Java UDP Server/Client

Overview

This repository is a lightweight Java UDP client/server proof of concept created to understand datagram networking and Wake-on-LAN communication patterns.

The project was intentionally kept small and dependency-free so the network behavior is easy to inspect, test, and extend.

Project Goal

This code was built as a learning and validation step before implementing Wake-on-LAN behavior in Android applications.

It demonstrates:

• UDP socket setup and communication in Java
• Request/response behavior over datagrams
• Basic service-style server behavior that listens continuously on a fixed port

Professional Context

This project was used to de-risk implementation decisions before mobile development work, specifically:

• validating low-level UDP behavior in a controlled Java environment
• confirming packet flow and response handling before Android integration
• creating a clear baseline reference for later product-facing Wake-on-LAN features

Architecture

• JavaUdpServer.java: starts a UDP listener on port 4445, receives packets, and responds with the current server timestamp
• JavaUdpClient.java: sends a UDP packet to 127.0.0.1:4445, waits for a response, and prints the returned timestamp

Run Locally

Compile:

javac JavaUdpServer.java
javac JavaUdpClient.java

Run in separate terminals:

java JavaUdpServer

java JavaUdpClient

Expected behavior:

• Server logs a request source, for example: Request from: /127.0.0.1:<random_port>
• Client prints Java runtime info, target endpoint, and a timestamp returned by the server

Related Repositories

• Android UDP client prototype: https://github.com/adamsinnott/AndroidDatagramUdpClient
• Wake-on-LAN Android implementation: https://github.com/adamsinnott/WakeOnLAN

Notes

• This repository is a focused learning project, not a production-ready service.
• The original inspiration came from Oracle UDP datagram examples and early community tutorials, then was adapted for Wake-on-LAN experimentation.