Using WebAssembly for Scientific Computing

Introduction

WebAssembly (Wasm) is a binary instruction format designed as a portable target for the compilation of high-level languages like C, C++, and Rust. It allows developers to run code at near-native speed by taking advantage of common hardware capabilities and provides a compact binary format that is designed for fast decoding and execution. In recent years, WebAssembly has gained significant traction as a tool for developing web applications, but its potential for scientific computing is also noteworthy.

In this article, we will explore the benefits of using WebAssembly in scientific computing contexts and discuss how to get started with a simple example.

Benefits of WebAssembly for Scientific Computing

There are several reasons why WebAssembly is well-suited for scientific computing tasks:

Performance: WebAssembly is designed for efficient execution, offering performance close to native code. This is especially valuable for compute-intensive tasks common in scientific computing.
Portability: WebAssembly code can run on any platform that supports a WebAssembly runtime, providing a truly cross-platform solution for scientific applications. This eliminates the need to maintain platform-specific codebases and simplifies deployment.
Language Support: WebAssembly can be compiled from various high-level languages, including C, C++, and Rust. This allows developers to leverage existing codebases and libraries in these languages.
Security: WebAssembly enforces a strong sandboxing model, which isolates the runtime environment from the underlying system. This can help prevent unintended side effects and security vulnerabilities in scientific applications.
Integration with Web Technologies: WebAssembly can be easily integrated with existing web technologies, allowing developers to create interactive scientific applications that can be deployed and accessed from a web browser.

Getting Started with WebAssembly for Scientific Computing

To demonstrate the usage of WebAssembly in scientific computing, let’s implement a simple example: calculating the dot product of two vectors.

Step 1: Install Emscripten

We will use Emscripten, a popular WebAssembly toolchain, to compile our code. To install Emscripten, follow the instructions on the official Emscripten website.

Step 2: Write the C Code

Let’s write a simple C program to calculate the dot product of two vectors:

// dot_product.c
#include <stddef.h>

double dot_product(const double* a, const double* b, size_t length) {
    double result = 0;
    for (size_t i = 0; i < length; ++i) {
        result += a[i] * b[i];
    }
    return result;
}

Step 3: Compile to WebAssembly

We will use Emscripten to compile the C code to WebAssembly:

emcc -O3 -s WASM=1 -s EXPORTED_FUNCTIONS="['_dot_product']" -o dot_product.js dot_product.c

This command generates two files: dot_product.wasm and dot_product.js. The .wasm file contains the compiled WebAssembly binary, while the .js file contains the JavaScript glue code that allows us to interact with the WebAssembly module.

Step 4: Load and Use the WebAssembly Module

We can now create an HTML file to load and use our WebAssembly module:

<!DOCTYPE html>
<html>
<head>
  <script src="dot_product.js"></script>
</head>
<body>
  <script>
    Module.onRuntimeInitialized = function() {
      const dot_product = Module.cwrap('dot_product', 'number', ['array', 'array', 'number']);
      
      const a = [1, 2, 3];
      const b = [4, 5, 6];
      const length = a.length;

      const result = dot_product(a, b, length);
      console.log("Dot product:", result);
    };
  </script>
</body>
</html>

When you open this HTML file in a web browser, you should see the following output in the console:

Dot product: 32

Conclusion

In this article, we have seen how WebAssembly can be used for scientific computing tasks. By leveraging the performance, portability, and language support offered by WebAssembly, developers can create efficient and cross-platform scientific applications. In our example, we demonstrated how to compile a simple C program to WebAssembly using Emscripten and interact with the compiled module using JavaScript.

As the WebAssembly ecosystem continues to grow, we can expect to see more use cases in scientific computing and other domains.