10+ Use Case System Actor. Actor in a use case diagram is any entity that performs a role in one given system. Use cases model the services, tasks, function that a system needs to perform.
A use case is drawn as a horizontal ellipse on a uml use case diagram, as you see in figure 1. We need to define what those users (actors) need from the system. This could be a person, organization or an external system and usually drawn like skeleton shown below.
A use case describes how actors uses a system to accomplish a particular goal.
10+ Use Case System Actor. Use cases model the services, tasks, function that a system needs to perform. On the other hand, notify itself cannot be modelled as an actor using its own use cases. In use case, we will describe 'how a system will respond to a given scenario?'. It is fairly identical to the one that can be found in ian sommerville's book software engineering edition here we can see that the actors of the system are the 'library users', 'library staff' and 'suppliers'.