learn-wasm-components

Goal

Create a WASM component function in any language that can be invoked from a host runtime. This example creates a Golang and Rust component to implement is-odd-or-even.wit. The components are hosted by the runtime/rust crate.

Install dependencies

Bytecode Alliance's wasm-tools and wit-bindgen are required to build a WASM component with TinyGo's.

cargo install wasm-tools
cargo install wit-bindgen-cli

brew tap tinygo-org/tools
brew install tinygo

Build steps

The component/golang and component/rust directories have a README.md files with instructions for building the WASM component.

runtime/rust can be run with cargo run with a COMPONENT_LANGUAGE env var specifying golang or rust. is-odd-or-even will be called with the arg to the program.

COMPONENT_LANGUAGE=golang cargo run -- 42

Inspecting components

wasm-tools validate is-odd-or-even.wasm --features component-model

wasm-tools component wit is-odd-or-even.wasm

Current state

	golang	rust
debug	107214	1750360
release	107214	1640355

Rust component is 16.3x larger than Golang component.

wasm-tools component wit output for each language's component varies and includes a lot of WASI imports that unused by the implementation.

golang component WIT

package root:component;

world root {
  import wasi:io/error@0.2.0;
  import wasi:io/streams@0.2.0;
  import wasi:cli/stdin@0.2.0;
  import wasi:cli/stdout@0.2.0;
  import wasi:cli/stderr@0.2.0;
  import wasi:clocks/wall-clock@0.2.0;
  import wasi:filesystem/types@0.2.0;
  import wasi:filesystem/preopens@0.2.0;

  export is-odd-or-even: func(number: s32) -> bool;
}

Rust component WIT

package root:component;

world root {
  import wasi:cli/environment@0.2.0;
  import wasi:cli/exit@0.2.0;
  import wasi:io/error@0.2.0;
  import wasi:io/streams@0.2.0;
  import wasi:cli/stdin@0.2.0;
  import wasi:cli/stdout@0.2.0;
  import wasi:cli/stderr@0.2.0;
  import wasi:clocks/wall-clock@0.2.0;
  import wasi:filesystem/types@0.2.0;
  import wasi:filesystem/preopens@0.2.0;

  export is-odd-or-even: func(number: s32) -> bool;
}

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