A framework for the definiton of a generative design pattern

Conventional design patterns found in many pattern atalogues are stati omponents of reusable design knowledge. They are fully des riptive of the problems they will solve, but the des riptive knowledge and design they provide does not des ribe how they an work with other patterns in a design and development pro ess. Therefore, the ontention of this thesis is that the knowledge ontained within stati design patterns is inadequate for the purpose of applying the patterns to generate a software ar hite ture with the intention of developing software systems. The fo us of this resear h has been the investigation of Design Patterns and their potential ontribution to a generative development pattern language. Generative design patterns are a tive and dynami : they des ribe how to reate something and an be observed in the resulting systems they help to reate. To this end, a framework is presented that identi es the notational qualities that an be applied to a design pattern for the bene t of implementing ar hite tural design. The impra ti ality of stati design patterns for ar hite tural design is addressed by revising the standard design pattern with a notation that des ribes the pattern as a generative omponent. The notation required for this revision is abstra ted in part from the ri h set of design notations and knowledge ontained within: (a) the quality driven pro esses ontained in development methods that ontributed to the now standard Uni ed Modelling Language (UML), (b) the des riptive ontent of two distin t pattern lassi ations i Design Patterns: Elements of Reusable Obje t-Oriented Software[45℄, ii A Catalogue of General-Purpose Software Design Patterns[104℄ and ( ) a known study of relationships between design patterns i Relationships Between Design Patterns[119℄. TABLE OF CONTENTS List of Figures vi List of Tables ix Chapter 1: Introdu tion 1 Chapter 2: Exploring The Link Between Software Development Methods And Patterns 6 2.1 Introdu tion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 2.1.1 Pattern / Method Analogy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 2.2 Obje t-Oriented Software Development Methods . . . . . . . . . . . . . . . . . . . . . . 7 2.3 Contemporary Software Development Methods . . . . . . . . . . . . . . . . . . . . . . . 9 2.3.1 Rational Uni ed Pro ess . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 2.3.2 Agile Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 2.3.3 Model Driven Ar hite ture (MDA) . . . . . . . . . . . . . . . . . . . . . . . . . . 22 2.4 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 Chapter 3: Understanding Design Pattern Notation 27 3.1 Introdu tion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 3.2 Patterns in Obje t-Oriented Software . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 3.2.1 The Pattern Con ept . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 3.2.2 Idioms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 3.2.3 Pattern Catalogues { (Design Patterns) . . . . . . . . . . . . . . . . . . . . . . . 28 i 3.2.4 Pattern Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 3.2.5 A Pattern Language . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 3.2.6 Design Pattern Stru ture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 3.2.7 Narrative Form (Portland) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37 3.3 De ning a Template . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 3.4 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55 Chapter 4: Relationships Between Patterns 56 4.1 Introdu tion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56 4.2 Classi ation of Design Patterns . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57 4.2.1 High Level Classi ation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57 4.2.2 Low Level Classi ation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59 4.3 Individual Relationships . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64 4.4 Pattern Map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68 4.5 Des ribing Relationships . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69 4.5.1 Classi ation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70 4.5.2 Problem Solving . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71 4.5.3 Asso iation Type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74 4.6 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76 Chapter 5: Pattern Modelling 77 5.1 Introdu tion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77 5.2 Sequen e Diagrams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78 5.3 Class Diagrams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82 5.4 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88 ii Chapter 6: A Generative Design Pattern 90 6.1 Introdu tion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90 6.2 Generative Pro ess . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91 6.2.1 Summary of Chapter Two . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91 6.2.2 Summary of Chapter Three . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91 6.2.3 Summary of Chapter Four . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91 6.2.4 Summary of Chapter Five . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92 6.3 Generative Pattern Format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92 6.4 Composite as a Generative Design Pattern . . . . . . . . . . . . . . . . . . . . . . . . . . 94 6.5 Con lusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104 6.6 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105 Chapter 7: Evaluation 106 7.1 Introdu tion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106 7.1.1 Evaluation Strategy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107 7.2 Metri s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108 7.3 Stati vs. Generative Patterns . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110 7.3.1 Introdu tion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110 7.3.2 A Simple Case Study using Composite and De orator . . . . . . . . . . . . . . . 112 7.3.3 A Simple Case Study using Composite, Command and Builder . . . . . . . . . . 115 7.3.4 A Case Study using Composite, Command, De orator and Builder . . . . . . . . 119 7.3.5 An Alternative Case Study using Composite, Command, De orator and Builder 124 7.4 Con lusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 130 7.5 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132 iii Chapter 8: Con lusion 133 Chapter 9: Future Work 135 9.1 Introdu tion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135 9.2 To label patterns by their Classi ation, Problem and Asso iation type . . . . . . . . . 136 9.2.1 Problem type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136 9.2.2 Classi ation type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136 9.2.3 Relational type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 137 9.3 A de nitive standard or formula for ombining or ex luding ombinations of patterns . . 138 9.4 Develop a ase tool for design using generative patterns . . . . . . . . . . . . . . . . . . 139 9.5 Formal Mathemati al Spe i ation of generative patterns . . . . . . . . . . . . . . . . . 139 9.6 Consideration of design patterns for de nition and usability . . . . . . . . . . . . . . . . 140 Bibliography 141 Appendix A: Composite ombines Command 150 Appendix B: Composite ombines Builder 158 Appendix C: Builder ombines Command ombines Composite 166 Appendix D: Builder Uses Command 177 Appendix E: Relationship Trees 186 E.0.1 Stru tural . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 186 E.0.2 Creational . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 187 E.0.3 Behavioural . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 188 Appendix F: Pattern Sour e Code and S enarios 189 iv F.1 Sour e Code { S enario 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 189 F.2 S enario 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 193 F.3 S enario 3, based on E kel[39℄ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 199 Appendix G: Software Metri Suite 208 G.1 Basi [16℄ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 208 G.2 Cohesion[16℄ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 209 G.3 Complexity[16℄ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 210 G.4 Coupling[16℄ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 213 G.5 En apsulation[16℄ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 218 G.6 Halstead[16℄ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 219 G.7 Inheritan e[16℄ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 220 G.8 Inheritan e-Based Coupling[16℄ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 220 G.9 Maximum[16℄ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 223 G.10 Polymorphism[16℄ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 223 G.11 Ratio[16℄ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 224 G.12 Test Coverage[16℄ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 225 Appendix H: Additional Case-Studies 226 H.1 A Simple Case Study using Composite and Builder . . . . . . . . . . . . . . . . . . . . . 226 H.2 A Simple Case Study using Command and Builder . . . . . . . . . . . . . . . . . . . . . 229 H.3 A Simple Case Study using Composite and Command . . . . . . . . . . . . . . . . . . . 232 Appendix I: An Example Design Pattern 235 I.1 Fa ade (Based on Gamma[45℄) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 235 v LIST OF FIGURES 2.1 MDA Development Life y le[66℄ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 2.2 MDA Transformation Pro ess[66℄ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 4.1 Relationships Between Design Patterns . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58 4.2 Creational Pattern Information Hierar hy . . . . . . . . . . . . . . . . . . . . . . . . . . 61 4.3 Behavioural Pattern Information Hierar hy . . . . . . . . . . . . . . . . . . . . . . . . . 62 4.4 Relationships Between Design Patterns (Based on Zimmer[119℄) . . . . . . . . . . . . . . 65 4.5 Pattern X uses, is used by . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66 4.6 Patterns Related to Composite . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69 4.7 Relationship between Composite and De orator . . . . . . . . . . . . . . . . . . . . . . . 75 5.1 Sequen e Diagram for the Broker Pattern . . . . . . . . . . . . . . . . . . . . . . . . . . 78 5.2 Sequen e Diagram for the Broker Pattern . . . . . . . . . . . . . . . . . . . . . . . . . . 79 5.3 Sequen e Diagram for the Dispat her View Pattern . . . . . . . . . . . . . . . . . . . . . 80 5.4 Dispat her in Controller Strategy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80 5.5 Dispat her in View Strategy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81 5.6 Composite Class Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83 5.7 Grand's Composite Class Diagram[48℄ . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84 5.8 Reverse Engineered Composite Class Diagram[48℄ . . . . . . . . . . . . . . . . . . . . . . 85 5.9 Composite Pattern . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86 5.10 Grand's De orator Class Diagrams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87 5.11 Grand's Builder Class Diagrams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88 vi 6.1 Stru ture of the Composite Pattern . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96 6.2 Relationship between Composite and De orator . . . . . . . . . . . . . . . . . . . . . . . 100 6.3 Use-Case Diagram Composite ombines De orator . . . . . . . . . . . . . . . . . . . . 101 6.4 Class Diagram Composite ombines De orator . . . . . . . . . . . . . . . . . . . . . . . 102 7.1 Generative vs. Stati { Composite and De orator . . . . . . . . . . . . . . . . . . . . . . 112 7.2 Generative vs. Stati { Command + Composite + Builder . . . . . . . . . . . . . . . . . 115 7.3 Generative vs. Stati { Command + Composite + Builder + De orator . . . . . . . . . 119 7.4 Example Appli ation using Stati Design Patterns . . . . . . . . . . . . . . . . . . . . . 124 7.5 Example Appli ation using Dynami Design Patterns . . . . . . . . . . . . . . . . . . . . 125 A.1 Relationship between Composite and Command . . . . . . . . . . . . . . . . . . . . . . . 151 A.2 Use-Case Diagram Composite ombines Command . . . . . . . . . . . . . . . . . . . . 151 A.3 Class Diagram Composite ombines Command . . . . . . . . . . . . . . . . . . . . . . 152 A.4 Sequen e Diagram Composite ombines Command . . . . . . . . . . . . . . . . . . . . 153 B.1 Relationship between Composite and Builder . . . . . . . . . . . . . . . . . . . . . . . . 159 B.2 Use-Case Diagram Composite ombines Builder . . . . . . . . . . . . . . . . . . . . . . 159 B.3 Class Diagram Composite ombines Builder . . . . . . . . . . . . . . . . . . . . . . . . 160 B.4 Sequen e Diagram Composite ombines Builder . . . . . . . . . . . . . . . . . . . . . . 161 C.1 Relationship between Builder, Command and Composite . . . . . . . . . . . . . . . . . . 167 C.2 Use-Case Diagram Builder ombines Command ombines Composite . . . . . . . . . . 168 C.3 Class Diagram Composite ombines Command . . . . . . . . . . . . . . . . . . . . . . 169 C.4 Sequen e Diagram Composite ombines Command . . . . . . . . . . . . . . . . . . . . 170 D.1 Relationship between Builder and Command . . . . . . . . . . . . . . . . . . . . . . . . 178 vii D.2 Use-Case Diagram Builder uses Command . . . . . . . . . . . . . . . . . . . . . . . . . 178 D.3 Class Diagram Builder uses Command . . . . . . . . . . . . . . . . . . . . . . . . . . . 179 D.4 Sequen e Diagram Builder uses Command . . . . . . . . . . . . . . . . . . . . . . . . . 180 E.1 Stru tural Hierar hy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 186 E.2 Creational Hierar hy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 187 E.3 Behavioural Hierar hy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 188 F.1 Use-Case Diagram Composite ombines De orator . . . . . . . . . . . . . . . . . . . . 193 F.2 Class Diagram Composite ombines De orator . . . . . . . . . . . . . . . . . . . . . . . 194 F.3 Use-Case Diagram Composite ombines De orator . . . . . . . . . . . . . . . . . . . . 199 F.4 Class Diagram Composite ombines De orator . . . . . . . . . . . . . . . . . . . . . . . 200 G.1 The relation among the di erent types of supplier lasses . . . . . . . . . . . . . . . . . 217 H.1 Generative vs. Stati { Composite and Builder . . . . . . . . . . . . . . . . . . . . . . . 226 H.2 Generative vs. Stati { Command and Builder . . . . . . . . . . . . . . . . . . . . . . . 229 H.3 Generative vs. Stati { Command and Composite . . . . . . . . . . . . . . . . . . . . . . 232 I.1 Fa ade as an Interfa e . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 235 I.2 Message Creator as Fa ade . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 236 viii LIST OF TABLES 3.1 Design Patterns' Notation[45℄ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 3.2 Bus hmann's Pattern Notation[20℄ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 3.3 Bus hmann's alternative ategories of Notation[19℄ . . . . . . . . . . . . . . . . . . . . . 32 3.4 Alexander's Pattern Notation[3℄ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 3.5 Coplien's Pattern Notation for a Generative Development-Pro ess[29℄ . . . . . . . . . . 34 3.6 Meszaros' Criteria on Pattern Stru ture[79℄ . . . . . . . . . . . . . . . . . . . . . . . . . 36 3.7 Varying Uses of Notation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 3.8 Amalgamating Notation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 3.9 Reje ted Notation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49 3.10 Reje ted Amalgamated Notation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51 3.11 A epted Notation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53 4.1 Design Pattern Classi ation[45℄ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57 4.2 Logi al Information for a Generative Design Pattern Iteration 1 . . . . . . . . . . . . . 59 4.3 Logi al Information for a Generative Design Pattern Iteration 2 . . . . . . . . . . . . . 62 4.4 Logi al Information for a Generative Design Pattern Iteration 3 . . . . . . . . . . . . . 67 4.5 Con rete Information for a Generative Design Pattern Iteration 1 . . . . . . . . . . . . 71 4.6 Con rete Information for a Generative Design Pattern Iteration 2 . . . . . . . . . . . . 74 4.7 Con rete Information for a Generative Design Pattern Iteration 3 . . . . . . . . . . . . 74 7.1 General statisti s for the Generative and Stati versions of Composite and De orator . . 113 7.2 Individual statisti s for the Generative and Stati versions of Composite and De orator 114 ix 7.3 Code statisti s for the Generative and Stati versions of Command + Composite + Builder116 7.4 Individual statisti s for the Generative and Stati versions of Command, Composite and Builder . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118 7.5 Code statisti s for the Generative and Stati versions of Command, Composite, De orator and Builder . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121 7.6 Individual statisti s for the Generative and Stati versions of Command, Composite, De orator and Builder . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123 7.7 Code statisti s for the Generative and Stati versions of a tou h s reen ash register . . 127 7.8 Individual statisti s for the Generative and Stati versions of Command, Composite, De orator and Builder . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 130 H.1 General statisti s for the Generative and Stati versions of Composite and Builder . . . 227 H.2 Individual statisti s for the Generative and Stati versions of Composite and Builder . . 228 H.3 General statisti s for the Generative and Stati versions of Command and Builder . . . 230 H.4 Individual statisti s for the Generative and Stati versions of Command and Builder . . 231 H.5 General statisti s for the Generative and Stati versions of Command and Composite . . 233 H.6 Individual statisti s for the Generative and Stati versions of Command and Composite 234 x 1 Chapter