High assurance system for tokyo metropolitan area railway network
K. Kera · 2005
L Introduction Large-scale public systems in today’s information control field require. that seveml conditions should be satisfied. Fmt, a phased-in construction of the system must be possible so that the system can be constructed over a long period of time. Second the system must be flexible and be adapted to meet the changes of social needs. All such systems are assumed to constantly grow, expand and change. We must modify the system in order to grow it; however, its reliability may be reduced by every modiftcation. In the case of a conventional system where it is assumed that there will be no growth, reliability is assured if the system is reliable when introduced. On the other hand, a growing system has the major problem of stable operation without reduction of reliability even as it is routinely modd the technology it uses is called asSuratl~ technology. 2. High-Assurance System Technology Autonomous Decentralimd System (ADS) architecture has been used mainly to realize high assumce computer systems in control systems field. Information Technology has developed remarkably in recent years, and the systems have many high functions. For example, a control system supplies not only conventional control function, but also various information se-vies and other heterogeneous functions. For such gmwing large-scale system in which heterogeneous functions co-exist, the mechanism to protect mutual violation from each other should be mpired. And the mechanism to minimize the effects to the existing functions should be necessary. Furthermore the mechanism to protect online system from test