Building Layered Web Applications with Microsoft ASP.NET 2.0
Building Layered Web Applications with Microsoft ASP.NET 2.0
An excellent introduction for beginners showing the fundamentals involved in architecting an application using the Custom Business Entities approach. Written by Wrox author, Imar Spaanjaars.
For more information on the designing the architecture for your ASP.net application check out the ASP.net Architecture forum and the Architecture Wiki entry on ASP.net.