CppConsoleDll

CppConsoleDll Sample

This sample demonstrates how to use WindowsML APIs from within a DLL that is consumed by a separate executable. This pattern is particularly useful when you need to share WindowsML functionality across multiple applications or isolate ML functionality in a separate module.

Overview

The sample consists of two projects:

1. WindowsMLWrapper.dll - A Dynamic Link Library that:

   • Uses the WindowsAppSDK with ML support
   • Exports C-style functions that can be easily consumed by other applications
   • Demonstrates proper string memory management using CoTaskMemAlloc
   • Shows how to use ONNX Runtime APIs from WindowsAppSDK

2. ConsoleClient.exe - A minimal console application that:

   • Dynamically loads the WindowsMLWrapper.dll
   • Calls the exported functions
   • Properly manages memory allocated by the DLL
   • Demonstrates error handling for DLL loading and function calls

Key Features

• WindowsAppSdkBootstrapInitialize: The DLL project uses WindowsAppSdkBootstrapInitialize=true to ensure proper initialization of the WindowsAppSDK runtime when loaded
• Memory Management: Exported functions use CoTaskMemAlloc to allocate strings, which are freed by the client using CoTaskMemFree
• Error Handling: Both the DLL and client demonstrate proper error handling patterns
• Minimal Dependencies: The client application has minimal dependencies and only links to what it needs

Building

Both projects are included in the main WindowsML-Samples.sln solution. When you build the solution:

1. WindowsMLWrapper.dll is built first
2. ConsoleClient.exe is built with a dependency on the DLL project
3. The DLL is automatically copied to the client's output directory

Running

After building, you can run ConsoleClient.exe directly. It will:

1. Load WindowsMLWrapper.dll from the same directory
2. Call the exported functions
3. Display the results in the console
4. Clean up and exit

Expected output:

Calling GetTestMessage from DLL...
Test message: WindowsML DLL is working correctly!
Calling GetOrtVersionString from DLL...
ONNX Runtime version: [ONNX Runtime version string]
DLL functions called successfully!

Architecture Notes

This pattern is useful in scenarios such as:

• Creating reusable ML components across multiple applications
• Isolating ML functionality in a separate process space
• Building plugin architectures where ML capabilities are loaded dynamically
• Separating concerns between UI and ML processing components

The DLL handles all WindowsAppSDK initialization and cleanup, while the client application can be kept lightweight and focused on its primary functionality.