.Net C# Multi Tier Application

The 3-Tier architecture has the following three tiers:

Data Tier

This tier consists of Database Servers. Here information is stored and retrieved. This tier keeps data neutral and independent from application servers or business logic. Giving data its own tier also improves scalability and performance.

Application Tier (Business Logic/Logic Tier)

The logic tier is pulled out from the presentation tier and, as its own layer, it controls an application’s functionality by performing detailed processing.

Presentation Tier

This is the topmost level of the application. The presentation tier displays information related to such services as browsing merchandise, purchasing, and shopping cart contents. It communicates with other tiers by outputting results to the browser/client tier and all other tiers in the network.

Lets take up creating a very simple multi tier application.

First we will see the Data Tier. Here I am using Sql Server 2005 as data store.



















Now we will create the Application Tier or the Business Tier. For this I am creating a Class Library Project.

using System.Data;
using System.Data.SqlClient;
using System.Configuration;

namespace ShalvinBusinessObject
{
public class BusinessObject
{
public DataTable GetCategories()
{
SqlConnection cnn;
SqlDataAdapter da;
DataSet ds = new DataSet();
cnn = new SqlConnection(@"Integrated Security=sspi;Initial Catalog=ShalvinPDBlog;Data Source=.\sqlexpress");
cnn.Open();
da = new SqlDataAdapter("spAllCategories", cnn);
da.Fill(ds, "Cat");
return ds.Tables["Cat"];
}
}

Goto Build, Build Solution for building the dll.

Creating the User Tier

Start a Windows Application Project.
Go to project, Add Reference, Select Browse and Navigate to the bin, release folder of the previously creating class library project. Select the dll.

Now you can access the dll from your project.



















using ShalvinBusinessObject;


BusinessObject bo;
private void Form1_Load(object sender, EventArgs e)
{
bo = new BusinessObject();
dataGridView1.DataSource = bo.GetCategories();
}

Here I am creating an Object of the Class in the previous dll and binding an dataGridView to the GetCategories method.