Object-Oriented Modeling Use Case Diagrams

Purpose of Use Case Diagrams

• Outline functional requirements of a system by illustrating interactions between users and system functionalities.
• Serve as a visual representation to enhance understanding of system behavior.

Actors in Use Case Diagrams

• Represent users or external systems that interact with the primary system.
• Can include both primary actors who initiate a use case and secondary actors that support it.

Use Case Diagrams in Analysis and Design

• Facilitate communication among stakeholders, ensuring a shared understanding of requirements.
• Help identify system functionality and user interactions early in the design process.

Typical Elements Not Found in Use Case Diagrams

• Non-functional requirements or performance metrics are not typical elements depicted.

Relationships Between Use Cases

• Illustrate how different functionalities are connected and interact with one another.
• Help in clarifying dependencies and interactions within the system.

Essential Stakeholders

• Include primary and secondary actors, developers, project managers, and end-users who have a vested interest in system functionality.

Association Notation

• Represents a direct communication link between actors and use cases, indicating interaction.

Required Use of One Use Case by Another

• Denoted by "Include" relationship, indicating that one use case is invoked within another.

Generalization Notation

• Indicates an inheritance relationship among use cases or actors, allowing for shared behaviors or attributes.

System Boundary in a Use Case Diagram

• Represented by a rectangle that separates system functionalities from user interactions.

Unit of Functionality

• Refers to distinct functionalities or services provided by the system, represented as use cases in the diagram.

Role of Primary Actor

• Initiates an interaction or use case with the system to achieve a goal.

Role of Secondary Actor

• Provides support or assistance to the primary actor, typically not initiating interactions.

Connecting Actors with Use Cases

• Done through association lines, demonstrating how actors engage with specific functionalities.

<< Include >> Relationship

• Signifies that one use case includes the behavior of another use case, promoting reuse and modular design.

<< Extend >> Relationship

• Allows a use case to extend the behavior of another use case, adding conditional or optional functionalities.

Defining Characteristic of an Association

• Represents a bidirectional relationship between an actor and a use case, indicating mutual participation in the interaction.