To fully understand the system's purpose you must know who the system is for, that is, who will be using the system.
Different user types are represented as actors.
An actor is anything or anyone that exchanges data with the system. An actor can be a user, external hardware, or
another system.
The difference between an actor and an individual system user is that an actor represents a particular class of user
rather than an actual user. Several users can play the same role, which means they can be one and the same actor. In
that case, each user constitutes an instance of the actor.
Ivar and Mark are operators of a recycling machine. When they are using the machine each is represented by an instance
of the actor Operator.
However, in some situations, only one person plays the role modeled by an actor. For example, there may be only one
individual playing the role of system administrator for a rather small system.
The same user can also act as several actors (that is, the same person can take on different roles).
Charlie uses the Depot-Handling System primarily as Depot Manager, but sometimes he also uses the Depot-Handling System
as ordinary Depot Staff.
For each actor identified, capture the name and brief description. See Guideline: Find and Outline Actors and Use Cases for some questions to help identify
actors.
It is also necessary to capture the use cases that this actor initiates and those use cases in which the actor plays a
secondary role.
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