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Enterprise Interop Made Easy: WASM Compiled Libraries for Java Developers

#webassembly #java #pdf #c

WebAssembly (WASM) is rapidly evolving into the “universal virtual machine”. Originally designed to let browsers run non‑JavaScript code, WASM has grown beyond its initial scope. Today, major toolchains such as C/C++, Rust, Go, Zig, and even higher‑level languages like Python and C# can compile to WASM, 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 means that compiling from WASM bytecode to JVM bytecode is not only possible but 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: Interoperability and sandboxed execution (no risky system calls).
  • Python: Fast integration with wrappers.
  • Python downside: Requires platform‑specific DLLs/shared libraries.
  • Java downside: Costly rewrites of large codebases.

WASM as the Bridge

With WASM, we no longer need to choose between rewriting or wrapping. Instead:

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

This yields 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

As a demonstration, we compiled a non‑trivial C/C++ library capable of rendering Microsoft Word .docx files to PDF. Using Chicory, we produced a native Java library published via Maven: WordSDK Java HelloWorld

Here’s how it integrates with e.g. Docx4J to produce a PDF:

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...    
final byte[] pdf=api.exportPDF();
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The result: a native JVM library that consumes WASM‑compiled C/C++ code, seamlessly integrated into Java enterprise workflows. Go to WordSDK Java HelloWorld to give it a try!

Performance

One of the most common questions when introducing a new runtime layer is: “But how fast is it?”

The good news: performance is excellent. Running WASM modules inside the JVM via Chicory is comparable to executing WASM in environments like Node.js. As with any virtual machine, there is a small overhead compared to native execution, but this is the same trade‑off developers already accept 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.

We are curious to hear how this approach could fit into your enterprise workflows — and if you’ve experimented with this approach yourself, we’d love to learn from your experiences too.

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