Use-case models

Use-case models provide detailed information about the behaviors of the system or software application that you are developing. Use-case diagrams depict the relationships between the uses cases and actors, and activity diagrams describe the flow of objects and control in each identified behavior.

You begin a development project by first identifying its users, the goals that the user wants to achieve, or a particular problem to be solved, and then discovering the functionality and environment of the system that will achieve these goals or solve the problem. You gather information about, and document, the functional requirements, and identify which requirements are associated with specific functions, tasks, or behaviors of the system. When you have identified the requirements, you can create a use-case model to describe the functionality in terms of how the system will be used.

The use-case model identifies the requirements of the system in terms of the functionality that must exist to achieve the goals set out by the user or to solve a problem identified by the user. Uses cases describe the major behaviors that you identify in the requirements and describe the value that the results give the users; they do not describe how the system operates internally. Actors are the users of the system and represent the different roles that people and other systems play when they interact with the system.

During requirements gathering, the requirements are structured and detailed. Requirement can come from many sources, but requirement documents and user interviews are common. You can manage the collection and documentation of requirements using IBM® Rational® RequisitePro®.

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