DISTRIBUTED MANAGEMENT FOR SOFTWARE MAINTENANCE IN A WIDE-AREA RAILWAY SYSTEM

In a large-scale real-time control system, functions of subsystems differ slightly although they seem to be identical. Functions change when hardware is replaced or when the function itself is upgraded. If the standard system is generated and is installed then to each subsystem, subsystems become different with maintenance being carried out in each subsystem to fit its operational conditions. Furthermore, subsystems are distributed in a wide area. Software maintenance therefore becomes very difficult. This paper describes a distributed management for software maintenance in the Tokyo metropolitan-area railway system (ATOS). This management has two phases: distributed management in generating programs and in executing programs. There it contributes to increase the accuracy and ensure the consistency of software maintenance.