To represent contexts, we use scenarios. Scenarios have also been widely used as a method of comparing design alternatives. Scenarios have not, however, been used as a tool to analyze quality, our primary utilization of them. We use scenarios to express the particular instances of each quality attribute important to the customer of a system. We then analyze the architecture under consideration with respect to how well or easily it satisfies the constraints imposed by each scenario.
Scenarios differ widely in breadth and scope.
We use scenarios as a brief description of an anticipated or desired use of a system. At this point in our work, scenarios are typically one sentence long and could more appropriately be called vignettes. We emphasize the use of scenarios appropriate to all roles involving a system. The operator role is one widely considered, but we also have roles for the system designer and modifier, the system administrator, and others, depending on the domain. When analyzing a system all roles relevant to that system must be considered since design decisions are made to accommodate all roles.