PublicData.eu is a research prototype of a pan-European data catalogue and federation mechanism, developed as part of the EU-funded <a href=http://lod2.eu>LOD2</a> project. Based on CKAN, the website is developed as a use case and an early adopter of the LOD2 linked data stack technologies. After the LOD2 project’s launch in September 2010, a first version of the website was released in June 2011.
The portal’s backend uses CKAN’s harvesting framework to retrieve, normalize and convert data set metadata from 25 catalogues across Europe, including national and regional as well as official and community-driven efforts. For example, the portal includes all instances of CKAN (such as data.gov.uk), France’s Data Publica, Swedens OpenGov.se, CSI Piemonte’s Dati Piemonte and several municipal catalogues, including those of London, Paris and Vienna. The site is also able to include geodata directories; such as the EU’s national INSPIRE registries. The harvesting of data sets is performed via an automated service, using APIs where available and screen-scraping for the remaining catalogues. Further key functionalities of the portal include:
- Multilingual metadata is managed within the system, allowing filtering and multilingual descriptions.
- A SPARQL (RDF query language) endpoint is offered additionally to the standard CKAN API to allow easy access to structured catalogue metadata. All data set views are RDFa-enabled and a RDF/DCat representation for each individual data set is available through an extended API.
- Applications and ideas developed during the Open Data Challenge competition are presented in an integrated catalogue with multiple screenshots and tagging. This helps to highlight the value of available data in general, as well as specific data sets.
- Categorisation is based on taxonomy normalisation, yielding a common set of dataset categories based on EUROVOC. This allows topical navigation across multiple data set languages.
- A custom visual style was applied to the portal, using CKANs advanced theming support to develop a functional and elegant interface.
- A map-based overview of data availability throughout Europe, demonstrating which countries are leading in their effort to open up government information.
During the remainder of the four-year runtime of the LOD2 project, further extensions to the portal have been planned, including full support for SKOS-based, multilingual thesauri, and work to integrate the LOD2 data processing components to enable automated conversion and refinement of linked data sources. Further research will include the use of domain-specific descriptions for extended data set metadata, e.g. for financial and legislative information.