Abstract. Scientific visualization and simulation specification and monitoring are sometimes addressed by object-oriented environments. Even though object orientation powerfully and elegantly models many application domains, integration of OO libraries in such systems remains a difficult task. The elegance and simplicity of object orientation is often lost in the integration phase, so combining OO and dataflow concepts is usually limited. We propose a system for visualization and simulation with a generic object-oriented way to simulation design, control and interactivity, which merges OO and dataflow modelling in a single abstraction. Advantages of the proposed system over similar tools are presented and illustrated by a comprehensive set ...