Creating SDKs for Multiple Platforms with KMP | Devfest Chennai

Kotlin Multiplatform or KMP is the talk of the town nowadays. Everyone is talking about it, lots of big orgs are using it as well, including Thoughtworks, Shopify, JioCinema, Cred etc.
While making the whole app with KMP (Kotlin Multiplatform) sounds fantastic, another really good use case would be to migrate your SDKs and libraries to KMP.
Whether you're a B2B company that offers SDKs and libraries to external clients or creating and using SDKs internally within your company, making it in KMP can help ensure consistency among different platforms, less time and effort spent, and in the end lower cost of maintenance.
In this talk, we'll discuss why and how you should create SDKs and migrate existing SDKs to KMP, and some best practices regarding the same, from a person who has done it in production, affecting millions of users.
In this session, we'll learn the following
- Why Kotlin Multiplatform for SDKs
- Difference between multiplatform and cross-platform
- How to support different platforms (Android, iOS, JS, Flutter etc.) when creating SDKs
- Performance optimization and handling threading for different platforms
- Best practices

Learn why and how to migrate or create new SDKs / libraries with Kotlin Multiplatform.
In this session, we'll learn the following
- Why Kotlin Multiplatform for SDKs
- Difference between multiplatform and cross-platform
- How to support different platforms (Android, iOS, JS, Flutter etc.) when creating SDKs
- Performance optimization and handling threading for different platforms
- Best practices

Transcript

1. Creating SDKs with Kotlin Multiplatform Rivu Chakraborty 🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social https://courses.rivu.dev/
2. • India’s first GDE (Google Developer Expert) for • More than 11 years in the Industry • Mobile Architect @ JioCinema • Previously ◦ Byju’s ◦ Paytm ◦ Gojek ◦ Meesho • Author (wrote multiple Kotlin books) • Speaker • Mentor • Community Person • YouTuber (?) 🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social Who am I? 󰞦
4. What’s an SDK?
5. 🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social What’s an SDK? 🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social Software Development Kit. Library/SDK
6. 🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social What’s an SDK? 🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social A code block, that helps your or client apps reduce redundancy, by using this library / SDK
7. 🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social Most Common SDK Use Cases 🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social • Analytics • Chat / Conversation • Ads • Image Processing • Audio-Video Processing
8. Rules for Developing SDK
9. 🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social SDK Rules 🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social 0. Should be Plug and Play
10. 🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social SDK Rules 🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social 0. Should be Plug and Play 1. Should be easy to remove
11. 🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social SDK Rules 🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social 0. Should be Plug and Play 1. Should be easy to remove 2. Should not add unnecessary extra dependencies to the client app
12. 🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social SDK Rules 🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social 0. Should be Plug and Play 1. Should be easy to remove 2. Should not add unnecessary extra dependencies to the client app 3. Interaction should be straightforward for the client
13. 🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social SDK Rules 🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social 0. Should be Plug and Play 1. Should be easy to remove 2. Should not add unnecessary extra dependencies to the client app 3. Interaction should be straightforward for the client 4. Data Types should be interoperable
14. 🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social SDK Rules 🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social 0. Should be Plug and Play 1. Should be easy to remove 2. Should not add unnecessary extra dependencies to the client app 3. Interaction should be straightforward for the client 4. Data Types should be interoperable 5. [Optional] Should allow client apps to implement own UI
15. Building an SDK
16. 🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social Building an SDK 🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social • Hire / Allocate Developers • Define Requirements • Plan Roadmap • Develop, maintain and test SDK integration • Cross Check Parity / Consistency across platforms • Setup SDK release • Maintain versioning across platforms
17. 🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social Building an SDK 🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social • Hire / Allocate Developers • Define Requirements • Plan Roadmap • Develop, maintain and test SDK integration • Cross Check Parity / Consistency across platforms • Setup SDK release • Maintain versioning across platforms Android 1x
18. 🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social Building an SDK 🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social • Hire / Allocate Developers • Define Requirements • Plan Roadmap • Develop, maintain and test SDK integration • Cross Check Parity / Consistency across platforms • Setup SDK release • Maintain versioning across platforms Android, iOS 2x
19. 🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social Building an SDK 🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social • Hire / Allocate Developers • Define Requirements • Plan Roadmap • Develop, maintain and test SDK integration • Cross Check Parity / Consistency across platforms • Setup SDK release • Maintain versioning across platforms Android, iOS, Web 3x
20. 🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social Building an SDK 🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social • Hire / Allocate Developers • Define Requirements • Plan Roadmap • Develop, maintain and test SDK integration • Cross Check Parity / Consistency across platforms • Setup SDK release • Maintain versioning across platforms Android, iOS, Web, tvOS ~4x
21. 🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social Building an SDK 🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social • Hire / Allocate Developers • Define Requirements • Plan Roadmap • Develop, maintain and test SDK integration • Cross Check Parity / Consistency across platforms • Setup SDK release • Maintain versioning across platforms Android, iOS, Web, tvOS, Tizen & WebOS [HTML5 TV] ~5x
22. 🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social Building an SDK 🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social • Hire / Allocate Developers • Define Requirements • Plan Roadmap • Develop, maintain and test SDK integration • Cross Check Parity / Consistency across platforms • Setup SDK release • Maintain versioning across platforms Android, iOS, Web, tvOS, Tizen & WebOS [HTML5 TV], WatchOS, WearOS ~7x
23. 🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social
24. 🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social Solution? 🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social Share Code across all Platforms
25. Current Solutions for Sharing Code across Platforms
26. 🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social Flutter 🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social 0. Should be Plug and Play 1. Should be easy to remove 2. Should not add unnecessary extra dependencies to the client app 3. Interaction should be straightforward for the client 4. Data Types should be interoperable 5. [Optional] Should allow client apps to implement own UI
27. 🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social React Native 🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social 0. Should be Plug and Play 1. Should be easy to remove 2. Should not add unnecessary extra dependencies to the client app 3. Interaction should be straightforward for the client 4. Data Types should be interoperable 5. [Optional] Should allow client apps to implement own UI
28. 🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social Kotlin Multiplatform 🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social 0. Should be Plug and Play 1. Should be easy to remove 2. Should not add unnecessary extra dependencies to the client app 3. Interaction should be straightforward for the client 4. Data Types should be interoperable 5. [Optional] Should allow client apps to implement own UI ✓
29. Why Kotlin Multiplatform [KMP/KMM]
30. 🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social 🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social • Developed by Jetbrains • Open Source • Supported by Google for Android Development • Supported by Spring for Server • Has own framework (Ktor) for asynchronous client and server applications • Has different targets for Different platforms. e.g. Kotlin/JVM, Kotlin/Native, Kotlin/JS, Kotlin/Wasm etc.
31. 🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social 🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social Kotlin Multiplatform
32. 🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social Kotlin Multiplatform 🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social Using Kotlin Code in projects to target more than one platform
33. 🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social Kotlin Multiplatform 🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social • Idiomatic Kotlin Language for all platforms • Low Risk ◦ You decide what to share, what not ◦ Option to use existing 3rd party libraries for each platform • Interoperability • Consistency across platforms • Export platform native SDK builds • Strong Community Support
34. Understanding Kotlin Multiplatform [KMP/KMM]
35. 🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social The Structure 🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social
36. 🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social The Structure 🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social Common JVM JS Native Android Server Apple Linux mingw iOS tvOS watchOS macOS linux_x64 linux_arm64 mingx64 iosX64 iosArm64 iosSimulatorArm64 tvosX64 tvosArm64 tvosSimulatorArm64 macosX64 macosArm64 watchosX64 watchosArm32 watchosArm64 watchosSimulatorArm64 watchosDeviceArm64
37. 🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social The Structure expect fun doSomething() actual fun doSomething() { //Platform specific logic here }
38. 🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social The Structure Directory Structure
39. 🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social The Structure expect fun getRandomUUID(): String commonMain
40. 🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social The Structure androidMain actual fun getRandomUUID(): String = UUID.randomUUID().toString()
41. 🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social The Structure iosMain actual fun getRandomUUID(): String = NSUUID().UUIDString()
42. 🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social The Structure jsMain import uuid actual fun getRandomUUID(): String = uuid.v4().toString()
43. 🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social The Structure Dependency Management val commonMain by getting { dependencies { implementation(libs.bundles.common.ktor) implementation(libs.coroutines.core) implementation(libs.kotlinx.datetime) implementation(libs.koin.core) implementation(libs.skie) } }
44. 🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social The Structure Dependency Management val jsMain by getting { dependencies { implementation(npm("uuid", "9.0.0")) implementation(libs.wire.runtime.js) } }
45. 🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social The Structure Dependency Management val androidMain by getting { dependencies { implementation(libs.ktor.client.okHttp) implementation(libs.okhttp.loggingInterce ptor) implementation(libs.koin.android) implementation(libs.sqlDelight.android) } }
46. 🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social The Structure Dependency Management val iosMain by getting { dependencies { implementation(libs.ktor.client.darwin) implementation(libs.sqlDelight.native) } }
47. 🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social The Structure Shared Common Code class EventsRepository( private val eventsRemoteDS: EventsRemoteDS, private val eventsLocalDS: EventsLocalDS, ) { suspend fun trackEvent( eventData: EventData, eventName: String, ) { //Logic to track Events ... } }
48. 🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social The Structure Exported SDK files Android .aar iOS .xcframework JS Minified js / NPM
49. 🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social The Structure Setting up Distribution val xcFramework = XCFramework("IndiaConferences") listOf( iosX64(), iosArm64(), iosSimulatorArm64(), ).forEach { it.binaries.framework { xcFramework.add(this) baseName = SDKConfig.sdkName } }
50. 🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social The Structure Setting up Distribution kmmbridge { spm() mavenPublishArtifacts() versionPrefix.set(SDKConfig.version) frameworkName.set(SDKConfig.sdkName) } https://kmmbridge.touchlab.co
51. 🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social The Structure Taking care of Interoperability https://skie.touchlab.co/ data class User @DefaultArgumentInterop.Enabled constructor( val id: String, val firstName: String, val lastName: String, val userType: UserType = UserType.User ) @EnumInterop.Enabled enum class UserType { User, Admin, }
52. 🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social The Structure Taking care of Interoperability https://skie.touchlab.co/ data class User @DefaultArgumentInterop.Enabled constructor( val id: String, val firstName: String, val lastName: String, val userType: UserType = UserType.User ) @EnumInterop.Enabled enum class UserType { User, Admin, } @JsExport object UserTypeJS { val User = UserType.User val Admin = UserType.Admin }
53. 🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social Versioning object LibraryConfig { val version = "1.0.0" const val groupId = "dev.rivu.kmp.sdkDemo" const val artifactIdSdk = "core" val sdkName = "demo-sdk" }
54. 🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social Reducing Size in JS js { browser { dceTask { keep("shared.dev.rivu.MyClass") } binaries.executable() } }
55. 🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social Using the bundle in JS
56. 🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social Using the XCFramework in iOS
57. IDEs and Tools
58. 🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social IDEs and Tools
59. Resources • https://speakerdeck.com/aldefy/a-hitchhikers-guide-to-kotlin-multiplatfor m • https://github.com/joreilly/PeopleInSpace • https://github.com/joreilly/Confetti • https://kotlinlang.org/docs/multiplatform.html • https://courses.rivu.dev
60. Thank You Rivu Chakraborty 🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social https://courses.rivu.dev/