Programme and Conference Chair of EUUG (European UNIX Systems User Group) Autumn Conference, Vienna 1989.

Programme and Conference Chair of UNIX Forum Conferences in Vienna (1986, 1987, 1988, 1990, 1991), UUGA (UNIX User Group Austria) and OCG (Austrian Computer Society).

Coordinator of the minitrack Virtual Shared Memory for Distributed Architectures at the 31st Hawaii International Conference on System Sciences (HICSS-31), January 1998.

Programme Committee member at EUUG (European UNIX Systems User Group) Spring Conference, Brussels 1989.

Programme Committee member at 3rd FODO'89 Conference (Foundations of Data Organisation), Paris, INRIA, June 1998.

Programme Committee member at RIDE-91 (Research Interests in Data Engineering) Workshop on Interoperability of Multidatabase Systems, Kyoto, Japan, IEEE.

Programme Committee member at the 7th Data Engineering Conference, Kyoto, Japan, April 1991, IEEE.

Programme Committee member at RIDE-92 (Research Interests in Data Engineering), Workshop on Transaction and Query Processing, Phoenix, Arizona.

Programme Committee member at the IEEE RIDE-93 (Research Interests in Data Engineering) Workshop on Interoperability of Multidatabase Systems, Vienna, April 17-23, 1993.

Programme Committee member at the 9th Data Engineering Conference, Vienna, April 1993, IEEE.

Programme Committee member at the Euromicro'93 Conference, Budapest, 1993.

Programme Committee member at the 10th Data Engineering Conference, Houston, Texas, February 1994, IEEE.

Programme Committee member at the International Conference on Applications of Databases ADB'94, June 21-23, 1994, Sweden.

Programme Committee member at the IEEE RIDE-96 (Research in Data Engineering) Workshop.

European Liason and Reviewing for First IFCIS International Conference on Cooperative Information Systems (CoopIS'96), Brussels, Belgium, June 19-21, 1996 Organized by IFCIS, The Int'l Foundation on Cooperative Information Systems.

Programme Committee member at the Austrian-Hungarian Workshop on Parallel and Distributed Systems (DAPSYS'98), Budapest, Hungary, September 1998.

1987-1990 Initiator and chair of the Austrian Prolog working group for the standardisation of Prolog.

1985-1995 Governing board member of the UUGA (UNIX User Group Austria). Participation in the governing board of the EUUG (European UNIX Systems User Group).

1988 Founding member of the ISO SC22 WG17 working group for the standardisation of Prolog.

Initiation and organization of UNIX Forum Conferences in Vienna (1986, 1987, 1988, 1990, 1991) together with the OCG (Austrian Computer Society), including exhibitions of UNIX hard and software.

Organization of the EUUG (European UNIX Systems User Group) Autumn Conference, Vienna 1989, together with the EUUG and the OCG (Austrian Computer Society).

Organization of a meeting of the ISO SC22 WG17 working group for standardisation of Prolog, Vienna 1990.

Local Arrangement Coordinator of the IEEE RIDE-93 (Research Interests in Data Engineering) Workshop, Vienna, April 17-23, 1993.

European Coordinator at the 10th Data Engineering Conference, Houston, Texas, February 1994, IEEE.

Coordinator of the Minitrack on Virtual Shared Memory for Distributed Architectures of the HICSS (Hawaii International Conference on System Sciences) 1998.

Technical Vice Chair of the Second European International Conference on Parallel and Distributed Systems (Euro-PDS'98), July 1-3, 1998 Vienna, Austria.

Advisory Committee Member of the 34th Hawaii International Conference on System Sciences (HICSS), IEEE Computer Society, 2001.

Advisory Committee Member of the 35th Hawaii International Conference on System Sciences (HICSS), IEEE Computer Society, 2002.

Organization of the Space Based Computing as Semantic Middleware for Enterprise Application Integration (SBC 2007) , Vienna, as part of the European Semantic Technology Conference, 2006.

Organization of the Event-Based Work Management Systems Workshop, Vienna, as part of the ARES Conference, 2007.