Code for "Flexible Data Access with Linq to SQL and the Entity Framework"

Article Description
Building a data access layer decouples the application from whatever persistence technology you may be using. LINQ to SQL and the ADO.NET Entity Framework allow you to achieve this decoupling.

The Flexible Data Access sample application demonstrates how to build a Data Access Layer (DAL) that exposes Data Transfer Objects (DTOs) so that clients can query and update the Northwind sample database without knowing how objects will be persisted. This includes a generic change-tracking collection for WPF and Windows Forms apps to submit collections of objects for batch udating with just one trip to the service.

This article is available at: http://msdn.microsoft.com/en-us/magazine/dd263098.aspx