SCHEDULE MANAGEMENT - AN OBJECT-ORIENTED APPROACH

In this paper we discuss the design of decision support systems, usable in several planning situations. We consider resource-constrained time-dependent scheduling problems with time as the important planning component. Instead of dealing with optimization aspects of the planning problem, we concentrate on schedule management, i.e. stepwise planning with respect to primitive functions, like handling single decisions or constraints. The design of these systems is based on a mathematical model, giving a formal characterization of a class of scheduling problems and allowing generic descriptions of scheduling objects like processors, operations, decisions and constraints. The model is applied to various scheduling problems, like resource constrained project scheduling, car routing, the construction of time tables both for schools and for nursery in hospitals. An object oriented implementation of the model, based on the natural hierarchy of scheduling problems, turns out to lead to a clear separation between the generic and the domain specific components of the schedule manager, minimizing redundant code and resulting in software with a high degree of maintainability.