Chicory Enables Native WebAssembly Execution on JVM

Introduction to the Chicory Native JVM WebAssembly Runtime

Chicory, a JVM-native WebAssembly runtime, allows executing .wasm modules without JNI or external dependencies. A JUnit 5 test successfully called the add(2, 40) function from a compiled .wasm module, returning 42.

Why This Matters

WebAssembly modules are inert without a host runtime, requiring imports to be resolved at instantiation. Traditional approaches rely on native runtimes or JNI, which add complexity. Chicory eliminates this by exposing WebAssembly exports as Java APIs, reducing integration overhead and enabling seamless JVM interoperability.

Key Insights

• “Chicory requires Java 11 LTS or later” (source: article)
• “Host functions fulfill imports, enabling JVM-JavaScript interoperability” (example: imports.wasm module)
• “Chicory used by Baeldung to demonstrate JVM WebAssembly integration” (tool + user)

Working Example

@Test
void givenAddModule_whenCallingAddWithTwoAndForty_thenResultIsFortyTwo() {
    InputStream wasm = getClass().getResourceAsStream("/chicory/add.wasm");
    assertNotNull(wasm);
    WasmModule module = Parser.parse(wasm);
    Instance instance = Instance.builder(module).build();
    ExportFunction add = instance.export("add");
    long[] result = add.apply(2, 40);
    assertEquals(42, (int) result[0]);
}

@Test
void givenImportDouble_whenCallingUseDouble_thenResultIsDoubled() {
    InputStream wasm = getClass().getResourceAsStream("/chicory/imports.wasm");
    assertNotNull(wasm);
    HostFunction doubleFn = new HostFunction(
        "host", "double", FunctionType.of(List.of(ValType.I32), List.of(ValType.I32)),
        (Instance instance, long... args) -> new long[] { args[0] * 2 }
    );
    Store store = new Store();
    store.addFunction(doubleFn);
    WasmModule module = Parser.parse(wasm);
    Instance instance = store.instantiate("imports", module);
    ExportFunction useDouble = instance.export("useDouble");
    long[] result = useDouble.apply(21);
    assertEquals(42L, result[0]);
}

Practical Applications

• Use Case: Java applications integrating WebAssembly modules for cross-platform computation (e.g., add.wasm for arithmetic).
• Pitfall: Unresolved imports during instantiation or missing export names at call time cause runtime exceptions.

References:

• https://www.baeldung.com/chicory-native-jvm-webassembly-runtime

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