7. Modeling interactions between objects

7.1 Scenario

At the end of the needs analysis phase, the UML model describes use cases and a number of object classes that represent what the user perceives. Each use case can be likened to the intervention of an actor who addresses a succession of stimuli to the system in order to control it and activate its functions. In UML, such a sequence of interactions between actors and the system is called a scenario. For a given use case, there may be different scenarios, each characterized by a beginning corresponding to its triggering, an end corresponding to the result it leads to, and successive sequences corresponding to the alternatives proposed and the reactions or decisions of the participants. A use case can be considered as a class of scenarios.

Initially,...