Representing user workarounds as a component of system dependability

Evaluation of system-level dependability can benefit from representing and assessing the effects of user workarounds as a response to system component failures. We assemble sequence diagrams that represent UML scenarios into mission graphs that contain all possible paths from a particular mission starting point to a particular mission success goal point. Analysis of these graphs reveals potential dependability bottlenecks and the existence of possible workarounds that can be intentionally added to a design, retrofitted to fit an existing design, or discovered as an emergent property of existing system and user behaviors. Simulations of a moderately complex distributed embedded system demonstrate that this approach has potential benefits for representing and improving system-level dependability by including the ability of users to perform simple workarounds to achieve mission objectives.