justjosias / lunatic-chat

A telnet chat server

Lunatic.chat

A telnet chat server written in Rust, running on Lunatic.

I wrote a blog post about the implementation, you can read it here. The implementation has significantly changed since the blog was written and updated to the new higher-level process architecture in lunatic.

If you just would like to try it out, join the hosted version with:

telnet eu.lunatic.chat

Architecture

The server is written in Rust. The Rust code is then compiled to WebAssembly and runs on top of Lunatic. Each connection runs in a separate (lightweight) process, has its own state and sends just a diff of esc-sequences back to the terminal to bring it up to date with the current render buffer.

Process architecture:

Each rectangle represents a process. The ClientProcess holds the current render state that can be changed by new commands coming from telnet or new messages from channels that the client joined. The CoordinatorSup is a supervisor that will restart the global coordinator if it dies. All processes that depend on the coordinator are linked to it, if it dies it will disconnect all clients and kill all channels.

Build & run instructions

If you have rustup installed:

# Add the wasm32-wasi target
> rustup target add wasm32-wasi
# Build the project
> cargo build

To run it, you will need to have lunatic on your PATH. If this is the case you can just run cargo run or find the generated telnet-chat.wasm file in the target folder and run it with lunatic path/to/telnet-chat.wasm.

Licence

MIT