ASP.NET 2.0 introduced the Application Services which are a
set of services used to manage user security from authenticating users,
creation of new users, retrieving user passwords, getting user roles, to loading
and saving per-user profile data from and into a database. These services to
function properly are configured through XML entries in the Web.config
The above services, as you can see, work only with web
applications. But the problems appear when you have multiple applications,
including Web and Windows client applications, with a shared database and all
of those applications need a way to authenticate and authorize users in
addition to processing a user’s profile and this could not be done before
Visual Studio 2008 and .NET 3.5.
With the release of Visual Studio 2008 and .NET 3.5, Client
Application Services have been introduced to the Windows Forms and Windows
Presentation Foundation applications. Basically, Client Application Services
make use of the ASP.NET AJAX Application Services to allow a Desktop
application to interact with the Membership, Role, and Profile providers.