dyu / spin-teavm-example

Example of Spin app written in Java using TeaVM-WASI and wit-bindgen

spin-teavm-example

This is a example demonstrating how to use TeaVM-WASI, wit-bindgen, and Spin to build and run a simple stateless web service in Java, targetting WebAssembly

Prerequisites

• A recent JDK (e.g. OpenJDK 18)
• Maven
• Spin 0.6.0
• cURL (or a web browser) for testing

On Ubuntu 22.04 x86_64, this should do the job:

sudo apt install openjdk-18-jdk maven curl
curl -L -O https://github.com/fermyon/spin/releases/download/v0.6.0/spin-v0.6.0-linux-amd64.tar.gz
tar xf spin-v0.6.0-linux-amd64.tar.gz
sudo cp spin /usr/local/bin/

Building, running, and testing

spin build
spin up &
curl http://localhost:3000

(Optional) Re-generate bindings

Prerequisites

• Rust
• A recent wit-bindgen (git commit 9609ca8 is known to work)

cargo install --git https://github.com/bytecodealliance/wit-bindgen \
    --rev 9609ca8daf2dadcb71082a1ad7ec86bbf0fbb5ef --locked wit-bindgen-cli

(Re-)generating the bindings

wit-bindgen guest teavm-java --export wit/spin-http.wit \
    --out-dir src/main/java/wit_spin_http/
wit-bindgen guest teavm-java --import wit/wasi-outbound-http.wit \
    --out-dir src/main/java/wit_wasi_outbound_http/