- Use Case Modelling is a very popular technique to find out user requirement
- Use cases describe the system from the user's point of view
- A use case defines the interactions between external actors and the system under consideration to accomplish a goal
- It describe the interaction between one or more actors and the system itself represented as a sequence of simple steps
- There are main formats used to express use cases: High-Level format and Expand format
- A High-Level use case describes a process very briefly. This format is typically useful during the early stages of a development project.
- An Expanded use case describes a process in more detail than a high level description. An expanded use case description includes a step by step description includes a step by step description of the typical course of events for the use case. It is sometimes useful during requirements gathering and analysis.
- A use case defines a sequence of actions performed by a system that yields and observable result of value to an actor
- A use case is always initiated by an actor
- A use case provides value to an actor
- A use case is complete
The Actor
An actor is usually drawn as a named stick figure, or alternatively as a class rectangle with the keyword
- What is an actor?
- Not part of the system
- Represents roles a user can play
- Represents human a machine or another system
- Activity exchange information with the system
- A give or a recipient
- Who will use the system?
- Who will maintain the system?
- What hardware does the system support or interact with?
- What other systems are needed for this system to work?
- Who will supply, use, or remove information?
- Who create it?
- Who displays or uses it?
- Who delete it?
- For each actor, ask the following questions
- What are the primary tasks the actor wants the system to perform>
- Will the actor create, store, change, remove, or read data in the system?
- Will the actor need to inform the system about sudden, external changes?
- Will the actor perform a system startup or termination?
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