Data Synchronization and Replication Framework for Modern Delphi Applications

Overview

DFDataSync is a comprehensive Delphi library designed to handle robust data synchronization and replication between local databases, remote servers, and offline clients. It provides a flexible framework for implementing data synchronization with conflict resolution, change tracking, and efficient differential synchronization.

Features

Bidirectional Synchronization: Support for uploading, downloading, or bidirectional sync operations
Intelligent Change Tracking: Track changes to your data with detailed metadata
Robust Conflict Resolution: Multiple strategies for resolving data conflicts
Differential Synchronization: Only transmit changed data for efficient network usage
Event-Driven Architecture: Full notification system for sync progress and events
Background Processing: Non-blocking sync operations via Delphi's task parallel library
Extensible Design: Easy to customize and extend for specific business needs
Automatic Scheduling: Built-in timer for periodic synchronization
FireDAC Integration: Seamless integration with FireDAC components

Requirements

Delphi 10.3 or higher
FireDAC components

Installation

Clone the repository or download the latest release
Add the source directory to your project's search path
Add DFDataSync to your uses clause

Quick Start Guide

Basic Setup

uses
  DFDataSync;

var
  SourceDB, TargetDB: TFDConnection;
  SourceEndpoint, TargetEndpoint: IDFSyncEndpoint;
  SyncController: TDFSyncController;
  
begin
  // Setup connections
  SourceDB := TFDConnection.Create(nil);
  SourceDB.ConnectionDefName := 'LocalDB';
  SourceDB.Connected := True;
  
  TargetDB := TFDConnection.Create(nil);
  TargetDB.ConnectionDefName := 'RemoteDB';
  TargetDB.Connected := True;
  
  // Create endpoints
  SourceEndpoint := TDFLocalDatabaseEndpoint.Create(SourceDB);
  TargetEndpoint := TDFLocalDatabaseEndpoint.Create(TargetDB);
  
  // Add entities to synchronize
  (SourceEndpoint as TDFLocalDatabaseEndpoint).AddEntity('Customers', 'Customers');
  (SourceEndpoint as TDFLocalDatabaseEndpoint).AddEntity('Orders', 'Orders');
  (TargetEndpoint as TDFLocalDatabaseEndpoint).AddEntity('Customers', 'Customers');
  (TargetEndpoint as TDFLocalDatabaseEndpoint).AddEntity('Orders', 'Orders');
  
  // Create and configure sync controller
  SyncController := TDFSyncController.Create(nil);
  SyncController.SetEndpoints(SourceEndpoint, TargetEndpoint);
  SyncController.SyncDirection := sdBidirectional;
  SyncController.ConflictResolution := crNewerWins;
  
  // Set up event handlers
  SyncController.OnConflict := HandleConflict;
  SyncController.OnProgress := ShowSyncProgress;
  SyncController.OnSyncComplete := SyncCompleted;
  
  // Start synchronization
  SyncController.StartSync;
end;

Change Tracking Tables

The framework automatically creates and manages these tables:

DFChangeLog: Records all data changes with metadata
DFSyncState: Tracks synchronization state across devices

Advanced Usage

Custom Conflict Resolution

procedure TMyForm.HandleConflict(Sender: TObject; const EntityName: string;
  const PrimaryKey: Variant; var Resolution: TDFConflictResolution);
begin
  // Show conflict dialog to user
  if MessageDlg('Conflict detected for ' + EntityName + '. Use local version?',
    mtConfirmation, [mbYes, mbNo], 0) = mrYes then
    Resolution := crSourceWins
  else
    Resolution := crTargetWins;
end;

Periodic Synchronization

// Set up automatic sync every 5 minutes
SyncController.SyncInterval := 5 * 60;

Progress Feedback

procedure TMyForm.ShowSyncProgress(Sender: TObject; const CurrentItem, TotalItems: Integer;
  const EntityName, OperationType: string);
begin
  ProgressBar1.Position := Round((CurrentItem / TotalItems) * 100);
  StatusLabel.Caption := Format('Synchronizing %s (%s): %d of %d', 
    [EntityName, OperationType, CurrentItem, TotalItems]);
end;

API Reference

Key Classes

TDFSyncController: Main class to coordinate synchronization operations
TDFDBChangeTracker: Tracks data changes in a database
TDFLocalDatabaseEndpoint: Represents a database endpoint for synchronization
TDFDiffEngine: Utility class for finding differences between datasets

Key Interfaces

IDFChangeTracker: Interface for tracking data changes
IDFSyncEndpoint: Interface for synchronization endpoints

License

This project is licensed under the MIT License - see the LICENSE file for details.

Contributions

Contributions are welcome! Please feel free to submit a Pull Request.

Credits

Developed by Delphifan
(c) 2025

https://github.com/delphifanforum/DFDataSync/