Enhancing ECA Rules for Distributed Active Database Systems

ECA (event/condition/action) rules have been developed for central active database systems. In distributed active database systems the problem of inaccessibility of partial systems raises and thus the undecidability of ECA conditions referring to remote systems. This work proposes an enhancement of ECA rules for distributed active database systems to react also in the case of inaccessibility and undecidability. Therefore, the ECA evaluation will be enhanced to a strict function with the inaccessibility state Ω and a new alternative action AA enriches the classical ECA rules. The advantages and the usage of this approach are shown by an example of maintaining data consistency in distributed active database systems.