26/2008 : Robustness in Complex Systems - State of the Art Report

RR Number

26/2008

Author(s)

Vaclav Mikolasek

Abstract

The research of robustness aims at identifying underlying structural and organizational principles of robust systems, that is, systems that keep delivering their function in spite of various unexpected perturbations. This report gives an account of the state of the art of the research of robustness in the context of complex adaptive systems (such as ecosystems) and complex computer systems. In this report, we point out the differences between robustness and dependability, and particularly fault-tolerance. We also discuss the roles of assumptions, constraints, and models when designing a system and argue that some of the prevailing assumptions should be reconsidered for the sake of robustness. Later, we list and outline a few well-tested design practices that will surely make up a significant part of a body of robust design guidelines. We see robustness as an interplay of resilience, adaptability, and recovery. These three concepts constitute a self-enforcing trinity. Resilience copes with temporary degradation of a service and therefore needs recovery which turns otherwise permanent failures into temporary ones. Recovery needs resilience because the process of a component recovery often implies a temporary service shortage, and the rest of the system must be able to deal with the shortage. Adaptability needs both resilience and recovery. The former because the means of adaptation may also ensue temporary lack of service, and the later because adaptation may consist of removing from and (re)integrating components into a system, both actions being supported by recovery.

Bibtex

@techreport{ mikolasek:2008-26,
  author =       "Vaclav Mikolasek",
  title =        "Robustness in Complex Systems - State of the Art Report",
  institution =  "Technische Universit{\"a}t Wien, Institut f{\"u}r Technische Informatik",
  address =      "Treitlstr. 1-3/182-1, 1040 Vienna, Austria",
  type =         "Research Report",
  year =         "2008",
  number =       "26/2008"
}

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