The Active Mechanism For Embedded Active Real-time Database

Real-time DBMS can support processing of transactions and data with timing constraints. The correctness of the running results of RDBMS not only depend on logic results, but also depend on when the results are produced. It is one of the most important problem worth doing some research that active rules are integrated into RDBMS, so RDBMS has active capabilities which means that system can switch automatically according to system's current state.Based on ARTs-EDB which is an active and real-time DBMS and developed by our research center, research in this paper are mainly about design and implementation of active mechanism supporting ARTs-EDB. Firstly, this paper presents the architecture of ARTs-EDB, the execution model of active mechanism in ARTs-EDB and interfaces between the modules of active mechanism and other subsystems of ARTs-EDB. Then giving the conceptions of active rules, implementation methods and execution schemas, this paper describes detections of different types of events in detail, especially about the detections of time events and complex events. Time events are a key part to realize the timing constraints and evaluation of time conditions of ARTs-EDB and this paper offers an algorithm for it. This paper also discusses the static analysis of active rules. Then this paper puts emphasis on the evaluation of condition of triggers and the execution of trigger. ARTs-EDB takes the S-A model as its trigger model. After description of conditions, its' evaluation is analyzed. To improve the performance of the system, according to nested transaction model, this paper offers a concurrent model to support the triggers' execution by analyzing nested transactions' description and correctness. According to triggers' execution mode and principle, its' sequentially and concurrently running have been realized. In the last part, from a systematic point of view, the implementation of active mechanism is analyzed and the relation between active mechanism and data manipulation, concurrency control, error handling are described.