UniFFI WASM Playground

NOTE: Further work is not happening in this repo. For more production-ready examples and build steps, see https://github.com/algorandfoundation/Algorand-Rust-FFIs

This is a repo that is being used to play around with UniFFI and WASM. It is based on the UniFFI Arithmetic Example. So far everything has been tested on MacOS.

For more information about UniFFI, see the official documentation and the README.

TL;DR: Write one Rust codebase, generate bindings for the following languages:

Python
Kotlin
Swift
React Native*
Kotlin Multiplatform*
Dart*
Go*
C#*
Ruby**

* = Third-party bindings ** = Legacy support

wasm-pack is also be used in conjunction with UniFFI to target JS (node and web) as well.

Key Files

build.rs: cargo build script that builds the C code (clang + empscripten for wasm) and generates the UniFFI scaffolding to ensure we match the UDL
src/lib.rs: The Rust library that contains the core logic.
consumers/python/playground.py: The python binding generated by uniffi-bindgen.
consumers/python/app.py: A python script that uses the FFI bindings to call into the Rust library.
consumers/web/pkg/playground.js: The bindings for the WASM generated by wasm-pack.
consumers/web/index.html: A simple webpage that uses WASM compiled from the Rust library.

What's been tested

Feature	Python	Web
Basic FFI bindings	✅	✅
Async HTTP FFI bindings	✅	✅
Error handling	✅	✅
Calling C lib (c -> rust -> target lang)	✅	✅

Building

Because of rust-lang/cargo#1197 we need to modify the surf features dynamically in Cargo.toml depending on if we're targeting wasm or not. This means instead of using cargo build directly we have a Python script build.py that does this and then calls either cargo build or wasm-pack build respectively.

To build the Python bindings: python build.py py

To build the web bindings: python build.py wasm

Running

To run the Python bindings: python consumers/python/app.py

To run the web bindings: cd consumers/web && python -m http.server

TODO