Lego

Lego is a serverless service with WebAssembly and wasmer.

Quick Guide

Prepare wasm

1. Write your wasm in any language you like, in AssemblyScript for example:

export function helloWorld() {
    return "Hello, Lego";
}

2. Tell Lego where to get/set bytes into memory by defining and exporting memory_ptr function:

let memory = new ArrayBuffer(1024);

export function memory_ptr(): usize {
    return changetype<usize>(memory);
}

// Help for set string into memory
function saveStringIntoMemory(data: String): usize {
    const len = raw.length;
    let view = new DataView(memory);
    for (let i=0;i<(len as i32);i++) {
        view.setUint8(i, raw.charCodeAt(i) as i8);
    }
    return len;
}

3. Export http_get hook to Lego:

export function http_get(inputLen: usize): usize {
    return saveStringIntoMemory(helloWorld());
}

4. Compiles into wasm and store in any path you like:

$ npm run build
$ cp ./build/helloworld.wasm /path/to/wasm/helloworld.wasm

Run Lego

1. Setup environment varialble LEGO_WASM_ROOT as the root locatoin of your wasms.

export LEGO_WASM_ROOT="/path/to/wasm"

2. Here we go ~

$ /path/to/lego

Request Lego

$ curl http://localhost:8000/helloworld | jq    # `helloworld` is the name of your wasm file without extension
{
  "result": "hello world"
}

You can find more AssemblyScript examples written in assemblyscripts.