Alien Server

A lightweight, custom HTTP server implementation written in Java that provides basic HTTP/1.1 functionality with a simple routing system.

Features

• HTTP/1.1 Protocol Support: Handles standard HTTP requests and responses
• Multi-threaded: Uses a thread pool to handle concurrent connections
• Custom HTTP Parser: Implements HTTP message parsing without external dependencies
• Routing System: Simple route-based request handling
• Error Handling: Comprehensive error responses for various HTTP status codes

Architecture

The server is built with a modular architecture:

• HTTP Layer: Core HTTP protocol implementation (parsing, responses, status codes)
• Routing: Simple route matching and handler delegation
• Handlers: Request processing logic
• Server: Connection management and threading

Getting Started

Prerequisites

• Java 8 or higher

Running the Server

1. Compile the project:

javac -cp . com/example/httpserver/*.java com/example/httpserver/**/*.java

2. Run the server:

java com.example.httpserver.HttpServerApp

3. The server will start on port 4221

API Endpoints

Built-in Routes

Method	Path	Description
GET	/hello	Returns "Hello, World!" message

Example Request

GET /hello HTTP/1.1
Host: localhost:4221

Example Response

HTTP/1.1 200 OK
Content-Type: text/plain
Content-Length: 13

Hello, World!

Adding Custom Routes

To add new routes, modify the Router constructor:

public Router() {
    addRoute("/hello", HttpMethod.GET, new HelloWorldHandler());
    addRoute("/custom", HttpMethod.GET, new CustomHandler());
}

Create custom handlers by implementing the RequestHandler interface:

public class CustomHandler implements RequestHandler {
    @Override
    public HttpResponse handle(HttpRequest request) {
        // Your custom logic here
        return new HttpResponse.Builder(HttpStatus.SUCCESS_200_OK)
                .withHeader("Content-Type", "application/json")
                .withBody("{\"message\": \"Custom response\"}")
                .build();
    }
}

Project Structure

com.example.httpserver/
├── HttpServerApp.java          # Main application entry point
├── handlers/
│   ├── RequestHandler.java     # Handler interface
│   └── HelloWorldHandler.java  # Default hello world handler
├── http/
│   ├── HttpMethod.java         # HTTP method enum
│   ├── HttpParser.java         # HTTP message parser
│   ├── HttpParsingException.java
│   ├── HttpRequest.java        # HTTP request model
│   ├── HttpResponse.java       # HTTP response model
│   ├── HttpStatus.java         # HTTP status codes
│   ├── HttpVersion.java        # HTTP version enum
│   └── HttpWriter.java         # HTTP response writer
├── routing/
│   └── Router.java             # Request routing logic
└── server/
    ├── ConnectionHandler.java  # Individual connection handler
    └── Server.java            # Main server class

Error Handling

The server provides comprehensive error handling:

• Parsing Errors: Invalid HTTP format returns 400 Bad Request
• Unsupported Methods: Returns 501 Not Implemented
• Route Not Found: Returns 404 Not Found
• Method Not Allowed: Returns 405 Method Not Allowed
• Internal Errors: Returns 500 Internal Server Error

Logging

The application uses SLF4J for logging. Configure your preferred logging implementation (Logback, Log4j, etc.) to see server logs.

Contributing

1. Fork the repository
2. Create a feature branch
3. Make your changes
4. Add tests if applicable
5. Submit a pull request

License

This project is open source and available under the MIT License.