Appeared in: 3rd International workshop on responsive Computer Systems 1993, New hampshire, USA (1993)
The protocols have bounded completion time, making them suitable for use in hard real-time systems. Multiple source ordering is imposed on the messages that pass through a mailbox. The protocols are shown to be tolerant of memory crashes, and of process or processor failures. The basic protocol tolerates only crash failures of processes, while the second protocol can also handle timing failures.