A rule model in active databases

Active databases are famous for the ability of monitoring events, reacting to them automatically. The active action is incorporated using rules attracting most of researcher´s attention. Base on the traditional E-C-A rule model, an E-RG model is proposed. Contrasted to E-C-A model, the E-RG model simplifies the coupling mode with only one coupling phase which can simplify the execution of rules and enhances the semantics of rules with a rule graph (named RG) which can capture the complex structure of a group of rules effectively. Not only the execution of three couple modes of rules in E-RG but also the execution of embedded rules are described in details.