botnet VS gc

I was/am working on a project (https://github.com/JMS55/botnet), where users upload scripts compiled to WASM to control entities on a game server, so that they can write custom behavior.

Never heard of extism before, but second using WASM for plugins/scripting/extensions. I'm using it for botnet(1). Each player uploads a WASM program to control their bots. Both the server and the bot SDK are written in Rust, and can share some code.

4. Speed

I'm hoping to write my thesis for my master's degree on this topic this year. I'm also in the process of writing a game like screeps, where users provide a WASM script to control units for an RTS-style game (without combat though) https://github.com/JMS55/botnet.

It's amazing how simple it is to constrain memory usage, runtime duration, and secure exported functions to a WASM VM. Performance is also great - currently about ~6 microseconds per tick per unit, up to ~200 microseconds when doing expensive pathfinding. All that, while letting you program your units in Rust - the same language as the server is written in, while being able to share code with the server, and not having to use something more script-y like lua.

The boilerplate sucks, but it works well when you don't need a ton of different functions. I use wasm as a scripting language for running isolated untrusted scripts in a game I'm developing, and it works really well https://github.com/JMS55/botnet.

I'm working on a Screeps-like game using WebAssembly. You compile a script to WebAssembly, and for each robot you control on the server, it runs the script in an isolated environment to choose an action for that robot. The goal is to write a program to coordinate your robots to gather resources and expand your control of the server.

Here's an example bot script: https://github.com/JMS55/botnet/blob/master/example_bot/src/...

The basic infrastructure of the project is more or less in place, besides a visual replay viewer which I'm working on right now. What's needed is a bunch of work in designing game mechanics and APIs. I don't actually have any plans beyond bots running around and harvesting randomly generated resources at the moment. Feel free to open a discussion on the github page if you're interested in Rust, WebAssembly, and video games.

https://github.com/JMS55/botnet

It may take some time for WasmGC to be usable by .NET. Based on the discussions the first version of WasmGC does not have a good way to handle a few .NET specific scenarios, and said scenarios are "post-post-mvp". [0]

My concern, of course, is that there is not much incentive for those features to be added if .NET is the only platform that needs them... at that point having a form of 'include' (to where a specific GC version can just be cached and loaded by another WASM assembly) would be more useful, despite the pain it would create.

[0] - https://github.com/WebAssembly/gc/issues/77

Yes, that's definitely true: a single GC will not be optimal for everything, or even possible. Atm interior pointers are not supported at all, for example, but they are on the roadmap for later:

https://github.com/WebAssembly/gc/blob/main/proposals/gc/Pos...

What launched now is enough WasmGC to support a big and useful set of languages (Java, Kotlin, Dart, OCaml, Scheme), but a lot more work will be required here!

GC proposal is from 2018: https://github.com/WebAssembly/proposals/issues/16 and there’s code: https://github.com/WebAssembly/gc/blob/master/proposals/gc/O...

Seems like an awefully long time for progress to be made, given all the possibilities it would unlock.

First is the size. Writing a server-side and client-side program is possible with Rust, and the resulting WASM package will be small enough. At the same time, Microsoft Blazor converts C# code to WASM, but the client delivery has to include the reduced .NET runtime, taking several megabytes for a script. The same is true for GoLang, even with an attempt to reduce the runtime delivery in TinyGo WASM. Developers want to work with their favorite languages, whether it is Java, Kotlin, Dart, C#, F#, Swift, Ruby, Python, C, C++, GoLang, or Rust. These languages produce groups of runtimes. For example, JVM and .NET have many common parts, Ruby and Python are dynamically interpreted at runtime, and all mentioned depend on automatic garbage collection. For smaller WASM packages, browser vendors can include extended runtime implementations, for example, by delivering a general garbage collector as part of WASM. Garbage collection support by WASM is currently in progress: WASM GC, .NET WASM Notes.

My understanding is that the main limitation is technical. WASM doens't do GC or the host system calling conventions and cannot interact directly with object from Javascript because of this. However, this is being worked[0] on and will be solved eventually. Even without this the performance overhead of bridging to JS is low enough that WASM frameworks can beat out React.

0: https://github.com/WebAssembly/gc/blob/main/proposals/gc/Ove...

I’ve just watched a video on YouTube from Google I/O 2023 on Flutter for the web. Kevin Moore explains that Flutter can compile to Wasm, but now that GC support has been added to the standard and WasmGC is supported in Chromium and Firefox, I’m quite intrigued.

I have found the main thread about using WebAssembly GC in C#: https://github.com/WebAssembly/gc/issues/77. If I understand it correctly, it is not possible to use the current prototype version of GC in C#.

The .net team has given their notes on it, the concern is more on the memory layout from what I remember. Though it may be possible still. The runtime would likely still ship some gc code, but only a subset for cases not supported by the wasm gc itself and a few more for interfacing with the gc service, which overall should still result on smaller payloads compared to current sizes.

I assume that's one of the parts of the work done at https://github.com/WebAssembly/gc - not happening any soon yet, but it'll eventually be done.