What are the advantages of using sessions in php?

PHP session is used to store and pass information from one page to another temporarily (until user close the website).

Table of Contents Show

PHP session_start() function
PHP $_SESSION
PHP Session Example
PHP Session Counter Example
PHP Destroying Session
What are the advantages of session?
What are the advantages of sessions over cookies?
Which are various advantages of using PHP explain cookie and session of PHP?
When should you use PHP session?
What is PHP session and how it works?

PHP session technique is widely used in shopping websites where we need to store and pass cart information e.g. username, product code, product name, product price etc from one page to another.

PHP session creates unique user id for each browser to recognize the user and avoid conflict between multiple browsers.

PHP session_start() function

PHP session_start() function is used to start the session. It starts a new or resumes existing session. It returns existing session if session is created already. If session is not available, it creates and returns new session.

Syntax

Example

PHP $_SESSION

PHP $_SESSION is an associative array that contains all session variables. It is used to set and get session variable values.

Example: Store information

Example: Get information

PHP Session Example

File: session1.php File: session2.php

PHP Session Counter Example

File: sessioncounter.php

PHP Destroying Session

PHP session_destroy() function is used to destroy all session variables completely.

File: session3.php

Last Update:2017-01-13 Source: Internet

Author: User

Advantages and disadvantages of using session variables in ASP
(Author: Green Apple Computer Studio)
Many people use session variables to develop ASP (Active Server Pages). These variables are very similar to variables that are common in any programming language and have the same advantages and drawbacks as common variables. Any command requires run time and storage space (even Goto ' s statement), and the session variable also needs its own run-time and storage space. Excessive use of Session variables can result in code redundancy and increased server operating costs below are some of the main ideas and experiences of my personal use of session variables.
Advantages
If you want to pass a variable between many Web pages, you can simplify the problem by using the session variable rather than passing the variable by querystring.
To make a Web site user-ready, consider using the session variable. Every visitor to your site has a user experience, and based on this, with the use of LDAP and such as Ms Site Server, you no longer have to place all the user processes into the session variable, which is dependent on the user's preferences.
You can use the session variable directly when you want to use it, rather than declaring it in advance, which is close to the use of variables in VB. After you use it, you do not have to consider releasing it because it is automatically released.
Disadvantages
The session variable and the cookie are of the same type. If a user sets the browser to be incompatible with any cookies, the user cannot use the session variable!
When a user accesses a page, the running environment of each session variable is generated automatically, and these session variables remain for 20 minutes after the user leaves the page! (In fact, these variables can always be retained to "timeout".) The length of time for "timeout" is set by the Web server administrator. The variables on some sites only last 3 minutes, some 10 minutes, and others remain to the default value of 20 minutes. So, if you place a larger object in the session (such as ADO recordsets,connections, etc.), then there's trouble! As the amount of site traffic increases, the server will not function properly!
Because the creation of session variables is very arbitrary, can be invoked at any time, do not require the developer to do accurate processing, so overuse of session variables will cause code unreadable and difficult to maintain.
Although "You can use the session variable directly at any time you want to use it without having to declare it beforehand, this approach is close to the use of variables in VB." After you use it, you do not have to consider releasing it, as it will automatically release. But, "who" thought there? What is the meaning of a variable? It all becomes less clear.
Summarize
The use of Session variables has both advantages and disadvantages. In my personal opinion, it's best to use less, but using them in some places really makes web development much simpler. Whether to use the session variable depends entirely on the individual's needs, regardless of whether it is used or not, to consider its pros and cons beforehand

Sessions are a simple way to store data for individual users against a unique session ID. This can be used to persist state information between page requests. Session IDs are normally sent to the browser via session cookies and the ID is used to retrieve existing session data. The absence of an ID or session cookie lets PHP know to create a new session, and generate a new session ID.

Sessions follow a simple workflow. When a session is started, PHP will either retrieve an existing session using the ID passed (usually from a session cookie) or if no session is passed it will create a new session. PHP will populate the $_SESSION superglobal with any session data after the session has started. When PHP shuts down, it will automatically take the contents of the $_SESSION superglobal, serialize it, and send it for storage using the session save handler.

By default, PHP uses the internal files save handler which is set by session.save_handler. This saves session data on the server at the location specified by the session.save_path configuration directive.

Sessions can be started manually using the session_start() function. If the session.auto_start directive is set to 1, a session will automatically start on request startup.

Sessions normally shutdown automatically when PHP is finished executing a script, but can be manually shutdown using the session_write_close() function.

Example #1 Registering a variable with $_SESSION.

<?php session_start(); if (!isset($_SESSION['count'])) { $_SESSION['count'] = 0; } else { $_SESSION['count']++; } ?>

Example #2 Unregistering a variable with $_SESSION.

<?php session_start(); unset($_SESSION['count']); ?>

Caution

Do NOT unset the whole $_SESSION with unset($_SESSION) as this will disable the registering of session variables through the $_SESSION superglobal.

Warning

You can't use references in session variables as there is no feasible way to restore a reference to another variable.

Note:
File based sessions (the default in PHP) lock the session file once a session is opened via session_start() or implicitly via session.auto_start. Once locked, no other script can access the same session file until it has been closed by the first script terminating or calling session_write_close().
This is most likely to be an issue on Web sites that use AJAX heavily and have multiple concurrent requests. The easiest way to deal with it is to call session_write_close() as soon as any required changes to the session have been made, preferably early in the script. Alternatively, a different session backend that does support concurrency could be used.

There are no user contributed notes for this page.

What are the advantages of session?

Session is secure and transparent from user because session object is stored on the server. Disadvantages: 1. Performance overhead in case of large number of user, because of session data stored in server memory. 2.

What are the advantages of sessions over cookies?

Sessions are more secured compared to cookies, as they save data in encrypted form. Cookies are not secure, as data is stored in a text file, and if any unauthorized user gets access to our system, he can temper the data.

A cookie's data can be modified, as the data is stored locally (on the client), where as a session's data is stored on the server, and can not be modified (by the client).

When should you use PHP session?

PHP session is used to store and pass information from one page to another temporarily (until user close the website). PHP session technique is widely used in shopping websites where we need to store and pass cart information e.g. username, product code, product name, product price etc from one page to another.

What is PHP session and how it works?

PHP responds by sending a unique token that identifies the current session. This is known as the session ID. In all subsequent requests, the browser sends the session ID to say, "Hey, it's me again." All other data related to the session is stored on the web server. Only the session ID gets passed back and forth.