Embedding from Rust (and Other Hosts)

The extension ABI is not tied to Java. An extension declares its contract in build.rs with the boomslang-hostgen DSL and emits ABI JSON; host-language adapters are generated from that JSON. Any WASM runtime that implements the same imports can run boomslang.wasm.

The Rust example host

examples/rust-host/ is a runnable Wasmtime embedder. Its build.rs turns an <extension>.abi.json into typed Wasmtime bindings:

cargo run --manifest-path examples/rust-host/Cargo.toml

The generated binding is a typed builder plus a register(&mut wasmtime::Linker<_>):

#![allow(unused)]
fn main() {
let host = BoomslangHostHostFunctions::builder()
    .with_call(|name, payload| Ok(format!("{name}: {payload}")))
    .with_log(|level, message| {
        eprintln!("[guest log:{level}] {message}");
        Ok(())
    })
    .build();

host.register(&mut linker)?;
}

Generated Rust host bindings also include an AsyncHostRegistry mirroring the Java one: typed async imports return registry tokens, and the stock call handler routes the reserved __async_* control calls through the same registry.

Embedding a full boomslang.wasm

The generated register covers the extension imports. A complete embedder additionally:

1. adds WASI preview1 imports to the same Linker
2. instantiates the module
3. drives execution through boomslang’s exported functions (alloc, compile_source, execute, and the output-buffer protocol)

The exported function contract is specified in the reference section (base ABI). Runtime assets (boomslang.wasm + the Python resource tree) are published on GitHub Releases — see Installation.