ABSTRACT
Information systems today play key roles in our daily lives. For example, in traveling from Tokyo to New York, one would go through a ticket reservation system for airline booking, weather forecast system for clothing selection, traffi c-light control system to drive safely to the airport, ATMs at the airport for cash, kiosks for airline check-in, turnstile systems, fl ights controlled by an air-traffi c control system, airplanes controlled by on-board avionics, and so forth. These systems are further supported by back-end services such as fi nancial and corporate management systems. These information systems are connected with one another directly or indirectly to form large-scale integrated information systems, which work to support our information-dependent daily lives. Dependability is defi ned here as the attribute of a system that provides continuous services to users. This defi nition will develop as this concept is discussed in depth in this book.
