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3SL Reference

Use Case Diagram (uc)

A Use Case identifies the ways of using a proposed system to achieve a particular goal or mission for a particular stakeholder. Taken together the set of all the Use Cases gives the project all of the useful ways to use the system, and illustrates the value that it will provide.

Example Use Case

A Use Case Diagram (uc) consists of a set of Actors and Use Cases and the relationships between them. Each Use Case description is first captured in text, and identifies the actors, pre-conditions, assumptions, post-conditions, and primary activities needed to accomplish the Use Case goal/mission.

For each Use Case one or more operational scenarios should be developed using Activity Diagrams so that all the operational activities and information exchanges can be understood for each possible scenario (e.g. normal conditions, off-normal conditions, different situations). The information derived from these scenarios help identify stakeholder functional requirements, external systems that must be interacted with and a high-level view of the information to be exchanged with the external systems (interfaces).