Developing State-enabled Applications With PHP

1. Using cookies

2. Using Sessions

1. The server knows that it needs to remember the State of browsing session

2. The server creates a cookie and uses the Set-Cookie header field in the HTTP response to pass the cookie to the browser

3. The browser reads the cookie field in the HTTP response and stores the cookie

4. This cookie information is passed along future browser-server communications and can be used in the PHP scripts as a variable

1. name - this is a mandatory parameter and is used subsequently to identify the cookie

2. value - the value of the cookie - e.g. if the cookie is used to store the name of the user, the value parameter will store the actual name - e.g. John

3. expiration_date - the lifetime of the cookie. After this date, the cookie expires and is unusable

4. path - the path refers to the URL from which the cookie is valid and allowed

5. domain - the domain the created the cookie and is allowed to read the contents of the cookie

6. secure - specifies if the cookie can be sent only through a secure connection - e.g. SSL enable sessions

[?php
//check if the $count variable has been associated with the count cookie
if (!isset($count)) {
    $count = 0;
} else {
    $count++;
}
setcookie("count", $count, time()+600, "/", "", 0);
?]

[html]
    [head]
        [title]Session Handling Using Cookies[/title]
    [/head]
    [body]
        This page has been displayed: [?=$count ?] times.
    [/body]
[/html]

1. The server knows that it needs to remember the State of browsing session

2. PHP generates a sssion ID and creates a session file to store future information as required by subsequent pages

3. A cookie is generated wih the session ID at the browser

4. This cookie that stores the session ID is transparently and automatically sent to the server for all subsequent requests to the server

[?php

//starts a session

session_start();

//informs PHP that count information needs to be remembered in the session file

if (!session_is_registered("count")) {

session_register("count");

$count = 0;

}

else {

$count++;

}

$session_id = session_id();

?]

[html]

[head]

[title]PHP Session Handling - Cookie-Enabled[/title]

[/head]

[body]

The current session id is: [?=$session_id ?]

This page has been displayed: [?=$count ?] times.

[/body]

[/html]

A summary of the functions that PHP provides for session handling are:

1. boolean start_session() - initializes a session

2. string session_id([string id]) - either returns the current session id or specify the session id to be used when the session is created

3. boolean session_register(mixed name [, mixed ...]) - registers variables to be stored in the session file. Each parameter passed in the function is a separate variable

4. boolean session_is_registered(string variable_name) - checks if a variable has been previously registered to be stored in the session file

5. session_unregister(string varriable_name) - unregisters a variable from the session file. Unregistered variables are no longer valid for reference in the session.

6. session_unset() - unsets all session variables. It is important to note that all the variables remain registered.

7. boolean session_destroy() - destroys the session. This is opposite of the start_session function.

[a href="[?=$url ?]"]Anchor Text[/a]

Building the URL using SID:

[a href="http://www.yoursite.com/yourphppage.php?[?=SID ?]"]Anchor Text[/a]