How and why Daily is using Rust for our WebRTC APIs
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In a multithreaded wasm app, do all threads have equal access to the DOM, or is it more like JS where there is a UI thread which can access all APIs and a bunch of worker threads which can only access a more limited set of APIs?
If the latter, has anyone sought to expose that constraint to the Rust type system? e.g. via a capabilities object that's neither Sync nor Send
I assume if it’s even possible, it might execute the code only if the main thread is not executing any events - which happens only once per eventloop iteration.
I guess what is happening is that worker can call into JS, but can not access the DOM or anything else living on the main thread. They have to send messages to the other thread, just as JavaScript workers would need to do.
You can (and should) use Web Workers[1], those run off the UI thread, but also don't have access to the DOM.
[1] https://developer.mozilla.org/en-US/docs/Web/API/Web_Workers...
it seems like these reasons to do something mysteriously only stay valid for the short period of time in which a technology has some kind of hype status and quickly fades when people realize that it's actually not that much improvement in practice and the hassles (training devs in new language, worse language ecosystem etc.) aren't actually worth it.
I don't think it matters what the Daily team originally intended. It is exciting/inspiring to me that they are trying to solve things differently. I think security for RTC is really important, so seeing more memory safe language usage makes me hopeful for the future.
All this new code also means people are really learning what goes into these problems. A whole new generation of coders are getting into the space and rethinking things. It is great.
In other words, we tried hard to document a lot of before-the-fact rationalizations to go with the inevitable after-the-fact rationalizations. :-)
Have you evaluated webrtc-rs yet? I haven't keep up to date with mediasoup, but I saw they have a rust effort. Have you evaluated that yet?
Seems possible to drop lots of C++ dependencies :)
`daily-core` is signaling, the (always evolving) low-level trickery needed to scale calls to 10,000+ participants, state management, and an opinionated internal API that lets us efficiently maintain public-facing API features like track management, and device selection.
There are some use-cases in every industry. * Finance/Company: earnings calls as mentioned before, all-hands meetings at companies (with several people queuing for questions and answers) * Live Events (music or talkshows) * Tutoring or education in general. * Healthcare and education -- Surgeries which are broadcast to several schools and have active collaboration from some doctors. The large-scale interaction can begin much earlier before the surgery.
Edit: Also, webrtc-rs doesn't work for me either; AFAIK, it doesn't yet have enough of the media stack, including hard stuff like echo cancellation.
People told me that unless you were a developer at a big company you can't build DTLS, SCTP and RTP Congestion Control either. Maybe the community implementations aren't as good yet, but I think it is a tortoise vs hare.
As it happens I am the author of the audio-buffer and constraint-algorithm implementations in webrtc-rs/media: https://github.com/webrtc-rs/media/commits?author=regexident
So even though we are not using webrtc-rs in Daily today, we are (or at least I am) contributing to it, in hopes of it becoming a feasible option at some point.
Regarding mediasoup, their Rust effort so far has focused mostly on the server side of things, whereas for this particular project we would be looking more towards the client side.
That would definitely be something we are considering contributing to, as it would, as you say, drop quite a significant amount of C++ (with additional benefits on the web side, too).
The server side is the hard part to work on. Also, one of the downsides of wasm is that it can be a pain to communicate out to the JS APIs, especially for doing lots of DOM manipulation. I'm not sure how sound this approach is really. It seems like you're going to do a lot of extra work in order to solve a problem that isn't much of a problem in the first place.
The client-side and server-side code end up being tightly coupled and you end up having a lot more client-side code than maybe is obvious if you're building an application that uses WebRTC in one specific way. For example, handling fast subscription to and un-subscription from batches of tracks is non-trivial, but important if you're implementing "grid mode" client views.
The goal of the approach we're taking here is to be able to support a bunch of different platforms at the same level of performance, stability, and feature parity. Web, iOS, and Android are the three most important platforms. But people are also using WebRTC on Flutter, native Linux, macOS, Windows, Unreal, Unity, and various embedded platforms.
Vincent here, fellow dev at Daily, working on daily-core and Daily for iOS. :)
We did evaluate webrtc-rs, but we found that it simply isn't yet were it would need to be in order to be a realistic replacement for libwebrtc.a today. As a matter of fact I am a member of the webrtc-rs org (https://github.com/orgs/webrtc-rs/people), having contributed the audio-buffer and constraint-algorithm implementations so far (https://news.ycombinator.com/item?id=31000261).
I personally have high hopes for being able to make the jump at some point. Just alone being able to toss the monstrous `build.rs` that currently ties ninja/gn (libwebrtc), cmake (libmediasoupclient), clang (our own bridging code) and bindgen (for header imports) together and makes things work across multiple platforms would almost be worth it for me. With Rust implementations of mediasoupclient and webrtc none of this hassle would be necessary. In pure Rust stuff just works.