A scenario is an elaboration on the user case model. A scenario will add more
detail to sub-cases by describing a specific sequence of events. The user cases and the
analysis scenarios together constitute the functional requirements for the system. The
object of the analysis scenario is to provide enough insight to enable the development
team to develop Object Interaction Diagrams. The analysis scenario is also an effective
way to define the requirements of each cycle in terms of which scenarios that must be
The scenarios are generated be evaluating each user case and outlining the
possible variations. Each variation is documented as its own scenario. The behavior of
the scenario is captured by listing the assumptions and outcomes of the scenario.
Scenarios are important because they identify ways in which the system must respond in
a given set of circumstances. However, it is difficult to generate assumptions because
they are often implicit in the situation.
The Analysis Scenario work-product is used to generate Analysis Object
Interaction Diagrams, Analysis State Models and Design Scenarios. Thus it forms a vital
link between the high level user cases and mid-range work products.