Exploring UDP: My Experience with User Datagram Protocol

Kacper Bąk
5 min readDec 29, 2022
Photo by KOBU Agency on Unsplash

UDP is a lightweight protocol that is well-suited for high-speed, low-latency communications. It is well suited for applications such as streaming media, real-time gaming, and telemetry. UDP is also well suited for distributed applications that require high throughput and low latency. Additionally, UDP is connectionless, making it easier to manage connections and ensure reliability. Finally, UDP is used for broadcast and multicast applications, which is often necessary in distributed systems.

I have used this protocol extensively in my software engineering career.

I have used it to develop several real-time applications, such as streaming audio and video, multiplayer gaming, voice over IP and data collection applications. UDP is a reliable, lightweight and fast protocol that is suitable for applications where a small amount of data needs to be transferred quickly and reliably. It is also a lot easier to configure than TCP, which requires a lot of overhead. UDP also works well in situations where a fast response time is required, such as in gaming applications.

I built a distributed application that used UDP to communicate between nodes.

The application was built to allow users to play a game on multiple computers in different locations.

The application was written in Java and used the UDP protocol to send messages between nodes. Each node had its own thread that would listen for incoming messages, process them and send responses back. The game logic was handled by the server node, which received incoming data and broadcasted game updates to all other nodes.

This application worked thanks to DatagramSocket which is a Java class that provides a mechanism for sending and receiving packets of data over a network using the UDP protocol. It implements the DatagramSocket interface for sending and receiving packets. It is used for communication between two or more network devices using a packet-based communication protocol.

All I had to do was create a DatagramSocket on the sender side, a DatagramPacket that contains the message to be sent. I then sent the packet using the DatagramSocket. I then created a DatagramSocket on the receiver side. I created a DatagramPacket to receive the data. I received the incoming message, using the receive() method on the DatagramSocket, and closed it.

import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;

public class UdpSender {
public static void main(String[] args) throws Exception {
String message = "Hello world!";
byte[] data = message.getBytes();
InetAddress address = InetAddress.getByName("localhost");
int port = 8888;
DatagramPacket packet = new DatagramPacket(data, data.length, address, port);
DatagramSocket socket = new DatagramSocket();
socket.send(packet);
socket.close();
}
}

The application was designed to be scalable and fault-tolerant, so that if one node crashed, the game could still be played without interruption. It also used a heartbeat mechanism to detect if any of the nodes were offline and automatically reconnect them.

The application was tested and deployed in a real-world environment to confirm its stability and performance. The application ran smoothly and allowed users to play the game with no noticeable latency or lag.

I used the protocol to broadcast messages, detect nodes, and send commands.

Broadcast Messages: The protocol can be used to broadcast messages to all nodes in the network by using the broadcast function. This function sends a message to all nodes in the network at the same time, allowing for quick and efficient communication.

import java.net.*;

public class BroadcastUDP {
public static void main(String[] args) throws Exception {
// Create a datagram socket
DatagramSocket socket = new DatagramSocket();

// Create message to send
String message = "Hello World!";
byte[] data = message.getBytes();

// Create broadcast address
InetAddress address = InetAddress.getByName("255.255.255.255");

// Create datagram packet with data and address
DatagramPacket packet = new DatagramPacket(data, data.length, address, 8888);

// Broadcast the message
socket.send(packet);

// Close the socket
socket.close();
}
}

Detect Nodes: The protocol can be used to detect nodes in the network by using the ping command. This command sends a request to all nodes in the network and prompts them to respond. The protocol will then receive the responses and be able to determine which nodes are active and which are not.

import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;

public class NodeDetector {
public static void main(String[] args) throws IOException {

DatagramSocket socket = new DatagramSocket(5000);
byte[] buf = new byte[256];
DatagramPacket packet = new DatagramPacket(buf, buf.length);
socket.receive(packet);
InetAddress address = packet.getAddress();
int port = packet.getPort();
packet = new DatagramPacket(buf, buf.length, address, port);
socket.send(packet);
socket.close();

System.out.println("Node detected from: " + address.getHostAddress());
}
}

Send Commands: The protocol can be used to send commands to specific nodes in the network by using the unicast function. This function sends a message to only one node in the network, allowing for more targeted and specific communications. This is useful when a command needs to be sent to a specific node or group of nodes.

import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;

public class UDPClient {
public static void main(String[] args) throws IOException {

// Create a socket and bind it to any available port on the local host machine
DatagramSocket socket = new DatagramSocket();

// Create an InetAddress object, representing the server
InetAddress address = InetAddress.getByName( "localhost" );

// Create a DatagramPacket with the data to be sent to the server
byte[] sendData = "My command".getBytes();
DatagramPacket sendPacket = new DatagramPacket(sendData, sendData.length, address, 9999);

// Send the packet
socket.send(sendPacket);

// Close the socket
socket.close();
}
}

I used UDP to send and receive data within a client-server system. The server was responsible for listening to incoming UDP packets and responding to them. The client was responsible for sending UDP packets to the server and processing the response. The system was used to transfer small amounts of data in real-time. The data was used to control a robotic arm. The client would send the coordinates of the desired position of the robotic arm and the server would process the data and send back the current position of the robotic arm.

UDP was used because of its low latency and simplicity. It was important for the system to respond quickly and reliably. Using UDP ensured that the data was transferred quickly and reliably. It also meant that there was no need to establish a connection and manage that connection, which would have added complexity to the system.

Overall, I have found UDP to be a reliable and efficient protocol for communication in distributed systems.

You should not use the UDP protocol when the data being transferred needs to be reliable and in-order. UDP is an unreliable, connectionless protocol that does not guarantee the delivery of data packets. It is best used for applications that require the rapid transmission of data, such as streaming audio and video.

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