Abstract:
Structures for the expression of fault-tolerance provisions in application software comprise the central topic of this article. Structuring techniques answer questions as to how to incorporate fault tolerance in the application layer of a computer program and how to manage the fault-tolerant code. As such, they provide the means to control complexity, the latter being a relevant factor for the introduction of design faults. This fact and the ever-increasing complexity of today's distributed software justify the need for simple, coherent, and effective structures for the expression of fault-tolerance in the application software. In this text we first define a " base " of structural attributes with which application-level fault-tolerance structures can be qualitatively assessed and compared with each other and with respect to the aforementioned needs. This result is then used to provide an elaborated survey of the state-of-the-art of application-level fault-tolerance structures.
