- Used in brainstorming and problem-solving to organize thoughts and identify patterns.
- A use case defines a specific case.
- For instance, “God speaks to you. God speaks Jesus Christ who is the Word. Jesus Christ authors faith in your heart. You must receive it.”
- That is a single use case.
- The actors are the Father, Jesus, and you.
- Faith is another entity or thing that is in the use case.
Creating a use case model involves identifying and representing how users (or “actors”) interact with a system to achieve specific goals. Here’s a step-by-step guide:
1. Identify the System
- Clearly define the system you are modeling. It could be a software application, a business process, or any entity where user interactions take place.
2. Identify Actors
- Actors represent the people, systems, or external entities that interact with the system. There are two types:
- Primary actors (those who directly use the system to achieve their goals).
- Secondary actors (systems or external entities that assist in fulfilling use cases, like databases or external services).
- Determine all actors that will interact with your system.
3. Identify Use Cases
- A use case describes a specific interaction between an actor and the system that leads to an outcome of value.
- Brainstorm all the possible goals an actor might want to accomplish with the system. Each goal becomes a potential use case.
- Some examples: “Login to the system”, “Place an order”, “Update profile”.
4. Define Use Case Scenarios
- For each use case, define a scenario that outlines:
- Main success scenario: The typical sequence of events where everything works as expected.
- Alternative paths: Different paths that might occur (e.g., user entering invalid data).
- Extensions: Exceptions or error cases that deviate from the main flow.
5. Draw the Use Case Diagram
- Use a UML (Unified Modeling Language) diagram to visually represent actors and use cases.
- Actors are depicted as stick figures.
- Use cases are depicted as ovals.
- Draw lines (associations) connecting actors to their relevant use cases.
- Optionally, use includes/extends relationships to show use case dependencies.
6. Detail the Use Cases (Optional)
- If needed, provide further documentation for each use case, including preconditions (what needs to be true before the use case can start), postconditions (what should be true after it finishes), and step-by-step descriptions of the interaction.
7. Review and Refine
- Review the use case model with stakeholders to ensure it accurately represents all possible interactions and goals.
- Iterate as necessary to include new use cases or refine the existing ones.