Use Case Diagram - Top Level Use Cases

The Use Case diagram describes the HybridSUV as a system that is utilized by a number of external roles. The diagram helps to set the context of all the roles (human and other systems) who interact with or get value from the system. The Use Case diagram, while appearing simplistic, provides a mechanism to ensure that all potential system interactions are defined and understood. The system itself is represented in the diagram by a Boundary element, which acts as container for the Use Cases, with the Actors lying outside the Boundary. In this diagram there are a number of external roles - other than the Driver - who will interact with the HybridSUV system, including the Registered Owner, Maintainer, Insurance Company and Department of Motor Vehicles.

The Use Cases appear in the Browser window and can be conveniently grouped into Actors and Use Cases. Any number of Use Case diagrams can then be defined that allow the Systems Engineer to visualize the Use Cases.

Enterprise Architect also provides a number of helpful and unique tools to assist the Systems Engineer to efficiently describe the Use Cases and define Scenarios that detail the steps representing the interaction between the Actor and the System. Once these have been defined the tool can automatically generate behavioral diagrams directly from the model.

Once the steps have been generated as model elements then the traceability can be added:

• Actor steps can be traced to Human Machine Interface Models
• System steps can be traced to Component Models.