Abstract Providing a reliable service in a continuously running real-timesystem is problematic. It is based on a time rigid scheduling, it avoids interrupts and has no dynamic memory allocation. Contrary, MARS has new important services within its operating system. A fault-tolerant global time scale with a precision of a few microseconds allows the synchronous execution of distributed cooperating tasks.
Tasks communicate through standardized messages with limited life time.
The reliable message transport service tolerates transient message losses using redundant datagrams. MARS strongest feature is to interpret each message as a state value, i.e. a newer value updates an older one. This gives notable advantages for the operating system and totally avoids queuing of events. Active redundant components produce the same messages. Due to the state semantics of messages redundant messages are masked out easily.