A business use case defines a sequence of actions that a business performs that yields an observable result of value (a work output) to a particular business actor or that shows how the business responds to a business event.
A system use case is a sequence of actions that a system performs that yields an observable result of value to a particular actor (someone or something outside the system that interacts with the system).
Use cases in Rational® Requirements Composer share the same rich-text behavior that is described in Working with text documents.Use cases also include a spell checker. Misspelled words are marked with a red wavy underline. Right-click a misspelled word to select from suggested spellings or to add it to the project dictionary.
A use-case diagram can include multiple use cases and the relationships between use cases and the persons, groups, or systems that interact to perform the use case. Use-case diagrams include the following elements:
Element | Explanation |
---|---|
Use Case | A use-case artifact. This is a textual specification that is created independently from a diagram and reused (or shared) in multiple use-case diagrams. It is displayed as a gray symbol in a diagram. To open the artifact, double-click a use case in a diagram. |
Use Case Placeholder | A symbol that is a placeholder for a use case in a diagram. This use case is created and used in a single use-case diagram. It is displayed as a white symbol in the diagram. |
Actor | An actor artifact that represents a person, group, or system that interacts with the use case. This is a textual explanation of the actor that is created independently from a diagram and is reused in multiple use-case diagrams. It is displayed as a gray symbol in a diagram. To open the actor artifact, double-click the actor in a diagram. |
Actor Placeholder | A symbol that is a placeholder for an actor in a diagram. The actor element is created and used in a single use-case diagram. It is displayed as a white symbol in the diagram. |
Association | A relationship between two elements in the diagram. |
System Boundary | Defines the extent of a system, which can include one or more use cases. The system boundary separates a system from actors and other systems. |
Use-case artifacts provide textual detail for a use case. These use-case specifications often include content that is based on a template or process guidance that is similar to the following outline. See the topic Use-case specification outline for a description of each section in the outline.