Introduction of 3-tier Architecture:It is basically a client server architecture which is based on three main layers. These layers are separated from each other. However, by creating layers we can place code on separate layer which is reusable for specific functions. That layer can directly communicate with its adjacent layer for performing specific tasks. For example, if in an application, the presentation layer needs to retrieve information from a backend database, it will use other layers for performing that task rather than embedding database calls within itself.Structure of 3-tier Architecture:3-tier architecture will consist of following layers.The Presentation Layer: This layer contains user interface (UI) elements of the application. Application could be a desktop based or web based application. That layer contains .aspx pages or windows forms which provide an interface for user to input data.
The Business Logic Layer: This tier receives requests from presentation layer and returns the result based on its business logics. This layer contains classes for performing various business and mathematical functions such as calculating aggregate values. This layer has no concern with UI controls and databases. Its sub layer (data access) will supply it its needed information from database.Data Access Layer: This layer directly interacts with database and store and retrieves information. On receiving request from upper layer (Business Logic) data access layer retrieves and transfer data from data base. This layer retrieves data by executing SQL stored procedures.
Purpose of 3-tier architecture in Asp.NET 3.5