Event specification in spatio-temporal database design

摘要

It is the main character of a computer supported land subdivision system that the spatio-temporal database is event-driven. The behavior aspect has to be taken into consideration and three types of relationships between events and states of land parcles must be represented while designing the spatio-temporal databases for such kinds of systems. This paper devoted to the description and representation of behavior aspect. Events in land subdivision procedure is analyzed and defined. The whole process of land subdivision can be viewed as a complicated "composite event" which is consisted of primitive events and event operators. With a formal event specification language, we might "compute" the pattern and process of composite events occureence via the occurrence of primitive events. Thus the process of land subdivision can be represented formally and the behavior of land subdividing might be monitored, simulated and deduced explicitly. In addition, with some restrictions triggering some operations, the system might response "actively" in some circumstance. With this approach proposed in the paper, it is possible to meet the requirements of the operational office GIS and provide a radically new method for the system procedure controlling. When the work-flow of the system changed, we just modify the combination pattern of composite events and need not change the database schema. It is useful for re-uability of specification and CASE tool design.