NET pages and user controls is a prominent example of a layered design.
The markup file defines the look and layout of the web form and the code behind file contains the presentation logic.
In the classic three tier design, applications break down into three major areas of functionality: Inside each of these tiers there may also exist a series of sub-layers that provide an even more granular break up the functional areas of the application.
NET along with some of the sub-tiers that you may encounter: Figure 1 – Three tiered ASP.
NET application with sub-tiers In the presentation layer, the code-behind mechanism for ASP.
Technical interviews normally contain a battery of questions to gauge your architectural knowledge during the hiring process, and your architectural ability only becomes more important as you ascend through the ranks.
So it’s always a good idea to make sure you have a good grasp on the fundamentals.
You also see sub-layers in the data tier with database systems.
Tables define the physical storage of data in a database, but stored procedures and views allow you to manipulate data as it goes into and out of those tables.
It’s a clean separation because both the markup and the code-behind layers house specific sets of functionality that benefit from being apart.
Designers don’t have to worry about messing up code to make user interface changes, and developers don’t have to worry about sifting through the user-interface to update code.
And when you are done writing the SQL Server DAL, your application has two functional data access layers.
In other words, your application has the means to support two databases.
You will begin noticing problems, however, if you ever need to support multiple databases, change databases, or even overhaul your current database significantly.