Fault Tolerance in Use-Case Modeling

Fault tolerance – an ability of a system to cope with errors – is an important characteristic of safety-critical systems. However, the current approaches to software development often ignore the fault tolerance aspect. This results in an ad-hoc and often incorrect introduction of the fault tolerance mechanisms into system design. In this paper, we summarize the experience gained in the formal development of a highly-reliable industrial robot and propose an approach which allows us to systematically capture requirements describing the fault tolerance mechanisms in use-case modeling. An application of our approach supports integrating fault tolerance consideration into the entire software development process.