PDL with Preferences

In the context of network management, Chomicki, Lobo and Naqvi have defined the specification language Policy Description Language (PDL) and later extended it by introducing monitors: constraints on the actions that the network manager can execute simultaneously. This article proposes PPDL, an extension of PDL with preferences that allows the specification of user-defined preferences on how to apply monitors. The new language adopts Brewka's approach to preferences introducing the "×" ordered disjunction connective. We illustrate the feature of PPDL in two interesting application examples: i) the specification of "separation of duties" constraints on user/role assignments in a workflow scenario and ii) an architecture for Web services selection. Since PPDL (as well as PDL) policy specifications can be computed by means of translation into answer set programs, we are able to provide an integrated framework based on answer set programming inferential engine.