-We now discuss UML's behavioral diagrams. Those diagrams that - -2
-have to do with the behavior, the dynamic aspects - -3
-of the system, rather than the static ones. The - -4
-first behavioral diagram I want to discuss is a very - -5
-fundamental one, the Use Case Diagram. So, let's start - -6
-by seeing what a Use Case is. A Use Case - -7
-represents two main things. First the sequence of interactions - -8
-of outside entities which is what we normally call actors - -9
-with the system that we're modelling and the second thing - -10
-is the system actions that yield an observable result of values - -11
-to the actors. And basically these two things, and nothing else - -12
-that the outside view of the system. So the view of - -13
-the system in which we look at the interaction between - -14
-this system, and the outside world. If you want to parallel, think - -15
-about designing a house. Considering how you would use the house. - -16
-And you might have seen use cases called with different names. - -17
-So for example, they're also called scenarios, scripts or user stories, - -18
-but in the context of UML, we'll call the use cases. - -19
-Now let's look at the basic notation for a use case, - -20
-which is fairly simple. We have a use case which is represented - -21
-by an oval, with a name, which is the name of - -22
-the use case. We have an actor, which is represented by - -23
-this icon and is normally identified by a role name. And - -24
-finally we have an edge which is a solid line that connects - -25
-actors and use cases and indicates that an actor - -26
-is the actor of a given use case. And just - -27
-for completeness let me note there are some additional notational - -28
-elements but now for simplicity we'll just use these ones. -- cgit 1.4.1