1. SESSION TRACKING BY
DINESH KUMAR.R

2. What is a session?
A session is a conversion between the server and a client. A conversion consists series of continuous request and response.
>In computing, a session is the period of activity between a user logging in and logging out of a (multi-user) system

3. Why should a session be maintained?
When there is a series of continuous request and response from a same client to a server, the server cannot identify from which client it is getting requests. Because HTTP is a stateless protocol.
When there is a need to maintain the conversational state, session tracking is needed
Solution is, when a client makes a request it should introduce itself by providing unique identifier every time. There are five different methods to achieve this.

4. Session tracking methods:
User authorization
Hidden fields
URL rewriting
Cookies
Session tracking API

5. Session Functions
session_name — Get and/or set the current session name
session_regenerate_id — Update the current session id with a newly generated one
session_decode — Decodes session data from a string
session_destroy — Destroys all data registered to a session
session_encode — Encodes the current session data as a string

6. Contd.
session_register — Register one or more global variables with the current session
session_set_save_handler — Sets user-level session storage functions
session_start — Initialize session data
session_unregister — Unregister a global variable from the current session
session_unset — Free all session variables

7. Session STARTING
Before storing user information in a PHP session, a session is to be started using session_start() function
This must be at the very beginning of the code, before any HTML or text is sent.
This function first checks if a session is already started and if none is started then it starts one
Session variables are stored in an associative array called $_SESSION[]. These variables can be accessed during lifetime of a session.

8. CREATING SESSION VARIABLE
A PHP session variable is used to store information about, or change settings for a user session. Session variables hold information about one single user, and are available to all pages in one application.
The correct way to store and retrieve session variables is to use the PHP $_SESSION variable.
$_SESSION[‘ ‘];
date;
Using array();

9. DESTROY SESSION & DELETE
session_destroy — Destroys all data registered to a session
SESSION_DESTROY();
The unset() function is used to free the specified session variable:
session_unset — Free sepecified session variables
SESSION_UNSET();

10. session_is_registered() checks whether or not a variable has been registered.
Its syntax is: boolean session_is_registered (string varname)
is_registered();
session_unregister — Unregister a global variable from the current session
Eg:sessionunreg();

11. isset() Function
Before using a session variable, check if it exists already
isset is a function that takes any variable you want to use and checks to see if it has been set.
That is, whether it has already been assigned a value.
Isset();

12. session_set_save_handler — Sets user-level session storage functions
session_encode — Encodes the current session data as a string
Encode();
session_decode — Decodes session data from a string
Eg:sessiondecode();

13. session_name — Get and/or set the current session name
Eg. Session_name();
session_regenerate_id — Update the current session id with a newly generated one
Eg.Session regenare();

14. Thank u