Software Design Methodology: From Principles to Architectural Styles

357 Pages·2005·3.88 MB·English

by  Hong Zhu

Software Design Methodology

Software Design Methodology

Hong Zhu

AMSTERDAM BOSTON HEIDELBERG LONDON NEW YORK OXFORD PARIS
SAN DIEGO SAN FRANCISCO SINGAPORE SYDNEY TOKYO
Butterworth-Heinemann
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First published 2005

Copyright © 2005, Hong Zhu. All rights reserved

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The following figure supplied courtesy of Diagram Visual Information Ltd
Figure 4.2
The following figures supplied courtesy of ACM Publications
Figures 4.9, 4.10, 4.12, 4.13, 4.16
The following figure supplied courtesy of AAAI Press
Figure 5.10

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Table of Contents
Preface x
1 Basic Concepts of Design 1
1.1 Introduction............................................................................................................2
1.2 Characteristics of design activities.........................................................................4
1.2.1 The input and start point of designs.............................................................4
1.2.2 The outcome and results of designs.............................................................4
1.2.3 Transformation of data.................................................................................5
1.2.4 Generation of new ideas..............................................................................5
1.2.5 Problem solving and decision making.........................................................5
1.2.6 Satisfying and discovering constraints.........................................................6
1.2.7 Evolution and optimisation in a solution space of diversity........................6
1.3 Essential elements of designs.................................................................................7
1.3.1 Statement of design problem and objectives................................................7
1.3.2 Constraints.................................................................................................11
1.3.3 Description of product...............................................................................11
1.3.4 Rationale....................................................................................................13
1.3.5 Plan of production......................................................................................14
1.3.6 Description of usage..................................................................................15
1.4 The factors that affect designs..............................................................................16
Summary..............................................................................................................21
Exercises...............................................................................................................23
2 Design Quality 27
2.1 Software quality models.......................................................................................28
2.1.1 Hierarchical models...................................................................................28
2.1.2 Relational models......................................................................................29
2.2 The effect of design on software quality...............................................................33
2.2.1 Efficiency...................................................................................................33
2.2.2 Correctness and reliability.........................................................................35
2.2.3 Portability..................................................................................................35
2.2.4 Maintainability...........................................................................................36
2.2.5 Reusability.................................................................................................36
ii Table of Contents
2.2.6 Interoperability..........................................................................................37
2.3 Quality attributes of software design....................................................................39
2.3.1 Witt, Baker and Merritt’s design objectives..............................................39
2.3.2 Parnas and Weiss’s requirements of good designs....................................40
2.3.3 Quality of development process.................................................................41
Summary..............................................................................................................43
Exercises...............................................................................................................44
3 Design Principles 47
3.1 Basic rules of software design..............................................................................48
3.1.1 Causes of difficulties.................................................................................48
3.1.2 Vehicles to overcome difficulties..............................................................51
3.1.3 Basic rules of software design...................................................................53
3.2 Design processes..................................................................................................55
3.2.1 The context of design in software development process............................55
3.2.2 Generic design process: descriptive models..............................................58
3.2.3 Design strategies: prescriptive models.......................................................60
3.3 Structure of software design methods...................................................................66
Summary..............................................................................................................68
Exercises...............................................................................................................68
4 Software Architecture 73
4.1 The notion of architecture.....................................................................................74
4.1.1 Architecture in the discipline of buildings.................................................74
4.1.2 Architecture in the discipline of computer hardware.................................77
4.1.3 The general notion of architecture.............................................................82
4.2 The notion of software architecture......................................................................84
4.2.1 Prescriptive models....................................................................................85
4.2.2 Descriptive models....................................................................................86
4.2.3 Multiple view models................................................................................87
4.2.4 The roles of architecture in software design..............................................92
4.3 Software architectural style..................................................................................94
4.3.1 Introductory examples...............................................................................94
4.3.2 The notion of software architectural style................................................101
Summary............................................................................................................104
Exercises.............................................................................................................106
5 Description of Software Architectures 111
5.1 The visual notation.............................................................................................112
5.1.1 Active and passive elements....................................................................112
5.1.2 Data and control.......................................................................................113
5.1.3 Relationships............................................................................................114
Software Design Methodology iii
5.1.4 Decomposition/composition of architectural elements............................115
5.2 Example 1: www client-server pair....................................................................117
5.3 Example 2: robot soccer UNSW.........................................................................120
5.4 Example 3: training centres’ management information system..........................123
Summary............................................................................................................130
Exercises.............................................................................................................131
6 Typical Architectural Styles 135
6.1 Data flow............................................................................................................138
6.1.1 The general data flow style......................................................................138
6.1.2 The pipe-and-filter sub-style....................................................................141
6.1.3 The batch sequential processing sub-style...............................................144
6.2 Independent components....................................................................................147
6.2.1 The general independent components style.............................................147
6.2.2 The event-based implicit invocation systems sub-style...........................149
6.2.3 The communicating processes sub-style..................................................152
6.3 Call and return....................................................................................................154
6.3.1 The general call and return style..............................................................154
6.3.2 The layered systems sub-style.................................................................158
6.3.3 Data abstraction: the abstract data type and object-oriented sub-styles...159
6.4 Data-centred.......................................................................................................162
6.5 Virtual machine..................................................................................................164
Summary............................................................................................................168
Exercises.............................................................................................................169
7 Using Styles In Design 173
7.1 Choices of styles.................................................................................................174
7.2 Combinations of styles.......................................................................................179
7.2.1 Hierarchical heterogeneous styles............................................................179
7.2.2 Simultaneously heterogeneous styles.......................................................180
7.2.3 Locationally heterogeneous styles...........................................................181
7.3 Case study: keyword frequency vector...............................................................184
7.3.1 Specification of the problem....................................................................184
7.3.2 Designs in various styles..........................................................................185
7.3.3 Analysis and comparison.........................................................................190
Summary............................................................................................................194
Exercises.............................................................................................................195
8 Architectural Design Space 199
8.1 Theory of design spaces.....................................................................................200
8.1.1 Structure of design spaces........................................................................200
8.1.2 Solving design synthesis and analysis problems......................................203
iv Table of Contents
8.2 Design space of architectural elements...............................................................205
8.2.1 Behaviour features...................................................................................205
8.2.2 Static features...........................................................................................210
8.3 Design space of architectural styles....................................................................216
8.3.1 Characteristic features of architectural styles..........................................216
8.3.2 Classification of styles.............................................................................218
Summary............................................................................................................221
Exercises.............................................................................................................222
9 Scenario-Based Analysis and Evaluation 225
9.1 The concept of scenario......................................................................................226
9.2 Scenarios for evaluating modifiability................................................................229
9.2.1 Changes of users’ functional requirements..............................................229
9.2.2 Changes of hardware environment..........................................................231
9.2.3 Changes of software environment...........................................................232
9.2.4 Changes of software components............................................................233
9.2.5 Evaluation of modifiability......................................................................234
9.3 Scenarios for evaluating performance................................................................235
9.3.1 Specification of operational profiles........................................................235
9.3.2 Evaluation and analysis of performance..................................................237
9.4 Scenarios for evaluating reusability....................................................................241
Summary............................................................................................................244
Exercises.............................................................................................................245
10 Analysis and Evaluation Of Modifiability: The SAAM Method··········249
10.1 The input and output...........................................................................................250
10.2 The process.........................................................................................................252
10.2.1 Development of scenarios........................................................................254
10.2.2 Description of candidate architecture......................................................255
10.2.3 Classification of scenarios.......................................................................258
10.2.4 Scenario evaluation..................................................................................258
10.2.5 Revealing scenario interaction.................................................................259
10.2.6 Overall evaluation....................................................................................261
10.3 Case study: analysing architectural designs of keyword frequency vector
extraction system................................................................................................263
10.3.1 Development of scenarios........................................................................263
10.3.2 Main program/subroutine with shared data architecture..........................263
10.3.3 Abstract data type architecture.................................................................267
10.3.4 Implicit invocation architecture...............................................................268
10.3.5 Pipe-and-filter architecture......................................................................270
10.3.6 Overall evaluation....................................................................................272
Summary............................................................................................................273
Exercises.............................................................................................................275
Software Design Methodology v
11 Quality Trade-Off Analysis: The ATAM Method 277
11.1 ATAM analysis process......................................................................................279
11.2 ATAM analysis activities....................................................................................283
11.2.1 Step 1: Present the ATAM.......................................................................283
11.2.2 Step 2: Present the business drivers.........................................................283
11.2.3 Step 3: Present the architectural design...................................................283
11.2.4 Step 4: Identify architectural design decisions.........................................284
11.2.5 Step 5: Generate the quality attribute utility tree.....................................284
11.2.6 Step 6: Analyse the architectural design decisions..................................285
11.2.7 Step 7: Brainstorm and prioritise scenarios.............................................291
11.2.8 Step 8: Analyse the architectural design decisions..................................293
11.2.9 Step 9: Present the results........................................................................293
Summary............................................................................................................295
Exercises.............................................................................................................296
12 Model-Based Analysis: The HASARD Method 299
12.1 Representation of quality models.......................................................................301
12.2 Construction of quality models...........................................................................306
12.2.1 Hazard identification................................................................................307
12.2.2 Cause-consequence analysis....................................................................310
12.2.3 Assembling graphic model......................................................................314
12.2.4 Identification of quality concerns............................................................315
12.3 Derivation of quality features.............................................................................317
12.3.1 Contribution factors of a quality concern................................................317
12.3.2 Sensitive quality attributes of a component.............................................318
12.3.3 Quality risks.............................................................................................320
12.3.4 Trade-off points.......................................................................................321
12.4 Case study: client-server web systems................................................................322
12.4.1 Description of the architecture.................................................................322
12.4.2 Construction of quality model.................................................................323
12.4.3 Analysis of quality features.....................................................................328
Summary............................................................................................................330
Exercises.............................................................................................................330
Index 335