.NET Framework has provided plenty of approaches to communication. Those choices include the following:
ASP.NET Web Services (commonly known as ASMX), providing interoperable SOAP-based communication
.NET Remoting, focusing on communication between .NET applications.
Enterprise Services, offering support for scalable, transactional applications.
System.Messaging, supporting queued messaging via Microsoft Message Queuing (MSMQ).
Web Services Enhancements (WSE), an extension to ASP.NET Web Services that provides support for more recent specifications such as WS-Security.