License server

Tharga.Wpf can verify that the installed application has a valid license by calling a remote license server. The server-side endpoint is intentionally minimal so you can run it on top of any backend that exposes two routes: license/check and license/key.

The Tharga.License NuGet package contains a turn-key implementation for ASP.NET Core hosts. You can also implement the endpoints yourself.

Client configuration

Set LicenseServerLocation in Options:

protected override void Options(ThargaWpfOptions options)
{
    options.LicenseServerLocation += config => config["LicenseServer"];
}

The delegate receives IConfiguration so the URL can be read from appsettings.json (or any other source you have wired into the host).

Checking the license during splash

Pass checkForLicense: true to the canonical startup helper or to ShowSplashAsync:

this.StartMainWindow<MainWindow>(
    showSplash: true,
    checkForUpdates: true,
    checkForLicense: true);

The splash makes a license/check call. The result is surfaced via IApplicationUpdateStateService.LicenseInfoEvent:

update.LicenseInfoEvent += (_, args) =>
{
    if (!args.IsValid)
    {
        // args.Message describes why — display, log, or block the user.
    }
};

When license check is enabled the splash also exposes a Client / Client Source hyperlink so the user can see which client identifier the server used.

Checking the license on demand

var update = ApplicationBase.GetService<IApplicationUpdateStateService>();
var isValid = await update.CheckForLicenseAsync();

Returns the boolean directly; subscribe to LicenseInfoEvent if you also want the human-readable message.

Server side — Tharga.License for ASP.NET Core

The Tharga.License package wraps the two endpoints in a controller-friendly shape. Wire it into your API project; the WPF host's calls to license/check and license/key resolve to the package's implementation, which in turn delegates the actual license lookup to your ILicenseClient.

ILicenseClient:

public interface ILicenseClient
{
    Task<(bool IsValid, string Message)> CheckLicenseAsync();
}

Implement it however your product handles licenses (per-tenant flag in MongoDB, KV in Azure, a third-party service, etc.) and Tharga.License's controller plumbing routes the WPF host's request to your implementation.

Disabling the license check

Leave LicenseServerLocation unset (the default). The client never makes the call, checkForLicense becomes a no-op, and CheckForLicenseAsync returns true.