chat VS chrono

TUIs over ssh/telnet can be a lot of fun. Especially in cases where multiple people can interact with each other on the server. It simplifies the programming model as you only have one state on the backend that you render to multiple connections. Syncing up everyone becomes trivial. You can also use some React concepts, like rendering a virtual TUI and sending just the right set of minimal escape sequences back to the user to bring their display up to date.

A few months ago I implemented a telnet chat server[0] for fun and it was surprisingly easy to do so. Even by using a wasm vm that I was still working on at the same time.

[0]: https://github.com/lunatic-solutions/chat

We are investing a lot of effort into making Lunatic feel native to the particular language and ecosystem. If you look at the Rust chat server we built in Lunatic (https://github.com/lunatic-solutions/chat), it fully integrates with cargo. You just run your typical “cargo run” command, it will compile the app to wasm and use lunatic to run it. If you want to run your test, you can just do “cargo test”.

wasm-bindgen is necessary only because it’s really hard right now to merge the wasm world and the JS one in the browser. We have the advantage here of staying out of the browser.

It took me around a week to build it with Rust + Lunatic and you can check out the code here. If you would like to try it out you can connect to it with:

Recently I implemented a command line chat server in Rust using an actor framework. I model each TCP connection as an actor.

Hi HN,

I'm working on an Erlang inspired WebAssembly runtime for the backend[0]. Recently I added TCP support and was looking for apps I could build with it. I ended up building a telnet line chat app. It was a great dogfooding experience and has a nice retro feel to it.

You can access the US server with:

> telnet lunatic.chat

or the EU one with:

> telnet eu.lunatic.chat

Pick the one closer to you, as all the rendering is done on the backend and lower latency will mean better UX.

The server is open source[1] and 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 it's 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. Everything is deployed to an ARM Linux box.

[0]: https://github.com/lunatic-solutions/lunatic

[1]: https://github.com/lunatic-solutions/chat

The server is open source and 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 it's 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. Everything is deployed to an ARM Linux box.

The problem is that this effects higher languages too, because they often build on libc. And on some OSes, they don't have a choice, because the system call interface is unstable and/or undocumented).

For example in rust, multiple time libraries were found to be unsound if `std::env::set_env` was ever called from a multi-threaded program. See:

https://github.com/time-rs/time/issues/293 and https://github.com/chronotope/chrono/issues/499

https://github.com/rust-lang/rust/issues/27970

https://github.com/rust-lang/rust/issues/90308

> I think library authors should be more relentless and break compatibility every few years. We just need some conventions to not do so very often.

I indeed did this years ago---I'm the original author of Chrono [1]---and it wasn't well received [2] [3] [4]. To be fair, I knew it was a clear violation of semantic versioning but I didn't see any point of obeying that until we've reached 1.0 so I went ahead. People complained a lot and I had to yank the problematic release. By then I realized many enough people religiously expect semantic versioning (for good reasons though) and it's wiser to avoid useless conflict.

[1] https://github.com/chronotope/chrono

[2] https://github.com/chronotope/chrono/issues/146#issuecomment...

[3] https://github.com/chronotope/chrono/issues/156

[4] https://github.com/chronotope/chrono/blob/main/CHANGELOG.md#...

On that note, it would also be good to configure cargo-deny so that a CI pipeline and any maintainer can easily audit the current dependency versions. Sometimes CVEs require a new major semver (looking at you, time 0.1.x and thus chrono 0.4.x), so it's not enough to rely on people installing the tool with semver-compatible updates. Automatically auditing dependencies is really important, and given how easy cargo-deny makes it, I don't think many projects have any excuse not to configure it.

The example has been randomly taken from the [Chrono][https://github.com/chronotope/chrono/blob/main/src/offset/utc.rs] crate.

libc isn't "just a wrapper". Is a massive legacy codebase filled with hacks, UBs and bugs: https://github.com/chronotope/chrono/issues/499

Would love to have people test this, you can leave feedback here: https://github.com/chronotope/chrono/issues/674.

Security issues? I'm looking at the open issues, but haven't noticed any that seem to be security related (no security related labels either). What am I missing here?