created_at2023-08-23 22:43:12.305783
updated_at2023-12-30 16:40:19.704459
descriptionWebAssembly component model implementation for any backend.
Douglas Dwyer



# wasm_component_layer [![Crates.io](https://img.shields.io/crates/v/wasm_component_layer.svg)](https://crates.io/crates/wasm_component_layer) [![Docs.rs](https://docs.rs/wasm_component_layer/badge.svg)](https://docs.rs/wasm_component_layer) [![Unsafe Forbidden](https://img.shields.io/badge/unsafe-forbidden-success.svg)](https://github.com/rust-secure-code/safety-dance/) `wasm_component_layer` is a runtime agnostic implementation of the [WebAssembly component model](https://github.com/WebAssembly/component-model). It supports loading and linking WASM components, inspecting and generating component interface types at runtime, and more atop any WebAssembly backend. The implementation is based upon the [`wasmtime`](https://github.com/bytecodealliance/wasmtime), [`js-component-bindgen`](https://github.com/bytecodealliance/jco), and [`wit-parser`](https://github.com/bytecodealliance/wasm-tools/tree/main) crates. ## Usage To use `wasm_component_layer`, a runtime is required. The [`wasm_runtime_layer`](https://github.com/DouglasDwyer/wasm_runtime_layer) crate provides the common interface used for WebAssembly runtimes, so when using this crate it must also be added to the `Cargo.toml` file with the appropriate runtime selected. For instance, the examples in this repository use the [`wasmi`](https://github.com/paritytech/wasmi) runtime: ```toml wasm_component_layer = "0.1.0" wasm_runtime_layer = { version = "0.1.1", features = [ "backend_wasmi" ] } ``` The following is a small overview of `wasm_component_layer`'s API. The complete example may be found in the [examples folder](/examples). Consider a WASM component with the following WIT: ```wit package test:guest interface foo { // Selects the item in position n within list x select-nth: func(x: list, n: u32) -> string } world guest { export foo } ``` The component can be loaded into `wasm_component_layer` and invoked as follows: ```rust use wasm_component_layer::*; // The bytes of the component. const WASM: &[u8] = include_bytes!("single_component/component.wasm"); pub fn main() { // Create a new engine for instantiating a component. let engine = Engine::new(wasmi::Engine::default()); // Create a store for managing WASM data and any custom user-defined state. let mut store = Store::new(&engine, ()); // Parse the component bytes and load its imports and exports. let component = Component::new(&engine, WASM).unwrap(); // Create a linker that will be used to resolve the component's imports, if any. let linker = Linker::default(); // Create an instance of the component using the linker. let instance = linker.instantiate(&mut store, &component).unwrap(); // Get the interface that the interface exports. let interface = instance.exports().instance(&"test:guest/foo".try_into().unwrap()).unwrap(); // Get the function for selecting a list element. let select_nth = interface.func("select-nth").unwrap().typed::<(Vec, u32), String>().unwrap(); // Create an example list to test upon. let example = ["a", "b", "c"].iter().map(ToString::to_string).collect::>(); println!("Calling select-nth({example:?}, 1) == {}", select_nth.call(&mut store, (example.clone(), 1)).unwrap()); // Prints 'Calling select-nth(["a", "b", "c"], 1) == b' } ``` ## Supported capabilities `wasm_component_layer` supports the following major capabilities: - Parsing and instantiating WASM component binaries - Runtime generation of component interface types - Specialized list types for faster - Structural equality of component interface types, as mandated by the spec - Support for guest resources - Support for strongly-typed host resources with destructors The following things have yet to be implemented: - String transcoders - A macro for generating host bindings - More comprehensive tests - Subtyping ## Optional features **serde** - Allows for the serialization of identifiers, types, and values. Note that serializing resources is not allowed, because resources may be tied to specific instances.
Commit count: 64

cargo fmt