type TUDPPacketHeader = packed record SequenceID: UInt32; PacketType: Byte; // 0 = data, 1 = ack, 2 = heartbeat Timestamp: TDateTime; end; Delphi provides robust support for UDP through both the legacy Indy components and the modern System.Net.Socket unit. Indy is ideal for rapid development and VCL applications, while System.Net.Socket offers better cross-platform compatibility and modern async patterns. Choose UDP when speed, simplicity, and broadcast capability are essential, but always implement application-level reliability when data integrity matters.
procedure TForm1.FormCreate(Sender: TObject); begin IdUDPServer1.DefaultPort := 8080; IdUDPServer1.Active := True; end; This unit provides a cleaner, non-blocking architecture and is ideal for FireMonkey (FMX) applications. Sending a UDP Datagram uses System.Net.Socket, System.Net.URLClient; procedure SendUDP(const AHost: string; APort: Integer; const AMessage: string); var Socket: TUdpSocket; RemoteEndpoint: TEndpoint; Bytes: TBytes; begin Socket := TUdpSocket.Create; try RemoteEndpoint := TEndpoint.Create(AHost, APort); Bytes := TEncoding.UTF8.GetBytes(AMessage); Socket.SendTo(RemoteEndpoint, Bytes, 0, Length(Bytes)); finally Socket.Free; end; end; Receiving UDP Datagrams (Async) type TUDPReceiver = class private FSocket: TUdpSocket; procedure OnDataAvailable(const AData: TBytes; AEndpoint: TEndpoint); public procedure StartListening(APort: Integer); end; procedure TUDPReceiver.StartListening(APort: Integer); begin FSocket := TUdpSocket.Create; FSocket.Listen(APort); // Bind to local port FSocket.ReceiveFrom(OnDataAvailable); // Non-blocking callback end; delphi udp
procedure SendUDPBytes(const AHost: string; APort: Integer; const Bytes: TBytes); var UDPClient: TIdUDPClient; begin UDPClient := TIdUDPClient.Create(nil); try UDPClient.Host := AHost; UDPClient.Port := APort; UDPClient.Send(TIdBytes(Bytes)); finally UDPClient.Free; end; end; The server component operates asynchronously using the OnUDPRead event. procedure TForm1
Introduction User Datagram Protocol (UDP) is a connectionless, lightweight transport layer protocol. Unlike TCP, UDP does not guarantee delivery, order, or error checking beyond the basic checksum. However, this simplicity makes it exceptionally fast and efficient for scenarios where speed outweighs reliability, such as real-time video streaming, online gaming, DNS queries, and local network discovery. Unlike TCP, UDP does not guarantee delivery, order,
type TForm1 = class(TForm) IdUDPServer1: TIdUDPServer; procedure IdUDPServer1UDPRead(AThread: TIdUDPListenerThread; const AData: TIdBytes; ABinding: TIdSocketHandle); end; procedure TForm1.IdUDPServer1UDPRead(AThread: TIdUDPListenerThread; const AData: TIdBytes; ABinding: TIdSocketHandle); var ReceivedString: string; RemoteIP: string; RemotePort: Integer; begin ReceivedString := TEncoding.UTF8.GetString(AData); RemoteIP := ABinding.PeerIP; RemotePort := ABinding.PeerPort;