Use case diagram
A use case diagram at its simplest is a representation of a user's interaction with the system that shows the relationship between the user and the different use cases in which the user is involved. A use case diagram can identify the different types of users of a system and the different use cases and will often be accompanied by other types of diagrams as well. The use cases are represented by either circles or ellipses.
While a use case itself might drill into a lot of detail about every possibility, a use-case diagram can help provide a higher-level view of the system. It has been said before that "Use case diagrams are the blueprints for your system". They provide the simplified and graphical representation of what the system must actually do.
Due to their simplistic nature, use case diagrams can be a good communication tool for stakeholders. The drawings attempt to mimic the real world and provide a view for the stakeholder to understand how the system is going to be designed. Siau and Lee conducted research to determine if there was a valid situation for use case diagrams at all or if they were unnecessary. What was found was that the use case diagrams conveyed the intent of the system in a more simplified manner to stakeholders and that they were "interpreted more completely than class diagrams".
The purpose of the use case diagrams is simply to provide the high level view of the system and convey the requirements in laypeople's terms for the stakeholders. Additional diagrams and documentation can be used to provide a complete functional and technical view of the system.
- McLaughlin et al, 2006, page 297
- Siau & Lee, 2004, page 234
- Gemino, A., Parker, D.(2009) "Use case diagrams in support of use case modeling: Deriving understanding from the picture", Journal of Database Management, 20(1), 1-24.
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- McLaughlin, B., Pollice, G., West, D. (2006). Head First Object Oriented Analysis and Design, O'Reilly Media, Inc.
- Siau, K., Lee, L. (2004). "Are use case and class diagrams complementary in requirements analysis? An experimental study on use case and class diagrams in UML", Requirements Engineering, 9(4), 229-237.
- Vidgen, R. (2003). "Requirements Analysis and UML: Use Cases and Class Diagrams", Computing & Control Engineering, 14(2), 12.