Edit

Share via

Windows ML APIs

For conceptual guidance, see Run ONNX models with Windows ML).

You can think of the APIs in the Microsoft.WindowsAppSDK.ML NuGet package as being the superset of these two sets:

The Microsoft.WindowsAppSDK.ML NuGet package

The Microsoft Windows ML runtime provides APIs for machine learning and AI operations in Windows applications. The Microsoft.WindowsAppSDK.ML NuGet package provides the Windows ML runtime .winmd files for use in both C# and C++ projects.

The pywinrt Python wheels

The Microsoft Windows ML runtime leverages the pywinrt project to provide Python access to the same Windows ML APIs. The package name is winui3-Microsoft.Windows.AI.MachineLearning. Additional packages are required to use Windows App SDK in python. For details, see the Run ONNX models with Windows ML topic.

Windows ML APIs

For API reference documentation, and code examples, see the Microsoft.Windows.AI.MachineLearning namespace.

Implementation notes

The Windows ML runtime is integrated with the Windows App SDK and relies on its deployment and bootstrapping mechanisms:

  • Automatically discovers execution providers compatible with current hardware
  • Manages package lifetime and updates
  • Handles package registration and activation
  • Supports different versions of execution providers

Framework-dependent deployment

Windows ML is delivered as a framework-dependent component. This means your app must either:

  • Reference the main Windows App SDK NuGet package by adding a reference to Microsoft.WindowsAppSDK (recommended)
  • Or, reference both Microsoft.WindowsAppSDK.ML and Microsoft.WindowsAppSDK.Runtime

For more information on deploying Windows App SDK applications, see the Package and deploy Windows apps documentation.

Using ONNX Runtime with Windows ML

For C++ applications, after registering execution providers, use the ONNX Runtime C API directly to create sessions and run inference.

For C# applications, use the ONNX Runtime directly for inference using the Microsoft.ML.OnnxRuntime namespace.

For Python applications, use the separate ONNX Runtime wheel (onnxruntime) for inference. For the experimental release, please use the onnxruntime-winml==1.22.0.post2 package from index https://aiinfra.pkgs.visualstudio.com/PublicPackages/_packaging/ORT-Nightly/pypi/simple.

Python notes

Initialize Windows App SDK

All Windows ML calls should happen after the Windows App SDK is initialized. This can be done with the following code:

from winui3.microsoft.windows.applicationmodel.dynamicdependency.bootstrap import (
    InitializeOptions,
    initialize
)
with initialize(options = InitializeOptions.ON_NO_MATCH_SHOW_UI):
    # Your Windows ML code here

Registration happens out of Windows ML

The ONNX runtime is designed in a way where the Python and native environments are separate. And native registration calls in the same process will not work for the Python environment. Thus, the registration of execution providers should be done with the Python API directly.

Remove pywinrt's packed vcruntime

The pywinrt project includes a msvcp140.dll in the winrt-runtime package. This may conflict with other packages. Please remove this dll to avoid this problem and install the missing vcruntime libraries with the vc redistributable

See also