Web application, cookies and sessions

UNIT - 5
WEB APPLICATION, COOKIES AND SESSIONS

Sending email
• Syntax: mail(to, subject, body, [headers]);
• Eg:
$to = 'email@example.com';
$subject = 'This is the subject';
$body = 'This is the body. It goes over multiple lines.';
mail ($to, $subject, $body);
• Subject line cannot include ‘n’.
• Body should not exceed 70 characters.
$body = wordwrap($body, 70);

Handling file uploads
• Steps
• Things to be considered:
• PHP- correct settings
• Temporary storage directory
• Final storage directory
• Allowing for file uploads:
php.ini

• Uploading files with PHP:
<form enctype="multipart/form-data" action="script.php"
method="post">
<input type="hidden" name="MAX_FILE_SIZE" value="30000" />
File <input type="file" name= "upload" />
• $_FILES: name, type, size, tmp_name, error.
• move_uploaded_file (temporary
_filename,/path/to/destination/filename);

PHP and Javascript
• Javascript with HTML code can be done in 2 ways:
• Inline
• External file
• Inline Javascript
<script type="text/javascript">
// A c t u a l J a v a S c r i p t c o d e.
</script>
• External Javascript
<script type="text/javascript" src="somefile.js"></script>

Comparison
JAVASCRIPT PHP
Client side program Server side program
Can detect the size of popup, browser window and
image mouse over
Cannot detect
Cannot interact with MySQL Can interact with MySQL
Cannot generate PHP code Can dynamically generate Javascript
.js .php
OOP approach Procedural and OOP approach
In HTML: <script type=“text/javascript”>
</script>
<?php
?>

Understanding HTTP headers
• the uploaded images are being stored in the ‘uploads’ directory.
• the images cannot be viewed directly in the Web browser using either
of the following:
http://www.example.com/uploads/ image.png or
<img src="image.png" />
• create a proxy script in PHP.
http://www.example.com/proxy.php? image=image.png
or
<img src="proxy.php?image=image.png" />

Header()
• used to redirect the Web browser from the current page to another.
• syntax: header(header string);
• header ('Location: http://www.example.com/page.php’);
• To send a file:
header("Content-Type:application/pdfn");
header ("Content-Disposition: attachment;
filename="somefile.pdf"n");
header ("Content-Length: 4096n");

Date and time function
• Date_default_timezone_set(tz);
• Checkdate();
• Date(format, [timestamp]);

• Eg:
echo date('F j, Y'); // January 26, 2011
echo date('H:i'); // 23:14
echo date('D'); // Sat
• mktime(): mktime (hour, minute, second, month, day, year);
• getdate():
$today = getdate( );
echo $today['month']; // October

Making the login functions
• header ('Location: http://www. example.com/page.php');
exit( );
• 3 step process:
• Email address
• Password
• Email address and password

Using cookies
• a way for a server to store information on the user’s machine.

Setting cookies
• Setcookie(name, value, expiration, path, host, secure, httponly);

Session
• Data stored on the server.
• Advantages of session over cookies:
• Secure
• More data
• Without cookies
• Advantages of cookies over session:
• Easier
• Less of server
• More time

Setting the session
• Session_start()

• Accessing the session: $_SESSION
• Deleting the session:
• Unset($_SESSION[‘var’]);
• $_SESSION=array();
• Session_destroy();

Improving session security
• Session ID and session data
• HTTP_USER_AGENT
$_SESSION[‘agent’]=md5($_SERVER[‘HTTP_USER_AGENT’]);

Web application, cookies and sessions

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