Windows Runtime Components

Windows Runtime (WinRT) components are the building blocks for modern Windows applications. They provide a standardized way for different languages and frameworks to interact with Windows system services and application logic.

What are WinRT Components?

WinRT components are essentially DLLs that expose interfaces following a specific COM-like ABI (Application Binary Interface). This ABI ensures interoperability, allowing applications written in C++, C#, Visual Basic, JavaScript, and other languages to consume and extend functionality provided by these components.

Key Characteristics:

  • Language Interoperability: Designed for seamless interaction across diverse programming languages.
  • Performance: Optimized for efficient execution, close to native performance.
  • Security: Built with security in mind, integrating with Windows security features.
  • Type System: Uses a rich type system that maps well to various languages.
  • Asynchronous Operations: Leverages asynchronous patterns for non-blocking operations.

Creating WinRT Components

You can create WinRT components using Visual Studio and languages like C++, C#, or Visual Basic. The process typically involves defining interfaces and implementing them in a way that adheres to the WinRT ABI.

Example: A simple C++ WinRT Component

Here's a conceptual example of a C++ WinRT component that exposes a simple greeting function:


// MyComponent.idl
namespace MyWinRTComponent {
    runtimeclass Greeter {
        static Windows.Foundation.IAsyncOperation GetGreetingAsync(String name);
    };
}

// MyComponent.cpp
#include "pch.h"
#include "Greeter.h"

using namespace winrt;
using namespace Windows::Foundation;
using namespace MyWinRTComponent;

IAsyncOperation Greeter::GetGreetingAsync(String name) {
    return create_async([name]() -> IAsyncOperation {
        // Simulate some asynchronous work
        co_await resume_after(std::chrono::milliseconds(100));
        return L"Hello, " + name + L" from WinRT!";
    });
}

Consuming a WinRT Component

Applications can consume these components by referencing the generated metadata (e.g., .winmd files) and using the language projections provided by the compiler.

JavaScript Usage Example:


import('MyWinRTComponent').then(component => {
    component.Greeter.getGreetingAsync("World").then(greeting => {
        console.log(greeting); // Output: Hello, World from WinRT!
    });
});

Runtime Class

A runtime class is the fundamental construct for defining a WinRT component's implementation. It encapsulates data and behavior, making it accessible to consumers through its defined interfaces.

Further Reading