WebAssembly Component Model

• WIT — .wit files describe the interface between components
• Canonical ABI: records/variants/strings cross the boundary without FFI
• jco (JS Component Tools) — transpile .wasm → pure JS
• Wasmtime 14+ — host runtime with Component Model out of the box
• WASI 0.2 is built on the Component Model

// hello.wit
package example:hello;
world app {
    export greet: func(name: string) -> string;
}

// Rust implementation
#[export_name = "greet"]
pub extern "C" fn greet(name: &str) -> String {
    format!("Hello, {}!", name)
}

• WASI
• Serverless containers