“Actually, we had something completely different in mind.” Not a sentence that you want to hear from a customer. But it happens. Because reality always shows us how different people communicate differently, or misunderstand things – Paul Watzlawick, the Austrian-American communication scientist, sends his greetings. When requirements in your software are misunderstood, imprecisely communicated or just not mentioned by the customer, that doesn’t just lead to uncomfortable conflict, it also costs you time and money. That is why use cases and use case diagrams have proven themselves in project management: a graphic visualization of the behavior of a system from the view of the user, described through defined visual means of UML (Unified Modeling Language). They offer great support when finding and defining requirements.
Use case diagram: a short definition
A use case diagram is a behavior diagram and visualizes the observable interactions between actors and the system under development. The diagram consists of the system, the related use cases and actors and relates these to each other:
System: What is being described?
Actor: Who is using the system?
Use Case: What are the actors doing?