基于S-A模型的触发器机制

A Trigger Mechanism Based on S-A Model

为了更有效地实现主动实时数据库的主动特性 ,从研究其主动机制入手 ,对传统的 E-C-A(EVENT-CONDITION-ACTION)模型进行了改进 ,提出了一种新的触发器模型—— S-A (SITUATION-ACTION)模型。该模型将事件和条件统一在情形之中 ,消除了复杂的事件 -条件匹配 ,简化了情形评价 ,使系统能更好地适应实时应用的要求。基于 S-A模型给出了一个触发器执行模型及实现方法。

In order to effectively realize the active characteristics of an active real time database,improvement is made on traditional Event Condition Action (E C A) model Starting with the study of its active mechanism,a new trigger model,that is Situation Action(S A) model,is proposed In the model,event and condition are unified in the cases,in which the match of complex event condition is eliminated,the evaluation of cases is simplified,thus the system could meet the needs of real time application A model of trigger execution and a method of implementation are given based on the S A model