Building a Web 2.0 Portal with ASP.NET 3.5

Chapter 4. Building the Data and Business Layers Using .NET 3.5

The data and business layers of the Dropthings portal use two of the hottest features of the .NET 3.0 and 3.5 frameworks: Windows Workflow Foundation (WF) and LINQ. The data layer makes good use of LINQ to SQL, a feature of .NET 3.5. The business layer is built largely with the WF released with .NET 3.0, using new language extensions in C# 3.0.

Introducing LINQ to SQL

LINQ, or Language integrated query, is a set of C# 3.0 language and .NET 3.5 framework features for writing structured queries over local object collections and remote data sources. With LINQ, you can query any collection that implements IEnumerable<>, including tables in a database.

LINQ to SQL is a lot of fun to work with and makes the task of writing a data access layer that generates highly optimized SQL amazingly simple. If you haven’t used LINQ to SQL before, brace yourself.

With LINQ to SQL, you design the database that the application will use and then use the Visual Studio 2008 Object/Relational Designer (sqlmetal.exe in LINQ Preview) to generate a class that represents the database with an appropriate object model. This is a giant step beyond having to handcode the entity and data access classes. Formerly, whenever the database design changed, you had to modify the entity classes and modify the insert, update, delete, and get methods in the data access layer. Of course, you could use third-party object-relational mapping (ORM) tools or some kind ...