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If the house is removed, then all
the rooms disappear, but not the furniture. The composite is here also referred to
as the owner of the parts, since it is responsible for them.
Similarly to the real world, there can be only one owner for a part in a composition.
The house/room example shows this clearly. A room of a house cannot
FIGURE 3-13
Association and actor.
uc Actor and association
Customer
Customer
Buy soft drink
?«system?»
Soft-drink vending
machine
FIGURE 3.14
Example for a composition.
class House
House
rooms
1..*
Room
inventory *
Furniture
157
concurrently belong to several houses. With an aggregation, in contrast, there can
be several aggregates concurrently. They are merely referenced by the aggregate.
For example, a piece of furniture can be assigned to several rooms. Another example
from a port logistics system is shown in Figure 3.15 . The containers are present
both as cargo in the ship and as delivery item in the shipment.
3.3.6 Dependency
FIGURE 3-15
Example for an aggregation.
8 Flow controllers are special classes with the primary task to control flows.


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