Coping with Change in Scheduling: Toward Proactive and Reactive Integration

In this paper we investigate the integration of off-line and on-line scheduling methodologies: scheduling is in fact a process where the proactive and reactive phases represent a continuum: the task of the scheduler should not be limited to the production of a sequence of activities, as well as the process of controlling schedule execution cannot be exclusively played on the ground of on-line reaction and activity dispatchment. We provide an empirical study which analyzes the mutual interactions among a set of off-line and on-line constraint-based scheduling approaches. We devise a set of execution management algorithms, and compare their behavior within an experimental framework which allows to directly assess the consequences of each chosen strategy combination, through simulated schedule executions. A number of interesting results are described, opening new perspectives for future work.