The development process of embedded systems is characterized by the cooperation of various domains: components of hardware and software have to be considered as well as components belonging to domains like mechanics, optics, pneumatics and so on. Although a lot of specialized methods for specification and simulation for each domain have been proposed in the recent years, there is a lack of a comprehensive method applicable to heterogeneous systems. The system designer often has to transform subsystems into the representation of tools used in the next step of refinement. Manual interventions are errorprone and time-consuming. This paper presents a new approach aiming at a flexible and automated design environment based on the technology of active databases. The main idea is a method for designing the modelling process. An extensible object algebra is introduced to overcome the problems mentioned above. The object set of the algebra is formed by meta objects, the operation set is for...