1. Introduction to ASP.net
Web programming
Week 11, day2

2. Cookies

3. Cookies
• HTTP is a stateless protocol; this means that the web server does not know
(or care) whether two requests comes from the same user or not; it just
handles each request without regard to the context in which it happens.
• Cookies are used to maintain the state in between requests—even when
they occur at large time intervals from each other.
• Cookies allow your applications to store a small amount of textual data
(typically,4-6kB) on a Web client browser.
• There are a number of possible uses for cookies, although their most
common one is maintaining state of a user

4. Creating cookie
C#
• Response.Cookies*"cookie“+ = "cookie value";
Response.Cookies["cookie"].Expires = DateTime.Now.AddMinutes(10); //
add expiry time
VB.net
• Response.Cookies("cookie“) = "cookie value”
Response.Cookies("cookie“).Expires = DateTime.Now.AddMinutes(10) //
add expiry time
• This simply sets a cookie variable named “cookie” with value
“cookie value” and this variable value will be available till next 10
minutes from current time

5. Accessing Cookies
C#
• Request.Cookies*"cookie“+ = "cookie value";
VB.net
• Request.Cookies("cookie“) = "cookie value";
Cookie as array
C#
• Response.Cookies["UserSettings"]["Font"] = "Arial";
• Response.Cookies["UserSettings"]["Color"] = "Blue";
• Response.Cookies["UserSettings"].Expires = DateTime.Now.AddDays(1d);

6. Cookie as array
Cookie as array
VB.net
• Response.Cookies("UserSettings")("Font") = "Arial"
• Response.Cookies("UserSettings")("Color") = "Blue"
• Response.Cookies("UserSettings").Expires = DateTime.Now.AddDays(1)

7. Destroying Cookies
• You cannot directly delete a cookie on a user's computer. However, you can
direct the user's browser to delete the cookie by setting the cookie's expiration
date to a past date. The next time a user makes a request to a page within the
domain or path that set the cookie, the browser will determine that the cookie
has expired and remove it.
• C#
if (Request.Cookies["UserSettings"] != null)
{
HttpCookie myCookie = new HttpCookie("UserSettings");
myCookie.Expires = DateTime.Now.AddDays(-1d);
Response.Cookies.Add(myCookie);
}

8. Destroying Cookies
• VB.net
If (Not Request.Cookies("UserSettings") Is Nothing) Then
Dim myCookie As HttpCookie
myCookie = New HttpCookie("UserSettings")
myCookie.Expires = DateTime.Now.AddDays(-1D)
Response.Cookies.Add(myCookie)
End If

9. Sessions

10. Sessions
• Session serve the same purpose of cookies that is sessions are used
to maintain the state in between requests
• The difference of session variables with cookies is that they are
stored in the server while cookie variables are stored on the client
(browser)
• In asp.net a session gets started when the user starts interacting
with the server, that is when the user first accesses a page from the
application
• Session can be used to store values as session variables which will be
available throughout the session

11. Sessions
• Session can support any type of object to store along with our own custom
objects
• For every client, session data is stored separately, which means session data is
stored on a per client basis

12. Creating session variables
C#
Session["FirstName"] = FirstNameTextBox.Text;
Session["LastName"] = LastNameTextBox.Text;
VB.net
Session("FirstName") = FirstNameTextBox.Text
Session("LastName") = LastNameTextBox.Text
Any .net framework object type can be stored in a session variable

13. Destroying a session variable
C#
Session.Remove("FirstName”);
Session.Remove("LastName“);
VB.net
SessionRemove ("FirstName")
SessionRemove ("LastName")

14. Destroying the session itself
C#
Session.clear(); //clears all the session variables
Session.Abandon(); //destroys the whole session
VB.net
Session.clear(); //clears all the session variables
Session.Abandon(); //destroys the whole session

15. Comparison
 cookies are stored in the user's
browser
 A cookie can keep information in the
user's browser until deleted by user or
set as per the timer. It will not be
destroyed even if you close the browser.
 Cookies can only store string
 we can save cookie for future
reference
 Sessions are stored in server
 A session is available as long as
the browser is opened. User cant
disable the session. It will be
destroyed if you close the browser
 Can store any object
 session can’t be.
Cookies Session

16. End of Day

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