Learning Tokio Through Projects: From Echo Servers to Distributed Systems

Posted on:September 19, 2025 at 01:23 PM

I want to get more comfortable with Tokio, Rust’s async runtime. Learning async Rust can feel intimidating, so I decided to take it step by step.

This is not a universal learning path. It is my personal plan, and I will update the list as I make progress and write dedicated articles for each project.

Beginner Level

  1. Async Echo Server
    Build a TCP server that accepts connections and echoes messages back.
    Concepts: TcpListener, TcpStream, spawning tasks with tokio::spawn.

  2. Chat Server (Multi-client Echo)
    Extend the echo server to broadcast messages from one client to all connected clients.
    Concepts: Using tokio::sync::broadcast channels for fan-out messaging, managing client lifetimes, handling dropped receivers.

  3. Simple HTTP Server
    Parse basic HTTP requests and return static responses, for example always return “Hello World”.
    Concepts: Async I/O parsing, handling request and response framing.

Intermediate Level

  1. Async File Downloader
    Given a URL, download the file asynchronously using reqwest with the Tokio runtime.
    Concepts: Async file I/O with tokio::fs, streaming large responses.

  2. Key-Value Store Server
    Create a TCP server where clients can SET and GET keys, similar to a toy Redis.
    Concepts: Parsing simple text protocols, storing state in memory, tokio::select!.

  3. WebSocket Chat Application
    Use tokio-tungstenite to build a chat app over WebSockets where clients can join rooms.
    Concepts: Higher-level protocols over TCP, managing multiple async streams.

Advanced Level

  1. Proxy Server (TCP Forwarder)
    Build a transparent TCP proxy that forwards traffic between client and target server.
    Concepts: Bidirectional stream handling, tokio::io::copy_bidirectional.

  2. Async DNS Resolver
    Implement a minimal DNS client that sends UDP queries and parses responses.
    Concepts: Working with tokio::net::UdpSocket, binary protocol parsing.

  3. Task Scheduler / Job Runner
    Write a daemon that accepts jobs, for example shell commands, over TCP and runs them concurrently.
    Concepts: Process management with tokio::process, cancellation with tokio::time, graceful shutdown.

  4. Miniature Distributed Key-Value Store
    Extend your KV store into a cluster where nodes replicate data across the network.
    Concepts: Peer-to-peer communication, Raft-like consensus at a basic level, handling network partitions.

Closing Thoughts

This list is my roadmap for learning Tokio. It might change as I progress, and I will keep updating it with links and refinements. If you are also learning async Rust, you might find some useful ideas here.