{"id":49436,"date":"2023-12-04T10:22:45","date_gmt":"2023-12-04T18:22:45","guid":{"rendered":"https:\/\/devblogs.microsoft.com\/dotnet\/?p=49436"},"modified":"2024-12-13T14:03:06","modified_gmt":"2024-12-13T22:03:06","slug":"extending-web-assembly-to-the-cloud","status":"publish","type":"post","link":"https:\/\/devblogs.microsoft.com\/dotnet\/extending-web-assembly-to-the-cloud\/","title":{"rendered":"Extending WebAssembly to the Cloud with .NET"},"content":{"rendered":"

WebAssembly (Wasm)<\/a> is an exciting new(ish) virtual machine and (assembly) instruction format. Wasm was born in the browser and is an important part of the Blazor<\/a> project. The second act for Wasm is cloud computing, for apps and functions. WebAssembly System Interface (WASI) is the new enabler, providing a way for WebAssembly code to call and implement arbitrary APIs, safely and across languages. It is now possible to create WASI apps with .NET using the wasi-experimental<\/code> workload in .NET 8. We’re exploring these new technologies and running .NET apps in this environment …. really, anywhere.<\/p>\n

This post will help you understand the broadening use of Wasm and describe what’s already possible with .NET. They say that history doesn’t repeat itself, but that it rhymes. We’re back for another round of “write once, run anywhere”. WASI apps are portable binaries that run on any hardware or operating system and are not specific to any programming language. This time, it feels different. It’s not just vendor neural; it’s everything neutral.<\/p>\n

Wasm and WASI<\/h2>\n

Wasm may be offering us a reboot of compute in the cloud, with the promise of a single cloud-native binary, higher density, and cheaper multi-tenancy. It also opens up the possibility of edge compute for the same reasons. In fact, CloudFlare<\/a> and Fastly<\/a> already host public compute at the edge with Wasm.<\/p>\n

Wasm is different than running an app in a Linux container, which is a (good and clever) re-packaging of existing standards and code. Wasm is more like running an app in an environment with no operating system, with just assembly code, memory, and standardized (and gated) access to the outside world (via WASI).<\/p>\n

The Hyperlight presentation at Build 2023<\/a> (4m video) provides insight into what a Wasm-enabled cloud might look like. It demonstrates a Blazor app running in a new lighweight and secure hypervisor. Hyperlight sparks the imagination on new hosting paradigms.<\/p>\n

WebAssembly System Interface (WASI)<\/a>, WebAssembly Interface Types (WIT)<\/a>, and WebAssembly Component Model<\/a> are the key specs in this latest round of Wasm innovation. They are very much still in the design phase and undergoing significant change<\/a>. This post (and the .NET 8 implementation) is oriented around WASI Preview 1. We expect the .NET 9 implementation to use WASI Preview 2.<\/p>\n

WIT and wit-bindgen<\/a> enable components written in any source language to communicate and with the host system. Implementation of WIT support for C#<\/a> is lead by @silesmo<\/a>. Wasm and WIT together define the Application Binary Interface (ABI)<\/a>.<\/p>\n

We expect WASI to become a standard set of WIT types that provide access to low-level functionality<\/a> (like getting the time<\/a> and reading a file<\/a>). These low-level types effectively form a “Wasm standard library” across programming languages and operating systems. We’re never had standard and shared functionality that Rust devs and .NET devs, for example, could both use. There isn’t any widely-deployed historical precedent of native code that exposed APIs with OO<\/a>-ish shape (like interfaces) that could be used across programming languages and operating systems.<\/p>\n

The standard WIT types start with wasi-<\/code> and define the “platform”. You can think of them in a similar way to the System<\/code> namespace in .NET (matching the ‘S’ in WASI). Continuing the analogy, you can create your own .NET namespaces beyond the System<\/code> ones, and the same is true with WIT.<\/p>\n

These posts do a great job of framing WASI in more detail.<\/p>\n