Working effectively at scale

Presented at BA:Swiftable in November, 2019.

Transcript

1. Working
   e!ectively
   at scale
   

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2. Francisco
   Díaz
   franciscodiaz.cl - @fco_diaz
   

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3. Startups
   2011 - 2017
   

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4. Airbnb
   2017 - today
   

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14. organizations ... are
    constrained to produce
    designs which are copies of
    the communication structures
    of these organizations
    — Conway's law
    

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15. How do you
    divide
    your codebase?
    

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16. Architectural layer
    

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17. User Flow
    

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18. What about
    Airbnb?
    

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20. 1 million lines
    of Swift
    

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21. ~80 commits
    to master on any given day to the repo (Android + iOS)
    

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22. Bigger
    buckets
    

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24. A user should be
    able to wishlist a
    listing from the
    booking flow
    

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25. How do they
    relate
    with each other?
    

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29. 50 min
    local clean builds
    

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30. ~30 min
    !
    

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31. Buck
    HTTP Cache
    https://github.com/airbnb/BuckSample
    

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33. ~5 min
    !
    

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36. Dependency
    inversion
    

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37. ‣High-level modules should not depend on low-
    level modules. Both should depend on abstractions.
    ‣Abstractions should not depend on details. Details
    (concrete implementations) should depend on
    abstractions.
    

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39. A user should be
    able to wishlist a
    listing from the
    booking flow
    

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41. Easy!
    WishListDataSource
    + interface!
    

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43. WishListDataSource
    is still visible
    

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45. Socializing
    best practices
    

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46. !
    

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47. +60
    iOS developers
    

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48. Automating
    best practices
    

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49. Groups
    Modules
    

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50. Groups
    Modules
    Module Types
    

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51. Module Types
    Feature + Interface
    Service + Interface
    

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52. Feature
    A screen or a flow
    in the app
    

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53. Service
    Manage shared
    state or resources
    

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56. How do we
    enforce these
    best practices?
    

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57. /services
    /service_interfaces
    /features
    /feature_interfaces
    

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58. def service_interface(
    name,
    deps):
    max_visibility = [
    "//ios/feature_interfaces/...",
    "//ios/features/...",
    "//ios/service_interfaces/...",
    "//ios/services/...",
    ]
    

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59. service_interface(
    name = "Networking",
    deps = [
    "//ios/service_interfaces/Logging",
    ],
    )
    

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60. feature(
    name = "Booking",
    deps = [
    "//ios/service_interfaces/Networking",
    "//ios/service_interfaces/WishListService",
    ],
    )
    

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61. iOS Platform
    

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62. Module creation
    needs to be easy
    

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65. rake
    make:module
    

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66. > Provide the type of module you want to create:
    1: Non Platform
    2: Feature
    3: Feature Interface
    4: Service
    5: Service Interface
    4
    > New module name:
    Swiftable
    > Provide a high level description of this module:
    This is a module to present at Swiftable
    

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67. Buck
    Human readable dependencies
    https://github.com/airbnb/BuckSample
    

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68. feature(
    name = "Booking",
    deps = [
    "//ios/service_interfaces/Networking",
    "//ios/service_interfaces/WishListService",
    "//ios/feature_interfaces/HelpCenter",
    ],
    )
    

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70. Feature
    A screen or a flow
    in the app
    

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74. Dev Apps
    

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75. ~1 min
    Dev Apps
    

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76. Big buckets
    Small
    playgrounds
    

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78. How do we
    get there?
    

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79. ~100 modules
    One module type: /libraries
    

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80. libraries/AirbnbBooking
    libraries/AirbnbBusinessTravel
    libraries/AirbnbHelpCenter
    libraries/AirbnbListings
    libraries/AirbnbNetworking
    libraries/AirbnbWishLists
    ...
    

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81. Before iOS Platform
    /libraries
    

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82. On the iOS Platform
    /services
    /service_interfaces
    /features
    /feature_interfaces
    

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83. How to get
    everybody
    on the iOS Platform?
    

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84. Remove libraries/
    and start over
    

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85. !
    

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86. Progressively
    migrate
    

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87. Let's
    migrate
    WishLists Data Source
    

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88. libraries/WishLists
    

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92. What are the
    dependency rules
    for libraries/?
    

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94. Inbound dependencies
    Outbound dependencies
    

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95. Inbound dependencies
    Outbound dependencies
    

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97. The interface module has
    stricter rules
    

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98. Migrate all the call
    sites
    

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99. As the owner of WishLists
    We don't
    control
    these
    

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101. Calculated
     tech debt
     

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102. Inbound dependencies
     Outbound dependencies
     

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104. we know our usage
     of Networking
     

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105. We control our dependencies
     

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106. Allow inbound dependencies from libraries/
     Don't allow outbound dependencies to libraries/
     

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107. libraries/ has access to the
     iOS Platform
     

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108. The iOS Platform doesn't
     have access to libraries/
     

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109. Code on
     the iOS Platform
     has good
     boundaries
     

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110. while we allow for
     easier migration
     

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111. def service_interface(
     name,
     visibility = []):
     max_visibility = [
     "//ios/feature_interfaces/...",
     "//ios/features/...",
     "//ios/service_interfaces/...",
     "//ios/services/...",
     ]
     add_visibility_for_legacy_module_structure(max_visibility)
     

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112. def add_visibility_for_legacy_module_structure(visibility):
     visibility.extend([
     "//ios/libraries/...",
     ])
     

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113. We started
     migrating
     from the bottom up
     

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114. Try it
     ourselves
     !rst
     

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115. Pilot
     with others teams
     

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116. Should I
     implement
     this?
     

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117. Most likely
     NO
     

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118. There's no
     silver bullet
     

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119. Adapt
     

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120. Summary
     1. Figure out where you're struggling
     2.Create and document best practices
     3.Automate best practices where needed
     

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121. ¡Gracias!
     franciscodiaz.cl/talks
     

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