This is in continuation with @mbabker's joomla#12068.

The implementation in the global configuration is a nice improvement. However the same effect can be achieved without introducing an new parameter 'shared_session'.
Database changes can also be avoided but it doesn't harm in any way, so I have skipped them.

administrator/components/com_config/model/application.php

@@ -254,26 +254,6 @@ public function save($data)
 			$table->purge(-1);
 		}
 
-		// Set the shared session configuration
-		if (isset($data['shared_session']))
-		{
-			$currentShared = isset($prev['shared_session']) ? $prev['shared_session'] : '0';
-
-			// Has the user enabled shared sessions?
-			if ($data['shared_session'] == 1 && $currentShared == 0)
-			{
-				// Generate a random shared session name
-				$data['session_name'] = JUserHelper::genRandomPassword(16);
-			}
-
-			// Has the user disabled shared sessions?
-			if ($data['shared_session'] == 0 && $currentShared == 1)
-			{
-				// Remove the session name value
-				unset($data['session_name']);
-			}
-		}
-
 		if (empty($data['cache_handler']))
 		{
 			$data['caching'] = 0;

administrator/components/com_config/model/form/application.xml

@@ -780,15 +780,15 @@
 			size="6" />
 
 		<field
-			name="shared_session"
+			name="session_name"
 			type="radio"
 			class="btn-group btn-group-yesno"
-			default="0"
+			default=""
 			label="COM_CONFIG_FIELD_SHARED_SESSION_LABEL"
 			description="COM_CONFIG_FIELD_SHARED_SESSION_DESC"
-			filter="integer">
-			<option value="1">JYES</option>
-			<option value="0">JNO</option>
+			filter="cmd">
+			<option value="shared">JYES</option>
+			<option value="">JNO</option>
 		</field>
 
 		<field

administrator/modules/mod_logged/tmpl/default.php

@@ -31,11 +31,11 @@
 				</strong>
 
 				<small class="small hasTooltip" title="<?php echo JHtml::tooltipText('JCLIENT'); ?>">
-					<?php if ($user->client_id === null) : ?>
-						<?php // Don't display a client ?>
-					<?php elseif ($user->client_id) : ?>
+					<?php if (JFactory::getApplication()->get('session_name')) : ?>
+						<?php // Don't display a client if we have a shared session ?>
+					<?php elseif ($user->client_id == 1) : ?>
 						<?php echo JText::_('JADMINISTRATION'); ?>
-					<?php else : ?>
+					<?php elseif ($user->client_id == 0) : ?>
 						<?php echo JText::_('JSITE'); ?>
 					<?php endif; ?>
 				</small>

administrator/modules/mod_status/mod_status.php

@@ -27,7 +27,7 @@
 $count = 0;
 
 // Get the number of backend logged in users if shared sessions is not enabled.
-if (!$config->get('shared_session', '0'))
+if ($config->get('session_name', '') == '')
 {
 	$query->clear()
 		->select('COUNT(session_id)')
@@ -61,7 +61,7 @@
 $online_num = 0;
 
 // Get the number of frontend logged in users if shared sessions is not enabled.
-if (!$config->get('shared_session', '0'))
+if ($config->get('session_name', '') == '')
 {
 	$query->clear()
 		->select('COUNT(session_id)')
@@ -75,7 +75,7 @@
 $total_users = 0;
 
 // Get the number of logged in users if shared sessions is enabled.
-if ($config->get('shared_session', '0'))
+if ($config->get('session_name', '') != '')
 {
 	$query->clear()
 		->select('COUNT(session_id)')

administrator/modules/mod_status/tmpl/default.php

@@ -40,7 +40,7 @@
 }
 
 // Print logged in user count based on the shared session state
-if (JFactory::getConfig()->get('shared_session', '0'))
+if (JFactory::getConfig()->get('session_name', '') != '')
 {
 	// Print the frontend logged in  users.
 	if ($params->get('show_loggedin_users', 1))

installation/model/configuration.php

@@ -144,7 +144,7 @@ public function createConfiguration($options)
 		// Session setting.
 		$registry->set('lifetime', 15);
 		$registry->set('session_handler', 'database');
-		$registry->set('shared_session', 0);
+		$registry->set('session_name', '');
 
 		// Generate the configuration class string buffer.
 		$buffer = $registry->toString('PHP', array('class' => 'JConfig', 'closingtag' => false));

libraries/cms/application/cms.php

@@ -198,7 +198,7 @@ public function checkSession()
 				$db->quote($user->username),
 			);
 
-			if (!$this->get('shared_session', '0'))
+			if ($this->get('session_name', '') == '')
 			{
 				$columns[] = $db->quoteName('client_id');
 				$values[] = (int) $this->getClientId();

modules/mod_whosonline/helper.php

@@ -32,12 +32,16 @@ public static function getOnlineCount()
 		$user_array  = 0;
 		$guest_array = 0;
 
-		$whereCondition = JFactory::getConfig()->get('shared_session', '0') ? 'IS NULL' : '= 0';
-
 		$query = $db->getQuery(true)
 			->select('guest, client_id')
-			->from('#__session')
-			->where('client_id ' . $whereCondition);
+			->from('#__session');
+
+		// Filter by client id only if shared session not enabled
+		if (JFactory::getConfig()->get('session_name', '') == '')
+		{
+			$query->where('client_id = 0');
+		}
+
 		$db->setQuery($query);
 
 		try
@@ -85,15 +89,19 @@ public static function getOnlineCount()
 	 **/
 	public static function getOnlineUserNames($params)
 	{
-		$whereCondition = JFactory::getConfig()->get('shared_session', '0') ? 'IS NULL' : '= 0';
-
 		$db    = JFactory::getDbo();
 		$query = $db->getQuery(true)
 			->select($db->quoteName(array('a.username', 'a.userid', 'a.client_id')))
 			->from('#__session AS a')
 			->where($db->quoteName('a.userid') . ' != 0')
-			->where($db->quoteName('a.client_id') . ' ' . $whereCondition)
-			->group($db->quoteName(array('a.username', 'a.userid', 'a.client_id')));
+			->group($db->quoteName(array('a.username', 'a.userid')));
+
+		// Filter by client id only if shared session not enabled
+		if (JFactory::getConfig()->get('session_name', '') == '')
+		{
+			$query->where($db->quoteName('a.client_id') . ' = 0');
+			$query->group($db->quoteName('a.client_id'));
+		}
 
 		$user = JFactory::getUser();
 

plugins/user/joomla/joomla.php

@@ -271,7 +271,7 @@ public function onUserLogout($user, $options = array())
 			return true;
 		}
 
-		$sharedSessions = $this->app->get('shared_session', '0');
+		$sharedSessions = $this->app->get('session_name', '') != '';
 
 		// Check to see if we're deleting the current session
 		if ($my->id == $user['id'] && (!$sharedSessions && $options['clientid'] == $this->app->getClientId()))