What is use case?
Use case a technique which use in requirement analysis. Simply it describes how a user uses a system to accomplish particular goal.
It’s a step of a particular use of the system by an actor or user.
Purpose of use case diagram
- Define goal of the system
- Define user interaction steps with the system.
- System architecture validation
- Easy to understand by end user and developer.
How do you write a Use Case?
Use case contains the following elements:
- Name – A clear verb/Noun/actor which describe the overall use case.
- Brief Description – A brief paragraph that describing the scope of use cases.
- Actors – A list of all types of users, who will use the system. Actor names should not correspond to job titles. Actor can be primary and secondary.
- Preconditions – List of conditions that need to be true when the use case begin.
- Basic Flow – It’s a set of steps that user need to take for successfully accomplish thegoal of use cases. A clear description what the system does in response to each user action.
- Alternate Flows – Capture the less common users, whose interaction with the system will very less.Document other, legitimate usage scenarios that can take place within this use case separately in this section. State the alternative course, and describe any differences in the sequence of steps that take place. Number each alternative course using the Use Case ID as a prefix, followed by “AC” to indicate “Alternative Course”. Example: X.Y.AC.1.
- Post Conditions – Anything that must be true when the use case is complete.