Architectural Reasoning for Safety Critical Software Applications

................................................................................................................. 3 CONTENTS.................................................................................................................. 5 LIST OF FIGURES ................................................................................................... 13 LIST OF TABLES ..................................................................................................... 17 ACKNOWLEDGEMENTS....................................................................................... 19 AUTHORS DECLARATION................................................................................... 21 ABBREVIATIONS .................................................................................................... 23 CHAPTER ONE: INTRODUCTION ...................................................................... 27 1.1 THE STATE OF ARCHITECTING ...................................................................... 27 1.1.1 Software Architecture........................................................................... 28 1.1.2 Safety and Software Architecture......................................................... 29 1.1.3 Requirements Engineering and Software Architecture........................ 31 1.2 RESEARCH CHALLENGES............................................................................... 31 1.2.1 Engineering Early-Stage Safety Requirements .................................... 33 1.2.2 Identifying and Selecting Design Alternatives for Safety..................... 34 1.2.3 Supporting Incremental Safety Argumentation.................................... 34 1.3 THESIS PROPOSITION..................................................................................... 35 1.4 DEFINITIONS ................................................................................................. 37 1.4.1 Safety and Risk ..................................................................................... 37 1.4.2 Accidents and Hazards......................................................................... 37 1.4.3 Failures, Errors and Faults ................................................................. 38 1.5 THESIS STRUCTURE....................................................................................... 39 CHAPTER TWO: DESIGNING THE ARCHITECTURE ................................... 43 2.