WebAssembly (Wasm) has gone beyond the browser and is emerging as a standard for portable libraries and applications with near-native performance. How can the JVM ecosystem benefit from WebAssembly, and play are role in it?

This session introduces Web Image, a new preview feature of GraalVM that enables JVM developers to compile applications into efficient Wasm modules. These modules can run in the browser, on mobile devices, and on managed Wasm-based clouds. They also provide the same benefits GraalVM is known for: fast startup, low CPU and memory footprint, simplified deployment, and improved security. We’ll explain how it works, highlight practical use cases, demo end-to-end workflows, and discuss current limitations and what’s coming next.

We’ll also spotlight GraalWasm, a new embeddable WebAssembly runtime for the JVM that lets you load and execute code written in Rust, C, C++, Go, and other languages compiled to Wasm—benefiting from the optimizing Graal JIT compiler for high performance. As a demonstration, we’ll run and debug an image-processing library written in Rust, compiled to Wasm, and integrated into a Spring Boot microservice.

If you’re interested in the future of GraalVM and WebAssembly, and how these innovations can impact your JVM-based projects, this session is for you!

Jfokus

A conference talk covering two complementary GraalVM and WebAssembly integration stories. First, GraalWasm — a WebAssembly runtime embeddable in JVM applications — is demonstrated by integrating a Rust image-processing library (Photon) into a Micronaut microservice compiled to native image with GraalVM, achieving near-native performance with JIT compilation and full cross-language debugging support in IntelliJ and VS Code. Second, the experimental 'Web Image' feature is introduced, which compiles JVM bytecode to WebAssembly using the native image pipeline with a Wasm backend, enabling Java applications like the Java compiler (javac) and Spring Shell to run in the browser. Current limitations include no threading, networking, or WASI support, but the feature is open source and already useful for client-side deployments.

GraalVM + Wasm: Fast, Efficient, Portable Apps, by Fabio Niephaus