DEPENDABLILITY ENGINEERING:
Dependability engineering is concerned with the techniques that are used to enhance the dependability of both critical and non-critical systems. These techniques support three complementary approaches that are used in developing dependable software:
1. Fault avoidance: The software design and implementation process should use approaches to software development that help avoid design and programming errors and so minimize the number of faults that are likely to arise when the system is executing. Fewer faults mean less chance of run-time failures.
2. Fault detection and correction: The verification and validation processes are designed to discover and remove faults in a program, before it is deployed for operational use. Critical systems require very extensive verification and validation to discover as many faults as possible before deployment and to convince the system stakeholders that the system is dependable.
3. Fault tolerance: The system is designed so that faults or unexpected system behavior during execution are detected at run-time and are managed in such a way that system failure does not occur. Simple approaches to fault tolerance based on built-in run-time checking may be included in all systems. However, more specialized fault-tolerance techniques (such as the use of fault-tolerant system architectures) are generally only used when a very high level of system availability and reliability is required.
