This article continues the series of articles about the .NET RIA Services framework and Silverlight 3. The scope of it is the DomainService class, which is used to create the business logic of the application and how it combines with the ADO.NET Data Model and the Enitity framework.
Here is a link to the live demo at this stage and the source code. Note that they will be updated with each article! ;)
Here are links to the previous parts of the series:
Creating applications with .NET RIA Service Part 1 - Introduction
Creating applications with .NET RIA Service Part 2 - Creating the project