In this article
What is a Use Case Diagram?
A use case diagram visually represents the interactions between actors (users or external systems) and a system. It outlines:
- Possible actions (use cases)
- Who can perform them (actors)
- Relationships between components
PlantUML generates these diagrams from text code, making them accessible to developers, clients, and team members alike.
Key Components
- Actors: External entities interacting with the system
- Use Cases: System functionalities from user perspective
- Relationships: Connections showing interactions
What is PlantUML?
PlantUML is an open-source tool that converts text into diagrams, eliminating manual drawing.
Key Features
- Text-Based Diagramming:
- Write code like
A -> B: Message - Automatically generates visual diagrams
- Write code like
- Multi-Diagram Support:
- UML (class, sequence, use case)
- Flowcharts, mind maps, Gantt charts
- Cross-Platform: Works in IDEs, wikis, and version control
- Version Control Friendly: Text-based format integrates with Git
@startuml Alice -> Bob: "Hello" Bob --> Alice: "Hi there" @enduml
Basic PlantUML Syntax
Understanding core syntax elements is essential for creating effective diagrams.
Actors
Syntax: actor ActorName
Use Cases
Syntax: usecase "Description"
Relationships
- Association:
Actor --> (UseCase) - Include:
(Base) ..> (Included) : <> - Extend:
(Base) ..> (Extension) : <> - Generalization:
Child --|> Parent
Steps to Create Diagram
Follow this systematic approach to build effective use case diagrams.
Step 1: Identify Actors
List all external entities interacting with your system.
Step 2: Define Use Cases
Outline system functionalities from each actor's perspective.
Step 3: Establish Relationships
Connect actors to their corresponding use cases.
Step 4: Write PlantUML Code
@startuml left to right direction actor Customer usecase "Place Order" Customer --> (Place Order) @enduml
Step 5: Generate Diagram
Render using PlantUML tools to visualize your diagram.
Practical Examples
Let's examine a complete library management system example.
Library System Components
- Actors: User, Guest, Librarian
- Use Cases: Borrow Book, Search Catalog, Manage Inventory
@startuml actor User actor Librarian User --> (Search Books) User --> (Borrow Book) Librarian --> (Manage Inventory) @enduml
When to Consider Alternatives
While PlantUML is powerful, visual tools may better suit some teams.
For teams preferring visual editing, consider:
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Final Words
PlantUML offers developers precise control over use case diagrams through code. While excellent for technical teams, visual alternatives like EdrawMax provide intuitive drag-and-drop interfaces for non-technical users.
The best approach depends on your team's skills and project requirements. For code-based documentation, PlantUML is ideal. For rapid prototyping and visual collaboration, consider graphical tools.
EdrawMax DesktopEdrawMax Online
