Web Api and ASP.NET MVC 4 supported chat application. Calls are made to this Web Api service to make basic crud operations. Service is separated from front-end(MVC) client layer to help with testing, security and scalability. Both service
and client uses entity framework 5 and sits on top mssql server 2012 to help with data storage and retrieval. I would also use signal R to help with client synchronization.