Example identity usage for web application.

identity.php

<?php
/**
 * @package     Joomla.Platform
 * @subpackage  Identity
 *
 * @copyright   Copyright (C) 2005 - 2011 Open Source Matters, Inc. All rights reserved.
 * @license     GNU General Public License version 2 or later; see LICENSE
 */

defined('JPATH_PLATFORM') or die;

/**
 * Identity value object for the Joomla Platform.
 *
 * @package     Joomla.Platform
 * @subpackage  Identity
 * @see         JObject
 * @since       12.3
 */
class JIdentity extends JObject
{
	public $accountId;

	public $name;

	public $email;

	public $password;

	public $block;

	public $sendEmail;

	public $registerDate;

	public $lastVisitDate;

	public $activation;

	public $params;

	public $links = array();
}

web.php

<?php
/**
 * @package     Example.Web
 * @subpackage  Application
 *
 * @license     GNU General Public License version 2 or later.
 */

/**
 * Example Web Application Class
 *
 * @package     Example.Web
 * @subpackage  Application
 * @since       1.0
 */
class EApplicationWeb extends JApplicationWeb
{
	// ...

	/**
	 * Get the application identity.
	 *
	 * @return  mixed  A JIdentity object or null.
	 *
	 * @since   12.1
	 */
	public function getIdentity()
	{
		return $this->identity;
	}

	/**
	 * Allows the application to load a custom or default identity.
	 *
	 * @param   JIdentity  $identity  An optional identity object. If omitted, the factory user is created.
	 *
	 * @return  EApplicationWeb  This method is chainable.
	 *
	 * @since   1.0
	 */
	public function loadIdentity(JIdentity $identity = null)
	{
		if ($identity)
		{
			$this->identity = $identity;
		}
		elseif ($this->session instanceof JSession)
		{
			$this->identity = $this->session->get('user', new JIdentity);
		}
		else
		{
			$this->identity = new JIdentity;
		}

		return $this;
	}

	/**
	 * Allows the application to load a custom or default session.
	 *
	 * @param   JSession  $session  An optional session object. If omitted, the session is created.
	 *
	 * @return  EApplicationWeb  This method is chainable.
	 *
	 * @since   1.0
	 */
	public function loadSession(JSession $session = null)
	{
		if ($session !== null)
		{
			$this->session = $session;

			return $this;
		}

		// Get the session handler from the configuration.
		$handler = $this->get('session.handler', 'none');

		// Initialize the options for JSession.
		$options = array(
			'name' => $this->get('session.name', md5(get_class($this) . $this->get('uri.base.host'))),
			'expire' => (($this->get('session.lifetime')) ? $this->get('session.lifetime') * 60 : 900),
			'force_ssl' => $this->get('force_ssl')
		);

		// Instantiate the session object.
		$session = JSession::getInstance($handler, $options);
		if ($session->getState() == 'expired')
		{
			$session->restart();
		}

		// If the session is new, load the user and registry objects.
		if ($session->isNew())
		{
			$session->set('registry', new JRegistry);
			$session->set('user', new JIdentity);
		}

		// Initialise the input for the session.
		$session->initialise($this->input);
		$session->start();

		// Set the session object.
		$this->session = $session;

		return $this;
	}

	/**
	 * Allows the application to set and persist an identity.
	 *
	 * @param   JIdentity  $identity  An optional identity object. If omitted, the factory user is created.
	 *
	 * @return  EApplicationWeb  This method is chainable.
	 *
	 * @since   1.0
	 */
	public function setIdentity(JIdentity $identity)
	{
		$this->identity = $identity;

		// Persist the identity into the session.
		$this->session->set('user', $this->identity);

		return $this;
	}

	// ...
}