Developers' Perception of Co-change Patterns: An Empirical Study (ICSME 2015)

Co-change clusters are groups of classes that frequently change together. They are proposed as an alternative modular view, which can be used to assess the traditional decomposition of systems in packages. To investigate developer’s perception of co-change clusters, we report in this paper a study with experts on six systems, implemented in two languages. We mine 102 co-change clusters from the version history of such systems, which are classified in three patterns regarding their projection to the package structure: Encapsulated, Crosscutting, and Octopus. We then collect the perception of expert developers on such clusters, aiming to ask two central questions: (a) what concerns and changes are captured by the extracted clusters? (b) do the extracted clusters reveal design anomalies? We conclude that Encapsulated Clusters are often viewed as healthy designs and that Crosscutting Clusters tend to be associated to design anomalies. Octopus Clusters are normally associated to expected class distributions, which are not easy to implement in an encapsulated way, according to the interviewed developers.

Transcript

1. Developers’ Perception of Co-change
   Patterns: An Empirical Study
   Luciana Silva, Marco T. Valente Marcelo Maia Nicolas Anquetil
   UFMG – Brazil UFU – Brazil INRIA – France
   ICSME 2015, Bremen
   

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2. What is a well-modularized
   system?
   2
   

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4. Modules should hide important design decisions
   or decisions that are likely to change
   [Parnas, 1972] .
   4
   

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5. How often changes are localized in modules?
   Do crosscutting changes reveal design
   problems?
   5
   

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6. Co-change Clusters
   6
   

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7. Co-change Clusters
   Assessing Modularity using Co-change Clusters
   Modularity 2014 7
   

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8. Co-change Clusters
   Co-change graph
   Assessing Modularity using Co-change Clusters
   Modularity 2014 7
   

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9. Co-change Clusters
   Co-change graph
   Co-change
   cluster
   Assessing Modularity using Co-change Clusters
   Modularity 2014 7
   

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10. Co-change Clusters
    Co-change graph
    Co-change
    cluster
    Assessing Modularity using Co-change Clusters
    Modularity 2014
    Distribution map
    7
    

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11. Distribution Maps
    8
    

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12. Co-change Patterns
    

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13. Encapsulated Clusters
    9 9 9 9 9
    9 9 9 9 9
    9 9 9 9 9
    9 9 9 9 9
    MorphicPager
    10 10 10 10 10
    SeasideExamples
    9 9 9 9 9
    9 9 9 9 9
    10 10 10 10 10
    SeasideCore
    10 10 10 10 10
    10 10 10 10 10
    10 10 10 10 10
    10 10 10 10 10
    10
    SeasideRendering
    9
    

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14. Encapsulated Clusters
    9 9 9 9 9
    9 9 9 9 9
    9 9 9 9 9
    9 9 9 9 9
    MorphicPager
    10 10 10 10 10
    SeasideExamples
    9 9 9 9 9
    9 9 9 9 9
    10 10 10 10 10
    SeasideCore
    10 10 10 10 10
    10 10 10 10 10
    10 10 10 10 10
    10 10 10 10 10
    10
    SeasideRendering
    Nice
    modules?
    9
    

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15. Crosscutting Clusters
    8
    8
    8 8
    8
    8 8
    8 8
    session
    8
    8
    action
    8 8
    8
    model.task
    8
    8 8
    model.egp
    8
    8 8
    model.involved
    8 8
    action.task
    8
    util
    10
    

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16. Crosscutting Clusters
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    8
    8 8
    8
    8 8
    8 8
    session
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    action
    8 8
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    model.task
    8
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    model.egp
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    8 8
    model.involved
    8 8
    action.task
    8
    util
    Crosscutting concern?
    Modularity flaw?
    Major refactoring?
    Re-architecting?
    10
    

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17. Octopus Clusters
    18 18
    18 18 18 18 18
    18 18 18 18 18
    18 18 18 18
    Finder
    18
    RoassalPaintings
    18 18 18 18 18
    18
    11
    

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18. Octopus Clusters
    18 18
    18 18 18 18 18
    18 18 18 18 18
    18 18 18 18
    Finder
    18
    RoassalPaintings
    18 18 18 18 18
    18
    Move class
    refactoring?
    11
    

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19. Research Questions
    RQ #1: To what extent do the proposed co-change patterns
    cover real instances of clusters?
    12
    

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20. Research Questions
    RQ #1: To what extent do the proposed co-change patterns
    cover real instances of clusters?
    RQ #2: How developers describe the clusters matching the
    proposed co-change patterns?
    12
    

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21. Research Questions
    RQ #1: To what extent do the proposed co-change patterns
    cover real instances of clusters?
    RQ #2: How developers describe the clusters matching the
    proposed co-change patterns?
    RQ #3: To what extent do the clusters matching the proposed
    co-change patterns indicate design anomalies?
    12
    

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22. Study Design
     Java
    System Description
    SysPol Automation of criminal investigation process
    13
    

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23. Study Design
    Pharo
    System Description
    Seaside Framework for web applications
    Moose Software and data analysis
    Fuel Object serialization framework
    Epicea Tool to share untangled commits
    Glamour Infrastructure for impl. browsers
    14
    

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24. Study Design
    Pharo
    System Description
    Seaside Framework for web applications
    Moose Software and data analysis
    Fuel Object serialization framework
    Epicea Tool to share untangled commits
    Glamour Infrastructure for impl. browsers
    14
    

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25. Study Design
    Pharo
    System Description
    Seaside Framework for web applications
    Moose Software and data analysis
    Fuel Object serialization framework
    Epicea Tool to share untangled commits
    Glamour Infrastructure for impl. browsers
    14
    

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26. Study Design
    15
    

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27. RQ#1. Do Pattern Cover Extracted
    Clusters?
    102 mined clusters
    16
    

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28. RQ#1. Do Pattern Cover Extracted
    Clusters?
    102 mined clusters
    16
    

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29. RQ#1. Do Pattern Cover Extracted
    Clusters?
    17
    

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30. RQ#1. Do Pattern Cover Extracted
    Clusters?
    17
    

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31. RQ#1. Do Pattern Cover Extracted
    Clusters?
    17
    

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32. RQ#1. Do Pattern Cover Extracted
    Clusters?
    18
    

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33. View Slide

34. 19
    RQ #2. Developer’s Perception
    

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35. RQ #2. Developer’s Perception
    Implement clean and well-defined concerns
    19
    

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36. RQ #2. Developer’s Perception
    10 10 10 10 10
    SeasideExamples
    10 10 10 10 10
    SeasideCore
    10 10 10 10 10
    10 10 10 10 10
    10 10 10 10 10
    10 10 10 10 10
    10
    SeasideRendering
    Rendering: web widgets and rendering logic
    Core: widget library
    Glamour
    20
    

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37. 10 10 10 10 10
    SeasideExamples
    10 10 10 10 10
    SeasideCore
    10 10 10 10 10
    10 10 10 10 10
    10 10 10 10 10
    10 10 10 10 10
    10
    SeasideRendering
    “The Presenter classes represent an abstract description for a widget, …
    concrete widget by the Renderer.
    … widget library (Core) is changed, the Renderer logic is also changed.
    After that, the Examples are updated.”
    Glamour’s Developer
    21
    RQ #2. Developer’s Perception
    

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38. 22
    RQ #3. Design Anomalies
    

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39. 22
    RQ #3. Design Anomalies
    

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40. “The developer … new browser … the guidelines for packages in
    Glamour.
    Despite of these classes define clearly the browser creation
    concern, ...”
    Glamour’s developer
    9 9 9 9 9
    9 9 9 9 9
    9 9 9 9 9
    9 9 9 9 9
    MorphicPager
    9 9 9 9 9
    9 9 9 9 9
    23
    RQ #3. Design Anomalies
    

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42. 24
    RQ #2. Developer’s Perception
    

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43. 24
    RQ #2. Developer’s Perception
    Functional Concerns
    “CreateArticle is a quite generic use case … .
    …, when implementing a new use case, … change classes
    associated to CreateArticle”
    Syspol’s developer
    

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44. RQ #2. Developer’s Perception
     Non-functional Concerns
    8
    8
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    8 8
    8 8
    session
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    action
    8 8
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    model.task
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    model.egp
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    model.involved
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    action.task
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    util
    This cluster implements Access to database and Article template
    25
    

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45. 26
    RQ #3. Design Anomalies
    

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46. 26
    RQ #3. Design Anomalies
    

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47. 27
    RQ #3. Design Anomalies
    

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48. Low cohesion/high coupling
    28
    RQ #3. Design Anomalies
    

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49. Low cohesion/high coupling
    Contains “one of the classes with the highest
    coupling in the system.”
    SysPol’s developer
    28
    RQ #3. Design Anomalies
    

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50. Complex concerns
    29
    RQ #3. Design Anomalies
    

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51. Complex concerns
    “this is a difficult part to understand in the system and
    its implementation is quite complex.”
    SysPol’s developer
    29
    RQ #3. Design Anomalies
    

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52. Package decomposition problem
    30
    RQ #3. Design Anomalies
    

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53. Package decomposition problem
    “this package includes implementation logic that should
    be in an under layer.”
    SysPol’s developer
    30
    RQ #3. Design Anomalies
    

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54. View Slide

55. 31
    RQ #2. Developer’s Perception
    

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56. 31
    RQ #2. Developer’s Perception
    18 18
    18 18 18 18 18
    18 18 18 18 18
    18 18 18 18
    Finder
    18
    RoassalPaintings
    18 18 18 18 18
    18
    Used to display visualizations inside browsers.
    Moose
    Browsers –
    Moose panels
    Generic class for
    visualization
    

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57. 32
    RQ #3. Design Anomalies
    

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58. 32
    RQ #3. Design Anomalies
    

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59. 33
    RQ #3. Design Anomalies
    

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60. 34
    RQ #3. Design Anomalies
    

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61. 35
    Could we Remove the Tentacles?
    

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62. “Unfortunately, … difficult to localize changes in just
    one package.
    …
    Shielding changes is not absolutely possible.”
    Glamour’s developer
    36
    

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63. Main Findings
    37
    

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64. Main Findings
    37
    

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65. Main Findings
    37
    

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