- University of Pretoria, Pretoria, South Africa, Extraordinary Professor, January 2015 – current.
- Nelson Mandela University, Port Elizabeth, South Africa, Adjunct Professor, April 2009 – 2019.
- CSIR Meraka Institute, Chief Researcher, Integrated Systems Analysis and Engineering, Smart Systems Competency Area, October 2016 – March 2018 (retired).
- CSIR Meraka Institute, Chief Researcher, Next Generation ICT Architectures, July 2015 – September 2016.
- CSIR Meraka Institute, Chief Researcher and Research Group Leader for the Enterprise Knowledge Engineering and Management Group (MEKE), August 2009 – June 2015.
- North West University, Vaal Triangle, South Africa, Extraordinary Professor, August 2009 – 2014.
- University of South Africa, Pretoria, South Africa, Professor Extraordinaire, June 2008 – December 2010.
- African Advanced Institute for Information & Communication Technology (Meraka Institute), Council for Scientific and Industrial Research (CSIR), Principal Researcher and Research Group Leader, June 2008 – July 2009.
- University of South Africa, Pretoria, South Africa, Director of the School of Computing, 2004 – 2005.
- University of South Africa, Pretoria, South Africa, Director of the Centre for Software Engineering, 2000 – May 2008.
- University of South Africa, Pretoria, South Africa, Head of Department of Computer Science and Information Systems, 1999 – 2004.
- University of South Africa, Pretoria, South Africa, Professor, 1999 – May 2008
- University of South Africa, Pretoria, South Africa, Associate Professor, 1998
- University of York, Visiting Research Fellow, 1992.
- University of South Africa, Pretoria, South Africa, Senior Lecturer, 1985 -1997.
- Extra-curricular Centre for Highly Gifted Children, Head Department of Informatics, 1981 – 1984.
- University of South Africa, Pretoria, South Africa, Lecturer, 1981 – 1984.
- North-West University, Potchefstroom, South Africa, Lecturer, 1980.
- North-West University, Potchefstroom, South Africa, Junior Lecturer, 1979.
- North-West University, Potchefstroom, South Africa, Research Assistant (part-time), 1977 – 1978.
- Atomic Energy Board of South Africa, Student Intern, 1975 – 1977.