Use Case Realizations

Requirements analysis begins with a realization of the use cases. The use case diagrams model the global view of the system. The flow of events captures the use case requirements by describing the different scenarios and conditions. A use case realization takes the use cases and realizes them through the use of activity and scenario diagrams. These diagrams are developed to help identify the objects, classes and object interactions required to carry out the intended behavior described by the use case. The use case realizations are intended to communicate the desired goals and expectations between the end user and the domain expert. Use cases are realized by a web of scenarios. There is a primary or normal flow scenario and secondary or what-if scenarios. All of the scenarios for a use case are used to help analyze a given system and describe the intended behavior. These realizations are important for a proper understanding of the system and the desired behavior.

In UML a use case realization is represented by a dashed oval. A line is drawn between the use case realization to its use case to show that it is being realized. The following diagram would be a use case realization diagram for the Maintain Video Catalog use case.