Note: The code in this repository was written by me as part of a self-learning exercise. The task was defined and the final implementation evaluated using generative AI (OpenAI’s ChatGPT). The project was used to improve my understanding of async networking, ownership, and message-passing in Rust.

📝 Homework Assignment: “Tackboard” – A Minimal Async Pub/Sub System

✅ Final Score: 10/10 — Excellent work!
Your implementation shows strong understanding of async concurrency, framing, message routing, and Rust’s ownership model. Clear structure, correct locking patterns, and thoughtful logging elevate this beyond a minimal pub/sub system.

Build a minimal in-memory publish/subscribe system over TCP where multiple clients can:

• Subscribe to a topic
• Publish a message to a topic
• Receive messages on topics they subscribed to

Components:

• tackboardlib: A library with:
  • Topic/message definitions
  • Serialization logic
  • Server data structures and logic
• tackboardsrv: A binary that runs the pub/sub server
• tackboardctl: A CLI client that connects, subscribes, and publishes

• Accepts multiple clients via TCP
• Keeps an in-memory HashMap<Topic, Vec<Sender<Message>>>
• On Publish, sends to all subscribed clients
• On Subscribe, registers the client for a topic

• Connects via TCP
• Can send Subscribe { topic } or Publish { topic, message } requests
• Listens to incoming messages and prints them

• Add timeouts: Disconnect clients who are idle for 30s
• Support unsubscribing
• Implement wildcard topic matching
• Write integration tests

#[derive(Serialize, Deserialize)]
pub enum ClientRequest {
    Subscribe { topic: String },
    Publish { topic: String, message: String },
}

#[derive(Serialize, Deserialize)]
pub enum ServerMessage {
    Message { topic: String, message: String },
    Ack,
    Error(String),
}

• tokio – async networking
• tokio_util::codec::LengthDelimitedCodec
• tokio_serde – serialize messages over TCP
• serde, serde_json
• clap for client CLI

tackboard/
├── Cargo.toml (workspace)
├── tackboardlib/
│   └── src/lib.rs
├── tackboardsrv/
│   └── src/main.rs
└── tackboardctl/
    └── src/main.rs

• Clients can connect to the server
• Subscribed clients receive published messages
• You’ve implemented proper error handling and logging
• Bonus if you add tests or make it robust to client disconnects