Summary: Component Based Design of Multitolerance
Anish Arora Sandeep S. Kulkarni
Department of Computer and Information Science 1
The Ohio State University
Columbus, Ohio 43210 USA
The concept of multitolerance abstracts problems in system dependability and pro
vides a basis for improved design of dependable systems. In the abstraction, each source
of undependability in the system is represented as a class of faults, and the corresponding
ability of the system to deal with that undependability source is represented as a type
of tolerance. Multitolerance thus refers to the ability of the system to tolerate multiple
faultclasses, each in a possibly different way.
In this paper, we present a component based method for designing multitolerance.
Two types of components are employed by the method, namely detectors and correctors.
A theory of detectors, correctors, and their interferencefree composition with intolerant
programs is developed, that enables stepwise addition of components to provide tolerance
to a new faultclass while preserving the tolerances to the previously added faultclasses.
We illustrate the method by designing a fully distributed, multitolerant program for a
Keywords : formal methods, compositional design, interferencefreedom, stepwise design,