The Design And Implementation Of Real-time Database System In Industrial Control

Real-time Database is the integration based on the technologies both of real-time controlling and of database system, which is widely used in the fields where there are urgent demands on the functions of database system and the properties of real-time transaction. And there are explicit limitations on data and transactions in the real-time DBS (DataBase System). Furthermore, the validity of DBS is based not only on the logic result of transactions, but also on its time. Based on the industrial process controlling, this paper studies the popular techniques of real-time DBS synthetically, and then gives the design and implementation of the Linux-based real-time database system in C language. The whole system includes the modules of transaction dealing, time controlling, security dealing, real-time data dealing, the historical data dealing and the user interface processing. And the system has a application interface for the client accessing. Therefore the real-time system can provide the functions, such as real-time data accessing, real-time controlling, exception handling and man-machine conversation, on the base of the formal modules. The critical technic of real-time DBS is how to bulid and maintain the databas system in RAMs. This paper analyses the memory managements of Linux platform, and implemente the technique of memory locking with the aid of Linux-based system calls on memory management. In order to improve the efficiency of DBS, which is affected by the data I/O operations, buffering and backing up the real-time data in the memory is applied to store the real-time data. Multi-process and the message-queue-based communication among them, according to the process scheduling managements in Linux, have been applied in the implementation. For the time-critical dealing of the transactions, there is the combination of event-driven processing and periodically querying in the design of real-time DBS. To control or customize the system, a Shell interface has been implemented and embedded in the real-time DBS in man-machine conversation. MySQL, the Free & Open Source Media database management system, and its API in C are applied in the communication of historical database. And the Web service on PHP make it avaliable for the clients to access the historical database on network. From the mentioned above, the powerful system calls of Linux-based platform and its resource in it are the base of this design & implementation. Furthermore, the properities of real-time and industrial controlling are taken into consideration in order to improve the efficiency of the DBS.