Tech

Re-using EDM in Nomisma.org

Since few years now Europeana has spent lot efforts in making the Europeana Data Model an interoperable framework for describing digital cultural heritage data. We strived in making EDM as re-usable as possible for the community. It is therefore always great to see such news!

EDM has been designed as a flexible model that is meant to be re-used by the Cultural Heritage community to cover their domain specific requirements. And it is exactly what the Nomisma.org project did by re-using only one part of the model.

When Europeana decided to incorporate the International Image Interoperability Framework (IIIF) service to its service infrastructure, we needed a solution to describe IIIF resources within EDM. As for every extension of the model, we tried to root as much as possible EDM into existing standards and expert communities. It was therefore natural for us to adopt the solutions defined by the IIIF community to enable links to IIIF resources in the metadata. The EDM profile for IIIF explains to data providers how to make their IIIF resources available as part of the metadata they send to Europeana.

Nomisma.org is a collaborative project that provides stable digital representations of numismatic concepts according to the principles of Linked Open Data. The project has updated their RDF data model with the features of the EDM profile for IIIF in order to serve the IIIF resources of their new data contributor (the Rutgers University's Badian Collection) into the Coinage of the Roman Republic Online portal.

In modeling terms, the Nomisma reference image currently represented as a foaf:depiction gives rise to an edm:WebResource. The new edm:WebResource is linked to a JSON-LD IIIF manifest or information object (via dcterms:isReferencedBy) and to the URI for the service (with the svcs:has_service property). The service (svcs:Service) should include several statements that defines it as a IIIF image service.

<edm:WebResource rdf:about="https://rucore.libraries.rutgers.edu/api/iiif/image/2.0/rutgers-lib:45878;PTIF-1/full/600,/0/default.jpg">
<svcs:has_service rdf:resource="https://rucore.libraries.rutgers.edu/api/iiif/image/2.0/rutgers-lib:45878;PTIF-1"/>
<dcterms:isReferencedBy rdf:resource="https://rucore.libraries.rutgers.edu/api/iiif/image/2.0/rutgers-lib:45878;PTIF-1/info.json"/>
</edm:WebResource>
<svcs:Service rdf:about="https://rucore.libraries.rutgers.edu/api/iiif/image/2.0/rutgers-lib:45878;PTIF-1">
<dcterms:conformsTo rdf:resource="http://iiif.io/api/image"/>
<doap:implements rdf:resource="http://iiif.io/api/image/2/level1.json"/>
</svcs:Service>

The user interface in Numishare (and Coinage of the Roman Republic Online) are now displaying coin images using the Leaflet IIIF-viewer and allows the query of the IIIF manifest metadata via the dcterms:isReferencedBy. An example of a Rutgers coin is available at http://numismatics.org/crro/id/rrc-474.2b (see "Denarius - Sydenham 999 - Crawford 474/2b.

The Nomisma case is a great example of the vision underpinning EDM in which data models can be designed is a decentralised way for specific domain applications while the created data remains interoperable.

This post is based on Ethan Gruber’s blog post: http://numishare.blogspot.nl/2017/01/rutgers-universitys-badian-collection.html

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