Building Native apps with MongoDB & Kotlin Multiplatform Mohit Sharma Developer Advocate, MongoDB codeWithMohit MongoDB 

Hi, I’m Mohit 👋 MongoDB, Dublin Developer Advocate Dubizzle (Olx), Dubai Mobile Evangelist and few more.. codeWithMohit 

Agenda ● Why KMM ? ● What is Data layer ? ● How does MongoDB fit in? ● Coding ● Q & A @codeWithMohit 

KMM ? @codeWithMohit 

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Another perspective UI Logic Data Layer Feature 

60% - Logic + Data* 40% UI UI Data Layer Logic Feature UI 

What is the data layer ? @codeWithMohit 

Views ViewModels / Presenter XML/Storyboard Compose/SwiftUI etc Datasource Logic layer (optional) High Level Architecture Local Cloud @codeWithMohit 

Repo Pattern Repo Cache Database Network API 1 API 2 @codeWithMohit 

Evolution Evilution Repo Cache Database Network API 3.1 API 3.2 API 2.1 API 2.2 API 1.1 API 1.2 API xx API xx API xx API xx API xx API xx API xx API xx @codeWithMohit 

Query Quest! @codeWithMohit 

Data synchronization JSON NATIVE OBJECT MSG QUEUE BACKEND OBJECT REST CALL TO API PUSH SERVICE PUSH NOTIFICATION COMPLEX CONFLICT RESOLUTION, RETRY & ERROR HANDLING POTENTIAL APP CRASH OFFLINE? INVALID DATA? SERVER ERROR? TIMED OUT? Backend database Mobile devices with local data Data Layer is a hard & complex problem !! WRITE CONFLICTS? @codeWithMohit 

App dataflow with MongoDB Out-of-the-box device-cloud synchronization Mobile-optimized database Ultra-lightweight and fast Object-oriented No ORM or DAO required Advanced security and permissions Built-in conflict resolution The leading developer data platform on the cloud Functions Triggers GraphQL DataAPI Data Access Control Atlas Realm KMM SDK Atlas Device Sync Search Charts Time Series @codeWithMohit 

Realm Reactive Notifications Built-in Encryption Offline-First, Background Sync Object Schema & Relationships Simple to Learn & Master Idiomatic Query Language 

Realm By MongoDB ● Free and Open Source Database ● Founded 2011. First release in 2014 ● C++ with Language SDK’s on top ● Part of MongoDB since 2019 

Realm By MongoDB 

Realm Query Language ● alwaysFalse ● alwaysTrue ● and ● beginGroup ● beginsWith ● between ● contains ● distinct ● endsWith ● endGroup ● equalTo ● greaterThan ● greaterThanOrEqual ● in ● isEmpty ● isNotEmpty ● isNotNull ● isNull ● lessThan ● lessThanOrEqual ● like ● limit ● maximumDate ● minimumDate ● not ● notEqualTo ● or ● sort ● average ● count ● sum ● max ● min @codeWithMohit 

Realm Query langua ge Realm Query language @codeWithMohit 

Atlas Device Sync Local and offline data access with fast, efficient device to cloud sync @codeWithMohit 

Atlas App Services Triggers Functions Data API User Authorization HTTPS Endpoints GraphQL @codeWithMohit 

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Show me the code !! @codeWithMohit 

Realm MongoDB Atlas Recap Atlas Device Sync SDK writes transaction The Realm SDK writes the transaction, commiting the object to disk, and sends the changes to the server Insert into collection MongoDB document inserted into the Atlas collection User makes change User logs into the app and makes an edit Change Detected Document changed by another user is picked up by changeStreams and forwarded to Atlas Device Sync Object Conversion Atlas Device Sync automatically translates MongoDB documents to Realm objects and syncs down to the device Object Conversion Atlas Device Sync automatically converts the Realm object to a MongoDB document Notification Realm commits the change to disk. A notification is fired and the UI is updated displaying the new change to the user 

Leading innovators leverage MongoDB’s mobile & device solution 

Thank you for your time. codeWithMohit