Embedded Real-time Systems, Real-time Database

With various kinds of technology including microelectronics, communication, computer, control and semiconductor growing up quickly, and the demands for intelligent control becoming more and more complex in many fields such as industry, architecture, medical treatment, national defence etc, embedded system is being widely used in recent years.Most embedded systems in some fields such as industry control,weapon system control and aircraft etc have a common characteristic, which has a strict demand in respond time,and these systems can be also called real-time systems.Building real-time systems now is a general practice. Howerver combing this with a database is not. General-purposed databases are not deterministic in their response time, so they cannot be integrated with a real-time system easily. For a single processor environment a protocol,called the simple transaction protocol, is developed so that it can provide a reliable hard real time service using transactions that can act as a basis for a database service. In this paper, the author mainly investigate how this protocol can be extended to a parallel environment. From this investigation it can be concluded that the timeliness that is present in the original version is hard to guarantee in parallel environments. Exploiting the parallelism introduces timing uncertainties that can be reduced by limiting preemption and stretching transaction sequencing. In this paper the author will perform research on the previous work related to real-time databases. The results will be used to develop an idea on how to exploit and refine some basic ideas available in real-time systems theory about schedulability and resource allocation to creat a straightforward database service, which is of course real-time. The focus is to provide a reasonable QoS(Quality of Service) level that can guarantee the timely completion of a set of database transactions in this environment. Depending on these ideas a simulation model will be made. The simulation shows that this model can be used as a basis for a database service in a soft-real system.