The simple event-condition-action (ECA) rule paradigm of active databases has proved very useful in many AI and database applications. However, its applicability goes beyond data management. ECA rules can be used in network management and monitoring, electronic commerce, security and access management, and other application areas to express policies - collections of general principles specifying the desired behavior of a system. In this paper we use a declarative policy description language PDL, in which policies are formulated as sets of ECA rules. The main contribution of the paper is a framework for detecting action conflicts and finding resolutions to these conflicts. Conflicts are captured as violations of action constraints. The semantics of rules, and conflict detection and resolution are defined axiomatically using logic programs. Given a policy and a set of action constraints the framework defines a monitor that filters the output of the policy to satisfy the constraints. We briefly describe the architecture of a PDL-based policy server being used to provide centralized administration of a soft switch in a communication network and show how it can be augmented to handle conflict resolution.
展开▼
