Use case modeling & analysis v 1
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Use case modeling is a technique for capturing requirements by describing how system actors interact with the system. Key aspects of use case modeling include: identifying actors and use cases; creating a use case diagram; describing use cases and their flows; and identifying relationships between use cases using include, extend, and generalization. Use case modeling helps elicit requirements, communicate with stakeholders, and generate test cases. The analysis process involves developing problem statements, identifying actors and use cases, creating an initial diagram, describing use cases, and refining the model through elaboration and prioritization.
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Use case modeling & analysis v 1
- 1. Use Case modeling & analysis By: Jigar Makhija
- 2. Requirement elicitation • A requirement describes a condition or capability to which a system must conform. • Requirements are supposed to represent what system should do as opposed to how the system should be built. • Requirements elicitation is the process of defining your system.
- 3. Use Case modeling for requirements elicitation • A use case is a sequence of transactions performed by a system that produces a measurable result for a particular actor. • A good use case must represent the point of view of the people who will use or interact with the system.
- 4. Use case modeling techniques • It is the process of describing the behavior of the target system from an external point of view. • Use case analysis allows the designer to focus on the requirements of the system, rather than on its implementation. • Use case analysis is a very useful tool for the designer to communicate with the client.
- 5. Use case model? • A use case model is a diagram or set of diagrams that show what the proposed s/w system is designed to do. components Actors Use case & their documentations Additional documentation such as use case descriptions and problem statements to identify use cases.
- 6. Actors • They are the entities that interact with the system. • An actor, represent a group of users taking on a particular role. actor People Computer h/w & devices External system
- 7. Types of actor Primary actor Secondary actor Primary actor • They are completely outside the system and drive the system requirements Secondary actor • They often appear to be more inside the system than outside
- 8. Use case • A use case is a sequence of actions a system performs to yield an observable result.
- 9. System boundaries • It defines the scope of the system being developed and are represented by rectangles in uml notation.
- 10. Use case analysis techniques • During the use case analysis process, the client and the users of the system are usually interviewed. • Describing a system’s use case is useful and important exercise because it helps to identify redundant or unclear functionalities.
- 11. Use case analysis may helpful in following areas: • Discovering new features(requirements). ▫ New use case often help generate new requirements as the system is analyzed and as the design takes shape. • Communicating with the clients. ▫ Their national simplicity makes use case diagrams a mechanism for early discussion with potential users and domain experts. • Generating test cases. ▫ A use case is a generalized description or template of a sequence of transaction, while a scenario is an instance of the use case which describes how the use case will be executed in a specific situation.
- 12. Uml notation for use case Use case Actor System boundary Association Generalization Extend Include <<extend>> <<include>>
- 13. Structuring use case with relationships UML supports three types of relationship for use case <<include>> <<extend>> generalization
- 14. The <<include>> relationship • <<include>> relationship are used when two or more use case share some common portion in the flow of events. Withdraw money Deposit money Login account <<include>> <<include>>
- 15. • <<extend>> relationship are used when two use cases are similar, but one does a bit more than the other. The <<extend>> relationship Withdraw money Process extra amount <<extend>> User
- 16. The generalization relationship • A child use case can inherit the behaviors, relationships and communication links of parent use case. • The relationship between the child use case and the parent use case is the generalization relationship. Pay bill Pay credit card bill Pay utility bill Customer
- 17. Base use case versus abstract use cases • Self study Documenting use cases Use case template
- 18. Prioritizing use cases factors to consider: • Architectural significance of the use case. • Use of new and untested technologies. • Problems that require substantial research effort. • Great improvement in efficiency of the business process. • Use cases that support major business processes.
- 19. Use case modeling and analysis process • Developing the problem statement. • Identifying the major actors and use cases. • Creating an initial use case diagram. • Describing briefly the use cases(with initial descriptions). • Identifying / refining candidate classes using textual analysis
- 20. Refining the use case model includes the following steps. • Developing base use case descriptions. • Iteratively elaborating on the base use cases descriptions and determining the <<extend>>,<<include>> and generalization relationships. • Developing instance scenarios. • Prioritizing use cases.
- 21. Tricks and tips in use case analysis • Use case as a communication tool. • Finding the right use cases. • Correct focus of base use case. • Good use case should be observable. • Use case versus process charts. • Apply textual analysis in different contexts. • Use bi-directional communication associations. • Structure use case models. • Specify use cases in detail… but not too much. • Fit use cases into system architecture.
- 22. That’s all for today…