Enterprise Interop Made Easy: WASM Compiled Libraries for Java Developers

Source: Dev.to

Introduction

WebAssembly (WASM) is rapidly evolving into the “universal virtual machine.” Originally designed to let browsers run non‑JavaScript code, WASM now supports toolchains such as C/C++, Rust, Go, Zig, and higher‑level languages like Python and C#, making it a powerful cross‑platform runtime.

WASM vs JVM: Two Stack Machines

Both the WASM Virtual Machine and the Java Virtual Machine (JVM) are stack‑based machines. This architectural similarity makes compiling WASM bytecode to JVM bytecode practical. Projects like Chicory demonstrate this by translating WASM modules into native JVM classes.

This approach solves a long‑standing problem:

How do we reuse existing C/C++ libraries in modern toolchains without rewriting everything?

Traditionally, developers faced two choices:

• The Java Approach – rewrite everything in Java for portability and security.
• The Python Approach – wrap native libraries via shared libraries/DLLs for quick integration.

Each has trade‑offs:

• Java – sandboxed execution, but costly rewrites of large codebases.
• Python – fast integration with wrappers, but requires platform‑specific DLLs/shared libraries.

WASM as the Bridge

With WASM, you can avoid the rewrite‑or‑wrap dilemma:

1. Compile existing C/C++ code to WASM.
2. Translate the WASM into JVM classes using Chicory.
3. Expose the result as a native Java library.

The outcome is a pure JVM artifact—no external DLLs, no native dependencies—while still leveraging proven C/C++ libraries.

Proof of Concept: DOCX to PDF in Java

A non‑trivial C/C++ library that renders Microsoft Word .docx files to PDF was compiled to WASM, then translated to a native Java library published via Maven: WordSDK Java HelloWorld.

Integration with Docx4J looks like this:

WordSDK.Worker api = WordSDK.createWorker(options);
// Create an import stream for feeding into WordSDK
OutputStream importStream = api.createImportStream();
// Feed the DOCX4J document into WordSDK
Docx4J.save(wordMLPackage, importStream, Docx4J.FLAG_NONE);
// Generate an in‑memory PDF for further processing...
byte[] pdf = api.exportPDF();

The result is a native JVM library that consumes WASM‑compiled C/C++ code, seamlessly integrated into Java enterprise workflows. Try it yourself at the WordSDK Java HelloWorld repository.

Performance

A common question is: “How fast is it?”
Running WASM modules inside the JVM via Chicory delivers performance comparable to executing WASM in environments like Node.js. There is a modest overhead compared to native execution—similar to the trade‑off already accepted when running code in the JVM or other managed runtimes.

Why This Matters

• Enterprise relevance – many systems still rely heavily on Java.
• Security – no native DLLs or system calls; everything runs inside the JVM sandbox.
• Portability – WASM makes libraries cross‑platform by design.
• Future‑proofing – WASM is becoming the universal compilation target, much like the JVM did for Java.

Special Thanks

Huge credit to the Chicory project. Its ability to compile non‑trivial WASM modules into JVM classes is a game‑changer for developers bridging ecosystems.