Active-U-Datalog: integrating active rules in a deductive database

The marriage between logic programming and databases has given rise to the definition of deductive databases. These systems allow the users to express data manipulations and queries in a declarative way, and permit efficient storage and retrieval of intensional knowledge. Another improvement in the database field has come from the use of active rules, linking the occurrence of certain events to a reaction (e.g., updates of some data). This kind of rules has proven to be very useful to ensure integrity constraints and to automatize common procedures. This paper presents an integration of active rules in U-Datalog, which is an extension to Datalog supporting declarative specification of updates based on a nonimmediate update semantics. The resulting language, called Active-U-Datalog, extends the semantics of U-Datalog in a conservative way, introducing a PARK-like semantics for active rules activation and firing, and for handling conflicting update requests.