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Cookies and sessions.

Mumbai University > information technology > sem 4> Web Programming

Marks: 10M

Year : Dec16

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cookie :

  • A cookie is a small piece of text stored on a user's computer by their browser. Common uses for cookies are authentication, storing of site preferences, shopping cart items, and server session identification.

  • Each time the users' web browser interacts with a web server it will pass the cookie information to the web server. Only the cookies stored by the browser that relate to the domain in the requested URL will be sent to the server. This means that cookies that relate to www.example.com will not be sent to www.exampledomain.com.

  • In essence, a cookie is a great way of linking one page to the next for a user's interaction with a web site or web application.

Setting and reading cookies

  • Using the [cookie_set] method we can set cookies to store information for use in later pages. The following code shows how easy it is to store a user's details such as their name and email address which they may have entered on a "Contact Us" form. This would then allow later pages to pre-populate forms with this information.

    Cookie_Set( 'UserDetails'='John Doe|[email protected]', -Domain='example.com', -Expires='1440', -Path='/' )

In this example the cookie named "UserDetails" contains the user name and email address delimited by a "pipe" character. This can be read and interpreted, then output in the following code.

local( userDetails = decode_url(cookie('UserDetails'))->split('|'))

if(#userDetails->size)=>{^
    'User Name = '+#userDetails->get(1)
    '<br />'
    'Email Address = '+#userDetails->get(2)
^}

session :

  • A session can be defined as a server-side storage of information that is desired to persist throughout the user's interaction with the web site or web application.

  • Instead of storing large and constantly changing information via cookies in the user's browser, only a unique identifier is stored on the client side (called a "session id"). This session id is passed to the web server every time the browser makes an HTTP request (ie a page link or AJAX request). The web application pairs this session id with it's internal database and retrieves the stored variables for use by the requested page.

Using Sessions

  • To store information that is not appropriate to store client-side, we use sessions. Lasso has built in session handling, and deals with the setting and retrieval of the cookie itself. It will automatically set and retrieve the session id, which is the only thing stored client-side.

  • To set up a new session, we first start the session, then add to it the variables we would like to store in it. Those variables are stored within Lasso's session database.

    // Start the session. session_start( 'mySessionName', -expires = 1440, -usecookie=true )

    // Add variables to the session if(session_result('mySessionName') != 'load') => { session_addVar('mySessionName', 'sv_userId') session_addVar('mySessionName', 'sv_userName') session_addVar('mySessionName', 'sv_userEmail') session_addVar('mySessionName', 'sv_favouriteColour') }

    !var_defined('sv_userId') ? var('sv_userId' = integer) !var_defined('sv_userName') ? var('sv_userName' = string) !var_defined('sv_userEmail') ? var('sv_userEmail' = string) !var_defined('sv_favouriteColour') ? var('sv_favouriteColour' = 'red')

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