The LoginWindows class is used only in multi-authentication (claims- and Forms-based) environments for ASMX applications.
Assembly: ProjectServerServices (in ProjectServerServices.dll)
The LoginWindows class is not used in Microsoft Project Server 2013 installations that have only claims authentication. Because of claims authentication, integrated Windows authentication works without a call to the Login() method in Windows Communication Foundation (WCF) applications.
For more information about developing ASMX-based applications in a multi-authentication environment, see Prerequisites for ASMX-based code samples in Project 2013.