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Object-Oriented Environmental Fault Tolerance

Lookup NU author(s): Professor Brian RandellORCiD


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Many entities in the real world that a software system has been designed to interact with, e.g., for controlling or monitoring purposes, exhibit quite different kinds of behaviour in their lifetime, in particular depending on whether or not they are functioning correctly. That is, these entities exhibit not only a normal behaviour but also one or more kinds of abnormal behaviour associated with the various faults which occur in the environment. These faults are referred to as environmental faults. In a class-based object-oriented language, such as C++, all objects of a given class must follow the same behaviour. However this requires that each object permanently belong to a particular class, imposing constraints on the mutability of its behaviour. This paper proposes solutions to the problem of finding means whereby objects representing such real-world entities can make such behaviour changes in a clear and explicit way, rather than through status-checking code which is normally embedded in the implementation of various methods. Our proposed solution defines statically the abnormal behaviour variants of an object, and runtime access to them is implemented through a delegation mechanism depending on the object's current state.

Publication metadata

Author(s): Rubira CMF, Randell B

Publication type: Conference Proceedings (inc. Abstract)

Publication status: Published

Conference Name: 6° Sympósio de Computadores Tolerantes a Falhas, XV Congresso da Sociedade Brasileira de Computação

Year of Conference: 1995

Pages: 417-439

Publisher: Instituto de Informática, Universidade Federal do Rio Grande do Sul