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Web Database Programming Week 7

Web Database Programming Week 7. Session Management & Authentication. Session. HTTP is stateless Each HTTP request is unrelated to one another Many Web applications need to retain State across HTTP requests E.g. Shopping cart

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Web Database Programming Week 7

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  1. Web Database Programming Week 7 Session Management& Authentication

  2. Session • HTTP is stateless • Each HTTP request is unrelated to one another • Many Web applications need to retain State across HTTP requests • E.g. Shopping cart • A Session defines an identifiable sequence of interactions between a particular client and a server

  3. Session Components • Session Identifier (SessionID) • Uniquely identify a session • Session variables • Store information related to a session, I.e. retain state across HTTP requests • E.g. content of shopping cart

  4. SessionID • Is transmitted between client and server with each HTTP request or response • Be default, transmitted as cookie (part of the HTTP header) • Stored in Web browser • E.g. “C:\Documents and Settings\Administrator\Local Settings\Temporary Internet Files\Cookie:administrator@www.fedex.com/” • If cookie is disabled • Put PHPSESSID (32 hex digits) in URL • E.g. http://www.xyz.com/demo.php?PHPSESSID=be20081806199800da22e243ef239391

  5. Session Variables • Stored in Web server • Each session has its own set of session variables • In PHP, each session has a session file • E.g. My shopping cart vs. your shopping cart • In PHP, access by $_SESSION[“variableName”]

  6. Session Illustration

  7. PHP Session Management • session_start() • If no session exists • Create a new sessionID and a session file to store session variables on the server • Send a cookie to browser with the sessionID • If session exists (the sessionID in the cookie sent by browser matches a sessionID on server) • Session variables in the session file will be loaded • NOTE: this function must be called before any HTML output

  8. PHP Session Management • isset($_SESSION[“variableName”]) • Check if the session variable exists • unset($_SESSION[“variableName”]) • Remove the session variable • $_SESSION = arry(); • Remove all session variable • session_destory(); • Remove the session file from the server • Note, cookie is still in browser

  9. Authentication • Check a username, password pair before grant access • Web server configuration files • Using database • HTTP Authentication • In HTTP header • Form-Based Authentication • Username, password sent as form variables • May need to use SSL for encryption

  10. Authentication and Session • Authenticate once • Form-based • Use session to retain the authenticated status • Until user destroys the session (logout) or session timeout

  11. Authentication Script • Include it at the beginning of each PHP page that needs authentication

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