I would like to thank my adviser, Prof. Dr. Albert Kündig, for giving me the possibility to develop my own ideas and for his confidence in my work. He introduced me in the field of embedded systems from where I learned many lessons on efficiency, simplicity and reusability. I am grateful to Dr. Matthias Anlauff for agreeing to be co-examiner of this thesis. MCS modelled on his Gem/Mex system. Especially his advice to represent undef as null saved me many redesigns.