1. Hasso-Plattner-Institut, University of Potsdam, Germany. E-mail: {dominic.wist,ralf.wollowski}@hpi.uni-potsdam.de
2. Senacor Technologies AG, Vordere Cramergasse 11, 90478 Nuremberg, Germany. E-mail: mark.schaefer@senacor.com
3. Institute of Computer Science, University of Augsburg, Germany. E-mail: walter.vogler@informatik.uni-augsburg.de