System Fault Tolerance Specification: Proposal of a Method Combining Semi-formal and Formal Approaches

Abstract

Abstract. The topic of the present work is the specification of system Fault Tolerance (FT). FT is considered a valid technique for increasing the dependability of critical automation systems by adding them the ability to operate in presence of faults. Two basic considerations stimulated the development of the present work. Firstly although a considerable amount of concepts and theory have been published around FT, a full-organized method supporting their application to the FT needs of a specific system is still missing. Furthermore, the availability of a methodology oriented to the specification of system FT is especially useful in view of integrating available FT software layers according to specific system needs. Goal of the present work is therefore to develop a methodology for the FT specification, to be used as a tool supporting the configuration of the tailorable FT software layer, which is currently under development within the TIRAN Project 1 . The presented approach to the FT specification is based on a combined use of two generalpurpose specification methods: the UML (Unified Modeling Language) graphical method and the TRIO (Tempo Reale ImplicitO) temporal logic. The main novelty of the proposed method consists in the identification and organization of a sequence of specification steps, which drive the industrial user in collecting and analyzing system dependability requirements and then in designing FT solutions, possibly tailoring already existing and configurable FT mechanisms.

Towards a Methodological Approach to Specification and Analysis of Dependable Automation Systems

“…The work on CDs and TRIO in DepAuDE takes its basis from the preliminary work in [11], in which the first ideas on the use of CD in the context of dependability analysis of automation systems and the possibilities of cooperation of TRIO specification with CD models were discussed. The work presented in this paper represents a step forward, by introducing a three steps incremental specification: the derivation of the TRIO specification structure from the UML Class Diagrams, a first completion of the specification with domain dependent knowledge and the full formalisation with application dependent knowledge.…”

/spl Rscr/έℒ: a fault tolerance linguistic structure for distributed applications

“…The target market segment concerns non-safety-critical distributed soft-real-time embedded systems [3]. TIRAN explicitly adopts formal techniques to support requirement specification and predictive evaluation [16]. This, together with the intensive testing on pilot applications, is exploited in order to: This same structure is replicated on each processing node of the system.…”