Wasmer based WebAssembly loader in JEE

Currently I'm experimenting a little bit with WASM and java. I found a java runtime from wasmer at https://github.com/wasmerio/wasmer-java. This acts as a JNI wrapper around the wasmer runtime. So this has to be installed on the execution node.

Combining it with quarkus, I created a solution, thats load some calculation functions provided in a WASM file on the classpath:

 

import java.io.InputStream;

import java.io.Serializable;

import javax.annotation.PostConstruct;

import javax.annotation.PreDestroy;

import javax.enterprise.context.ApplicationScoped;

import org.wasmer.Instance;

@ApplicationScoped

public class WasmBean implements Serializable{

public static String WASM = "calculator.wasm";

Instance instance = null;

public WasmBean() {

}

@PreDestroy

void preDestroy(){

instance.close();

}

@PostConstruct

void postConstruct() {

try {

InputStream instream = WasmBean.class.getClassLoader().getResourceAsStream(WASM);

// Reads the WebAssembly module as bytes.

byte[] wasmBytes = instream.readAllBytes();

// Instantiates the WebAssembly module.

instance = new Instance(wasmBytes);

} catch(Exception ex){

throw new RuntimeException(ex);

}

}

public Object[] invoke(String function, Object ... args) {

return instance.exports.getFunction(function).apply(args);

}

}

 

 

This can be used by a REST service afterwards as follows:

 

@GET

@Path("/add")

@Produces(MediaType.TEXT_PLAIN)

public String add(@QueryParam("a") int first, @QueryParam("b") int second) {

LOG.info("call"+first +"+"+second);

Object[] results =bean.invoke("add", first, second);

StringBuilder b = new StringBuilder();

for (Object o : results) {

b.append(o.toString());

}

return b.toString();

}

 

Since WASM modules can be created from several origins, not only Rust and C, but also COBOL (https://github.com/cloudflare/cobweb), this enables secure reuse of existing old function libraries via WASM modules...

 

The complete source code can be found at https://github.com/hurzelpurzel/wasm-experiments.git