JWebAssembly

JWebAssembly is a Java to WebAssembly Compiler. It uses Java class files as input.

Status of the project

Finished Components

• Java byte code parser
• test framework
• Public API of the Compiler

Partially Finished

• Binary format file writer (134 of 201 byte code instructions)
• Text format file writer (134 of 201 byte code instructions)

Open Features

• Exception handling - required the next version of WebAssembly
• Multiple threads - required the next version of WebAssembly
• Memory Management - required the next version of WebAssembly
• Gradle plugin to easy integrate it in the build process
• Eclipse build command to see compiler errors in in the IDE.

Required Java Version

JWebAssembly requires Java SE 8 or higher. It is tested with Java SE 8 on travis-ci.org.

Usage

Exporting functions

To export a Java function to make it accessible from JavaScript you need add the annotation org.webassembly.annotation.Export

import org.webassembly.annotation.Export;

@Export
public static int add( int a, int b ) {
    return a + b;
}

Java Limits

In version 1 of WebAssembly you can only compile:

• static methods
• use the data types int, long float and double

Alternatives

• TeaVM