Build

$ cargo xtask dist

# For release mode (smaller binary):
$ cargo xtask dist release

# 1. runs `cargo build --target wasm32-wasi`
# 2. adapts wasm module to Component model using `wasi_snapshot_preview1`
# 3. copies Component to dist folder for use

The xtask will build the component, adapt it to preview2, and copy it to the dist folder for useby the host.

Use in Rust

To see the component used in action, run the example binary:

$ cargo run --example smoke

Use in Javascript

This package also uses jco to build Javascript bindings for the component. See the xtask readme for details.

The JS bindings are found in dist/js and the use of the ESM export can be found in the jco docs.

Just like in Rust, you'll need to create a package that creates any imports used in the wasm.

For example, for a world called smoke create a package in javascript and import the smoke component:

// javascript/package.json
// ...
	"dependencies": {
		"@bytecodealliance/preview2-shim": "^0.0.9", // <-- required for preview2
		"smoke": "file:../js-smoke" // <-- write your fns, import the component package
	}
// ...

Once your import functions are written and depended upon, the wasm can use it in its calls.

Refs:

Main inspiration for this example: https://github.com/bytecodealliance/wasmtime/blob/afd9aced3b91ae4eab7c72e0ed4cc241ef93dc89/crates/test-programs/tests/reactor.rs

https://github.com/bytecodealliance/wit-bindgen/tree/main

Wit syntax: https://github.com/WebAssembly/component-model/blob/main/design/mvp/WIT.md

Smoke Wit: https://github.com/bytecodealliance/wit-bindgen/blob/e69cf5db8754f829637e25491c560ec0d9728852/tests/runtime/smoke/world.wit

WIT and Component Model https://docs.rs/wasmtime/latest/wasmtime/component/macro.bindgen.html