WCF Windows Communication Foundation (WCF) is a framework for building service-oriented applications by utilizing asynchronous messages and service endpoints. Citrix Virtual Apps and Desktops is a great example of a VDI platform which is developed under Microsoft .NET and the WCF framework. For more details about WCF, refer to the official page at https://docs.microsoft.com/en-us/dotnet/framework/wcf/whats-wcf.