Towards maintaining integrity of federated databases

Supporting integrity constraints is essential for database systems. In consequence, global integrity constraints must be dealt with by federated database systems. Although a lot of work has been done on transaction management in multidatabase systems, the treatment of semantic integrity constraints (e.g. uniqueness conditions), especially detecting (potential) violations and specifying necessary reactions, is often omitted. In this paper, we propose a very flexible way to realize global integrity maintenance in federated database systems. We aim at integrating the active rule paradigm into a federated database framework. Thereby, integrity constraints involving multiple component database systems can easily be supported. Active rules provide a powerful mechanism for communication and cooperation between heterogeneous database systems. In addition, they are to be used for specifying enforcement of constraints in case of violation. For enforcing constraints the existing local mechanisms (e.g. triggers) of the component database systems can be employed. In case this is not possible, an additional layer has to be introduced which realizes the active rule mechanism for the component database system