24 April 2022

This sample demonstrates using Microsoft.FeatureManagement 2.5.1 (latest) in a WPF desktop application that targets .NET Framework 4.6.1. The sample uses conditional feature flags, where the condition is a targeting filter and the targeted audience is an allow list of user IDs.

There are two sample applications:

• WpfDotNetFx461FeatureFlagsAzureAppConfig loads feature flags from Azure App Configuration;
• WpfDotNetFx461FeatureFlagsLocalAppSettingsConfig loads feature flags from the local AppSettings.json file.

The library WpfDotNetFx461FeatureFlagsCommon contains a few types used in both applications.

• ICustomUser/CustomUser defines a custom user type for expressing the user's identity.
• ICustomContextAccessor/CustomContextAccessor provides access to a custom user.
• CustomTargetingContextAccessor provides access to the custom targeting context for feature filtering.

If the user identity is passed in a regular targeting context, most of these custom context types wouldn't be necessary.

Notes on version compatibility.

• .NET Framework 4.6.1 supports .NET Standard 2.0 and no higher, see .NET Standard 2.0 in the "Select .NET Standard version" section.
• Microsoft.Framework 2.5.1 (latest) supports .NET Standard 2.0
• Microsoft.Extentions.Configuration.AzureAppConfiguration 5.0.0 (latest) supports .NET Standard 2.0.

WpfDotNetFx461FeatureFlagsAzureAppConfig needs an Azure App Configuration connection string in the App constructor in App.xaml.cs.

WpfDotNetFx461FeatureFlagsLocalAppSettingsConfig defines a CustomFeatureManager that derives from IFeatureManager which implement feature management over configuration loaded from AppSettings.json.

Does not yet implement groups or percentages in the targeting filter. Groups seems straightforward. Percentages, however, require a persistent store in order for feature enablement to be 'sticky' for the user: once the feature is enabled for a user, it continues to be enabled for that user.

Does not implement other filter types.

• FeatureManagement-Dotnet / src / Microsoft.FeatureManagement
  • Targeting
    • ContextualTargetingFilter.cs Implements the targeting filter for a regular context.

Microsoft.Extensions.Configuration

• Configuration in .NET

Azure App Configuration

• Use feature filters to enable conditional feature flags