Chapter 10 Managing State Information Using Sessions

PHP Programming2 Problems with Cookies  Not every client computer is secure Cookies may be accessible to hackers  Many client computers do not accept cookies Spyware gathers user information from a local computer for marketing and advertising purposes without the user’s knowledge

PHP Programming3 Using Sessions  A session is a continuous period of access  A session is created for each user that requests a PHP page from a Website  During a session, a PHP script stores state information on a Web server  Only available for current browser session  Allows you to maintain state information even when clients disable cookies  More secure than cookies

PHP Programming4 Starting a Session  Use the session_start() function Starts a new session or continues an existing one Generates a unique session ID  A random alphanumeric string like: 7f39d7dd020773f115d753c71290e11f Creates a text file on the Web server  Same name as the session ID, preceded by sess_  Call session_start() before any HTML output

PHP Programming5 Starting a Session (continued)  Stored in the Web server directory specified by session.save_path directive in php.ini configuration file  session_start() does not accept any parameters, nor does it return a value <?php session_start();...

PHP Programming6 Session ID  If a client’s Web browser is configured to accept cookies, the session ID is assigned to a temporary cookie named PHPSESSID  Pass the session ID as a query string or hidden form field to any Web pages that are called as part of the current session  Use session_id() to retrieve Session ID <?php session_start(); echo “Session ID:”. session_id(); ?>

PHP Programming7 Working with Session Variables  Session state information is stored in the $_SESSION autoglobal  When session_start() function is called: PHP initializes a new $_SESSION autoglobal or Retrieves any variables for the current session (based on the session ID) into the $_SESSION autoglobal  Calling session_start() while an existing session is in progress does not create a new session  If session_start() is not called, $_SESSION values will not be available

PHP Programming8 Working with Session Variables <?php session_start(); $_SESSION['firstName'] = “Mickey"; $_SESSION['lastName'] = “Mouse"; $_SESSION['occupation'] = “actor"; ?>

PHP Programming9 Working with Session Variables  Use the isset() function to ensure that a session variable is set before you attempt to use it <?php session_start(); if (isset($_SESSION['firstName']) && isset($_SESSION['lastName']) && isset($_SESSION['occupation'])) echo $_SESSION['firstName']. " ". $_SESSION['lastName']. " is an ". $_SESSION['occupation']; ?>

PHP Programming10 Deleting a Session Variable  Use unset() function against the appropriate entry in $_SESSION[]

PHP Programming11 Deleting a Session  To delete a session manually: 1. Execute the session_start() function 2. Use the array() construct to reinitialize the $_SESSION autoglobal 3. Use session_destroy() to delete the session <?php session_start(); $_SESSION = array(); session_destroy(); ?>

Fruit Enter your favorite fruit:&nbsp storeFruit2.php showFruit2.php getFruit2.php

PHP Programming13 Practice  Modify your login form so that it uses session variables instead of cookies to store the login name and password.