book Page i Thursday, March 20, 2003 7:21 PM Software Architecture in Practice Third Edition Second Edition i The SEI Series in Software Engineering Visit informit.com/sei for a complete list of available products. T he SEI Series in Software Engineering represents is a collaborative undertaking of the Carnegie Mellon Software Engineering Institute (SEI) and Addison-Wesley to develop and publish books on software engineering and related topics. The common goal of the SEI and Addison-Wesley is to provide the most current information on these topics in a form that is easily usable by practitioners and students. Books in the series describe frameworks, tools, methods, and technologies designed to help organizations, teams, and individuals improve their technical or management capabilities.
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Software Architecture in Practice Third Edition Len Bass Paul Clements Rick Kazman ▲ ▼▼ Addison-Wesley Upper Saddle River, NJ • Boston • Indianapolis • San Francisco New York • Toronto • Montreal • London • Munich • Paris • Madrid Capetown • Sydney • Tokyo • Singapore • Mexico City The The The SEI SEIinSeries SEI Series Series ininSoftware SoftwareEngineering Software Engineering Engineering Many of the designations used by manufacturers and sellers to distinguish their products are claimed as trademarks. Where those Many Many of of the designations the designations appeardesignations used in this book, and by used bymanufacturers the manufacturers publisher and was awareandsellers of to distinguish asellers claim, thetheir to distinguish trademark products their arebeen products designations have claimed are printed claimedwith ini- tialas trademarks. ascapital letters orWhere trademarks. Where those thosedesignations in all capitals.
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aCopyright Firstwritten printing,request © 2013 March toPearson 2011PearsonEducation, Education,Inc., Permissions Department, 200 Old Tappan Road, Old Tappan, New Jersey 07657, or you may fax your request to (201) 236-3290. All rights reserved. Printed in the United States of America. This publication is protected by copy- ISBN-13: right, and 978-0-321-81573-6 permission must be obtained from the publisher prior to any prohibited reproduction, stor- ISBN-10: 0-321-81573-4 age in a retrieval system, or transmission in any form or by any means, electronic, mechanical, photo- copying, Text printedrecording, or likewise.
in the United Torecycled States on obtain permission to useinmaterial paper at Courier from Westford, this work, please submit a Massachusetts. written Fifth requestSeptember printing, to Pearson Education, Inc., Permissions Department, One Lake Street, Upper Saddle 2015 River, New Jersey 07458, or you may fax your request to (201) 236-3290. ISBN-13: 978-0-321-81573-6 ISBN-10: 0-321-81573-4 Text printed in the United States on recycled paper at Courier in Westford, Massachusetts. Second printing, May 2013 Contents Preface xv Reader’s Guide xvii Acknowledgments xix Part ONE Introduction 1 CHAPTER 1 What Is Software Architecture? 3 1.1 What Software Architecture Is and What It Isn’t 4 1.2 Architectural Structures and Views 9 1.4 What Makes a “Good” Architecture? 19 1.6 For Further Reading 22 1.7 Discussion Questions 23 CHAPTER 2 Why Is Software Architecture Important? 25 2.1 Inhibiting or Enabling a System’s Quality Attributes 26 2.2 Reasoning About and Managing Change 27 2.3 Predicting System Qualities 28 2.4 Enhancing Communication among Stakeholders 29 2.5 Carrying Early Design Decisions 31 2.6 Defining Constraints on an Implementation 32 2.7 Influencing the Organizational Structure 33 2.8 Enabling Evolutionary Prototyping 33 v vi Contents 2.9 Improving Cost and Schedule Estimates 34 2.10 Supplying a Transferable, Reusable Model 35 2.11 Allowing Incorporation of Independently Developed Components 35 2.12 Restricting the Vocabulary of Design Alternatives 36 2.13 Providing a Basis for Training 37 2.15 For Further Reading 38 2.16 Discussion Questions 38 CHAPTER 3 The Many Contexts of Software Architecture 39 3.1 Architecture in a Technical Context 40 3.2 Architecture in a Project Life-Cycle Context 44 3.3 Architecture in a Business Context 49 3.4 Architecture in a Professional Context 51 3.6 How Is Architecture Influenced? 56 3.7 What Do Architectures Influence? 57 3.9 For Further Reading 59 3.10 Discussion Questions 60 Part TWO Quality Attributes 61 CHAPTER 4 Understanding Quality Attributes 63 4.1 Architecture and Requirements 64 4.3 Quality Attribute Considerations 65 4.4 Specifying Quality Attribute Requirements 68 4.5 Achieving Quality Attributes through Tactics 70 4.6 Guiding Quality Design Decisions 72 4.7 Summary 76 Contents vii 4.8 For Further Reading 77 4.9 Discussion Questions 77 CHAPTER 5 Availability 79 5.1 Availability General Scenario 85 5.2 Tactics for Availability 87 5.3 A Design Checklist for Availability 96 5.5 For Further Reading 99 5.6 Discussion Questions 100 CHAPTER 6 Interoperability 103 6.1 Interoperability General Scenario 107 6.2 Tactics for Interoperability 110 6.3 A Design Checklist for Interoperability 114 6.5 For Further Reading 116 6.6 Discussion Questions 116 CHAPTER 7 Modifiability 117 7.1 Modifiability General Scenario 119 7.2 Tactics for Modifiability 121 7.3 A Design Checklist for Modifiability 125 7.5 For Further Reading 128 7.6 Discussion Questions 128 CHAPTER 8 Performance 131 8.1 Performance General Scenario 132 8.2 Tactics for Performance 135 8.3 A Design Checklist for Performance 142 8.5 For Further Reading 145 8.6 Discussion Questions 145 CHAPTER 9 Security 147 9.1 Security General Scenario 148 9.2 Tactics for Security 150 viii Contents 9.3 A Design Checklist for Security 154 9.5 For Further Reading 157 9.6 Discussion Questions 158 CHAPTER 10 Testability 159 10.1 Testability General Scenario 162 10.2 Tactics for Testability 164 10.3 A Design Checklist for Testability 169 10.5 For Further Reading 172 10.6 Discussion Questions 173 CHAPTER 11 Usability 175 11.1 Usability General Scenario 176 11.2 Tactics for Usability 177 11.3 A Design Checklist for Usability 181 11.5 For Further Reading 183 11.6 Discussion Questions 183 CHAPTER 12 Other Quality Attributes 185 12.1 Other Important Quality Attributes 185 12.2 Other Categories of Quality Attributes 189 12.
