Cookies:
It is a client side state
management technique. Cookies are created at client hard drive by browser. When
a user visit the website first time, server gets the request and send the
cookies information to browser and browser write the information into hard drive
of client machine. When user visits website again the cookies information is read
by the browser from client machine if exists and sent to the server.
Cookies are two types:
1. Persistent:
If we store information in cookie with an expiration date then it is called
persistent cookie. Means the information stored in cookie will expire after
that expiration time.
2. Non-Persistent:
We store information in cookie without expiration date. Means the information
stored in cookie will be stored till user is using the same browser. Use non
persistent cookie for the information that is secure.
Let us understand it with an
example:
Cookies_Demo2.aspx:
<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Cookies_Demo2.aspx.cs" Inherits="Cookies_Demo2" %>
<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title></title>
</head>
<body>
<form id="form1" runat="server">
<div>
Name: <asp:TextBox ID="txtName" runat="server"></asp:TextBox>
Password:<asp:TextBox ID="txtPassword" runat="server"></asp:TextBox>
<asp:Label ID="lblResult" runat="server"></asp:Label>
<asp:Button ID="btnSubmit" runat="server" OnClick="btnSubmit_Click" Text="Submit"/>
</div>
</form>
</body>
</html>
Cookies_Demo2.aspx.cs:
using System;
public partial class Cookies_Demo2 : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
if (Request.Cookies["name"] != null)
{
txtName.Text = Request.Cookies["name"].Value.ToString();
}
if (Request.Cookies["password"] != null)
{
txtPassword.Text = Request.Cookies["password"].Value.ToString();
}
}
protected void btnSubmit_Click(object sender, EventArgs e)
{
Response.Cookies["name"].Value
= txtName.Text;
Response.Cookies["password"].Value
= txtPassword.Text;
Response.Cookies["name"].Expires
= DateTime.Now.AddMinutes(10);
Response.Cookies["password"].Expires
= DateTime.Now.AddMinutes(10);
lblResult.Text = "Request send successfully.";
}
}
Here in the above example when user will click on “Submit”
button after entering the user name and password server will create cookies “name”
and “password” using the “Response” object.
If you want to make cookie as
persistent the use the “Expires” property and set the value as mentioned above.
Now, close the browser and open
it with same URL. If you open it within 10 minutes then information stored in
cookie will assigned into the “txtName” and “txtPassword”. But after 10 minutes
it will destroy.
Important Notes:
1. Use
cookies for small size of information. Cookie size cannot be more than 4KB i.e.
4096 bytes
2. 20
cookies are allowed per domain.
