Project 6: An async HTTP Server

A simple, concurrent HTTP/1.1 server from scratch that can serve static files and handle multiple simultaneous connections using Zig’s async/await framework.

Quick Reference

Attribute Value
Primary Language Zig
Alternative Languages Go, Rust, Node.js
Difficulty Level 3: Advanced
Time Estimate 1-2 weeks
Knowledge Area Networking / Concurrency
Tooling A high-performance web server
Prerequisites Project 3. A basic understanding of HTTP.

What You Will Build

A simple, concurrent HTTP/1.1 server from scratch that can serve static files and handle multiple simultaneous connections using Zig’s async/await framework.

Why It Matters

This project builds core skills that appear repeatedly in real-world systems and tooling.

Core Challenges

  • Accepting TCP connections → maps to using std.net.tcpListen and accept in a loop
  • Handling multiple clients concurrently → maps to spawning an async frame for each connection
  • Parsing HTTP requests → maps to manual string and buffer manipulation
  • Managing the event loop → maps to understanding how suspend and resume interact with the evented I/O system

Key Concepts

  • Async Functions: Zig Documentation chapter on async.
  • Event-driven I/O: “Operating Systems: Three Easy Pieces”, Ch. 6 (Concurrency)
  • TCP Sockets: “The Sockets Networking API” by W. Richard Stevens

Real-World Outcome

$ zig build run
Listening on http://127.0.0.1:8080
Handling connection from 127.0.0.1:54321
  -> GET /index.html HTTP/1.1
  <- HTTP/1.1 200 OK
Handling connection from 127.0.0.1:54322
  -> GET /style.css HTTP/1.1
  <- HTTP/1.1 200 OK

Implementation Guide

  1. Reproduce the simplest happy-path scenario.
  2. Build the smallest working version of the core feature.
  3. Add input validation and error handling.
  4. Add instrumentation/logging to confirm behavior.
  5. Refactor into clean modules with tests.

Milestones

  • Milestone 1: Minimal working program that runs end-to-end.
  • Milestone 2: Correct outputs for typical inputs.
  • Milestone 3: Robust handling of edge cases.
  • Milestone 4: Clean structure and documented usage.

Validation Checklist

  • Output matches the real-world outcome example
  • Handles invalid inputs safely
  • Provides clear errors and exit codes
  • Repeatable results across runs

References