Design and Implementation of Scheduling Systems: More Advanced Concepts

This chapter focuses on a number of issues that have come up in recent years in the design, development, and implementation of scheduling systems. The first section discusses issues concerning uncertainty, robustnessRobustness and reactive decision making. In practice, schedules often have to be changed because of random events. The more robust the original schedule is, the easier the rescheduling is. This section focuses on the generation of robust schedules as well as on the measurement of their robustness. The second section considers machine learning mechanisms. No system can consistently generate good solutions that are to the liking of the user. The decision-maker often has to tweak the schedule generated by the system in order to make it usable. A well-designed system can learn from past adjustments made by the user; the mechanism that enables the system to do this is called a learning mechanism. The third section focuses on the design of scheduling engines. An engine often contains an entire library of algorithms. One procedure may be more appropriate for one type of instance or data set, while another procedure may be more appropriate for another type of instance. The user should be able to select, for each instance, which procedure to apply. It may even be the case that a user would like to tackle an instance using a combination of various procedures. This third section discusses how a scheduling engine should be designed in order to enable the user to adapt and combine algorithms in order to achieve maximum effectiveness. The fourth section goes into reconfigurable systems. Experience has shown that system development and implementation is very time consuming and costly. In order to reduce the costs, efforts have to be made to maintain a high level of modularity in the design of the system. If the modules are well designed and sufficiently flexible, they can be used over and over again without any major changes. The fifth section focuses on design aspects of web-based scheduling systems. This section discusses the effects of networking on the design of such systems. The sixth and last section discusses a number of other issues and presents a view of how scheduling systems may look like in the future.