After reading the following articles about Java's support for WebAssembly, both introduced TeaVM's Fermyon fork version (WASI compatible) as promising, so I decided to give it a try.
- https://seb.deleuze.fr/posts/webassembly-impact-on-programming-languages/
- https://www.javaadvent.com/2022/12/webassembly-for-the-java-geek.html
Prepare a pom.xml as follows:
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.example</groupId>
<artifactId>hello-wasm</artifactId>
<version>1.0.0-SNAPSHOT</version>
<properties>
<teavm.version>0.2.7</teavm.version>
<maven.compiler.source>1.8</maven.compiler.source>
<maven.compiler.target>1.8</maven.compiler.target>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
</properties>
<dependencies>
<dependency>
<groupId>com.fermyon</groupId>
<artifactId>teavm-classlib</artifactId>
<version>${teavm.version}</version>
<scope>provided</scope>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.1</version>
</plugin>
<plugin>
<groupId>com.fermyon</groupId>
<artifactId>teavm-maven-plugin</artifactId>
<version>${teavm.version}</version>
<executions>
<execution>
<id>web-client</id>
<goals>
<goal>compile</goal>
</goals>
<configuration>
<targetDirectory>
${project.build.directory}/generated/wasm/teavm-wasm
</targetDirectory>
<targetType>WEBASSEMBLY</targetType>
<mainClass>com.example.Main</mainClass>
<debugInformationGenerated>true</debugInformationGenerated>
<minifying>false</minifying>
<optimizationLevel>SIMPLE</optimizationLevel>
</configuration>
</execution>
</executions>
</plugin>
</plugins>
</build>
</project>
Prepare a Hello World Java code:
package com.example;
public class Main {
public static void main(String[] args) {
System.out.println("Hello world!");
}
}
Compile via Maven Plugin:
./mvnw clean package
The following files are generated:
$ tree target/generated
target/generated
└── wasm
└── teavm-wasm
├── classes.wasm
├── classes.wasm-runtime.js
├── classes.wasm.c
├── classes.wast
└── node_modules
└── @bjorn3
└── browser_wasi_shim
└── src
├── fd.js
├── fs_core.js
├── fs_fd.js
├── wasi.js
└── wasi_defs.js
6 directories, 9 files
Run with wasmtime:
$ wasmtime target/generated/wasm/teavm-wasm/classes.wasm
Hello world!
It worked!
Looking at this sample, it seems like you can do a lot.
The source code I tried this time is at https://github.com/making/hello-wasm-java