Introducing the ClickOnce API

The ClickOnce on-demand API is exposed through the ApplicationDeployment class in the System.Deployment.Application namespace in the System.Deployment.dll framework assembly. This assembly is already referenced when you create a Windows Forms project in Visual Studio. This class includes functionality for programmatically controlling the update process, gathering information about the current deployment, and managing data files.

An additional class that is not technically part of the ClickOnce APIs, but that exposes some capabilities you will use in conjunction with the ClickOnce API, is the Application class from the System.Windows.Forms namespace. The Application class exposes the ability to restart an application after an update has been downloaded, as well as properties that let you obtain path information for the application folders that are created by ClickOnce when an application is deployed.