- Elements of use case diagram
A use case diagram is used to view the behavior of a system in such way that:
- the user can understand how to use each element.
- the developer can implement these elements.
For example, the behavior of a cell phone can be described via a use case diagram.
Elements of use case diagram
A use case diagram includes the following elements:
- Actor: represents the role of the users that interact with the application. For example, a person who works in a bank as a loan manager. If they have an account in the same bank, they will also play the role of customer.
- Use case: describes a sequence of actions performed by the application. For example, place an order, enter an invoice, create a new customer entry, etc, ...
A use case describes the actions performed by an application but it does not specify how the application performs these actions.
- Relationship: describes the behavior of an actor with a use case. Three types of relationships are available:
- Association: Structural relationship between two linked elements.
- Dependency: Indicates that one element uses or depends on another element. For example, a bank customer may get cash from an ATM. In this case, the Get Cash action depends on the Customer.
To withdraw money, the Customer must enter a PIN number. In this case, the Get Cash action depends on the Password Input.
- Generalization: Relationship in which elements are organized based on a hierarchy.
- there are two types of Customer actor: Individual Customer or Enterprise Customer.
- there are two ways to verify the user's identity: a password or a fingerprint.
- Package: divides and organizes the diagram representation (in the same way that directories organize files). Each package can contain actors and use cases.
For more details on the actions available on use case diagrams, see Operations performed on use case diagrams
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