Stuff I've learned about WASM and WASI

WASM_WASI_Notes.md

WASM and WASI Notes

Web Assembly can make use of OS capabilities with the Web Assembly System Interface. It allows calls to OS functionality like clock, fs, network etc.

Spec

• WASM is the fourth W3C web standard next to HTML, CSS and JS
• WASI is an additional spec that standardizes how Web Assembly can do more than just run in a sandboxed environment but interact with system resources.

Ecosystem

• Runtimes supporting WASI:
  • wasmtime
  • wasmer
  • wasm3
• wasmer offers a package manager for WASM modules called WAPM
• WASI needs to be implemented for each language/platform (browsers use a memory FS)
• WASI is bound to the WASM module as imports during instanciation
• Many languages already compile to WASM: C/C++ via Emscripten, Rust, many more to come
• WASM runs in JS engines by default, Other languages can use bindings for a WASM runtime like WASMER
• edge support: for example in cloudflare workers

WASM Benefits

• More lightweight than containers
• Highly portable (just need a WASM runtime)
• Functions as a compile target for nearly every language

Why does the majority not use WASM?

• No killer feature for majoriy classic web use cases, extra effort not justified since JS does the job well enough already
• high performance:
  • web
    • TensorFlow JS
    • Google Earth
    • Unity (Game Engine)
    • Auto CAD
  • devops: lightweight deployments with WASM and Docker
• edge computing: very fast startup (example: Cloud flare workers
• using a different language that doesn't run in the browser: Python in the browser (PyScript
• security: sandboxed enviroment, fine-grained control over what the WASM program can see (env vars, folder & files, args, sockets, etc)