wit-bindgen VS wasi-sdk

The component model is already shipping in Wasmtime, and will be stable for use in Node.js and in browsers via jco (https://github.com/bytecodealliance/jco) soon. WASI Preview 2 will be done in December or January, giving component model users a stable set of interfaces to use for scheduling, streams, and higher level functionality like stdio, filesystem, sockets, and http on an opt-in basis. You should look at wit-bindgen (https://github.com/bytecodealliance/wit-bindgen) to see some of the languages currently supported, and more that will be mature enough to use very soon (https://github.com/bytecodealliance/componentize-py)

Right now jco will automatically generate the JS glue code which implements a Component Model runtime on top of the JS engine's existing WebAssembly implementation. So, yes, Components are a composition of Wasm Modules and JS code is handling passing values from one module/instance to another. You still get the performance benefits of running computation in Wasm.

One day further down the standardization road, we would like to see Web engines ship a native implementation of the Component Model, which might be able to make certain optimizations that the JS implementation cannot. Until then you can consider jco a polyfill for a native implementation, and it still gives you the power to compose isolated programs written in many languages and run them in many different contexts, including the Web.

(Disclosure: I am co-chair of WASI, Wasmtime maintainer, implemented many parts of WASI/CM)

Thank you!

To your point, the primary consideration for choosing the languages is their support for WebAssembly, and WASI in particular.

Due to Spin's heavy use of WASI and the component model, languages that have first party support in the WIT bindings generator (https://github.com/bytecodealliance/wit-bindgen) are the easiest to implement, followed by languages that can be built on top of the support for those with first party support.

For example, the JavaScript support is built by embedding QuickJS (in particular, Shopify's Javy project — https://github.com/fermyon/spin-js-sdk), which then uses the Rust SDK.

There are many options, but what worked best for me is compiling with cargo-wasi and loading the resulting Wasm file with browser_wasi_shim. Using wasm32-wasi instead of wasm32-unknown-unknown requires a bit more work (the communication with JS has to be set up manually), but gives the flexibility of having just a Wasm file that can be dropped in and loaded dynamically. (There's wit-bindgen for generating wrapping code according to an interface definition but I didn't have much success with it.)

I've been playing with creating a go version of the abi for use with wit-bindgen because the current one uses cgo https://github.com/bytecodealliance/wit-bindgen

wit-bindgen - Language Binding Generator for WASM Interface Type

wit-bindgen-rust = { git = "https://github.com/bytecodealliance/wit-bindgen.git", rev = "60e3c5b41e616fee239304d92128e117dd9be0a7" }

Yep, you're right. For this, there are a few options. The ones most relevant to you are fp-bindgen, which targets Wasmer, and wit-bindgen, which targets wasmtime.

Are you evaluating if WebAssembly Component Model, its WIT format and related tooling like wit-bindgen could be a good fit for your multiple languages support?

[package] name = "sentiment" version = "0.1.0" edition = "2021" # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html [dependencies] wit-bindgen-rust = { git = "https://github.com/bytecodealliance/wit-bindgen.git", rev = "60e3c5b41e616fee239304d92128e117dd9be0a7" } vader_sentiment = { git = "https://github.com/ckw017/vader-sentiment-rust" } lazy_static = "1.4.0" [lib] crate-type = ["cdylib"]

I would really love being able to take any POSIX command line tool, compile that to WASI, and run it on (at least) Linux, Windows and macOS like a regular executable without having to install a separate WASI runtime.

I'm a 'WASI convert' since I was able to take an ancient 8-bit assembler written in the mid-90's (http://xi6.com/projects/asmx/), compile that as-is with the WASI SDK (https://github.com/WebAssembly/wasi-sdk), and then integrate it into a VSCode extension (https://marketplace.visualstudio.com/items?itemName=floooh.v...).

A similar problem is I have is a shader cross-compiler (https://github.com/floooh/sokol-tools) which needs to run Linux, macOS and Windows and takes too long to build locally, thus I currently need to distribute that as pre-built binaries. Compiling this to WASI works, but the filesystem access restrictions built into current wasm runtimes are a hassle to manage, and it would require a WASI runtime to be separately installed).

There is the WASI SDK if you want to target WASI from C/C++:

https://github.com/WebAssembly/wasi-sdk

It may not have all the amenities of Emscripten, but it's way less bulky.

The most direct way to debug WebAssembly is through the WebAssembly System Interface (WASI). In itk-wasm, we can build to WASI with the WASI SDK by specifying the itkwasm/wasi toolchain image. A backtrace can quickly be obtained with the itk-wasm CLI. Or, a fully fledged debugger session can be started with LLDB.

We use the add_executable command to build executables with itk-wasm. The Emscripten and WASI toolchains along with itk-wasm build and execution configurations are contained in itk-wasm dockcross Docker images invoked by the itk-wasm command line interface (CLI). Note that the same code can also be built and tested with native operating system toolchains. This is useful for development and debugging.

A more lightweight tool than emscripten is the WASI SDK (https://github.com/WebAssembly/wasi-sdk/releases). However, it doesn't generate JS or HTML.

wget https://github.com/WebAssembly/wasi-sdk/releases/download/wasi-sdk-16/wasi-sdk-16.0-macos.tar.gz

First, we’ll download the wasi-sdk. We’ll use wasi-sdk-16.0-linux.tar.gz, the latest version available when writing this article. We’ll move the file to the /opt directory and unpack it as follows:

I'm intrigued. Pretty good write-up about it here. One would need an ebuild for wasi-libc and an ebuild for wasi-sdk.

The previously mentioned PR for wasm32-unknown-unknown compatibility solved this by including libc .c files from OpenBSD. My go to solution is different though. I prefer to build using the wasi-sdk (a WASI-enabled WebAssembly C/C++ toolchain).

There's also the https://github.com/WebAssembly/wasi-sdk repo which is kind of a meta-build-system for all this.

But in FreeBSD we build all the pieces directly, here's our build recipes (with some hacks due to llvm's cmake code being stupid sometimes):

compiler-rt (from llvm): https://github.com/freebsd/freebsd-ports/blob/main/devel/was...

libc (from what you linked): https://github.com/freebsd/freebsd-ports/blob/main/devel/was...

libc++ (from llvm): https://github.com/freebsd/freebsd-ports/blob/main/devel/was...