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Handling sessions with PHPHandling sessions with PHPHandling sessions with PHPHandling sessions with PHP

Advanced Digital Media Technology Center-University of Colombo School of Computing

Samantha Mathara Arachchi,B.Sc,Pg.Dip(Com.Tech.),Pg.Dip.(IM),M.Sc.(IM),MCS(SL) MACM,MIEEE

e-mail:(ssp@ucsc.cmb.ac.lk)

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Managing the "Memory" of the BrowserManaging the "Memory" of the BrowserManaging the "Memory" of the BrowserManaging the "Memory" of the Browser

Web pages are normally completely without memory.

Each time a person visits a page, the web server happily sends the page with no idea if thevisitor is viewing the page for the first time or the hundredth. Often times this is not a

problem.

Sometimes, however, it is a big problem, such as when you want to identify a user, in orderto interact with that person in various ways, even if he/she moves between differentwebpages.

One method is to use cookies, which are totally dependent on the settings of the clientsweb browser.

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What is a session ?What is a session ?What is a session ?What is a session ?

A session is a series of related interactions between a single client & a web

server, taking place over an extended period of time.

It is a method of making Data persist, even when you exit one page & go toanother.

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Session VariablesSession VariablesSession VariablesSession Variables

How do we make the Browser remember a certain unit of data while we navigate

from page to page? Simply, assign that data to a session variable, using thefollowing format - $_SESSION[ > ].

eg. :- $_SESSION[stu_name] = Mr. ABC,

$_SESSION[stu_id] = 8880123

Here, stu_name and stu_id uniquely identify a variable.

Another method is, to use the predefined function session_register( )

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Starting or Resuming SessionsStarting or Resuming SessionsStarting or Resuming SessionsStarting or Resuming Sessions

A function called session_start() is used to start/create or resume a session in a

particular webpage, based on the session id based on a GET or POST variable or acookie.

This allows you to access the session variables input through a previous webpage.

This is called initializing sessions.

Two important points that have to be remembered about this function are,- Every sessions enabled page requires it.

- You must put it before any HTML or PHP output (including blank linesor spaces).

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Stopping SessionsStopping SessionsStopping SessionsStopping Sessions

Often times, you will need to destroy a session completely. This is a simple two step

process:session_unset();session_destroy();

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Sample CodesSample CodesSample CodesSample Codes