The success of our project depends on their acceptance. Unfortunately, it is
not always possible to ask our future users directly. In this case, we try to fi nd a
suitable substitute, e.g., somebody in product management or marketing.
We use the standard symbol for actors??”the stick man??”to represent users
( Figure 2.12 ).
An external system is a system that interacts directly with the system to be
modeled. In its role as an interaction partner, the external system is seen merely
as a black box. This external system can be the system under development in
another project, and our system would then assume the role of an external
system from their point of view.
An external system is denoted as a box ( Figure 2.13 ).
A user system is a type of external system that serves as a medium for a
user to interact with our system. Typical user systems are keyboard, display, and
dashboards.
Whether we model the keyboard as an interaction partner or the user directly
as an actor depends on the project. It can be useful for technical systems to
FIGURE 2-12
A user ??? customer.
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