An actor initiates a use case, and an actor (possibly the initiator, but not necessarily) receives something of value from the use case. The graphic representation is straightforward. An ellipse represents a use case, a stick figure represents an actor is on the right. The actor’s name appears just below the actor. The name of the use case appears either inside the ellipse or just below it. An association line connects an actor to the use case, an represents communication between the actor and the use case. The association line is solid, like the line that connects associated classes. One of the benefits of use case analysis is that it shows the boundary between the system and the outside world. Actors are typically outside the system, whereas use cases are inside. You use a rectangle (with the name of the systems somewhere inside) to represent the system boundary. The rectangle encloses the system’s use case.
USE Case model diagram show below.
NOTE: - In a use case model, a stick figure represents an actor, an ellipse represents an actor, an ellipse represents communication between the actor and the use case.
Understanding the Use Case
What about the use case? Here are some possibilities: “provide security levels,” “ Create a proposal,” store a proposal,” “use email,” Share database information,” perform accounting,” “Connect to the LAN from outside the LAN,” Connect to the internet,” “share database information,” “Catalog proposals,” Use prior proposals,” and “ Share printer,” Based on this information,High-level use case diagrams shows below.
Note: - The hierarchy of users who will interact with the LAN. This set of use cases constitutes the functional requirements for the LAN.