Patterns For Fault Tolerant Software

Software patterns have revolutionized the way developer’s and architects think about how software is designed, built and documented. This new title in Wiley’s prestigious Series in Software Design Patterns presents proven techniques to achieve patterns for fault tolerant software. This is a key reference for experts seeking to select a technique appropriate for a given system. Readers are guided from concepts and terminology, through common principles and methods, to advanced techniques and practices in the development of software systems. References will provide access points to the key literature, including descriptions of exemplar applications of each technique. Organized into a collection of software techniques, specific techniques can be easily found with sufficient detail to allow appropriate choices for the system being designed.

The growing complexity of modern software systems increases the di?culty of ensuring the overall dependability of software-intensive systems. Complexity of environments, in which systems operate, high dependability requirements that systems have to meet, as well as the complexity of infrastructures on which they rely make system design a true engineering challenge. Mastering system complexity requires design techniques that support clear thinking and rigorous validation and veri?cation. Formal design methods help to achieve this. Coping with complexity also requires architectures that are t- erant of faults and of unpredictable changes in environment. This issue can be addressed by fault-tolerant design techniques. Therefore, there is a clear need of methods enabling rigorous modelling and development of complex fault-tolerant systems. This bookaddressessuchacuteissues indevelopingfault-tolerantsystemsas: – Veri?cation and re?nement of fault-tolerant systems – Integrated approaches to developing fault-tolerant systems – Formal foundations for error detection, error recovery, exception and fault handling – Abstractions, styles and patterns for rigorousdevelopment of fault tolerance – Fault-tolerant software architectures – Development and application of tools supporting rigorous design of depe- able systems – Integrated platforms for developing dependable systems – Rigorous approaches to speci?cation and design of fault tolerance in novel computing systems TheeditorsofthisbookwereinvolvedintheEU(FP-6)projectRODIN(R- orous Open Development Environment for Complex Systems), which brought together researchers from the fault tolerance and formal methods communi- 1 ties. In 2007 RODIN organized the MeMoT workshop held in conjunction with the Integrated Formal Methods 2007 Conference at Oxford University.

In architecting dependable systems, what is required to improve the overall system robustness is fault tolerance. Many methods have been proposed to this end, the solutions are usually considered late during the design and implementation phases of the software life-cycle (e.g., Java and Windows NT exception handling), thus reducing the effectiveness error and fault handling. Since the system design typically models only normal behaviour of the system while ignoring exceptional ones, the implementation of the system is unable to handle abnormal events. Consequently, the system may fail in unexpected ways due to faults.It has been argued that fault tolerance management during the entire life-cycle improves the overall system robustness and that different classes of threats need to be identified for and dealt with at each distinct phase of software development, depending on the abstraction level of the software system being modelled.This book builds on this trend and investigates how fault tolerance mechanisms can be applied when engineering a software system. In particular, it identifies the new problems arising in this area, introduces the new models to be applied at different abstraction levels, defines methodologies for model-driven engineering of such systems and outlines the new technologies and validation and verification environments supporting this.

The production of a new version of any book is a daunting task, as many authors will recognise. In the field of computer science, the task is made even more daunting by the speed with which the subject and its supporting technology move forward. Since the publication of the first edition of this book in 1981 much research has been conducted, and many papers have been written, on the subject of fault tolerance. Our aim then was to present for the first time the principles of fault tolerance together with current practice to illustrate those principles. We believe that the principles have (so far) stood the test of time and are as appropriate today as they were in 1981. Much work on the practical applications of fault tolerance has been undertaken, and techniques have been developed for ever more complex situations, such as those required for distributed systems. Nevertheless, the basic principles remain the same.

This book brings together 19 papers focusing on the application of rigorous design techniques to the development of fault-tolerant, software-based systems. It is an outcome of the REFT 2005 Workshop on Rigorous Engineering of Fault-Tolerant Systems held in conjunction with the Formal Methods 2005 conference at Newcastle upon Tyne, UK, in July 2005.

The first ESPRIT programme contained several ambitious projects. of which REQUEST. with its wide brief covering all issues of assessment of quality and reliability of software process and product. was one. Within REQUEST. the research described in this volume. concerning those special problems of software that is required to have extremely high reliability. was particularly difficult and ambitious. The problems of software reliability are essentially twofold. On the one hand there is a concern with methods for achieving adequate reliability. on the other hand there is a need to evaluate what has actually been achieved in a particular case. Naturally. far more effort has been spent over the years on the former problem; indeed. there is a sense in which all of conventional software engineering can be seen as a response to this problem. However. it is becoming clearer than ever that we can only claim to have a truly sCientific approach. and so justify the description software engineering. when we are able to measure the attributes of process and product. It is still common to find software development methods recommended to users on purely anecdotal grounds. This is not good enough. Rational choices between rival approaches can only be made on the basis of quantified costs and benefits. Even more worrying is the tendency to argue that a software product can be depended upon merely because it has been developed by honest men using such anecdotal 'good practice'.

Look to this innovative resource for the most comprehensive coverage of software fault tolerance techniques available in a single volume. It offers you a thorough understanding of the operation of critical software fault tolerance techniques and guides you through their design, operation and performance. You get an in-depth discussion on the advantages and disadvantages of specific techniques, so you can decide which ones are best suited for your work. The book examines key programming techniques such as assertions, checkpointing, and atomic actions, and provides design tips and models to assist in the development of critical fault tolerant software that helps ensure dependable performance. From software reliability, recovery, and redundancy... to design and data diverse software fault tolerance techniques, this practical reference provides detailed insight into techniques that can improve the overall dependability of your software.