Pros of Wasmtime

• Performance: Wasmtime is designed to be a high-performance WebAssembly runtime, with a focus on efficient execution and low overhead.
• Modularity: Wasmtime is built with a modular architecture, allowing for easy integration with other components and the ability to customize the runtime.
• Ecosystem: Wasmtime is part of the Bytecode Alliance, a collaboration of companies and individuals working to improve the WebAssembly ecosystem.

Cons of Wasmtime

• Complexity: Wasmtime is a more complex and feature-rich runtime compared to Wasmi, which may make it more challenging to set up and configure.
• Learning Curve: Developers new to WebAssembly may find the Wasmtime ecosystem and documentation more daunting than the simpler Wasmi.
• Overhead: Wasmtime's focus on performance and features may come with some additional overhead compared to the more lightweight Wasmi.

Code Comparison

Wasmi:

let mut store = Store::new();
let module = Module::from_bytes(&store, &wasm_bytes)?;
let instance = Instance::new(&store, &module, &[])?;
let result = instance.get_export("add")?.get_func().unwrap()(&[42.into(), 24.into()])?;

Wasmtime:

let mut config = Config::new();
let engine = Engine::new(&config);
let module = Module::from_binary(&engine, &wasm_bytes)?;
let mut store = Store::new(&engine);
let instance = Instance::new(&mut store, &module, &[])?;
let result = instance.get_export("add")?.get_func().unwrap()(&mut store, &[42.into(), 24.into()])?;

Pros of WebAssembly/WASI

• Provides a standardized interface for WebAssembly modules to interact with the host environment, making it easier to write portable and secure WebAssembly applications.
• Supports a wide range of host environments, including the web, servers, and embedded systems.
• Offers a rich set of system APIs, including file I/O, networking, and process management, allowing WebAssembly modules to perform a wide range of tasks.

Cons of WebAssembly/WASI

• The WASI specification is still evolving, and there may be some inconsistencies or missing features compared to more mature system APIs.
• Adoption of WASI may be slower than some other WebAssembly-related projects, as it requires coordination and agreement among various stakeholders.
• The learning curve for developers who are new to WebAssembly and WASI may be steeper compared to more established technologies.

Code Comparison

wasmi-labs/wasmi

fn execute_module(
    module: &Module,
    imports: &ModuleImportResolver,
    params: &[RuntimeValue],
) -> Result<Vec<RuntimeValue>, Error> {
    let mut instance = ModuleInstance::new(module, imports)?;
    instance.run_start_function()?;
    instance.invoke_export("_start", params)
}

WebAssembly/WASI

fn run_wasm(wasm_bytes: &[u8]) -> Result<(), anyhow::Error> {
    let mut store = Store::new(&Engine::default());
    let module = Module::new(&store, wasm_bytes)?;
    let instance = Instance::new(&module, &imports(&mut store))?;
    let start = instance.get_export("_start").unwrap().into_func().unwrap();
    start.call(&mut store, &[])?;
    Ok(())
}

Pros of WebAssembly/wabt

• Provides a comprehensive set of tools for working with WebAssembly, including a disassembler, assembler, and interpreter.
• Supports a wide range of WebAssembly features, including the latest version of the specification.
• Offers a well-documented and actively maintained codebase.

Cons of WebAssembly/wabt

• May have a larger codebase and dependencies compared to wasmi-labs/wasmi, which could make it less suitable for certain use cases.
• May have a steeper learning curve for developers unfamiliar with the WebAssembly ecosystem.

Code Comparison

WebAssembly/wabt (wabt_wasm2wat.cc):

void WasmBinaryReader::OnFunctionBody(uint32_t index) {
  if (options_->read_debug_names) {
    ReadLocalNames(index);
  }

  stream_->WriteMemoryDump(data_, end_ - data_, "code", index);
  ReadFunctionBody(index);
}

wasmi-labs/wasmi (lib.rs):

pub fn execute_module(
    module: &Module,
    args: &[RuntimeValue],
) -> Result<Vec<RuntimeValue>, Error> {
    let mut instance = ModuleInstance::new(module)?;
    let main_function = instance.find_export_by_name("main")
        .ok_or(Error::Function("main"))?
        .as_func()
        .ok_or(Error::Function("main"))?;
    main_function.invoke(args)
}

Pros of wasm-bindgen

• Easier Interoperability: wasm-bindgen provides a more seamless integration between Rust and JavaScript, making it easier to call Rust functions from JavaScript and vice versa.
• Automatic Bindings Generation: wasm-bindgen can automatically generate the necessary bindings, reducing the amount of boilerplate code you need to write.
• Improved Developer Experience: wasm-bindgen comes with a set of tools and utilities that enhance the developer experience, such as the ability to generate TypeScript definitions.

Cons of wasm-bindgen

• Increased Complexity: wasm-bindgen adds an additional layer of complexity to the build process, which may be a drawback for some users.
• Potential Performance Impact: The additional abstractions and tooling provided by wasm-bindgen may introduce a small performance overhead compared to a more low-level approach like wasmi.
• Limited Scope: wasm-bindgen is primarily focused on the integration between Rust and JavaScript, while wasmi is a more general-purpose WebAssembly interpreter.

Code Comparison

Here's a brief code comparison between wasm-bindgen and wasmi:

wasm-bindgen (Rust):

#[wasm_bindgen]
pub fn add(a: i32, b: i32) -> i32 {
    a + b
}

wasmi (Rust):

fn add(a: i32, b: i32) -> i32 {
    a + b
}

The main difference is that wasm-bindgen requires the use of the #[wasm_bindgen] attribute, which generates the necessary boilerplate code for interoperability with JavaScript. In contrast, wasmi provides a more low-level and flexible approach, allowing you to define your WebAssembly functions directly.