Introduction
Today, in this article let's play around with one of the interesting and most useful concepts of design patterns, which will be hosted in a web app.

Question: What is Proxy Pattern?

In simple terms "In this pattern, an interface actually points out to the specific implemented class to perform a specific operation".

I think we are now good to go to implement this wonderful concept.

Step 1: The complete code of Default.aspx looks like this:

<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="Default.aspx.cs" Inherits="ProxyPatternApplication._Default" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml">

<head id="Head1" runat="server">

<title></title>

</head>

<body>

<form id="form1" runat="server">

<div>

<h1 style="text-align: center; font-family: Verdana; font-size: large; color: Maroon">

Proxy Pattern - Design Patterns</h1>

<center>

<table>

<tr>

<td>

<asp:Label ID="Label1" runat="server" Text="Please Enter First Number" Font-Size="Small"

Font-Bold="true" Font-Italic="true" Font Names="Verdana"></asp:Label>

</td>

<td>

<asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>

</td>

</tr>

<tr>

<td>

<asp:Label ID="Label2" runat="server" Text="Please Enter Second Number" Font-Size="Small"

Font-Bold="true" Font-Italic="true" Font-Names="Verdana"></asp:Label>

</td>

<td>

<asp:TextBox ID="TextBox2" runat="server"></asp:TextBox>

</td>

</tr>

<tr>

<td colspan="2">

<asp:Button ID="Button1" runat="server" Text="Addition" Width="165px" Font-Names="Verdana" BackColor="Orange" OnClick="Button1_Click" />

</td>

</tr>

<tr>

<td colspan="2">

<asp:Button ID="Button2" runat="server" Text="Subtraction" Width="165px" Font-Names="Verdana" BackColor="Orange" OnClick="Button2_Click" />

</td>

</tr>

<tr>

<td colspan="2">

<asp:Button ID="Button3" runat="server" Text="Multiplication" Width="165px" Font-Names="Verdana" BackColor="Orange" OnClick="Button3_Click" />

</td>

</tr>

<tr>

<td colspan="2"><asp:Button ID="Button4" runat="server" Text="Division" Width="165px" Font-Names="Verdana"

BackColor="Orange" OnClick="Button4_Click" />

</td>

</tr>

</table>

<table>

<tr>

<td colspan="2">

<asp:Label ID="lblResult" runat="server" Font-Names="Verdana" ForeColor="Brown"></asp:Label>

</td>

</tr>

</table>

</center>

</div>

</form>

</body>

</html>

Step 2: The complete code of IAdd.cs looks like this:

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

namespace ProxyPatternApplication

{

public interface IAdd

{

double Add(double a, double b);

}

}

Step 3: The complete code of ISub.cs looks like this:

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

namespace ProxyPatternApplication

{

public interface ISub

{

double Sub(double a, double b);

}

}

Step 4: The complete code of IMul.cs looks like this:

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

namespace ProxyPatternApplication

{

public interface IMul

{

double Mul(double a, double b);

}

}

Step 5: The complete code of IDiv.cs looks like this:

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

namespace ProxyPatternApplication

{

public interface IDiv

{

double Div(double a, double b);

}

}

Step 6: The complete code of AdditionClass.cs looks like this:

using System;

using System.Collections.Generic;

using System.Linq;

using System.Web;

namespace ProxyPatternApplication

{

public class AdditionClass : IAdd

{

public double Add(double a, double b)

{

return a + b;

}

}

}

Step 7: The complete code of SubtractionClass.cs looks like this:

using System;

using System.Collections.Generic;

using System.Linq;

using System.Web;

namespace ProxyPatternApplication

{

public class SubtractionClass : ISub

{

public double Sub(double a, double b)

{

return a - b;

}

}

}

Step 8: The complete code of MultiplicationClass.cs looks like this:

using System;

using System.Collections.Generic;

using System.Linq;

using System.Web;

namespace ProxyPatternApplication

{

public class MultiplicationClass : IMul

{

public double Mul(double a, double b)

{

return a * b;

}

}

}

Step 9: The complete code of DivisionClass.cs looks like this:

using System;

using System.Collections.Generic;

using System.Linq;

using System.Web;

namespace ProxyPatternApplication

{

public class DivisionClass : IDiv

{

public double Div(double a, double b)

{ return a / b;

}

}

}

Step 10: The complete code of Default.aspx.cs looks like this:

using System;

using System.Collections.Generic;

using System.Linq;

using System.Web;

using System.Web.UI;

using System.Web.UI.WebControls;

namespace ProxyPatternApplication

{

public partial class _Default : System.Web.UI.Page

{

protected void Page_Load(object sender, EventArgs e)

{

}

public void Button1_Click(object sender, EventArgs e)

{

if (string.IsNullOrEmpty(TextBox1.Text) || string.IsNullOrEmpty(TextBox2.Text))

{

lblResult.Text = "Please Enter Some Values";

}

else

{

lblResult.Text = "Addition Result of " + TextBox1.Text + " and " + TextBox2.Text + " is: <b>" + objAdd.Add(Convert.ToDouble(TextBox1.Text), Convert.ToDouble(TextBox2.Text)).ToString() + "</b>"; TextBox1.Text = ""; TextBox2.Text = "";

}

}

public void Button2_Click(object sender, EventArgs e)

{

if (string.IsNullOrEmpty(TextBox1.Text) || string.IsNullOrEmpty(TextBox2.Text))

{

lblResult.Text = "Please Enter Some Values";

}

else

{

lblResult.Text = "Subtraction Result of " + TextBox1.Text + " and " + TextBox2.Text + " is: <b>" + objSub.Sub(Convert.ToDouble(TextBox1.Text), Convert.ToDouble(TextBox2.Text)).ToString() + "</b>"; TextBox1.Text = ""; TextBox2.Text = "";

}

}

public void Button3_Click(object sender, EventArgs e)

{

if (string.IsNullOrEmpty(TextBox1.Text) || string.IsNullOrEmpty(TextBox2.Text))

{

lblResult.Text = "Please Enter Some Values";

}

else

{

lblResult.Text = "Multiplication Result of " + TextBox1.Text + " and " + TextBox2.Text + " is: <b>" + objMul.Mul(Convert.ToDouble(TextBox1.Text), Convert.ToDouble(TextBox2.Text)).ToString() + "</b>"; TextBox1.Text = ""; TextBox2.Text = "";

}

}

public void Button4_Click(object sender, EventArgs e)

{

if (string.IsNullOrEmpty(TextBox1.Text) || string.IsNullOrEmpty(TextBox2.Text))

{

lblResult.Text = "Please Enter Some Values";

}

else

{

lblResult.Text = "Division Result of " + TextBox1.Text + " and " + TextBox2.Text + " is: <b>" + objDiv.Div(Convert.ToDouble(TextBox1.Text), Convert.ToDouble(TextBox2.Text)).ToString() + "</b>"; TextBox1.Text = ""; TextBox2.Text = "";

}

}

#region Instance VariblesIAdd objAdd = new AdditionClass();ISub objSub = new SubtractionClass();IMul objMul = new MultiplicationClass();IDiv objDiv = new DivisionClass();#endregion

}

}

Step 11: The output of the application looks like this:

Output1.png

Step 12: The output of the nothing entered application looks like this:

Output2.png

Step 13: The output of the addition operation application looks like this:

Output3.png

I hope this article is useful for you. I look forward to your comments and feedback.