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159 lines
6.2 KiB
HTML
159 lines
6.2 KiB
HTML
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<html>
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<head>
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<title>ADODB Session Management Manual</title>
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<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
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<XSTYLE
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body,td {font-family:Arial,Helvetica,sans-serif;font-size:11pt}
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pre {font-size:9pt}
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.toplink {font-size:8pt}
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/>
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</head>
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<body bgcolor="#FFFFFF">
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<h3>ADODB Session Management Manual</h3>
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<p>
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V3.94 13 Oct 2003 (c) 2000-2003 John Lim (jlim#natsoft.com.my)
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<p> <font size=1>This software is dual licensed using BSD-Style and LGPL. This
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means you can use it in compiled proprietary and commercial products. </font>
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<p>Useful ADOdb links: <a href=http://php.weblogs.com/adodb>Download</a> <a href=http://php.weblogs.com/adodb_manual>Other Docs</a>
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<h3>Introduction</h3>
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<p>PHP is packed with good features. One of the most popular is session variables.
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These are variables that persist throughout a session, as the user moves from page to page. Session variables are great holders of state information and other useful stuff.
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<p>
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To use session variables, call session_start() at the beginning of your web page,
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before your HTTP headers are sent. Then for every variable you want to keep alive
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for the duration of the session, call session_register($variable_name). By default,
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the session handler will keep track of the session by using a cookie. You can save objects
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or arrays in session variables also.
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<p>The default method of storing sessions is to store it in a file. However if
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you have special needs such as you:
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<ul>
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<li>Have multiple web servers that need to share session info</li>
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<li>Need to do special processing of each session</li>
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<li>Require notification when a session expires</li>
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</ul>
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<p>Then the ADOdb session handler provides you with the above additional capabilities
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by storing the session information as records in a database table that can be
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shared across multiple servers.
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<h4>ADOdb Session Handler Features</h4>
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<ul>
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<li>Ability to define a notification function that is called when a session expires. Typically
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used to detect session logout and release global resources.
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<li>Optimization of database writes. We crc32 the session data and only perform an update
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to the session data if there is a data change.
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<li>Support for large amounts of session data with CLOBs (see adodb-session-clob.inc.php). Useful
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for Oracle.
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<li>Support for encrypted session data, see adodb-cryptsession.inc.php. Enabling encryption
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is simply a matter of including adodb-cryptsession.inc.php instead of adodb-session.inc.php.
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</ul>
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<h3>Setup</h3>
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<p>There are 3 session management files that you can use:
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<pre>
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adodb-session.inc.php : The default
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adodb-session-clob.inc.php : Use this if you are storing DATA in clobs
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adodb-cryptsession.inc.php : Use this if you want to store encrypted session data in the database
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<strong>Examples</strong>
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GLOBAL $HTTP_SESSION_VARS;
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include('adodb.inc.php');
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include('adodb-session.php');
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session_start();
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session_register('AVAR');
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$HTTP_SESSION_VARS['AVAR'] += 1;
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print "<p>\$HTTP_SESSION_VARS['AVAR']={$HTTP_SESSION_VARS['AVAR']}</p>";
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To force non-persistent connections, call adodb_session_open first before session_start():
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GLOBAL $HTTP_SESSION_VARS;
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include('adodb.inc.php');
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include('adodb-session.php');
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adodb_sess_open(false,false,false);
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session_start();
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session_register('AVAR');
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$HTTP_SESSION_VARS['AVAR'] += 1;
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print "<p>\$HTTP_SESSION_VARS['AVAR']={$HTTP_SESSION_VARS['AVAR']}</p>";
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To use a encrypted sessions, simply replace the file:
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GLOBAL $HTTP_SESSION_VARS;
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include('adodb.inc.php');
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include('adodb-cryptsession.php');
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session_start();
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And the same technique for adodb-session-clob.inc.php:
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GLOBAL $HTTP_SESSION_VARS;
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include('adodb.inc.php');
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include('adodb-session-clob.php');
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session_start();
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<h4>Installation</h4>
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1. Create this table in your database (syntax might vary depending on your db):
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<a name=sessiontab></a>
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create table sessions (
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SESSKEY char(32) not null,
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EXPIRY int(11) unsigned not null,
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EXPIREREF varchar(64),
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DATA text not null,
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primary key (sesskey)
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);
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For the adodb-session-clob.inc.php version, create this:
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create table sessions (
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SESSKEY char(32) not null,
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EXPIRY int(11) unsigned not null,
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EXPIREREF varchar(64),
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DATA CLOB,
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primary key (sesskey)
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);
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2. Then define the following parameters. You can either modify
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this file, or define them before this file is included:
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$ADODB_SESSION_DRIVER='database driver, eg. mysql or ibase';
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$ADODB_SESSION_CONNECT='server to connect to';
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$ADODB_SESSION_USER ='user';
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$ADODB_SESSION_PWD ='password';
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$ADODB_SESSION_DB ='database';
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$ADODB_SESSION_TBL = 'sessions'
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3. Recommended is PHP 4.0.6 or later. There are documented
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session bugs in earlier versions of PHP.
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<h4>Notifications</h4>
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If you want to receive notifications when a session expires, then
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you can tag a session with an <a href="#sessiontab">EXPIREREF</a> tag (see the definition of
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the sessions table above), and before the session record is deleted,
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we can call a function that will pass the contents of the EXPIREREF
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field as the first parameter, and the session key as the 2nd parameter.
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To do this, define a notification function, say NotifyFn:
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function NotifyFn($expireref, $sesskey)
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{
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}
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Then you need to define a global variable $ADODB_SESSION_EXPIRE_NOTIFY.
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This is an array with 2 elements, the first being the name of the variable
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you would like to store in the EXPIREREF field, and the 2nd is the
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notification function's name.
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In this example, we want to be notified when a user's session
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has expired, so we store the user id in the global variable $USERID,
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store this value in the EXPIREREF field:
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$ADODB_SESSION_EXPIRE_NOTIFY = array('USERID','NotifyFn');
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Then when the NotifyFn is called, we are passed the $USERID as the first
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parameter, eg. NotifyFn($userid, $sesskey).
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NOTE: When you want to change the EXPIREREF, you will need to modify a session
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variable to force a database record update because we checksum the session
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variables, and only perform the update when the checksum changes.
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</pre>
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<p>
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Also see the <a href=docs-adodb.htm>core ADOdb documentation</a>.
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</body>
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</html>
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