A use case is a methodology used in system analysis to identify, clarify, and organize system requirements. The use case is made up of a set of possible sequences of interactions between systems and users in a particular environment and related to a particular goal. It consists of a group of elements (for example, classes and interfaces) that can be used together in a way that will have an effect larger than the sum of the separate elements combined. The use case should contain all system activities that have significance to the users. A use case can be thought of as a collection of possible scenarios related to a particular goal, indeed, the use case and goal are sometimes considered to be synonymous.
A use case (or set of use cases) has these characteristics:
- Organizes functional requirements
- Models the goals of system/actor (user) interactions
- Records paths (called scenarios) from trigger events to goals
- Describes one main flow of events (also called a basic course of action), and possibly other ones, called exceptional flows of events (also called alternate courses of action)
- Is multi-level, so that one use case can use the functionality of another one.
Use cases can be employed during several stages of software development, such as planning system requirements, validating design, testing software, and creating an outline for online help and user manuals.
|Getting started with use case methodology|
|To explore how use case is used in the enterprise, here are some additional resources for learning about use case methodology:|
|The pros and cons of use case diagrams: Putting too much into a use case diagram can often render the otherwise useful technique of use cases almost useless. Kevlin Henney recommends a more balanced and restrained approach in order to not lose readers in a myriad of bubbles and microscopic text.|
|From use case diagrams to context diagrams: It's tempting to consider use case diagrams as context diagrams because they do show context. But having one diagram for both will result in an unreadable cloud of bubbles.|
|Five use case traps to avoid: Employing use cases during software requirements analysis helps you improve your chances of developing software that truly meets their needs. But there are traps you should avoid, says expert Karl E. Wiegers.|
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