HTTP Server

This project implements a simple HTTP 1.0 server in Java.

Table of Contents

• Architecture
• Features
• Routing
• Error Handling
• Testing

Architecture

The server utilizes a synchronous API with a hybrid threading model to efficiently handle client requests.

• Virtual Threads for I/O: Each client connection is handled in its own virtual thread (VirtualThreadPerTaskExecutor), which is ideal for I/O-bound tasks like reading requests and writing responses. This allows the server to handle a large number of concurrent connections with minimal overhead.
• Work-Stealing Pool for Request Building: A work-stealing thread pool (Executors.newWorkStealingPool()) is used for the initial processing of requests. This ensures that CPU-intensive tasks, such as parsing request lines and headers, are distributed efficiently across available processor cores.

Features

• HTTP 1.0 Support: The server understands and processes basic HTTP 1.0 requests.
• Express.js-like Routing API: The server provides a simple and intuitive API for defining routes, inspired by the popular Node.js framework, Express.
• JSON Body Parsing: The server can parse and validate JSON request bodies.
• Basic Request Validation: The server performs initial checks on incoming requests to ensure they are well-formed.

Routing

Routing is handled by a custom trie-based router (TrieRouter). This data structure provides efficient matching of request paths to their corresponding handlers.

• Path Parameters: The router supports dynamic path segments (e.g., /users/:id), which are extracted and made available to the request handler.
• HTTP Verb Matching: Routes are associated with specific HTTP verbs (GET, POST, PUT, DELETE), allowing for different handlers for the same path but different methods.

Error Handling

The server includes basic error handling and responds with appropriate HTTP status codes:

• 400 Bad Request: Sent for malformed requests, such as invalid request lines or incorrect JSON syntax in the body.
• 404 Not Found: Sent when no handler is found for the requested path.
• 405 Method Not Allowed: Sent when a request is made to a valid path but with an unsupported HTTP method.
• 500 Internal Server Error: Sent when an unexpected exception occurs during request processing.

Testing

The project includes a suite of unit tests written using JUnit 6 and Mockito. These tests cover the core components of the server, including the HttpServer, ClientRequestHandler, and TrieRouter, ensuring their correctness and reliability.