| During these years, Distributed real-time control systems,widely used in the field of safety critical systems. But there is few distributed system strong enough to stand against attacks, like a a weak building. To defend these systems from attacks and meet the need of improving the system security and dependability, it is necessary to safely operate and upgrade the systems .At the beginning of this paper, a basic real-time system model of programmable controler has been analyzed. Then some novel security mechanisms are explored and investigated for time critical system. In this paper, a command pattern is introduce in the system architecture, and furthermore, an online upgradable model to realize system upgrading safely is presented.Most embedded software is developed in units or components, with developers working in parallel on their respective parts, which are then integrated into a finished system. Typically, developers will test individual units before moving ahead to final integration. One key problem developers face is the inability to see what sections of software code have actually been executed during testing, which makes it difficult to identify high-risk areas. Finally, as software runs on production hardware in a real-world application, it constantly responds to interrupts and data from a variety of I/O devices. As a result, software code behaves very differently in this environment than it did while under development, and there is little assurance that what appeared to be stable while running in the development environment is still stable in the deployed product. This paper provide a logical analyze solution for embedded system.Debugging a faulty program can be very hard and time-consuming. The programmer usually reexecutes his program, while zooming in on the root cause of the bug. However, sometimes bugs seem to appear only intermittently, making it even harder for the programmer to solve them. The main reason for this is that when... |
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