DEGAS - A DATABASE OF AUTONOMOUS OBJECTS

In this paper we introduce DEGAS (Dynamic Entities Get Autonomous Stat us), an active temporal data model based on autonomous objects. The na tural combination of active and temporal databases is discussed. The a ctive dimension of DEGAS means that we define the behaviour of objects in terms of production rules. The temporal dimension means that the h istory of an object is included in the DEGAS data model. Further novel features of DEGAS are the encapsulation of the complete behaviour of an object, both potential and actual. Thus, DEGAS combines dynamic and structural specifications in one model. In addition, DEGAS allows eas y evolution of object capabilities through a clear distinction between inherent types and capabilities that can be acquired and lost. This a ddon mechanism makes DEGAS very suitable as a formalism for role model ling. Finally, the rule model in DEGAS is both simple, through the use of finite automata, and general, because it allows different strategi es for dealing with constraints and reacting to events in other object s. (C) 1997 Elsevier Science Ltd.