extension
- Basic viewer http://graves.cl/visualRDF/?url=http://sdi.eea.europa.eu/catalogue/srv/eng/rdf.search?any=gaul
Geonetwork currently does not provide SPARQL query support but could be harvested by tools like Virtuoso.
- Support DCAT as a schema plugin
- Support DCAT editing / import
- Add DCAT to CSW ?
- Add associated resources management to DC and DCAT plugins (like ISO19139 parents, services, sources, feature catalogs, online resources, ... http://geonetwork-opensource.org/manuals/trunk/fra/users/editor/metadata_link/linking.html#associer-des-ressources-a-une-fiches)
- Make all rdf:resource link to the different type of objects in RDF format (to follows link) eg.
- For keywords use ids if available (eg. in GEMET http://www.eionet.europa.eu/gemet/concept/4678)
GeoNetwork nodes publishing opendata
GeoNetwork nodes describing opendata resources:
- GrandLyon using dublin core and a opendata category http://catalogue.data.grandlyon.com/geosource/apps/rechercher/?
- Région Aquitaine using ISO19139 and a opendata category http://ids.pigma.org/geonetwork/
- EEA catalog is harvested by the semantic data service (a Virtuoso node)
- List of all entries in SDS: http://semantic.eea.europa.eu/sources.action?searchString=sdi.eea.europa.eu&pageN=2&view=Filter&type=
- Catalogue entry:
- Look at any record with harvesting date of 21-22/11 e.g. http://semantic.eea.europa.eu/source.action?view=&harvestSource.url=http%3A%2F%2Fsdi.eea.europa.eu%3A80%2Fcatalogue%2Fsrv%2Feng%2Frdf.metadata.get%3Fuuid%3D074b8e76-5e49-467c-aa30-ed013afd41a9 http://semantic.eea.europa.eu/source.action?view=&harvestSource.url=http%3A%2F%2Fsdi.eea.europa.eu%3A80%2Fcatalogue%2Fsrv%2Feng%2Frdf.metadata.get%3Fuuid%3D08e7b052-3c4c-4545-943f-63db46be0a66
Actions to take
- DCAT: we need to create a schema for geoNetwork (there are some based on RDF) for import (and edit)
- DCAT view with DCAT export button
- CSW with DCAT format