Towards agent-oriented specification of information systems

| Abstract | Objects in information systems usually have a very long lifespan. Therefore, it often happens that during the life of an object external requirements are changing, e.g. changes of laws. Such changes often require the object to adopt another behavior. In consequence, it is necessary to get a grasp of dynamically changing object behavior. Unfortunately, not all possible changes can in general be taken into account in advance at speciication time. Hence, current object speci-cation approaches cannot deal with this problem. Flexible extensions of object speciication are needed to capture such situations. The concept of agent which can be seen as a further development of the concept of object seems to provide a more adequate basis for modeling such information system dynamics. In comparison to traditional objects, agents are exible in that sense they may change their behavior dynamically during system run-time, i.e. the behavior of an agent is not (or can not be) completely determined at compile or speciica-tion time. In order to get a grasp of such properties, we need an agent-oriented speciication framework which goes beyond the existing object-oriented ones. Our approach can be described as follows: We start from a well-known object-oriented speciication framework for information systems which allows us to describe structure as well as long-term behavior of objects in information systems. We extend this object-oriented framework by introducing a certain form of knowledge as part of the internal state of objects. Here, we especially concentrate on the speciication of evolving temporal behavior. For that, we propose an extension (called Evolving Temporal Logic) of classical temporal logic approaches to object speciication. We propose a two-level speciication framework for mod-eling of information systems in terms of agents. The rst level contains usual attributes and events, which describe the xed behavior of an agent. In the second level, the possible evolution of the agent speciication is speciied. Example: In Figure 1 the structure of a possible specii-cation of an agent class Account is sketched. The specii-cation language used here can be considered as an extension of the object-oriented language Troll Jungclaus et al. 1996]. Similar to objects, agents have attributes (e.g. Balance) and events (e.g. Withdraw). The part of the behavior speciication which must not be changed is speciied in the rigid axioms section. In our example the eeect of the events Withdraw and Deposit on the attribute Balance is xed. In addition to the …