Software Design: Creating Solutions for Ill-Structured Problems

365 Pages·2020·10.644 MB·English

by  David Budgen

Software Design
Chapman & Hall/CRC Innovations in Software Engineering and Software Development
Series
Richard LeBlanc
Seattle University, Washington, USA
This series covers all aspects of software engineering and software development. Books
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effective.
Introduction to Combinatorial Testing
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Jon Duncan Hagar
Software Essentials Design and Construction
Adair Dingle
Software Metrics A Rigorous and Practical Approach, Third Edition
Norman Fenton, James Bieman
Computer Games and Software Engineering
Kendra M. L. Cooper, Walt Scacchi
Evidence-Based Software Engineering and Systematic Reviews
Barbara Ann Kitchenham, David Budgen, Pearl Brereton
Engineering Modeling Languages Turning Domain Knowledge into Tools
Benoit Combemale, Robert France, Jean-Marc Jézéquel, Bernhard Rumpe, James Steel,
Didier Vojtisek
Speed, Data, and Ecosystems Excelling in a Software-Driven World
Jan Bosch
Introduction to Software Engineering, Second Edition
Ronald J. Leach
Software Design, Third Edition
David Budgen
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Software Design
Creating Solutions for Ill-
Structured Problems
Third Edition
David Budgen
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Library of Congress Cataloging-in-Publication Data
Names: Budgen, David, author.
Title: Software design : creating solutions for ill-structured problems /
David Budgen.
Description: Third edition. | Boca Raton : CRC Press, 2021. | Series:
Chapman & Hall/CRC innovations in software engineering | Includes
bibliographical references and index.
Identifiers: LCCN 2020037195 (print) | LCCN 2020037196 (ebook) | ISBN
9781138196612 (paperback) | ISBN 9780367676568 (hardcover) | ISBN
9781315300078 (ebook)
Subjects: LCSH: Computer software--Development.
Classification: LCC QA76.76.D47 B83 2021 (print) | LCC QA76.76.D47
(ebook) | DDC 005.1--dc23
LC record available at https://lccn.loc.gov/2020037195
LC ebook record available at https://lccn.loc.gov/2020037196
ISBN: 9780367676568 (hbk)
ISBN: 9781138196612 (pbk)
ISBN: 9781315300078 (ebk)
Typeset in Computer Modern font
by KnowledgeWorks Global Ltd.
To the late Jim Tomayko.
Historian, software engineer, teacher, sportsman, coach, aviator, author, fam-
ily man, and an inspiring friend who had a huge heart for others, whatever
their role in life.

Contents
Preface to the Third Edition xiii
The City Car Club 1
I Addressing Ill-Structured Problems 5
1 What Is Designing About? 7
1.1 When is design needed? . . . . . . . . . . . . . . . . . . . . . 7
1.2 A bit about software . . . . . . . . . . . . . . . . . . . . . . 10
1.3 What exactly do we mean by ‘design’? . . . . . . . . . . . . 12
1.4 Three perspectives upon design thinking . . . . . . . . . . . 14
Key take-home points about what designing is about . . . . . . . 16
2 Doing Design 19
2.1 Designing as a creative process . . . . . . . . . . . . . . . . . 19
2.2 Ill-structured problems . . . . . . . . . . . . . . . . . . . . . 21
2.3 What does a designer do? . . . . . . . . . . . . . . . . . . . . 24
2.4 A simple example: the house move . . . . . . . . . . . . . . . 27
Key take-home points about designing . . . . . . . . . . . . . . . 28
3 Managing the Design Process 31
3.1 Cognitive capacity . . . . . . . . . . . . . . . . . . . . . . . . 31
3.2 The power of abstraction . . . . . . . . . . . . . . . . . . . . 32
3.3 Modelling and making design choices . . . . . . . . . . . . . 34
3.4 Recording design decisions . . . . . . . . . . . . . . . . . . . 35
3.5 Communicating ideas about a design model . . . . . . . . . . 37
Key take-home points about the design process . . . . . . . . . . . 40
4 Design Knowledge 43
4.1 What do expert software designers do? . . . . . . . . . . . . 43
4.2 Some software design principles . . . . . . . . . . . . . . . . 49
4.2.1 Fitness for purpose . . . . . . . . . . . . . . . . . . . . 49
4.2.2 Separation of concerns . . . . . . . . . . . . . . . . . . 50
vii
viii Contents
4.2.3 Minimum coupling . . . . . . . . . . . . . . . . . . . . 51
4.2.4 Maximum cohesion . . . . . . . . . . . . . . . . . . . . 52
4.2.5 Information hiding . . . . . . . . . . . . . . . . . . . . 52
4.3 The evolution of design ideas . . . . . . . . . . . . . . . . . . 53
4.4 The nature of expert design knowledge . . . . . . . . . . . . 55
Key take-home points about design knowledge . . . . . . . . . . . 57
5 Empirical Knowledge about Software Design 59
5.1 Measuring software development processes . . . . . . . . . . 59
5.1.1 Measuring physical phenomena . . . . . . . . . . . . . 60
5.1.2 Measuring human reactions . . . . . . . . . . . . . . . 61
5.2 Empirical studies in software engineering . . . . . . . . . . . 63
5.2.1 The empirical spectrum . . . . . . . . . . . . . . . . . 64
5.2.2 The research protocol . . . . . . . . . . . . . . . . . . 65
5.2.3 Qualitative studies . . . . . . . . . . . . . . . . . . . . 65
5.2.4 Quantitative studies . . . . . . . . . . . . . . . . . . . 66
5.2.5 Case studies. . . . . . . . . . . . . . . . . . . . . . . . 67
5.3 Systematic reviews . . . . . . . . . . . . . . . . . . . . . . . . 69
5.4 Using empirical knowledge . . . . . . . . . . . . . . . . . . . 71
Key take-home points about empirical knowledge . . . . . . . . . 72
II Design as a Noun: How Software Is Structured 75
6 Software Architecture 77
6.1 What architecture provides for us . . . . . . . . . . . . . . . 77
6.2 Architectural style . . . . . . . . . . . . . . . . . . . . . . . . 79
6.2.1 Pipe-and-filter architectural style . . . . . . . . . . . . 82
6.2.2 Call-and-return architectural style . . . . . . . . . . . 83
6.2.3 Data-centred repository architectural style. . . . . . . 84
6.3 Architectural patterns . . . . . . . . . . . . . . . . . . . . . . 87
6.3.1 Model-view-controller (MVC) . . . . . . . . . . . . . . 88
6.3.2 Layers . . . . . . . . . . . . . . . . . . . . . . . . . . . 90
6.4 Empirical knowledge about architecture . . . . . . . . . . . . 91
Key take-home points about software architecture . . . . . . . . . 92
7 Modelling Software Properties 93
7.1 What is a design model? . . . . . . . . . . . . . . . . . . . . 93
7.2 Representations, perspectives and viewpoints . . . . . . . . . 96
7.2.1 The constructional viewpoint . . . . . . . . . . . . . . 100
7.2.2 The behavioural viewpoint . . . . . . . . . . . . . . . 101
7.2.3 The functional viewpoint . . . . . . . . . . . . . . . . 101
7.2.4 The data-modelling viewpoint . . . . . . . . . . . . . . 102
7.3 Design notations . . . . . . . . . . . . . . . . . . . . . . . . . 102
Contents ix
7.3.1 Textual description forms . . . . . . . . . . . . . . . . 103
7.3.2 Box and line description forms . . . . . . . . . . . . . 103
7.3.3 Mathematical notations . . . . . . . . . . . . . . . . . 105
7.4 Empirical knowledge related to viewpoint notations . . . . . 106
Key take-home points about design modelling . . . . . . . . . . . 107
8 Sketching Design Models 109
8.1 Why do designers sketch? . . . . . . . . . . . . . . . . . . . . 109
8.2 Sketching: developing informal models . . . . . . . . . . . . . 110
8.3 Characterising the design elements . . . . . . . . . . . . . . . 112
8.3.1 Software design as an ISP . . . . . . . . . . . . . . . . 112
8.3.2 Sketching initial models . . . . . . . . . . . . . . . . . 113
8.4 Empirical knowledge about the use of sketching . . . . . . . 116
Key take-home points about sketching . . . . . . . . . . . . . . . . 116
9 Modelling Software Processes 119
9.1 Characteristics of software processes . . . . . . . . . . . . . . 119
9.2 Modelling function: the data-flow diagram (DFD) . . . . . . 121
9.3 Modelling behaviour: the state transition diagram (STD) and
the state transition table (STT) . . . . . . . . . . . . . . . . 126
9.4 Modelling data: the entity-relationship diagram (ERD) . . . 130
9.5 Modelling construction: the structure chart . . . . . . . . . . 134
9.6 Empirical knowledge about modelling processes . . . . . . . 136
Key take-home points about modelling processes . . . . . . . . . . 136
10 Modelling Objects and Classes 139
10.1 Characteristics of objects and classes . . . . . . . . . . . . . 140
10.1.1 The notion of an object . . . . . . . . . . . . . . . . . 141
10.1.2 Objects and classes . . . . . . . . . . . . . . . . . . . . 145
10.2 Relationships between objects . . . . . . . . . . . . . . . . . 150
10.3 Conceptual issues for object modelling . . . . . . . . . . . . . 153
10.4 Object modelling: the issue of notations . . . . . . . . . . . . 156
10.5 Modelling construction: the class diagram . . . . . . . . . . . 157
10.5.1 Distinguishing classes from objects . . . . . . . . . . . 158
10.5.2 Class relationships . . . . . . . . . . . . . . . . . . . . 159
10.6 Modelling behaviour: the statechart and the message sequence
diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 161
10.6.1 The statechart . . . . . . . . . . . . . . . . . . . . . . 161
10.6.2 The message sequence diagram . . . . . . . . . . . . . 164
10.7 Modelling function: the activity diagram . . . . . . . . . . . 167
10.8 Use cases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 169
10.9 Empirical knowledge about modelling objects and classes . . 172