☕ Java Coffee Socket Demo

A fun and educational Java networking project demonstrating:

• Java Blocking I/O (BIO) sockets
• Java Non-Blocking I/O (NIO) with selectors
• A high-performance Netty server and client

The project simulates a small “coffee shop” where a client sends a coffee order, and the server replies with the prepared drink.
It’s designed as a progression from BIO → NIO → Netty so beginners can understand how networking evolves from simple to high-performance frameworks.

🚀 Features

✔ Java BIO Version

• Uses ServerSocket + Socket
• Blocking read/write
• One thread per client (classic approach)

✔ Java NIO Version

• Uses Selector, ServerSocketChannel, SocketChannel
• Non-blocking I/O
• Event-driven architecture
• Single-threaded high scalability

✔ Netty Version

• Uses industry-standard networking framework
• EventLoopGroups + pipelines
• Automatic encoding/decoding
• Clean, simple handlers
• High-performance, production-grade networking

📂 Project Structure

java-coffee-socket-demo/
│
├─ javaio/               → Blocking I/O version
│   ├─ CoffeeShopServer.java
│   └─ CoffeeCustomer.java
│
├─ javanio/              → Non-blocking NIO version
│   ├─ NioCoffeeServer.java
│   └─ NioCoffeeCustomer.java
│
├─ netty/                → Netty version (recommended)
│   ├─ NettyCoffeeServer.java
│   └─ NettyCoffeeCustomer.java
│
├─ lib/                  → Netty JAR (if plain Java project)
│
└─ README.md

▶️ Running the Project

1. BIO Version

Start the server:

java javaio.CoffeeShopServer

Start the client:

java javaio.CoffeeCustomer

2. NIO Version

Start the server:

java javanio.NioCoffeeServer

Start the client:

java javanio.NioCoffeeCustomer

3. Netty Version (recommended)

Start the server:

java netty.NettyCoffeeServer

Start the client:

java netty.NettyCoffeeCustomer

📦 Dependencies

If using plain Java project, place this JAR into /lib and add to Build Path:

netty-all-4.1.109.Final.jar

📘 Learning Goals

This project helps you understand:

• How sockets work in Java
• Blocking vs non-blocking I/O
• Selectors and events
• How Netty simplifies networking
• How real servers handle connections

Perfect for beginners learning networking step-by-step.

⭐ License

Free to use and modify.