Kotlin Multiplatform in Production

Update on the state of the Kotlin Multiplatform universe, current libraries, and how to get started.

Transcript

1. Kotlin Multiplatform In Production
   Kevin Galligan
   

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3. Touchlab
   

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4. Community
   community!
   

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6. What is Kotlin Multiplatform?
   

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7. kot·lin mul·ti·plat·form
   /ˌkätˈlin məltiˈplatfôrm,ˌkätˈlin məltīˈplatfôrm/
   noun
   noun: kotlin multiplatform
   1.optional, natively-integrated, open-source, code sharing platform, based on the popular,
   modern language kotlin. facilitates non-ui logic availability on many platforms.
   

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8. Optional Sharing
   Low risk. No Big Decisions.
   

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9. Natively Integrated
   smooth interop
   

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10. open source
    

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11. Code Sharing
    not “cross platform”
    

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12. popular
    

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13. popular
    

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14. popular
    

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15. language & tools
    

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16. modern
    

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17. Not UI
    well, not necessarily UI
    

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18. Shared UI == Failure!
    

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19. Shared Logic == Computers
    

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20. Many Platforms
    

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21. Kotlin
    

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22. Kotlin
    JVM
    

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23. Kotlin
    JVM JS
    

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24. Kotlin
    JVM JS Native
    

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25. Kotlin
    JVM JS Native
    iOS Mac
    Linux Windows
    Android/NDK Others…
    

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26. Kotlin
    JVM JS Native
    iOS Mac
    Linux Windows
    Android/NDK Others…
    Webassembly
    

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27. Kotlin
    JVM JS Native
    iOS Mac
    Linux Windows
    Android/NDK Others…
    Webassembly
    Many Platforms
    

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28. Why Kotlin?
    High Efficiency
    Low Risk
    Modern Language/Tools
    Highly Engaged Community
    

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29. mobile is easy
    

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30. mobile is easy
    

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31. Status
    

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32. Q3
    Q2 Q4 Q1 Q2
    2018 2019
    0 .6
    v0.7
    v0.8
    v0.8.2
    v0.9.3
    IDE tooling!
    Coroutines?
    

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33. Q3
    Q2 Q4 Q1 Q2
    2018 2019
    0 .6
    v0.7
    v0.8
    v0.8.2
    v0.9.3
    IDE tooling!
    Coroutines? K/N 1.0, Kotlin 1.3
    Gradle 4.10+
    Android Studio
    

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34. Q3
    Q2 Q4 Q1 Q2
    2018 2019
    0 .6
    v0.7
    v0.8
    v0.8.2
    v0.9.3
    IDE tooling!
    Coroutines? K/N 1.0, Kotlin 1.3
    Gradle 4.10+
    Android Studio
    Other samples/libraries
    Production deployments
    Compiler plugins!
    MT Coroutines!
    

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35. Q3
    Q2 Q4 Q1 Q2
    2018 2019
    0 .6
    v0.7
    v0.8
    v0.8.2
    v0.9.3
    IDE tooling!
    Coroutines? K/N 1.0, Kotlin 1.3
    Gradle 4.10+
    Android Studio
    Compiler plugins!
    Other samples/libraries
    Production deployments
    Paid license/debugger
    Reactive Library
    Big Production Apps
    Webassembly stuff?
    MT Coroutines!
    

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36. TL;DR March
    start getting real end of Q1
    

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37. SHARED CODE
    FOR
    ANDROID & IOS
    

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38. Common
    

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39. Common mainThread?
    

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40. expect val mainThread:Boolean
    

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41. expect val mainThread:Boolean
    actual val mainThread: Boolean
    get() = Looper.myLooper() === Looper.getMainLooper()
    

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42. expect val mainThread:Boolean
    actual val mainThread: Boolean
    get() = Looper.myLooper() === Looper.getMainLooper()
    actual val mainThread: Boolean
    get() = NSThread.isMainThread()
    

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43. expect val mainThread:Boolean
    actual val mainThread: Boolean
    get() = Looper.myLooper() === Looper.getMainLooper()
    actual val mainThread: Boolean
    get() = NSThread.isMainThread()
    actual val mainThread: Boolean = true
    

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44. expect fun currentTimeMillis():Long
    expect fun backgroundTask(backJob:()-> B, mainJob:(B) -> Unit)
    expect fun backgroundTask(backJob:()->Unit)
    expect fun networkBackgroundTask(backJob:()->Unit)
    expect fun initContext():NativeOpenHelperFactory
    expect fun goFreeze(a:T):T
    expect fun T.freeze2(): T
    expect fun simpleGet(url:String):String
    expect fun logException(t:Throwable)
    expect fun settingsFactory(): Settings.Factory
    expect fun createUuid():String
    

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45. expect class Date {
    fun toLongMillis():Long
    }
    expect class DateFormatHelper(format:String){
    fun toDate(s:String):Date
    fun format(d:Date):String
    }
    

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46. actual class Date(val date:java.util.Date) {
    actual fun toLongMillis(): Long = date.time
    }
    actual class DateFormatHelper actual constructor(format: String) {
    val dateFormatter = object : ThreadLocal(){
    override fun initialValue(): DateFormat = SimpleDateFormat(format)
    }
    actual fun toDate(s: String): Date = Date(dateFormatter.get()!!.parse(s))
    actual fun format(d: Date): String = dateFormatter.get()!!.format(d.date)
    }
    

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47. fun initPlatformClient(
    staticFileLoader: (filePrefix: String, fileType: String) -> String?,
    analyticsCallback: (name: String, params: Map) -> Unit,
    clLogCallback: (s: String) -> Unit) {
    

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48. fun initPlatformClient(
    staticFileLoader: (filePrefix: String, fileType: String) -> String?,
    analyticsCallback: (name: String, params: Map) -> Unit,
    clLogCallback: (s: String) -> Unit) {
    AppContext.initPlatformClient ({filePrefix, fileType ->
    loadAsset("${filePrefix}.${fileType}")},
    {name: String, params: Map ->
    val event = CustomEvent(name)
    //Loop
    Answers.getInstance().logCustom(event)
    },
    { Log.w("MainApp", it) })
    

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49. let appContext = AppContext()
    appContext.doInitPlatformClient(staticFileLoader: loadAsset,
    analyticsCallback:
    analyticsCallback,
    clLogCallback: csLog)
    func loadAsset(filePrefix:String, fileType:String) -> String?{
    do{
    let bundleFile = Bundle.main.path(forResource: filePrefix,
    ofType: fileType)
    return try String(contentsOfFile: bundleFile!)
    } catch {
    return nil
    }
    }
    

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50. Common
    

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51. JVM Native
    Common
    

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52. JVM Native
    Common
    Framework
    

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53. JVM Native
    Common
    Framework
    

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54. JVM Native
    Common
    Android
    Stuff
    Framework
    iOS Stuff
    

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55. Libraries!
    

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56. Jetbrains
    • Ktor
    • Kotlinx.Coroutines
    • Kotlinx.io
    • Kotlinx.serialization
    • Atomic-fu (maybe?)
    

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57. Community
    • Sqldelight
    • Knarch.db
    • Multiplatform Settings
    • Stately
    • OKIO2 (developing)
    • Timber (sort of)
    

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58. Community
    • Sqldelight
    • Knarch.db
    • Multiplatform Settings
    • Stately
    • OKIO2 (developing)
    • Timber (sort of)
    

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60. SQLiter
    trim, lightly opinionated SQLite driver
    

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61. SQLit
    trim, lightly opinionated SQLite driver
    

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62. Targets
    Native SQLite
    

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63. Targets
    Native SQLite
    Native SQL
    Encrypted
    

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64. Targets
    Native SQLite
    Native SQL
    Encrypted
    Android SQLite
    

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65. Targets
    Native SQLite
    Native SQL
    Encrypted
    Android SQLite
    Android SQL
    Encrypted
    

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66. Targets
    Native SQLite
    Native SQL
    Encrypted
    Android SQLite
    Android SQL
    Encrypted
    JS?
    

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69. Public Service Announcement
    if you understand anything about native…
    

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70. STATE
    

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71. 3 Ecosystems
    JVM, JS, and Native
    

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72. Kotlin/Native State Rules
    

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73. Rule #1
    Live state belongs to 1 thread
    

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74. Rule #2
    Frozen state can be shared by threads
    

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75. No threading primitives
    No “synchronized”, “volatile”, etc
    

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76. Runtime Safety
    Kotlin/Native can verify safe mutability
    

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77. JVM/JS?
    See Kotlinconf keynote
    

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78. Short term pain
    Tradeoff for future
    

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79. How does Kotlin know?!
    

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80. FROZEN!
    

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81. FROZEN!
    

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82. Runtime Designation
    AKA a flag
    

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83. Call freeze()
    

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84. One-way operation
    No unfreeze()
    

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85. class TalkExamples{
    var justCountingStuff:Int = 0
    init {
    backgroundCall {
    //do something
    justCountingStuff++
    }.freeze()
    }
    }
    

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86. class TalkExamples{
    var justCountingStuff:Int = 0
    init {
    backgroundCall {
    //do something
    justCountingStuff++
    }.freeze()
    }
    }
    

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87. Usually OK
    Data objects should be immutable
    

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88. Global state more difficult
    Service object, large memory state
    

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89. Passing State
    

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90. DetachedObjectGraph(TransferMode.SAFE) { ListData("asdf") }
    

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91. val data = ListData("asdf")
    DetachedObjectGraph(TransferMode.SAFE) { data }
    

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92. private val stateBox: AtomicReference> = AtomicReference(
    DetachedObjectGraph(mode = TransferMode.SAFE,
    producer = { mutableListOf() as Any })
    )
    private val lock = NSLock()
    internal fun withLockDetached(proc: (MutableList) -> MutableList) {
    lock.lock()
    try {
    stateBox.value = DetachedObjectGraph(mode = TransferMode.SAFE,
    producer = {
    val dataList = stateBox.value.attach() as MutableList
    proc(dataList) as Any
    })
    } finally {
    lock.unlock()
    }
    }
    

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93. Detaching Time
    must visit whole graph
    

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97. Atomics!
    Mutable immutable
    

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98. AtomicInt/AtomicLong
    

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99. AtomicReference
    Update with frozen objects
    

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100. val lambdas = AtomicReference(null)
     fun initPlatformClient(
     staticFileLoader: (filePrefix: String, fileType: String) -> String?,
     analyticsCallback: (name: String, params: Map) -> Unit,
     clLogCallback: (s: String) -> Unit) {
     lambdas.value = PlatformLambdas(
     staticFileLoader,
     analyticsCallback,
     clLogCallback).freeze()
     }
     

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101. Stately!
     v0.3.1~ish
     

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102. Multiplatform Definitions
     • freeze() method and frozen info
     • Atomics (Int, Long, Reference)
     • K/N state-related annotations (@ThreadLocal/
     @SharedImmutable)
     • Shared Collections!
     

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103. More Info and Tutorials
     https://github.com/touchlab/KotlinMultiplatformStuff
     

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104. Making a Library!
     a very small library
     

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105. Download Intellij EAP
     https://www.jetbrains.com/idea/nextversion/
     

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110. targets {
     fromPreset(presets.jvm, 'jvm')
     // This preset is for iPhone emulator
     // Switch here to presets.iosArm64 to build library for iPhone device
     fromPreset(presets.iosX64, 'ios') {
     compilations.main.outputKinds('FRAMEWORK')
     }
     }
     

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111. targets {
     fromPreset(presets.jvm, 'jvm')
     // This preset is for iPhone emulator
     // Switch here to presets.iosArm64 to build library for iPhone device
     fromPreset(presets.macosX64, 'ios') /*{
     compilations.main.outputKinds('FRAMEWORK')
     }*/
     }
     

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112. targets {
     fromPreset(presets.jvm, 'jvm')
     fromPreset(presets.js, 'js')
     fromPreset(presets.macosX64, 'macos')
     fromPreset(presets.iosX64, 'iosX64')
     fromPreset(presets.iosArm32, 'iosArm32')
     fromPreset(presets.iosArm64, 'iosArm64')
     }
     

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113. Live Coding is a Bad Idea
     don’t be a hero
     

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114. Go to Github
     https://github.com/kpgalligan/MyNewLibrary
     

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115. Much More
     obviously
     

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116. Libraries Needed
     • File Access
     • Date (310 port)
     • Mocking (and other test support)
     • Reactive
     • UI State
     

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117. Getting Started
     

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118. Join Kotlin Slack
     https://slack.kotlinlang.org
     

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119. Sample Apps
     the conference apps
     

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120. https://github.com/touchlab/DroidconKotlin/
     

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121. Sample Libraries
     Stately
     SQLDelight
     

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122. Office Hours - Kotlin Multiplatform
     2pm in Coblenz
     

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124. kevin@touchlab.co
     @kpgalligan
     

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125. kevin@touchlab.co
     @kpgalligan
     Join the team
     !
     

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