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An Action Task specifies a concrete operation that must be executed within an action (see figure below).

The Extensible Object Constraint Action Task

An Action Task's operation uses a specific action resource. For an Action Task's duration, other tasks are required to leave enough of the action resource's capacity to carry out the task's operation. An Action Resource Constraint (ARC) internally projects an action resource's capacity and reflects an overload of the resource by its cost function.

The Extensible Conventional Action Resource Constraint

Each Action Task must be linked to a specific ARC of the required ResourceType (see figure below). The Action Task that is to be executed at the Current Time on an action resource is determined by the ARC by demanding a special value for the task's ExecutionState variable.

The Structural Constraint Action Task

In addition, all ARCs must have a different ResourceType. To realize this, we can use an All Different constraint (see following figure). This constraint ensures that all connected variables have different values.

The Extensible Conventional Constraint All Different

An ARC must have its ResourceType variable connected to an All Different constraint (see figure below). The requirement that there be no other All Different constraint for different ARCs is enforced by the structural constraint All Different (upper alternative of the testing part).

The Structural Action Resource Constraint

The uniqueness of an ARC's ResourceType also ensures that an Action Task cannot be connected to two ARCs at the same time.

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Last update:
May 20, 2001 by Alexander Nareyek