The Greek Open Data Day followed the footsteps of yearly open data days and hackathons co-organized by IMIS and GFOSS since 2010. This year, more than 160 members of the open data community were present, marking a milestone for open data in Greece. The participation, interest and efforts of all volunteers were an unprecedented success!

Prof. Yannis Ioannidis, President of "Athena" RC, welcomed all participants and reaffirmed the dedication of Athena RC towards supporting open data, both through EU-leading research activities and volunteer work by Athena researchers. Among others, he highlighted the disruptive gains from geodata.gov.gr, the open data portal developed by IMIS and presented the ongoing work of "Athena" RC for open data infrastructures, in the context of OpenAIRE, CLARIN, GeoKnow, and multiple other research projects.

The General Secretary of Information Systems, Haris Theoharis, was also present during the event, highlighting the importance of open data for the transparency and monitoring of the tax administration. Further, he informed all participants to expect even more open financial data provided by the Greek public sector in the near future, and invited all volunteers to help the public administration through knowledge transfer and the development of value added services.

A number of short presentations then took place, where researchers and open data practitioners presented open data technologies, tools, and initiatives. Highlights include the announcement for the beta operation of datahub.gr, an open data portal developed by IMIS with the goal to support the public administration in open data publishing. Further, the GeoKnow and DIACHRON EU research projects presented their planned work towards open geospatial data and provenance for the Data Web, and their contribution in EU's data economy. Finally, publispending.gr was presented, a web site analyzing and visualizing open public spending data, highlighting the benefits of open data for transparency.

In parallel, five workshops were organized in which more than 60 members of the open data community were trained by researchers of IMIS in open data technologies. Again, the participation was remarkable and IMIS promised that more similar training events will take place in the near future. The workshops were: a) open data publishing, where civil servants were trained on how to publish open data through datahub.gr, b) building linked open data, where participants were trained on how to create LOD from published open data, c) statistical open data, where participants were trained on how to use the Data Cube vocabulary and publish LOD from actual open data provided by the Greek Statistical Authority, d) anonymizing data, where the emphasis was on placed on informing potential privacy risks from open data publishing and technical means to mitigate them, and e) publishing business registers as LOD, where participants were trained step-by-step on how to publish available open data from business registers as LOD.

The Greek Open Data Day ended with a debate, which had the following question: "Open or Closed Data?" The aim was to expose the intricacies and complexities involved when publishing open data and empower participants with an arsenal of arguments in order to knowledgably promote open data. Several important issues where raised, involving the true economical benefits of open data, potential dangers for privacy, application in research activities, transparent public services, etc. For the record, open data won, but everyone acknowledged that much work needs to be done on educating the public and private sector.

Reported by Spiros Athanasiou - IMIS/ATHENA RC