Rediscovering. Modularity. Stuttgart JUG November 20 th 2012

Transcription

1 Rediscovering Modularity Stuttgart JUG November 20 th 2012

2 Modularity Manage complexity by Encapsulation

3 Information hiding Modularity Manage complexity by Encapsulation

4 Defined interface Information hiding Modularity Manage complexity by Encapsulation

5 Information hiding Defined interface Clear responsibility Modularity Manage complexity by Encapsulation

6 Information hiding Defined interface Clear responsibility Modularity Manage complexity by Cohesion Encapsulation

7 Information hiding Defined interface Clear responsibility Modularity Manage complexity by Cohesion Encapsulation Coupling

8 Information hiding Defined interface Clear responsibility Cohesion Modularity Manage complexity by Encapsulation Coupling Abstraction

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11 Information hiding Defined interface Clear responsibility Encapsulation Cohesion Coupling Abstraction

12 Information hiding Defined interface Clear responsibility Encapsulation Coupling Abstraction Cohesion Modularity

13 Complexity Composition

14 Complexity Composition Cyclomatic Complexity (CC)

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19 (same problem)

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21 Information hiding Defined interface Clear responsibility Encapsulation Coupling Abstraction Cohesion Modularity

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23 Complexity Composition Cyclomatic Complexity (CC)

24 Complexity Composition Compositional Complexity (CC)

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27 Packages Classes

28 Defined interface? Information hiding? Clear responsibility Encapsulation Coupling? Abstraction Cohesion Modularity?

29 Complexity Composition Compositional Complexity (CC)

30 Complexity Composition Compositional Complexity (CC) +Hierarchical => Scalable

31 Coupling

32 Dependencies

33 Dependencies

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36 Tangles

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47 =

48 = Not scalable!!

49 Ideally Start with a loose architecture

50 Ideally Start with a loose architecture Let suitable architecture emerge, without baggage

51 Ideally Start with a loose architecture Let suitable architecture emerge, without baggage At some point stronger, higher-level abstractions are needed

52 Ideally Start with a loose architecture Let suitable architecture emerge, without baggage At some point stronger, higher-level abstractions are needed (~50Kloc Martin, Foote)

53 Ideally Start with a loose architecture Let suitable architecture emerge, without baggage At some point stronger, higher-level abstractions are needed (~50Kloc Martin, Foote) Restructure to defined architecture

54 Ideally Start with a loose architecture Let suitable architecture emerge, without baggage At some point stronger, higher-level abstractions are needed (~50Kloc Martin, Foote) Restructure to defined architecture Iterate with development

55 Ideally Start with a loose architecture Let suitable architecture emerge, without baggage At some point stronger, higher-level abstractions are needed (~50Kloc Martin, Foote) Restructure to defined architecture Iterate with development Strengthen with growth

56 0.7.2 Mar 04

57 0.8.6 Oct 04

58 0.8.7 Apr 05

59 Erosion Sometimes the developers manage to maintain this purity of design through the initial development and into the first release. More often something goes wrong. The software starts to rot like a piece of bad meat. Bob Martin, Agile Software Development

60 0.8.8 May 05

61 1.0.0 Jun 06

62 1.3.0 Nov 07

63 1.3.5 Sep 08

64 Cost

65 Cost Miserable developers

66 Cost Miserable developers Cost per feature increases

67 Cost Miserable developers Cost per feature increases Unexpected impacts of change

68 Cost Miserable developers Cost per feature increases Unexpected impacts of change Unreliable schedules

69 Cost Miserable developers Cost per feature increases Unexpected impacts of change Unreliable schedules Test cycles increase

70 Cost Miserable developers Cost per feature increases Unexpected impacts of change Unreliable schedules Test cycles increase Reuse less

71 Cost Miserable developers Cost per feature increases Unexpected impacts of change Unreliable schedules Test cycles increase Reuse less Value of your code base declines

72 Technical Debt

73 Technical Debt

74 Technical Debt

75 Technical Debt

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83 bstraction

84 bstraction

85 bstraction

86 bstraction

87 bstraction

88 bstraction

89 Abstraction

90 Abstraction

91 Refactoring Restructuring

92 Refactoring Changing code without modifying behavior to improve nonfunctional attributes. Restructuring Reorganizing a code-base without modifying the code to improve modularity

93 Refactoring Changing code without modifying behavior to improve nonfunctional attributes. Code is readable Restructuring Reorganizing a code-base without modifying the code to improve modularity Code-base is understandable

94 Refactoring Changing code without modifying behavior to improve nonfunctional attributes. Code is readable A lot of invasive code editing Restructuring Reorganizing a code-base without modifying the code to improve modularity Code-base is understandable Minimal invasive code editing

95 Refactoring Changing code without modifying behavior to improve nonfunctional attributes. Code is readable A lot of invasive code editing Scope: small worlds of a few classes at a time; what you see in the IDE. Restructuring Reorganizing a code-base without modifying the code to improve modularity Code-base is understandable Minimal invasive code editing Scope: whole code base; what you don t see in the IDE

96 Retrofitting

97 Retrofitting Physical or virtual?

98 Retrofitting Physical or virtual? Top-down or bottom-up?

99 Retrofitting Physical or virtual? Top-down or bottom-up? Bust big class tangles

100 Retrofitting Physical or virtual? Top-down or bottom-up? Bust big class tangles Create a structured model (levelized+cc) (use strategies)

101 Retrofitting Physical or virtual? Top-down or bottom-up? Bust big class tangles Create a structured model (levelized+cc) (use strategies) Adjust module boundaries (strengthen abstractions)

102 Retrofitting Physical or virtual? Top-down or bottom-up? Bust big class tangles Create a structured model (levelized+cc) (use strategies) Adjust module boundaries (strengthen abstractions) Define layers, visibility

103 Retrofitting Physical or virtual? Top-down or bottom-up? Bust big class tangles Create a structured model (levelized+cc) (use strategies) Adjust module boundaries (strengthen abstractions) Define layers, visibility Repair violations in the implementation levels

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105 Structure101

106 Restructure101 Structure101

107 Restructure101 Structure101 Visualization

108 Restructure101 Structure101

109 Architecture Modularity Structure Mud defined, communicated, enforced interfaces, responsibility encapsulation, coupling Thank you!