Problem 2
Explain why it is reasonable to assume that the use of dependable processes will lead to the creation of dependable software.
Problem 3
Give two examples of diverse, redundant activities that might be incorporated into dependable processes.
Problem 5
Imagine you are implementing a software-based control system. Suggest circumstances in which it would be appropriate to use a fault-tolerant architecture, and explain why this approach would be required.
Problem 6
You are responsible for the design of a communications switch that has to provide \(24 / 7\) availability, but which is not safety-critical. Giving reasons for your answer, suggest an architectural style that might be used for this system.
Problem 7
It has been suggested that the control software for a radiation therapy machine, used to treat patients with cancer, should be implemented using N-version programming. Comment on whether or not you think this is a good suggestion.
Problem 8
Give two reasons why different versions of a system based around software diversity may fail in a similar way.
Problem 9
Explain why you should explicitly handle all exceptions in a system that is intended to have a high level of availability.
