Model Driven Architecture : European MDA Workshops: Foundations and Applications, MDAFA 2003 and MDAFA 2004, Twente, The Netherlands, June 26-27, 2003, and Linköping, Sweden, June 10-11, 2004, Revised Selected Papers - Uwe Aßmann, Mehmet Aksit, Arend Rensink ((Lecture Notes in Computer Science))