Notes on Calling WebAssembly from Java with Chicory

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Chicory is a WebAssembly Runtime on the JVM. It is implemented purely in Java, and can be used without native libraries or JNI.

By adding the following dependency, you can load and execute wasm on a Java application.

		<dependency>
			<groupId>com.dylibso.chicory</groupId>
			<artifactId>runtime</artifactId>
			<version>0.0.10</version>
		</dependency>

Create a sample wasm file from a WAT file. Create the following file SumSquared.wat.

It adds two i32 parameters and returns the squared value.

(module
  (func (export "SumSquared")
    (param $value_1 i32) (param $value_2 i32)
    (result i32)
    (local $sum i32)

    (i32.add (local.get $value_1) (local.get $value_2))
    local.set $sum
    (i32.mul (local.get $sum) (local.get $sum))
  )
)

Convert it to wasm using wat2wasm.

wat2wasm SumSquared.wat 

SumSquared.wasm will be generated. Load and execute this wasm in Java.

package org.example;

import com.dylibso.chicory.runtime.ExportFunction;
import com.dylibso.chicory.runtime.Instance;
import com.dylibso.chicory.runtime.Module;
import com.dylibso.chicory.wasm.types.Value;

public class Main {
	public static void main(String[] args) {
		Module module = Module.builder("SumSquared.wasm").build();
		Instance instance = module.instantiate();

		ExportFunction iterFact = instance.export("SumSquared");
		Value result = iterFact.apply(Value.i32(2), Value.i32(3))[0];
		System.out.println("Result: " + result.asInt()); // should print "Result: 25" (= (2 + 3)^2)
	}
}

Run the Java application.

$ mvn -q compile exec:java -Dexec.mainClass=org.example.Main                   
Result: 25

The full source code is here.

It seems to be a good way to incorporate a plugin mechanism into a Java application.