Extism: Writing WASM Extensions for Multi-Language Applications and Plugins
Introduction to Extism: A WebAssembly Library for Extending Applications and Plugins
WebAssembly (WASM) was initially developed to provide web applications with a means to run high-performance, portable binaries within a sandboxed environment. As the technology evolves beyond the browser, new and innovative use cases are emerging. One of the most promising applications is using WASM to add programmability and extensibility to applications, a trend that is gaining traction in the software development community.
Extism is a software library that facilitates the integration of WebAssembly extensions into applications, enabling them to be more modular and customizable. By managing the interface between your host application and WASM extensions, Extism simplifies the process of extending your application’s capabilities. This allows developers to focus on creating functionality rather than grappling with WASM’s data types or calling conventions.
The Extism library is designed to be versatile and works with a wide array of popular programming languages. Currently, it supports languages such as C/C++, Java, JavaScript, Go, Rust, Ruby, Python, and various .NET languages, including C# and F#. Additionally, Extism can be utilized with Elixir, PHP, OCaml, Zig, Haskell, and D. The library, written in Rust, provides a C-types interface, making it accessible to any language that supports a C foreign-function interface, with only a modest amount of additional work required.
Creating plugins or WASM extensions with Extism is flexible and not restricted to any specific language. Although Rust is a natural fit due to Extism’s own implementation, developers can also use AssemblyScript (which compiles directly to WASM), JavaScript, Go, C#, F#, C, Haskell, or Zig. This flexibility allows developers to choose the best language for their specific use case while benefiting from WASM’s performance and portability.
Extism’s core philosophy revolves around making applications extendable with WASM plugins, allowing for a wide range of customization. Whether you want to add a small feature or overhaul a significant part of your application, Extism supports varying levels of extensibility. Moreover, its WASM runtime handles critical aspects such as sandboxing and memory management, offering robust process protection and isolation compared to other extensibility solutions like embedding a Lua interpreter.
In summary, Extism opens up new possibilities for enhancing applications through WebAssembly, providing an easy-to-use interface for integrating WASM extensions. By supporting a broad range of programming languages and offering deep integration capabilities, Extism enables developers to build more modular and flexible software solutions. As the use of WebAssembly continues to expand, tools like Extism will play a crucial role in shaping the future of application extensibility and modularity.