Why Offline-First?
Mobile users expect apps to work anywhere—in elevators, underground transits, or remote areas with spotty network coverage. A poorly designed app freezes or crashes when connection is lost. An Offline-First design stores all user interactions locally first, and syncs them to the cloud in the background when connectivity returns.
Local Storage Options
- SQLite/Room: The standard relational database for native Android/iOS and Flutter.
- Hive/WatermelonDB: High-performance key-value and relational local databases for cross-platform frameworks.
Conflict Resolution Strategies
When syncing local data back to the server, conflicts can occur if the data was modified elsewhere. Common conflict resolution strategies include:
- Last-Write-Wins (LWW): The record with the newest timestamp overrides the other. Simple but can lead to data loss.
- Client-Wins / Server-Wins: Explicit rules dictating which source is trusted.
- Conflict-Free Replicated Data Types (CRDTs): Advanced mathematical structures that merge changes automatically.