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PHP State
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HTTP is a stateless protocol, which means that once a web
server completes a request, the connection goes away
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1 2 3 4 "Hello, server!" "Hello, client!" "Hello again!"
"Sorry, but I don't know you" 4
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maintaining state is to use
One technique for maintaining state is to use cookies
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A cookie is a bit of information that the server can give to a client
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On every subsequent request, the client will give that
cookie back to the server
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1 2 3 4 Request Response + Cookie Request + Cookie Response Client
Server Request 1 Response + Cookie 2 Request + Cookie 3 Response 4
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Client Server Request + Cookie 5 Response 6 7 8
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The server can store any data in a cookie (within limits),
such as user ID, preferences, etc.
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1 2 3 4 "Hello, server!" "Hello, client! Your ID is 4646"
"Hello again! I'm user 4646" 3 "Hi, user 4646!" 4
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Language: Color: Save English v | Red Settings
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1 2 3 4 Request White page in French Client Server Request + form data
(default) 2 Server Client Request + form data 3 Red page in English lang=en; color=red 4
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5 6 7 8 Request Red page in English Client Server Request
lang=en; color=red 5 Red page in English 6 Server Client Request lang=en; color=red 7 Red page in English 8
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GET /tentang/profil-universitas HTTP/1.1
Host: ub.ac.id Connection: keep-alive Accept: text/html User-Agent: Chrome/ Accept-Encoding: gzip, deflate Accept-Language: id,en-US Referer: Cookie: lang=en; color=red
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So, cookies are like variables that
can be recognized by different pages
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Use the setcookie() function to send a cookie to the browser
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setcookie(name[,value[,expire[,path[,domain[,secure]]]]]);
![setcookie(name[,value[,expire[,path[,domain[,secure]]]]]);](http://slideplayer.com./slide/16393773/95/images/17/setcookie%28name%5B%2Cvalue%5B%2Cexpire%5B%2Cpath%5B%2Cdomain%5B%2Csecure%5D%5D%5D%5D%5D%29%3B.jpg "setcookie(name[,value[,expire[,path[,domain[,secure]]]]]);")
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setcookie(‘userid’, ‘4646’); setcookie(‘lang’, ‘en’);
setcookie(‘color’, ‘red’);
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for a particular cookie
name is a unique name for a particular cookie
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The name must not contain whitespace or semicolons
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attached to this cookie
value is the string value attached to this cookie
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The original specification limited the total size of a cookie to 4 KB
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expire is the expiration date
for this cookie
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If not specified, the browser saves the cookie in memory:
when the browser exits, the cookie disappears
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For example, to expire the cookie in two hours' time, pass
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Because cookies are sent as headers in the response,
setcookie() must be called before any content is sent
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<!DOCTYPE html> <html> <?php setcookie(‘userid’, 4646); ?> <head> ...
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<?php setcookie(‘userid’, 4646); ?>
<!DOCTYPE html> <html> <head> ...
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Cookies are automatically sent to the web server
(and received/parsed by PHP) each time a user visits a server
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Cookies sent by clients are available through the
$_COOKIE array
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The key is the cookie name, and the value is the cookie's value field
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$lang = $_COOKIE[‘lang’];
$color = $_COOKIE[‘color’];
![$lang = $_COOKIE[‘lang’];](http://slideplayer.com./slide/16393773/95/images/32/%24lang+%3D+%24_COOKIE%5B%E2%80%98lang%E2%80%99%5D%3B.jpg "$color = $_COOKIE[‘color’];")
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Write this to set_cookie.php!
<?php setcookie(‘name’, ‘Supono’); ?> <!DOCTYPE html> <html> <head></head> <body> <h1>Cookies set!</h1> <a href=“read_cookie.php”>Check</a> </body></html>
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Write this to read_cookie.php!
<!DOCTYPE html> <html> <head></head> <body> <h1>Hello, <?php echo isset($_COOKIE[‘name’]) ? $_COOKIE[‘name’] : ‘guest’; ?> !</h1> <a href=“set_cookie.php”>Set</a> <a href=“remove_cookie.php”>Remove</a> </body></html>
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Write this to remove_cookie.php!
<?php setcookie(‘name’, ’’); ?> <!DOCTYPE html> <html> <head></head> <body> <h1>Cookies removed!</h1> <a href=“read_cookie.php”>Check</a> </body> </html>
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Sessions are similar to cookies
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While cookie data are stored on the client, session data are
stored on the server
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It means clients do not have access to the session data
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It also means that, unlike cookies, session data are not included
in HTTP requests
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1 2 3 4 Request White page in French Client Server Request + form
(default) + ID 9876 2 Server Client Request + form + ID 9876 3 Red page in English 4
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5 6 7 8 Request + ID 9876 Red page in English Client Server
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lang=id; color=yellow
preferences 9876 lang=en; color=red 9877 lang=id; color=yellow 9878 lang=fr; color=green
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Each first-time visitor is issued
a unique session ID
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By default, the session ID is stored in a cookie called PHPSESSID
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Since session data are stored on the server, they can be any size
we want
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Registered variables are loaded into the associative array $_SESSION
by the session_start() function
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session_start(); $_SESSION[‘hits’] = $_SESSION[‘hits’] + 1;
![session_start(); $_SESSION[‘hits’] = $_SESSION[‘hits’] + 1;](http://slideplayer.com./slide/16393773/95/images/47/session_start%28%29%3B+%24_SESSION%5B%E2%80%98hits%E2%80%99%5D+%3D+%24_SESSION%5B%E2%80%98hits%E2%80%99%5D+%2B+1%3B.jpg "session_start(); $_SESSION[‘hits’] = $_SESSION[‘hits’] + 1;")
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call session_destroy()
To end a session, call session_destroy()
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By default, PHP session ID cookies expire when the browser closes
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advantages over cookies:
Sessions brings some advantages over cookies:
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(1) Session can save large amount of data
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(2) Since cookies are sent included in HTTP headers, sessions can save bandwidth
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(3) Session data is much more secure
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bye.
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