Ppresident and general director of the ‘Athena’ Research and Innovation Center in Athens and a professor in the Department of Informatics and Telecommunications of the University of Athens. From 1986 to 1997 he taught in the Department of Computer Sciences of the University of Wisconsin–Madison.

His research interests include electronic infrastructures (digital libraries and repositories, data infrastructures), database and information systems, personalisation and social networks, data science, human–computer interaction and several application areas (life sciences, cultural heritage, biodiversity, physical sciences), topics on which he has published over 150 articles in leading journals. He also holds three patents.

He has been a co-coordinator of all the OpenAIRE projects and a partner in many research projects, including the currently active Human Brain Project and OpenMinTeD. He is an ACM and IEEE Fellow, a member of Academia Europaea and a recipient of several research and teaching awards. He has also served as the chair of ACM SIGMOD, the international association of researchers on data management.

He is the Greek delegate to the European Strategy Forum on Research Infrastructures [ESFRI], a member of the ESFRI executive board and the ESFRI representative to the e-Infrastructures Reflection Group [e-IRG].