Writing A Use Case Explained
A use case is a list of interactions between a user and a system, which must be performed to achieve a specific goal. Knowing how to write a use case is a critical skill for business analysts and developers.
A use case encompasses a list of sequential actions that provide a measurable value to a user, who is trying to achieve a certain goal by interacting with a system. A use case can be thought of as a collection of possible scenarios related to a particular goal. Creating the use case is a fundamental methodology used in system analysis to identify, simplify, clarify, and organize system requirements. For more about use cases, click here.
How to Write a Use Case: Step 1
Identify the users of the system. Create a profile for each category of users: Identify all potential roles played by the users, and list all potential interactions that the users may have with the system.
Each user will fulfill a certain role, defined by the specific goal they are trying to achieve. For instance, if a user is trying to use an online marketplace to make a purchase, they are fulfilling the role of “buyer”. If a user is trying to use the same system (the online marketplace) to make a sale, they are fulfilling the role of “seller”. You have then identified two categories of users: Buyers and sellers. Identify and list the different categories of users that will interact with your system.
How to Write a Use Case: Step 2
Identify the goals associated with each user’s role (i.e., why the user is interacting with the system in the first place).
Your users are categorized by the different goals that they are using your system to achieve. Your buyers want to make purchases; your sellers want to make sales. They are using your system to achieve these goals. It is important that you outline what your system must be capable of, in order to allow each category of users to achieve each category of goal.
How to Write a Use Case: Step 3
Create a list of sequential actions performed by each type of user in order to achieve each goal.
What are the steps that each category of user must take to achieve their specific goals? If a user shows up wanting to make a purchase, what is the sequence of tasks that they must perform before they can do so? Do they need to create an account? Browse or search through listings for a product? Submit payment information? Place an order? Write down each step that the user must perform, from beginning to end. This will tell you what your system must do in each case of use.
Tip: Maintain the same level of abstraction throughout each use case. Higher level use case steps should be treated as lower level use case goals.
How to Write a Use Case: Step 4
Structure the use case, according to an appropriate model, template, or diagram.
A use case should be simple, concise and clear. You may end up organizing the above information in this manner:
User A →System Interaction A1 → System Interaction A2→ System Interaction A3 → Goal A
User B →System Interaction B1 → System Interaction B2→ System Interaction B3 → Goal B
User C →System Interaction C1 → System Interaction C2→ Goal C
User D →System Interaction D1 → System Interaction D2→ System Interaction D3 → Goal D
Once you’ve outlined your use case, you can assemble this information in the form of a use case template or diagram. Use case diagrams are the “blueprints” of your system. They are meant to be simple and clear, and function on the level of abstraction appropriate for your current analysis.
To learn more about use case templates and diagrams, click here.