android-data-layer

To build an offline-first data layer, use the Repository pattern to coordinate Room database queries and remote API calls, applying stale-while-revalidate synchronization to keep local data available during network interruptions.

The outbox pattern queues local write operations in the Room database, using WorkManager to sync these pending changes with the remote API once network connectivity is restored, ensuring reliable offline data synchronization.

Mapping DTO, Entity, and Domain models involves converting API responses into Room entities for local persistence, then transforming those entities into Domain types, keeping the presentation layer isolated from data source specifics.

Observable Room queries use Kotlin Flow to automatically emit updated data whenever the underlying database table changes, allowing the UI to reactively update without manually polling for fresh results.

Yes, the repository pattern requires distinct DTO, Entity, and Domain models to separate remote API structures from local Room persistence, ensuring clean architecture boundaries between data sources and the domain layer.

The best way to fetch and cache remote API data is implementing stale-while-revalidate within the Repository pattern, serving cached Room data immediately while triggering background coroutines to fetch and update the local database.