Types of Actor in a Use Case Model
Actors in use case modeling can be people, other systems, temporal triggers, or event triggers.
An actor specifies the role played by a user or any other system that interacts with the subject. It can represent a role played by a human user, external hardware, or other subjects.
Actors are always outside the system, interacting directly with the system by initiating a use case, providing input to the system, and/or receiving output from the system.
An actor does not necessarily represent a specific physical entity, for example, a timer that triggers the sending of an email alert.
Primary vs Supporting Actors
Primary Actor: a user whose defined user goal and is fulfilled by the system
Supporting Actors: a user who provides a service (e.g., information) to the system.
Non-Human Actors
We often miss key personas during the use case mapping process because they only identify human actors. For non human actors we can identify:
System/Software
Hardware
Timer/Clock
