Architecture

Overview

SyncLayer is built on a three-layer architecture designed for offline-first applications:

Local Storage Layer

The foundation of SyncLayer is built on Isar, a high-performance NoSQL database for Flutter.

• ✓Zero-copy object access for maximum performance
• ✓ACID compliance for data integrity
• ✓Automatic indexing for fast queries
• ✓Version tracking for conflict detection
• ✓Offline queue for pending operations

@collection
class SyncEntity {
  Id id = Isar.autoIncrement;
  
  late String collectionName;
  late String entityId;
  late String data; // JSON string
  late int version;
  late DateTime lastModified;
  late bool isSynced;
}

Sync Engine

The sync engine is event-driven and handles all synchronization logic:

SyncLayer.events.listen((event) {
  if (event is SyncStartedEvent) {
    // Sync started
  } else if (event is SyncCompletedEvent) {
    // Sync completed successfully
  } else if (event is SyncErrorEvent) {
    // Handle sync error
  } else if (event is ConflictDetectedEvent) {
    // Conflict detected
  }
});

SyncConfig(
  maxRetries: 3,
  retryDelay: Duration(seconds: 2),
  // Retry delays: 2s, 4s, 8s
)

Backend Adapters

SyncLayer uses the adapter pattern to support multiple backends:

abstract class BackendAdapter {
  Future<Map<String, dynamic>> pull(
    String collection,
    DateTime? lastSync,
  );
  
  Future<void> push(
    String collection,
    List<Map<String, dynamic>> changes,
  );
  
  Future<void> delete(
    String collection,
    String id,
  );
}

Built-in adapters:

Data Flow

Understanding how data flows through SyncLayer:

Performance Considerations

• ✓Batch operations for improved throughput
• ✓Lazy loading for large datasets
• ✓Indexed queries for fast lookups
• ✓Debounced sync to reduce network calls
• ✓Compression for network transfers