wasi-libc VS wasmtime

WebAssembly has a set of extended interfaces collectively called the WebAssembly System Interface (WASI). This bit is chugging its way through standardization, due to be finalized in 2025. But if there is one thing we should have collectively learned from the standardization of HTML, CSS, HTTP, JavaScript, and onward, standards-based implementations often stabilize and reach production readiness far sooner than the standards body can walk its lumbering gate to a final ratification. While WASI continues to add new interfaces, the core interfaces (components, file system, environments, and so on) have long been stable, and have long been deployed into production.

https://wasi.dev/

wow I didn't know this was a thing. thanks for filling me in!

Standardization Efforts: Projects like WASI aim to create an ABI standard that facilitates better integration between WebAssembly and the host operating system. However, WASI’s full browser support, especially for web-specific APIs like WebGPU, is still a work in progress.

Now there are projects like WASI that allows for interfacing with system resources for WASM code this allows for devs to target WASM runtime for their apps sliding the apps to run locally on any OS without any porting required. This could be a game changer in the future like Docker and containers was in the past decade.

So it doesn’t seem like there has been progress on a pseudo-random number generator function for typst, but there are multiple other ways to solve this: 1. Just don’t. Typst has this functional philosophy, there one input always produces the same output. (not an answer to your question tho) 2. Interface with a webassembly module which has a random number generator. So you could e.g. compile c to wasm and statically link a libc version. You would then just have to export the rand() function. (You could use any lang for this, which has a stdlib with a pseudo random number generator) 3. Implement your own. Random number generators are actually not that hard something like an LCG isn’t to complex. (Id provide an example but im on my phone rn)

Actually WASI[0] will be a better alternative, IIRC extism serialize and deserialize the data that you want to pass every time, adding a lot of overhead.

[0] https://wasi.dev

Actually, it was in wasi-libc: https://github.com/WebAssembly/wasi-libc/blob/main/libc-bott...

Proper isolation in C# is only now becoming a thing, with .Net support for WASI, which is essentially a WebAssembly sandbox which can be given extremely granular privileges (such as access to spefic file system directories, or an effective virtual file system). As an upside, the idea is that it should be possible to write the WASI packages in more or less anything.

Wasm Labs dev here :)

In mod_wasm, there are some differences with a pure CGI implementation. When Apache boots, it loads the configuration and initializes the WasmVM. When a new HTTP request arrives, the VM is ready so you don't need to initialize a different process to manage it.

You still need to process the request and pass the data to the Wasm module. This step is done via STDIN through the WebAssembly System Interface (WASI) implementation [0]. The same happens in the opposite direction, as the module returns the data via STDOUT.

So, the CGI pattern is still there, but it doesn't require new processes and all the code runs in a sandbox.

However this is not the only way you can run a Wasm module. In this specific case, we use CGI via WASI. In other cases, you may compile a module to fulfill a specific API, like ProxyWasm [1] to create HTTP filters for proxies like Envoy.

- [0] https://wasi.dev/

- [1] https://github.com/proxy-wasm/spec

Standards help in a completely different way, too: since all of the HTTP support is now built using wasi-http, applications built with the new SDK that don’t make use of the Spin-specific APIs we also support can run in any environment that supports wasi-http, such as Wasmtime and Node.js (via JCO).

If you’re on Windows, check out the precompiled packages: https://github.com/bytecodealliance/wasmtime/releases

You should look at embedding Wasmtime into your C.

https://github.com/bytecodealliance/wasmtime/tree/main/examp...

And a special thank you to everyone who has been contributing and continues contribute to the WebAssembly ecosystem particularly to the maintainers of the Bytecode Alliance projects, the Wasmtime project and the developers working on WASI and the WebAssembly component model. Their work is instrumental in supporting Spin.

For the audience that would be looking to use the WASM Component Model, and not be an infrastructure implementer of it, whether or not they meet some definition of a method, the component model does define things called resources [1] that have "methods". You'll hold a "handle" to it like you would in your own programming language with the expected drop and/or GC semantics (once implemented [2]) because code is generated to access it like any other FFI like C/C++.

With that in mind, the other confusing thing one may come across is composition vs linking within your WASM runtime that supports the Component Model. When you hear "composition" think of compile-time merging of libraries such that the bundle may have less unresolved dependencies of WASM code/implemented component interfaces. Anything unresolved needs to be linked at runtime with your WASM runtime of choice, like wasmtime [3]. Pretty interesting reading/potential after reading if you ask me -- sounds like you could implement something like a custom Java classloader hierarchy.

But I'd agree with a statement saying it is still a long way for general usage.

[1] https://github.com/WebAssembly/component-model/blob/5a34794d...

[2] https://github.com/WebAssembly/gc

[3] https://github.com/bytecodealliance/wasmtime/blob/ba8131c6bf...

[4] https://www.digitalocean.com/community/tutorials/java-classl...

Since you're using Rust, the Cranelift JIT compiler implements something like this[0] to construct an e-graph for its expression rewriting subsystem called ISLE, however if I'm not mistaken it is for disjoint sets (not intervals), and therefore it does not deal with ordering.

Maybe you can adapt it for your use case and add those new constraints in?

Keep in mind though that this was not written to be in the hot-path itself, you could probably do significantly better by pouring your soul into some SIMD adventure (though SIMD in Rust is usually very annoying to write)

Best of luck, hope this helps!

[0] https://github.com/bytecodealliance/wasmtime/blob/7dcb9bd6ea...

Just a documentation change, fortunately:

https://github.com/bytecodealliance/wasmtime/commits?author=...

They've submitted little documentation tweaks to other projects, too, for example:

https://learn.microsoft.com/en-us/cpp/overview/whats-new-cpp...

I don't know whether this is a formerly-legitimate open source contributor who went rogue, or a deep-cover persona spreading innocuous-looking documentation changes around to other projects as a smokescreen.

WebAssembly is extremely portable. WebAssembly runs on: all major web browsers, V8 runtimes like Node.js, and independent Wasm runtimes like Wasmtime, Lucet, and Wasmer.