Chapter 3. ER Diagrams, Domain Model, and N-Layer Architecture

In the last chapter, we saw the basic layering of the monolithic 1-tier 1-layer architectural style in action, with the UI layer having code-behind classes as the sub-layer. This 1-tier 1-layer architecture is the default style in ASP.NET and Visual Studio 2005/2008. To overcome the limitations of this style, we can further break the application code into n-layers, where the number "n" actually depends on the project requirements.

In this chapter we will:

• Learn the 2-layer style

• Understand ER diagrams

• Understand what a domain model is, and what UML relationships are

• Learn the 3-layer style

• Learn about object data source controls

Let's revisit the 1-tier ASP.NET application configuration described in the last chapter.

Note

Note that the application as a whole including database and client browser is three tier.

As mentioned in the last chapter, we can call this 1-tier architecture a 3-tier architecture if we include the browser and database...