diff --git a/apps/bootstrap/protected/config/main.php b/apps/bootstrap/protected/config/main.php
index 20b5e7e..f19dead 100644
--- a/apps/bootstrap/protected/config/main.php
+++ b/apps/bootstrap/protected/config/main.php
@@ -4,6 +4,11 @@ return array(
 	'id' => 'hello',
 	'basePath' => dirname(__DIR__),
 	'preload' => array('log'),
+	'modules' => array(
+		'debug' => array(
+			'class' => 'yii\debug\Module',
+		)
+	),
 	'components' => array(
 		'cache' => array(
 			'class' => 'yii\caching\FileCache',
diff --git a/apps/bootstrap/protected/views/layouts/main.php b/apps/bootstrap/protected/views/layouts/main.php
index 1e8a3af..a81f983 100644
--- a/apps/bootstrap/protected/views/layouts/main.php
+++ b/apps/bootstrap/protected/views/layouts/main.php
@@ -58,6 +58,7 @@ $this->registerAssetBundle('app');
 	</div>
 	<?php $this->endBody(); ?>
 </div>
+<?php $this->widget('yii\debug\Toolbar'); ?>
 </body>
 </html>
 <?php $this->endPage(); ?>
diff --git a/framework/assets.php b/framework/assets.php
index 10a450a..7ee177d 100644
--- a/framework/assets.php
+++ b/framework/assets.php
@@ -35,4 +35,11 @@ return array(
 		),
 		'depends' => array('yii'),
 	),
+	'yii/debug' => array(
+		'sourcePath' => __DIR__ . '/assets',
+		'js' => array(
+			'yii.debug.js',
+		),
+		'depends' => array('yii'),
+	),
 );
diff --git a/framework/assets/yii.debug.js b/framework/assets/yii.debug.js
new file mode 100644
index 0000000..4e32d89
--- /dev/null
+++ b/framework/assets/yii.debug.js
@@ -0,0 +1,26 @@
+/**
+ * Yii debug module.
+ *
+ * This JavaScript module provides the functions needed by the Yii debug toolbar.
+ *
+ * @link http://www.yiiframework.com/
+ * @copyright Copyright (c) 2008 Yii Software LLC
+ * @license http://www.yiiframework.com/license/
+ * @author Qiang Xue <qiang.xue@gmail.com>
+ * @since 2.0
+ */
+
+yii.debug = (function ($) {
+	return {
+		load: function (id, url) {
+			$.ajax({
+				url: url,
+				//dataType: 'json',
+				success: function(data) {
+					var $e = $('#' + id);
+					$e.html(data);
+				}
+			});
+		}
+	};
+})(jQuery);
diff --git a/framework/assets/yii.validation.js b/framework/assets/yii.validation.js
index fd098be..5fa8492 100644
--- a/framework/assets/yii.validation.js
+++ b/framework/assets/yii.validation.js
@@ -1,7 +1,7 @@
 /**
  * Yii validation module.
  *
- * This JavaScript module provides the validation methods for the built-in validaotrs.
+ * This JavaScript module provides the validation methods for the built-in validators.
  *
  * @link http://www.yiiframework.com/
  * @copyright Copyright (c) 2008 Yii Software LLC
diff --git a/framework/debug/Module.php b/framework/debug/Module.php
new file mode 100644
index 0000000..3421d95
--- /dev/null
+++ b/framework/debug/Module.php
@@ -0,0 +1,17 @@
+<?php
+/**
+ * @link http://www.yiiframework.com/
+ * @copyright Copyright (c) 2008 Yii Software LLC
+ * @license http://www.yiiframework.com/license/
+ */
+
+namespace yii\debug;
+
+/**
+ * @author Qiang Xue <qiang.xue@gmail.com>
+ * @since 2.0
+ */
+class Module extends \yii\base\Module
+{
+	public $controllerNamespace = 'yii\debug\controllers';
+}
\ No newline at end of file
diff --git a/framework/debug/Toolbar.php b/framework/debug/Toolbar.php
new file mode 100644
index 0000000..84b55c8
--- /dev/null
+++ b/framework/debug/Toolbar.php
@@ -0,0 +1,38 @@
+<?php
+/**
+ * @link http://www.yiiframework.com/
+ * @copyright Copyright (c) 2008 Yii Software LLC
+ * @license http://www.yiiframework.com/license/
+ */
+
+namespace yii\debug;
+
+use Yii;
+use yii\base\Widget;
+use yii\helpers\Html;
+
+/**
+ * @author Qiang Xue <qiang.xue@gmail.com>
+ * @since 2.0
+ */
+class Toolbar extends Widget
+{
+	public $debugAction = 'debug';
+	public $enabled = YII_DEBUG;
+
+	public function run()
+	{
+		if ($this->enabled) {
+			$id = 'yii-debug-toolbar';
+			$url = Yii::$app->getUrlManager()->createUrl($this->debugAction, array(
+				'tag' => Yii::getLogger()->tag,
+			));
+			$this->view->registerJs("yii.debug.load('$id', '$url');");
+			$this->view->registerAssetBundle('yii/debug');
+			echo Html::tag('div', '', array(
+				'id' => $id,
+				'style' => 'display: none',
+			));
+		}
+	}
+}
diff --git a/framework/debug/controllers/DefaultController.php b/framework/debug/controllers/DefaultController.php
new file mode 100644
index 0000000..ca90920
--- /dev/null
+++ b/framework/debug/controllers/DefaultController.php
@@ -0,0 +1,22 @@
+<?php
+/**
+ * @link http://www.yiiframework.com/
+ * @copyright Copyright (c) 2008 Yii Software LLC
+ * @license http://www.yiiframework.com/license/
+ */
+
+namespace yii\debug\controllers;
+
+use yii\web\Controller;
+
+/**
+ * @author Qiang Xue <qiang.xue@gmail.com>
+ * @since 2.0
+ */
+class DefaultController extends Controller
+{
+	public function actionIndex($tag)
+	{
+		echo $tag;
+	}
+}
\ No newline at end of file
diff --git a/framework/logging/Logger.php b/framework/logging/Logger.php
index 5c9a89d..b557c5e 100644
--- a/framework/logging/Logger.php
+++ b/framework/logging/Logger.php
@@ -82,6 +82,11 @@ class Logger extends Component
 	 * @var Router the log target router registered with this logger.
 	 */
 	public $router;
+	/**
+	 * @var string a tag that uniquely identifies the current request. This can be used
+	 * to differentiate the log messages for different requests.
+	 */
+	public $tag;
 
 	/**
 	 * Initializes the logger by registering [[flush()]] as a shutdown function.
@@ -89,6 +94,7 @@ class Logger extends Component
 	public function init()
 	{
 		parent::init();
+		$this->tag = date('Ymd-His', microtime(true));
 		register_shutdown_function(array($this, 'flush'), true);
 	}