Scenario Networks for Software Specification and Scenario Management TR-2001-15

Scenarios are widely used to specify the desired behavior of a system, but managing the large collection of scenarios that frequently result and making a scenario-based specification complete are challenging tasks. Scenario networks address these challenges while retaining the many advantages of scenarios during software specification activities. A scenario network is a collection of scenarios that has been integrated into a single entity by the specification of the sequential and concurrent relationships among its component scenarios. The addition of these relationships specifies the larger-scale behavior that is typically missing from a collection of scenarios, and ties scenarios together in a way that either indicates no gaps in the description are present, or makes gaps obvious. Scenario networks provide procedural guidance for scenario creation and support for scenario management. Gaps in the structure of a scenario network correspond to missing or incomplete scenarios, and the closing of these gaps result in the completion of the scenario collection. A scenario network organizes the collection of its scenarios, and its structure indicates several kinds of scenario relationships, including equivalence relations dividing them into equivalence classes. These relationships address some of the challenges associated with scenario management.