An Ontology for Constructing Scheduling Systems
Stephen F. Smith, Marcel Becker · 1997
In this paper, we consider the use of ontologies as a basis for structuring and simplifying the process of constructing domain-specific problem-solving tools. We focus specifically on the task of scheduling. Though there is commonality in scheduling system requirements and design at several levels across application domains, differ-ent scheduling environments invariably present different challenges (e.g., different dominating constraints, different objectives, different domain structure, different sources of uncertainty, etc.), and hence we can expect high-performance ap-plication systems to require customized solu-tions. Unfortunately, the time and cost associ-ated with such domain-specific system develop-ment at present is typically quite large. Our work toward overcoming this application construction bottleneck has led to the devel-opment of OZONE, a toolkit for configuring constraint-based scheduling systems. A cen-tral component of OZONE is its scheduling on-tology, which defines a reusable and extensi-ble base of concepts for describing and repre-senting scheduling problems, domains and con-straints. The OZONE ontology provides a frame-work for analyzing the information requirements of a given target domain, and a structural foun-dation for constructing an appropriate domain model. Through direct association of software component capabilities with concepts in the on-tology, the ontology promotes rapid configuration of executable systems and allows concentration of modeling effort on those idiosyncratic aspects of the target domain. The OZONE ontology and toolkit represent a synthesis of extensive prior work in developing constraint-based scheduling models for a range of applications in manufac-turing, space and transportation logistics. We first motivate the use of ontologies as model building tools, establishing linkages to recent con-cepts in software engineering and proposing an extended view of ontologies that includes capabil-ity descriptions. We then describe our perspec-tive on the structure of planning and schedul-ing domain models and summarize major com-ponents of current OZONE scheduling ontology.