The first phase in developing information systems is often called conceptual modelling phase. The model constructed is the first formal document describing the desired system. The conceptual model must deal with structural \em and behavioural aspects of the world. The complexity of such a model often prevents a detailed understanding by the later users. One way to estimate if (s)he really gets what (s)he wants are prototype systems constructed by conventional programming. We propose a way to construct prototypes from formal specifications by means of transformation into a kernel language that can be executed in a suitable distributed runtime environment. We introduce the modelling language, the basic execution mechanism, and the basic architecture of the runtime system.