According to the domain models presented in Section 3.3, a task is made up
of a temporal sequence of activities. The temporal consistency constraint
states that, for a given task, each activity can only start when the previous
one is finished. In order to process an activity, a resource should be avail-
able. The kind of resource depends on the type of activity. The resource con-
sistency constraint states that a resource can process only one activity at a
time. In a give period of time, a resource can process a sequence of activities
belonging to different tasks.
In the first scenario, each carrier represents a resource. The city is par-
titioned into delivery areas and each area is assigned to only one carrier. A
delivery area corresponds to a mail delivery task. A delivery task is made up
of a sequence of delivery activities corresponding to different delivery
routes. Each carrier performs the activities of a single task.
The scenario set in the fitness club brings an additional complexity to the
scheduling problem. The scheduler tool should model and manage inter-
dependent resources. This is the case of several athletes using the same set
of training machines for their exercises. Both athletes and machines are
resources that perform activities (i.e. the exercises). Each athlete is assigned
a predefined set of workouts (the training task). The temporal and resource
constraints apply both to the athletes and to the training machines.
Figure 3.4 depicts the revised analysis model. Relationship nextOf indicates
that a resource executes sequences of non-overlapping activities.
Let's consider the situation before the execution of the scheduling
Each activity records the temporal parameters as specified by the user.
They represent the preferences of the user and thus the scheduler should
try to satisfy them as much as possible.
1 .. 1
1 .. 1
1 .. 1
made up of
1 .. n
1 .. n
Figure 3.4 The revised analysis model