first step：pip install componentize-py

package example:component;
world example {
    export add: func(x: s32, y: s32) -> s32;
}

secend step：create a add.wit and execute componentize-py --wit-path add.wit --world example bindings .

the third：use app.py to implement the add.wit import example

class Example(example.Example):
    def add(self, x: int, y: int) -> int:
        return x + y

fourth：generate component componentize-py --wit-path add.wit --world example componentize app -o add.wasm

fifth：use rust host to load and execute component https://github.com/bytecodealliance/component-docs/blob/main/component-model/examples/example-host/src/main.rs

git clone https://github.com/bytecodealliance/component-docs.git && cd component-docs/component-model/examples/example-host rm -rf Cargo.lock && rm -rf target cargo run --release -- 1 2 ../../../../add.wasm

print 1 + 2 = 3

This tutorial walks through how to compose a component to build a Wasm calculator. The WIT package for the calculator consists of a world for each mathematical operator add an op enum that delineates each operator. The following example interface only has an add operation:

package docs:adder@0.1.0;


interface add {
    add: func(a: u32, b: u32) -> u32;
}

world adder {
    export add;
}

package docs:calculator@0.1.0;

interface calculate {
    enum op {
        add,
    }
    eval-expression: func(op: op, x: u32, y: u32) -> u32;
}

world calculator {
    export calculate;
    import docs:adder/add;
}

world app {
    import calculate;
}

To expand the exercise to add more components, add another operator world, expand the enum, and modify the command component to call it.

To compose a calculator component with an add operator, run the following:

(cd calculator && cargo component build --release)
(cd adder && cargo component build --release)
(cd command && cargo component build --release)
cd ..
wasm-tools compose calculator/target/wasm32-wasip1/release/calculator.wasm -d adder/target/wasm32-wasip1/release/adder.wasm -o composed.wasm
wasm-tools compose command/target/wasm32-wasip1/release/command.wasm -d composed.wasm -o final.wasm

Now, run the component with wasmtime:

wasmtime run final.wasm 1 2 add
1 + 2 = 3

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