Vishwamohan.NET

The terms tier and layer are frequently used interchangeably, but actually there is a difference between them: Tiers indicate a physical separation of components, which may mean different assemblies such as DLL, EXE etc on the same server or multiple servers; but layers refers to a logical separation of components, such as having distinct namespaces and classes for the Database Access Layer (DAL), Business Logic Layer (BLL) and User Interface Layer (UIL). Therefore, tier is about physical separation and units of deployment, and layers are about logical separation and units of design.
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In this section, I will connect Business Logic Layer (BLL) to Data Access Layer and then User Interface Layer (UIL) to Business Logic Layer (BLL).
Note: If you are developing an enterprise application please see my next article on “Understanding 3-Tier vs. 3-Layer Architecture”.. [More]

In this section, I will show you how to connect Data Access Layer(DAL) to previously designed database customer table in Part -1. But in order to access the database we will require connection string, so let's define the connection string called “LocalSqlServer” in web.config file.. [More]

This is an example for creating a 3-tier web application. You can add additional tier to the base design but a traditional 3-tier app mainly refers the following:
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