README

mORMot2 Multi-Socket Connections

A Pascal/Delphi implementation demonstrating mORMot2 async socket programming with connection management, logging, automatic reconnection capabilities, and real-time screenshot sharing.

🚀 Key Features

• Handle-Based Connection Management - Uses TPollAsyncConnectionHandle for unique client identification
• Logging - Comprehensive logging with timestamps and connection lifecycle tracking
• Automatic Reconnection - Intelligent client reconnection with exponential backoff
• Thread-Safe Operations - Critical sections protecting all shared data structures
• Real-time Connection Tracking - Live ListView updates with IP addresses and nicknames
• Message Broadcasting - Send to all clients or individual selected clients
• 🆕 Screenshot Sharing - Compressed JPEG screenshots with zlib compression
• 🆕 Simplified API - Clean SendData(TBytes) method for all communications
• 🆕 Enhanced Commands - All|message and Selected|message command format
• Memory Leak Prevention - Proper resource cleanup and object lifecycle management
• Cross-Platform Ready - Windows, Linux, macOS compatibility via mORMot2
• Simple Protocol with Magic Markers - Binary protocol using TBytes for all data
• String-Based Commands - Intuitive command parsing with pipe-delimited format
• Robust Stream Parser - Magic marker detection and fragmented TCP data handling

📊 Connection Lifecycle

Server Side Flow

1. Client Socket Connect
   ???
2. TConnection.AfterCreate()
   - Generate unique Handle ID
   - Add to fClients dictionary
   - Update connection counter
   - Wait for nickname registration
   ???
3. Client sends "NewCon|NickName" via protocol
   ??? 
4. TConnection.ProcessCommand()
   - Parse nickname using StringOf(TBytes)
   - Update UserData with nickname
   - Add to ListView with IP + nickname
   - Complete registration process
   ???
5. Normal operation (message exchange, screenshots)
   ???
6. TConnection.OnClose()
   - Remove from all collections by Handle
   - Update ListView and counters
   - Log disconnection event

Client Side Flow

1. TAsyncClient.Create()
   ???
2. TConnection.AfterCreate()
   - Generate unique nickname (Client + timestamp)
   - Send "NewCon|NickName" via SendData()
   - Update UI to connected state
   - Stop reconnection timer
   ???
3. Normal operation (receive server messages, capture screenshots)
   ???
4. TConnection.OnClose()
   - Update UI to disconnected state
   - Trigger OnConnectionLost()
   - Start reconnection timer
   ???
5. Automatic reconnection attempts every 3 seconds

📡 Simple Protocol Implementation

Protocol Structure

Magic Marker + Data Size + Data
[$CAFEBABE ] [UInt32    ] [TBytes]
4 bytes      4 bytes      Variable

Key Features

• Magic Marker: $CAFEBABE for protocol identification
• Binary Safe: Uses TBytes for all data transmission
• String Commands: Pipe-delimited format like 'NewCon|ClientName'
• Simplified API: SendData(BytesOf('Command|Data')) method

Usage Example

// NEW: Simplified sending with SendData method
SendData(BytesOf('NewCon|' + ClientName));
SendData(BytesOf('All|Hello everyone!'));
SendData(BytesOf('Selected|Private message'));

// Screenshot with binary data
SendData(BytesOf('ScreenShot|') + CompressedImageData);

// Receiving data  
procedure ProcessCommand(const Data: TBytes);
var
  sl: TStringList;
begin
  sl := TStringList.Create;
  try
    sl.Delimiter := '|';
    sl.StrictDelimiter := True;
    sl.DelimitedText := StringOf(Data);
    
    if sl[0] = 'NewCon' then
      RegisterClient(sl[1])
    else if sl[0] = 'All' then
      ShowMessage('Broadcast: ' + sl[1])
    else if sl[0] = 'ScreenShot' then
      ProcessScreenshot(Copy(Data, 11, Length(Data)));
  finally
    sl.Free;
  end;
end;

🖼️ Screenshot Functionality

Client-Side Screenshot Capture

function CaptureScreenshot: TBytes;
begin
  // 1. Capture screen as bitmap
  // 2. Convert to JPEG (30% quality)
  // 3. Apply zlib compression
  // 4. Return compressed TBytes
end;

// Automatic screenshot on server request
if sl[0] = 'GetScreenShot' then
begin
  ScreenshotData := CaptureScreenshot;
  SendData(BytesOf('ScreenShot|') + ScreenshotData);
end;

Server-Side Screenshot Processing

if sl[0] = 'ScreenShot' then
begin
  TThread.Queue(nil,
    procedure
    var
      imageData: TBytes;
      jpgImage: TJPEGImage;
    begin
      // Extract compressed image data (skip "ScreenShot|" prefix)
      imageData := Copy(Data, 11, Length(Data));
      
      // Decompress zlib data
      // Load JPEG from decompressed data
      // Display in TImage component
      Form1.Image1.Picture.Assign(jpgImage);
      Form1.Image1.Stretch := True;
    end);
end;

📋 Usage Instructions

1. Start the Server

1. Open Server/Server.dproj in Delphi
2. Compile and run (F9)
3. Server starts on port 3434
4. Status bar shows "Status: Active"

2. Connect Clients

1. Open Client/Client.dproj in Delphi
2. Compile and run multiple instances
3. Each client auto-connects and registers
4. Watch ListView populate with client info

3. Test Messaging

• Right-click in server ListView → "Send to All"
• Select client → Right-click → "Send to Selected"
• Messages appear in client log windows with clear labels:
  • "Message to all: Hello everyone!"
  • "Message to me: Private message"

4. Test Screenshot Sharing

• Select client → Right-click → "Get Screenshot"
• Client captures and sends compressed screenshot
• Screenshot appears in server's Image component
• Real-time visual monitoring capability

5. Test Reconnection

• Close client applications
• Server automatically removes from ListView
• Restart clients - automatic reconnection
• Registration happens seamlessly

🎓 Learning Outcomes

This implementation demonstrates:

1. mORMot2 Async Framework - Proper use of TAsyncServer/TAsyncClient
2. Connection Lifecycle - AfterCreate/OnClose pattern implementation
3. Thread Safety - Critical sections and proper synchronization
4. Resource Management - RAII and automatic cleanup
5. Network Programming - Client-Server communication
6. Binary Data Handling - Screenshot compression and transmission
7. Error Handling - Comprehensive exception management
8. UI Integration - Real-time updates and visual feedback
9. API Design - Clean, simplified method interfaces
10. Image Processing - JPEG compression and zlib optimization

Perfect foundation for building scalable network applications with mORMot2.

Made with ❤️ using Delphi RAD Studio