diff --git a/framework/rbac/Assignment.php b/framework/rbac/Assignment.php
index c2a9f56..576017e 100644
--- a/framework/rbac/Assignment.php
+++ b/framework/rbac/Assignment.php
@@ -19,24 +19,24 @@ use yii\base\Object;
 class Assignment extends Object
 {
 	private $_auth;
-	private $_itemName;
 	private $_userId;
+	private $_itemName;
 	private $_bizRule;
 	private $_data;
 
 	/**
 	 * Constructor.
 	 * @param IManager $auth the authorization manager
-	 * @param string $itemName authorization item name
 	 * @param mixed $userId user ID (see [[User::id]])
+	 * @param string $itemName authorization item name
 	 * @param string $bizRule the business rule associated with this assignment
 	 * @param mixed $data additional data for this assignment
 	 */
-	public function __construct($auth, $itemName, $userId, $bizRule = null, $data = null)
+	public function __construct($auth, $userId, $itemName, $bizRule = null, $data = null)
 	{
 		$this->_auth = $auth;
-		$this->_itemName = $itemName;
 		$this->_userId = $userId;
+		$this->_itemName = $itemName;
 		$this->_bizRule = $bizRule;
 		$this->_data = $data;
 	}
diff --git a/framework/rbac/DbManager.php b/framework/rbac/DbManager.php
new file mode 100644
index 0000000..5f64694
--- /dev/null
+++ b/framework/rbac/DbManager.php
@@ -0,0 +1,574 @@
+<?php
+/**
+ * @link http://www.yiiframework.com/
+ * @copyright Copyright (c) 2008 Yii Software LLC
+ * @license http://www.yiiframework.com/license/
+ */
+
+namespace yii\rbac;
+
+use Yii;
+use yii\db\Connection;
+use yii\db\Query;
+use yii\base\Exception;
+use yii\base\InvalidConfigException;
+
+/**
+ *
+ * @author Qiang Xue <qiang.xue@gmail.com>
+ * @author Alexander Kochetov <creocoder@gmail.com>
+ * @since 2.0
+ */
+class DbManager extends Manager
+{
+	/**
+	 * @var Connection|string the DB connection object or the application component ID of the DB connection.
+	 * After the DbManager object is created, if you want to change this property, you should only assign it
+	 * with a DB connection object.
+	 */
+	public $db = 'db';
+	/**
+	 * @var string the name of the table storing authorization items. Defaults to 'tbl_auth_item'.
+	 */
+	public $itemTable = 'tbl_auth_item';
+	/**
+	 * @var string the name of the table storing authorization item hierarchy. Defaults to 'tbl_auth_item_child'.
+	 */
+	public $itemChildTable = 'tbl_auth_item_child';
+	/**
+	 * @var string the name of the table storing authorization item assignments. Defaults to 'tbl_auth_assignment'.
+	 */
+	public $assignmentTable = 'tbl_auth_assignment';
+
+	private $_usingSqlite;
+
+	/**
+	 * Initializes the application component.
+	 * This method overrides the parent implementation by establishing the database connection.
+	 */
+	public function init()
+	{
+		if (is_string($this->db)) {
+			$this->db = Yii::$app->getComponent($this->db);
+		}
+		if (!$this->db instanceof Connection) {
+			throw new InvalidConfigException("DbManager::db must be either a DB connection instance or the application component ID of a DB connection.");
+		}
+		$this->_usingSqlite = !strncmp($this->db->getDriverName(), 'sqlite', 6);
+		parent::init();
+	}
+
+	/**
+	 * Performs access check for the specified user.
+	 * @param mixed $userId the user ID. This should can be either an integer and a string representing
+	 * @param string $itemName the name of the operation that need access check
+	 * the unique identifier of a user. See [[User::id]].
+	 * @param array $params name-value pairs that would be passed to biz rules associated
+	 * with the tasks and roles assigned to the user. A param with name 'userId' is added to this array,
+	 * which holds the value of `$userId`.
+	 * @return boolean whether the operations can be performed by the user.
+	 */
+	public function checkAccess($userId, $itemName, $params = array())
+	{
+		$assignments = $this->getAssignments($userId);
+		return $this->checkAccessRecursive($userId, $itemName, $params, $assignments);
+	}
+
+	/**
+	 * Performs access check for the specified user.
+	 * This method is internally called by [[checkAccess()]].
+	 * @param mixed $userId the user ID. This should can be either an integer and a string representing
+	 * the unique identifier of a user. See [[User::id]].
+	 * @param string $itemName the name of the operation that need access check
+	 * @param array $params name-value pairs that would be passed to biz rules associated
+	 * with the tasks and roles assigned to the user. A param with name 'userId' is added to this array,
+	 * which holds the value of `$userId`.
+	 * @param Assignment[] $assignments the assignments to the specified user
+	 * @return boolean whether the operations can be performed by the user.
+	 */
+	protected function checkAccessRecursive($userId, $itemName, $params, $assignments)
+	{
+		if (($item = $this->getItem($itemName)) === null) {
+			return false;
+		}
+		Yii::trace('Checking permission: ' . $item->getName(), __METHOD__);
+		if (!isset($params['userId'])) {
+			$params['userId'] = $userId;
+		}
+		if ($this->executeBizRule($item->getBizRule(), $params, $item->getData())) {
+			if (in_array($itemName, $this->defaultRoles)) {
+				return true;
+			}
+			if (isset($assignments[$itemName])) {
+				$assignment = $assignments[$itemName];
+				if ($this->executeBizRule($assignment->getBizRule(), $params, $assignment->getData())) {
+					return true;
+				}
+			}
+			$query = new Query;
+			$parents = $query->select(array('parent'))
+				->from($this->itemChildTable)
+				->where('child=:name', array(':name' => $itemName))
+				->createCommand($this->db)
+				->queryColumn();
+			foreach ($parents as $parent) {
+				if ($this->checkAccessRecursive($userId, $parent, $params, $assignments)) {
+					return true;
+				}
+			}
+		}
+		return false;
+	}
+
+	/**
+	 * Adds an item as a child of another item.
+	 * @param string $itemName the parent item name
+	 * @param string $childName the child item name
+	 * @return boolean whether the item is added successfully
+	 * @throws Exception if either parent or child doesn't exist or if a loop has been detected.
+	 */
+	public function addItemChild($itemName, $childName)
+	{
+		if ($itemName === $childName) {
+			throw new Exception("Cannot add '$itemName' as a child of itself.");
+		}
+		$query = new Query;
+		$rows = $query->from($this->itemTable)
+			->where('name=:name1 OR name=:name2', array(
+				':name1' => $itemName,
+				':name2' => $childName
+			))
+			->createCommand($this->db)
+			->queryAll();
+		if (count($rows) == 2) {
+			if ($rows[0]['name'] === $itemName) {
+				$parentType = $rows[0]['type'];
+				$childType = $rows[1]['type'];
+			} else {
+				$childType = $rows[0]['type'];
+				$parentType = $rows[1]['type'];
+			}
+			$this->checkItemChildType($parentType, $childType);
+			if ($this->detectLoop($itemName, $childName)) {
+				throw new Exception("Cannot add '$childName' as a child of '$itemName'. A loop has been detected.");
+			}
+			$this->db->createCommand()
+				->insert($this->itemChildTable, array(
+					'parent' => $itemName,
+					'child' => $childName,
+				));
+			return true;
+		} else {
+			throw new Exception("Either '$itemName' or '$childName' does not exist.");
+		}
+	}
+
+	/**
+	 * Removes a child from its parent.
+	 * Note, the child item is not deleted. Only the parent-child relationship is removed.
+	 * @param string $itemName the parent item name
+	 * @param string $childName the child item name
+	 * @return boolean whether the removal is successful
+	 */
+	public function removeItemChild($itemName, $childName)
+	{
+		return $this->db->createCommand()
+			->delete($this->itemChildTable, 'parent=:parent AND child=:child', array(
+				':parent' => $itemName,
+				':child' => $childName
+			)) > 0;
+	}
+
+	/**
+	 * Returns a value indicating whether a child exists within a parent.
+	 * @param string $itemName the parent item name
+	 * @param string $childName the child item name
+	 * @return boolean whether the child exists
+	 */
+	public function hasItemChild($itemName, $childName)
+	{
+		$query = new Query;
+		return $query->select(array('parent'))
+			->from($this->itemChildTable)
+			->where('parent=:parent AND child=:child', array(
+				':parent' => $itemName,
+				':child' => $childName))
+			->createCommand($this->db)
+			->queryScalar() !== false;
+	}
+
+	/**
+	 * Returns the children of the specified item.
+	 * @param mixed $names the parent item name. This can be either a string or an array.
+	 * The latter represents a list of item names.
+	 * @return Item[] all child items of the parent
+	 */
+	public function getItemChildren($names)
+	{
+		if (is_string($names)) {
+			$condition = 'parent=' . $this->db->quoteValue($names);
+		} elseif (is_array($names) && !empty($names)) {
+			foreach ($names as &$name) {
+				$name = $this->db->quoteValue($name);
+			}
+			$condition = 'parent IN (' . implode(', ', $names) . ')';
+		}
+		$query = new Query;
+		$rows = $query->select(array('name', 'type', 'description', 'bizrule', 'data'))
+			->from(array(
+				$this->itemTable,
+				$this->itemChildTable
+			))
+			->where($condition . ' AND name=child')
+			->createCommand($this->db)
+			->queryAll();
+		$children = array();
+		foreach ($rows as $row) {
+			if (($data = @unserialize($row['data'])) === false) {
+				$data = null;
+			}
+			$children[$row['name']] = new Item($this, $row['name'], $row['type'], $row['description'], $row['bizrule'], $data);
+		}
+		return $children;
+	}
+
+	/**
+	 * Assigns an authorization item to a user.
+	 * @param mixed $userId the user ID (see [[User::id]])
+	 * @param string $itemName the item name
+	 * @param string $bizRule the business rule to be executed when [[checkAccess()]] is called
+	 * for this particular authorization item.
+	 * @param mixed $data additional data associated with this assignment
+	 * @return Assignment the authorization assignment information.
+	 * @throws Exception if the item does not exist or if the item has already been assigned to the user
+	 */
+	public function assign($userId, $itemName, $bizRule = null, $data = null)
+	{
+		if ($this->usingSqlite() && $this->getItem($itemName) === null) {
+			throw new Exception("The item '$itemName' does not exist.");
+		}
+		$this->db->createCommand()
+			->insert($this->assignmentTable, array(
+				'userid' => $userId,
+				'itemname' => $itemName,
+				'bizrule' => $bizRule,
+				'data' => serialize($data)
+			));
+		return new Assignment($this, $userId, $itemName, $bizRule, $data);
+	}
+
+	/**
+	 * Revokes an authorization assignment from a user.
+	 * @param mixed $userId the user ID (see [[User::id]])
+	 * @param string $itemName the item name
+	 * @return boolean whether removal is successful
+	 */
+	public function revoke($userId, $itemName)
+	{
+		return $this->db->createCommand()
+			->delete($this->assignmentTable, 'itemname=:itemname AND userid=:userid', array(
+				':userid' => $userId,
+				':itemname' => $itemName
+			)) > 0;
+	}
+
+	/**
+	 * Returns a value indicating whether the item has been assigned to the user.
+	 * @param mixed $userId the user ID (see [[User::id]])
+	 * @param string $itemName the item name
+	 * @return boolean whether the item has been assigned to the user.
+	 */
+	public function isAssigned($itemName, $userId)
+	{
+		$query = new Query;
+		return $query->select(array('itemname'))
+			->from($this->assignmentTable)
+			->where('itemname=:itemname AND userid=:userid', array(
+				':userid' => $userId,
+				':itemname' => $itemName
+			))
+			->createCommand($this->db)
+			->queryScalar() !== false;
+	}
+
+	/**
+	 * Returns the item assignment information.
+	 * @param mixed $userId the user ID (see [[User::id]])
+	 * @param string $itemName the item name
+	 * @return Assignment the item assignment information. Null is returned if
+	 * the item is not assigned to the user.
+	 */
+	public function getAssignment($userId, $itemName)
+	{
+		$query = new Query;
+		$row = $query->from($this->assignmentTable)
+			->where('itemname=:itemname AND userid=:userid', array(
+				':userid' => $userId,
+				':itemname' => $itemName
+			))
+			->createCommand($this->db)
+			->queryRow();
+		if ($row !== false) {
+			if (($data = @unserialize($row['data'])) === false) {
+				$data = null;
+			}
+			return new Assignment($this, $row['userid'], $row['itemname'], $row['bizrule'], $data);
+		} else {
+			return null;
+		}
+	}
+
+	/**
+	 * Returns the item assignments for the specified user.
+	 * @param mixed $userId the user ID (see [[User::id]])
+	 * @return Assignment[] the item assignment information for the user. An empty array will be
+	 * returned if there is no item assigned to the user.
+	 */
+	public function getAssignments($userId)
+	{
+		$query = new Query;
+		$rows = $query->from($this->assignmentTable)
+			->where('userid=:userid', array(':userid' => $userId))
+			->createCommand($this->db)
+			->queryAll();
+		$assignments = array();
+		foreach ($rows as $row) {
+			if (($data = @unserialize($row['data'])) === false) {
+				$data = null;
+			}
+			$assignments[$row['itemname']] = new Assignment($this, $row['userid'], $row['itemname'], $row['bizrule'], $data);
+		}
+		return $assignments;
+	}
+
+	/**
+	 * Saves the changes to an authorization assignment.
+	 * @param Assignment $assignment the assignment that has been changed.
+	 */
+	public function saveAssignment($assignment)
+	{
+		$this->db->createCommand()
+			->update($this->assignmentTable, array(
+				'bizrule' => $assignment->getBizRule(),
+				'data' => serialize($assignment->getData()),
+			), 'itemname=:itemname AND userid=:userid', array(
+				'userid' => $assignment->getUserId(),
+				'itemname' => $assignment->getItemName()
+			));
+	}
+
+	/**
+	 * Returns the authorization items of the specific type and user.
+	 * @param mixed $userId the user ID. Defaults to null, meaning returning all items even if
+	 * they are not assigned to a user.
+	 * @param integer $type the item type (0: operation, 1: task, 2: role). Defaults to null,
+	 * meaning returning all items regardless of their type.
+	 * @return Item[] the authorization items of the specific type.
+	 */
+	public function getItems($userId = null, $type = null)
+	{
+		$query = new Query;
+		if ($userId === null && $type === null) {
+			$command = $query->from($this->itemTable)
+				->createCommand($this->db);
+		} elseif ($userId === null) {
+			$command = $query->from($this->itemTable)
+				->where('type=:type', array(':type' => $type))
+				->createCommand($this->db);
+		} elseif ($type === null) {
+			$command = $query->select(array('name', 'type', 'description', 't1.bizrule', 't1.data'))
+				->from(array(
+					$this->itemTable . ' t1',
+					$this->assignmentTable . ' t2'
+				))
+				->where('name=itemname AND userid=:userid', array(':userid' => $userId))
+				->createCommand($this->db);
+		} else {
+			$command = $query->select('name', 'type', 'description', 't1.bizrule', 't1.data')
+				->from(array(
+					$this->itemTable . ' t1',
+					$this->assignmentTable . ' t2'
+				))
+				->where('name=itemname AND type=:type AND userid=:userid', array(
+					':userid' => $userId,
+					':type' => $type
+				))
+				->createCommand($this->db);
+		}
+		$items = array();
+		foreach ($command->queryAll() as $row) {
+			if (($data = @unserialize($row['data'])) === false) {
+				$data = null;
+			}
+			$items[$row['name']] = new Item($this, $row['name'], $row['type'], $row['description'], $row['bizrule'], $data);
+		}
+		return $items;
+	}
+
+	/**
+	 * Creates an authorization item.
+	 * An authorization item represents an action permission (e.g. creating a post).
+	 * It has three types: operation, task and role.
+	 * Authorization items form a hierarchy. Higher level items inheirt permissions representing
+	 * by lower level items.
+	 * @param string $name the item name. This must be a unique identifier.
+	 * @param integer $type the item type (0: operation, 1: task, 2: role).
+	 * @param string $description description of the item
+	 * @param string $bizRule business rule associated with the item. This is a piece of
+	 * PHP code that will be executed when [[checkAccess()]] is called for the item.
+	 * @param mixed $data additional data associated with the item.
+	 * @return Item the authorization item
+	 * @throws Exception if an item with the same name already exists
+	 */
+	public function createItem($name, $type, $description = '', $bizRule = null, $data = null)
+	{
+		$this->db->createCommand()
+			->insert($this->itemTable, array(
+				'name' => $name,
+				'type' => $type,
+				'description' => $description,
+				'bizrule' => $bizRule,
+				'data' => serialize($data)
+			));
+		return new Item($this, $name, $type, $description, $bizRule, $data);
+	}
+
+	/**
+	 * Removes the specified authorization item.
+	 * @param string $name the name of the item to be removed
+	 * @return boolean whether the item exists in the storage and has been removed
+	 */
+	public function removeItem($name)
+	{
+		if ($this->usingSqlite()) {
+			$this->db->createCommand()
+				->delete($this->itemChildTable, 'parent=:name1 OR child=:name2', array(
+					':name1' => $name,
+					':name2' => $name
+				));
+			$this->db->createCommand()
+				->delete($this->assignmentTable, 'itemname=:name', array(
+					':name' => $name,
+				));
+		}
+
+		return $this->db->createCommand()
+			->delete($this->itemTable, 'name=:name', array(
+				':name' => $name
+			)) > 0;
+	}
+
+	/**
+	 * Returns the authorization item with the specified name.
+	 * @param string $name the name of the item
+	 * @return Item the authorization item. Null if the item cannot be found.
+	 */
+	public function getItem($name)
+	{
+		$query = new Query;
+		$row = $query->from($this->itemTable)
+			->where('name=:name', array(':name' => $name))
+			->createCommand($this->db)
+			->queryRow();
+
+		if ($row !== false) {
+			if (($data = @unserialize($row['data'])) === false) {
+				$data = null;
+			}
+			return new Item($this, $row['name'], $row['type'], $row['description'], $row['bizrule'], $data);
+		} else
+			return null;
+	}
+
+	/**
+	 * Saves an authorization item to persistent storage.
+	 * @param Item $item the item to be saved.
+	 * @param string $oldName the old item name. If null, it means the item name is not changed.
+	 */
+	public function saveItem($item, $oldName = null)
+	{
+		if ($this->usingSqlite() && $oldName !== null && $item->getName() !== $oldName) {
+			$this->db->createCommand()
+				->update($this->itemChildTable, array(
+					'parent' => $item->getName(),
+				), 'parent=:whereName', array(
+					':whereName' => $oldName,
+				));
+			$this->db->createCommand()
+				->update($this->itemChildTable, array(
+					'child' => $item->getName(),
+				), 'child=:whereName', array(
+					':whereName' => $oldName,
+				));
+			$this->db->createCommand()
+				->update($this->assignmentTable, array(
+					'itemname' => $item->getName(),
+				), 'itemname=:whereName', array(
+					':whereName' => $oldName,
+				));
+		}
+
+		$this->db->createCommand()
+			->update($this->itemTable, array(
+				'name' => $item->getName(),
+				'type' => $item->getType(),
+				'description' => $item->getDescription(),
+				'bizrule' => $item->getBizRule(),
+				'data' => serialize($item->getData()),
+			), 'name=:whereName', array(
+				':whereName' => $oldName === null ? $item->getName() : $oldName,
+			));
+	}
+
+	/**
+	 * Saves the authorization data to persistent storage.
+	 */
+	public function save()
+	{
+	}
+
+	/**
+	 * Removes all authorization data.
+	 */
+	public function clearAll()
+	{
+		$this->clearAssignments();
+		$this->db->createCommand()->delete($this->itemChildTable);
+		$this->db->createCommand()->delete($this->itemTable);
+	}
+
+	/**
+	 * Removes all authorization assignments.
+	 */
+	public function clearAssignments()
+	{
+		$this->db->createCommand()->delete($this->assignmentTable);
+	}
+
+	/**
+	 * Checks whether there is a loop in the authorization item hierarchy.
+	 * @param string $itemName parent item name
+	 * @param string $childName the name of the child item that is to be added to the hierarchy
+	 * @return boolean whether a loop exists
+	 */
+	protected function detectLoop($itemName, $childName)
+	{
+		if ($childName === $itemName) {
+			return true;
+		}
+		foreach ($this->getItemChildren($childName) as $child) {
+			if ($this->detectLoop($itemName, $child->getName())) {
+				return true;
+			}
+		}
+		return false;
+	}
+
+	/**
+	 * @return boolean whether the database is a SQLite database
+	 */
+	protected function usingSqlite()
+	{
+		return $this->_usingSqlite;
+	}
+}
diff --git a/framework/rbac/IManager.php b/framework/rbac/IManager.php
new file mode 100644
index 0000000..6eeb661
--- /dev/null
+++ b/framework/rbac/IManager.php
@@ -0,0 +1,173 @@
+<?php
+/**
+ * @link http://www.yiiframework.com/
+ * @copyright Copyright (c) 2008 Yii Software LLC
+ * @license http://www.yiiframework.com/license/
+ */
+
+namespace yii\rbac;
+
+/**
+ * IManager interface is implemented by an auth manager application component.
+ *
+ * @author Qiang Xue <qiang.xue@gmail.com>
+ * @author Alexander Kochetov <creocoder@gmail.com>
+ * @since 2.0
+ */
+interface IManager
+{
+	/**
+	 * Performs access check for the specified user.
+	 * @param mixed $userId the user ID. This should be either an integer or a string representing
+	 * the unique identifier of a user. See [[User::id]].
+	 * @param string $itemName the name of the operation that we are checking access to
+	 * @param array $params name-value pairs that would be passed to biz rules associated
+	 * with the tasks and roles assigned to the user.
+	 * @return boolean whether the operations can be performed by the user.
+	 */
+	public function checkAccess($userId, $itemName, $params = array());
+
+	/**
+	 * Creates an authorization item.
+	 * An authorization item represents an action permission (e.g. creating a post).
+	 * It has three types: operation, task and role.
+	 * Authorization items form a hierarchy. Higher level items inheirt permissions representing
+	 * by lower level items.
+	 * @param string $name the item name. This must be a unique identifier.
+	 * @param integer $type the item type (0: operation, 1: task, 2: role).
+	 * @param string $description description of the item
+	 * @param string $bizRule business rule associated with the item. This is a piece of
+	 * PHP code that will be executed when [[checkAccess()]] is called for the item.
+	 * @param mixed $data additional data associated with the item.
+	 * @throws \yii\base\Exception if an item with the same name already exists
+	 * @return Item the authorization item
+	 */
+	public function createItem($name, $type, $description = '', $bizRule = null, $data = null);
+	/**
+	 * Removes the specified authorization item.
+	 * @param string $name the name of the item to be removed
+	 * @return boolean whether the item exists in the storage and has been removed
+	 */
+	public function removeItem($name);
+	/**
+	 * Returns the authorization items of the specific type and user.
+	 * @param mixed $userId the user ID. Defaults to null, meaning returning all items even if
+	 * they are not assigned to a user.
+	 * @param integer $type the item type (0: operation, 1: task, 2: role). Defaults to null,
+	 * meaning returning all items regardless of their type.
+	 * @return Item[] the authorization items of the specific type.
+	 */
+	public function getItems($userId = null, $type = null);
+	/**
+	 * Returns the authorization item with the specified name.
+	 * @param string $name the name of the item
+	 * @return Item the authorization item. Null if the item cannot be found.
+	 */
+	public function getItem($name);
+	/**
+	 * Saves an authorization item to persistent storage.
+	 * @param Item $item the item to be saved.
+	 * @param string $oldName the old item name. If null, it means the item name is not changed.
+	 */
+	public function saveItem($item, $oldName = null);
+
+	/**
+	 * Adds an item as a child of another item.
+	 * @param string $itemName the parent item name
+	 * @param string $childName the child item name
+	 * @throws \yii\base\Exception if either parent or child doesn't exist or if a loop has been detected.
+	 */
+	public function addItemChild($itemName, $childName);
+	/**
+	 * Removes a child from its parent.
+	 * Note, the child item is not deleted. Only the parent-child relationship is removed.
+	 * @param string $itemName the parent item name
+	 * @param string $childName the child item name
+	 * @return boolean whether the removal is successful
+	 */
+	public function removeItemChild($itemName, $childName);
+	/**
+	 * Returns a value indicating whether a child exists within a parent.
+	 * @param string $itemName the parent item name
+	 * @param string $childName the child item name
+	 * @return boolean whether the child exists
+	 */
+	public function hasItemChild($itemName, $childName);
+	/**
+	 * Returns the children of the specified item.
+	 * @param mixed $itemName the parent item name. This can be either a string or an array.
+	 * The latter represents a list of item names.
+	 * @return Item[] all child items of the parent
+	 */
+	public function getItemChildren($itemName);
+
+	/**
+	 * Assigns an authorization item to a user.
+	 * @param mixed $userId the user ID (see [[User::id]])
+	 * @param string $itemName the item name
+	 * @param string $bizRule the business rule to be executed when [[checkAccess()]] is called
+	 * for this particular authorization item.
+	 * @param mixed $data additional data associated with this assignment
+	 * @return Assignment the authorization assignment information.
+	 * @throws \yii\base\Exception if the item does not exist or if the item has already been assigned to the user
+	 */
+	public function assign($userId, $itemName, $bizRule = null, $data = null);
+	/**
+	 * Revokes an authorization assignment from a user.
+	 * @param mixed $userId the user ID (see [[User::id]])
+	 * @param string $itemName the item name
+	 * @return boolean whether removal is successful
+	 */
+	public function revoke($userId, $itemName);
+	/**
+	 * Returns a value indicating whether the item has been assigned to the user.
+	 * @param mixed $userId the user ID (see [[User::id]])
+	 * @param string $itemName the item name
+	 * @return boolean whether the item has been assigned to the user.
+	 */
+	public function isAssigned($userId, $itemName);
+	/**
+	 * Returns the item assignment information.
+	 * @param mixed $userId the user ID (see [[User::id]])
+	 * @param string $itemName the item name
+	 * @return Assignment the item assignment information. Null is returned if
+	 * the item is not assigned to the user.
+	 */
+	public function getAssignment($userId, $itemName);
+	/**
+	 * Returns the item assignments for the specified user.
+	 * @param mixed $userId the user ID (see [[User::id]])
+	 * @return Item[] the item assignment information for the user. An empty array will be
+	 * returned if there is no item assigned to the user.
+	 */
+	public function getAssignments($userId);
+	/**
+	 * Saves the changes to an authorization assignment.
+	 * @param Assignment $assignment the assignment that has been changed.
+	 */
+	public function saveAssignment($assignment);
+	/**
+	 * Removes all authorization data.
+	 */
+	public function clearAll();
+	/**
+	 * Removes all authorization assignments.
+	 */
+	public function clearAssignments();
+	/**
+	 * Saves authorization data into persistent storage.
+	 * If any change is made to the authorization data, please make
+	 * sure you call this method to save the changed data into persistent storage.
+	 */
+	public function save();
+	/**
+	 * Executes a business rule.
+	 * A business rule is a piece of PHP code that will be executed when [[checkAccess()]] is called.
+	 * @param string $bizRule the business rule to be executed.
+	 * @param array $params additional parameters to be passed to the business rule when being executed.
+	 * @param mixed $data additional data that is associated with the corresponding authorization item or assignment
+	 * @return boolean whether the execution returns a true value.
+	 * If the business rule is empty, it will also return true.
+	 */
+	public function executeBizRule($bizRule, $params, $data);
+}
diff --git a/framework/rbac/Item.php b/framework/rbac/Item.php
index ba78e60..d09196f 100644
--- a/framework/rbac/Item.php
+++ b/framework/rbac/Item.php
@@ -202,7 +202,7 @@ class Item extends Object
 
 	/**
 	 * Returns the children of this item.
-	 * @return array all child items of this item.
+	 * @return Item[] all child items of this item.
 	 * @see IManager::getItemChildren
 	 */
 	public function getChildren()
diff --git a/framework/rbac/Manager.php b/framework/rbac/Manager.php
index 2f77e10..4846546 100644
--- a/framework/rbac/Manager.php
+++ b/framework/rbac/Manager.php
@@ -83,7 +83,7 @@ abstract class Manager extends Component implements IManager
 	 * This is a shortcut method to [[IManager::getItems()]].
 	 * @param mixed $userId the user ID. If not null, only the roles directly assigned to the user
 	 * will be returned. Otherwise, all roles will be returned.
-	 * @return array roles (name=>AuthItem)
+	 * @return Item[] roles (name=>AuthItem)
 	 */
 	public function getRoles($userId = null)
 	{
@@ -95,7 +95,7 @@ abstract class Manager extends Component implements IManager
 	 * This is a shortcut method to [[IManager::getItems()]].
 	 * @param mixed $userId the user ID. If not null, only the tasks directly assigned to the user
 	 * will be returned. Otherwise, all tasks will be returned.
-	 * @return array tasks (name=>AuthItem)
+	 * @return Item[] tasks (name=>AuthItem)
 	 */
 	public function getTasks($userId = null)
 	{
@@ -107,7 +107,7 @@ abstract class Manager extends Component implements IManager
 	 * This is a shortcut method to [[IManager::getItems()]].
 	 * @param mixed $userId the user ID. If not null, only the operations directly assigned to the user
 	 * will be returned. Otherwise, all operations will be returned.
-	 * @return array operations (name=>AuthItem)
+	 * @return Item[] operations (name=>AuthItem)
 	 */
 	public function getOperations($userId = null)
 	{
diff --git a/framework/rbac/PhpManager.php b/framework/rbac/PhpManager.php
index 08f5c83..3f471c6 100644
--- a/framework/rbac/PhpManager.php
+++ b/framework/rbac/PhpManager.php
@@ -52,8 +52,8 @@ class PhpManager extends Manager
 	 * @param string $itemName the name of the operation that need access check
 	 * the unique identifier of a user. See [[User::id]].
 	 * @param array $params name-value pairs that would be passed to biz rules associated
-	 * with the tasks and roles assigned to the user.
-	 * Since version 1.1.11 a param with name 'userId' is added to this array, which holds the value of <code>$userId</code>.
+	 * with the tasks and roles assigned to the user. A param with name 'userId' is added to
+	 * this array, which holds the value of `$userId`.
 	 * @return boolean whether the operations can be performed by the user.
 	 */
 	public function checkAccess($userId, $itemName, $params = array())
@@ -61,6 +61,7 @@ class PhpManager extends Manager
 		if (!isset($this->_items[$itemName])) {
 			return false;
 		}
+		/** @var $item Item */
 		$item = $this->_items[$itemName];
 		Yii::trace('Checking permission: ' . $item->getName(), __METHOD__);
 		if (!isset($params['userId'])) {
@@ -71,6 +72,7 @@ class PhpManager extends Manager
 				return true;
 			}
 			if (isset($this->_assignments[$userId][$itemName])) {
+				/** @var $assignment Assignment */
 				$assignment = $this->_assignments[$userId][$itemName];
 				if ($this->executeBizRule($assignment->getBizRule(), $params, $assignment->getData())) {
 					return true;
@@ -97,7 +99,9 @@ class PhpManager extends Manager
 		if (!isset($this->_items[$childName], $this->_items[$itemName])) {
 			throw new Exception("Either '$itemName' or '$childName' does not exist.");
 		}
+		/** @var $child Item */
 		$child = $this->_items[$childName];
+		/** @var $item Item */
 		$item = $this->_items[$itemName];
 		$this->checkItemChildType($item->getType(), $child->getType());
 		if ($this->detectLoop($itemName, $childName)) {
@@ -142,7 +146,7 @@ class PhpManager extends Manager
 	 * Returns the children of the specified item.
 	 * @param mixed $names the parent item name. This can be either a string or an array.
 	 * The latter represents a list of item names.
-	 * @return array all child items of the parent
+	 * @return Item[] all child items of the parent
 	 */
 	public function getItemChildren($names)
 	{
@@ -176,7 +180,7 @@ class PhpManager extends Manager
 		} elseif (isset($this->_assignments[$userId][$itemName])) {
 			throw new Exception("Authorization item '$itemName' has already been assigned to user '$userId'.");
 		} else {
-			return $this->_assignments[$userId][$itemName] = new Assignment($this, $itemName, $userId, $bizRule, $data);
+			return $this->_assignments[$userId][$itemName] = new Assignment($this, $userId, $itemName, $bizRule, $data);
 		}
 	}
 
@@ -222,7 +226,7 @@ class PhpManager extends Manager
 	/**
 	 * Returns the item assignments for the specified user.
 	 * @param mixed $userId the user ID (see [[User::id]])
-	 * @return array the item assignment information for the user. An empty array will be
+	 * @return Assignment[] the item assignment information for the user. An empty array will be
 	 * returned if there is no item assigned to the user.
 	 */
 	public function getAssignments($userId)
@@ -236,22 +240,24 @@ class PhpManager extends Manager
 	 * they are not assigned to a user.
 	 * @param integer $type the item type (0: operation, 1: task, 2: role). Defaults to null,
 	 * meaning returning all items regardless of their type.
-	 * @return array the authorization items of the specific type.
+	 * @return Item[] the authorization items of the specific type.
 	 */
 	public function getItems($userId = null, $type = null)
 	{
-		if ($type === null && $userId === null) {
+		if ($userId === null && $type === null) {
 			return $this->_items;
 		}
 		$items = array();
 		if ($userId === null) {
 			foreach ($this->_items as $name => $item) {
+				/** @var $item Item */
 				if ($item->getType() == $type) {
 					$items[$name] = $item;
 				}
 			}
 		} elseif (isset($this->_assignments[$userId])) {
 			foreach ($this->_assignments[$userId] as $assignment) {
+				/** @var $assignment Assignment */
 				$name = $assignment->getItemName();
 				if (isset($this->_items[$name]) && ($type === null || $this->_items[$name]->getType() == $type)) {
 					$items[$name] = $this->_items[$name];
@@ -368,6 +374,7 @@ class PhpManager extends Manager
 	{
 		$items = array();
 		foreach ($this->_items as $name => $item) {
+			/** @var $item Item */
 			$items[$name] = array(
 				'type' => $item->getType(),
 				'description' => $item->getDescription(),
@@ -376,6 +383,7 @@ class PhpManager extends Manager
 			);
 			if (isset($this->_children[$name])) {
 				foreach ($this->_children[$name] as $child) {
+					/** @var $child Item */
 					$items[$name]['children'][] = $child->getName();
 				}
 			}
@@ -383,6 +391,7 @@ class PhpManager extends Manager
 
 		foreach ($this->_assignments as $userId => $assignments) {
 			foreach ($assignments as $name => $assignment) {
+				/** @var $assignment Assignment */
 				if (isset($items[$name])) {
 					$items[$name]['assignments'][$userId] = array(
 						'bizRule' => $assignment->getBizRule(),
@@ -457,6 +466,7 @@ class PhpManager extends Manager
 			return false;
 		}
 		foreach ($this->_children[$childName] as $child) {
+			/** @var $child Item */
 			if ($this->detectLoop($itemName, $child->getName())) {
 				return true;
 			}