Minutes: Node.js Global Summit Session 1 — The WebAssembly System Interface and Node.js by Colin Ihrig.

Web WebAssembly

• No garbage collector
• Four data types
• Reads/writes data from/to a linear memory

WebAssembly Text Format (Wat)

• Human readable representation of Wasm
• Written as S-expressions

WebAssembly Binary Toolkit (Wabbit)

• Eg. Convert between Wasm, wat and C
• https://github.com/WebAssembly/wabt

WebAssembly in Node.js

WebAssembly.compile() WebAssembly.instantiate()

Node can import Wasm files.

WebAssembly System Interface (WASI)

• Provides system calls
• Enhance non-Web use cases

WASI Security Model

• Application can only access sandboxed paths
• syscalls have associated “right” __WASIT_RIGHT_PATH_OPEN
• syscalls like open()

Defining Sandbox with Preopens

• Preopens map host paths to sandbox paths
• Application accesses sandbox paths

Compiling from C to WebAssembly

• libc
• clang 8+

Think of JavaScript (and WA)

• Open Web Technology

UVWasi and Support in Node.js

• c++ bindings for uvwasi and small JS API
• wasi core module

WASI Example

wasi-worker Module