diff --git a/framework/yii/base/Controller.php b/framework/yii/base/Controller.php
index c22b584..5b8debb 100644
--- a/framework/yii/base/Controller.php
+++ b/framework/yii/base/Controller.php
@@ -132,7 +132,7 @@ class Controller extends Component
 	 * the route will start from the application; otherwise, it will start from the parent module of this controller.
 	 * @param string $route the route to be handled, e.g., 'view', 'comment/view', '/admin/comment/view'.
 	 * @param array $params the parameters to be passed to the action.
-	 * @return integer the status code returned by the action execution. 0 means normal, and other values mean abnormal.
+	 * @return mixed the result of the action
 	 * @see runAction
 	 * @see forward
 	 */
diff --git a/framework/yii/web/Response.php b/framework/yii/web/Response.php
index ad9d29f..4783ffd 100644
--- a/framework/yii/web/Response.php
+++ b/framework/yii/web/Response.php
@@ -34,6 +34,12 @@ class Response extends \yii\base\Response
 	 */
 	public $format = self::FORMAT_HTML;
 	/**
+	 * @var array the formatters for converting data into the response content of the specified [[format]].
+	 * The array keys are the format names, and the array values are the corresponding configurations
+	 * for creating the formatter objects.
+	 */
+	public $formatters;
+	/**
 	 * @var string the charset of the text response. If not set, it will use
 	 * the value of [[Application::charset]].
 	 */
@@ -134,7 +140,9 @@ class Response extends \yii\base\Response
 	 */
 	private $_headers;
 
-
+	/**
+	 * Initializes this component.
+	 */
 	public function init()
 	{
 		if ($this->version === null) {
@@ -157,6 +165,13 @@ class Response extends \yii\base\Response
 		return $this->_statusCode;
 	}
 
+	/**
+	 * Sets the response status code.
+	 * This method will set the corresponding status text if `$text` is null.
+	 * @param integer $value the status code
+	 * @param string $text the status text. If not set, it will be set automatically based on the status code.
+	 * @throws InvalidParamException if the status code is invalid.
+	 */
 	public function setStatusCode($value, $text = null)
 	{
 		$this->_statusCode = (int)$value;
@@ -194,9 +209,13 @@ class Response extends \yii\base\Response
 		$this->clear();
 	}
 
+	/**
+	 * Clears the headers, cookies, content, status code of the response.
+	 */
 	public function clear()
 	{
 		$this->_headers = null;
+		$this->_cookies = null;
 		$this->_statusCode = null;
 		$this->_content = null;
 		$this->statusText = null;
@@ -643,8 +662,9 @@ class Response extends \yii\base\Response
 	 * The existing content will be overwritten.
 	 * Depending on the value of [[format]], the data will be properly formatted.
 	 * @param mixed $data the data that needs to be converted into the response content.
-	 * @param string $format the format of the response. The following formats are
-	 * supported by the default implementation:
+	 * @param string $format the format of the response. The [[formatters]] property specifies
+	 * the supported formats and the corresponding formatters. Additionally, the following formats are
+	 * supported if they are not found in [[formatters]]:
 	 *
 	 * - [[FORMAT_RAW]]: the data will be treated as the response content without any conversion.
 	 *   No extra HTTP header will be added.
@@ -656,8 +676,8 @@ class Response extends \yii\base\Response
 	 *   header will be set as "text/javascript". Note that in this case `$data` must be an array
 	 *   with "data" and "callback" elements. The former refers to the actual data to be sent,
 	 *   while the latter refers to the name of the JavaScript callback.
-	 * - [[FORMAT_XML]]: the data will be converted into XML format, and the "Content-Type"
-	 *   header will be set as "application/xml" if no previous "Content-Type" header is set.
+	 * - [[FORMAT_XML]]: the data will be converted into XML format. Please refer to [[XmlResponseFormatter]]
+	 *   for more details.
 	 */
 	public function setContent($data, $format = null)
 	{
@@ -667,8 +687,28 @@ class Response extends \yii\base\Response
 		$this->_content = $this->formatContent($data, $format);
 	}
 
+	/**
+	 * Formats the given data as the specified format.
+	 * @param mixed $data the data to be formatted.
+	 * @param string $format the format to use.
+	 * @return string the formatting result.
+	 * @throws InvalidParamException if `$format` is not supported
+	 * @throws InvalidConfigException if the formatter for the specified format is invalid
+	 */
 	protected function formatContent($data, $format)
 	{
+		if (isset($this->formatters[$format])) {
+			$formatter = $this->formatters[$format];
+			if (!is_object($formatter)) {
+				$formatter = Yii::createObject($formatter);
+			}
+			if ($formatter instanceof ResponseFormatter) {
+				return $formatter->format($this, $data);
+			} else {
+				throw new InvalidConfigException("The '$format' response formatter is invalid. It must implement the ResponseFormatter interface.");
+			}
+		}
+
 		switch ($this->format) {
 			case self::FORMAT_RAW:
 				return $data;
@@ -686,7 +726,7 @@ class Response extends \yii\base\Response
 					throw new InvalidParamException("The 'jsonp' response requires that the data be an array consisting of both 'data' and 'callback' elements.");
 				}
 			case self::FORMAT_XML:
-				// todo
+				return Yii::createObject('yii\web\XmlResponseFormatter')->format($this, $data);
 			default:
 				throw new InvalidConfigException("Unsupported response format: $format");
 		}
diff --git a/framework/yii/web/ResponseFormatter.php b/framework/yii/web/ResponseFormatter.php
new file mode 100644
index 0000000..0e9af47
--- /dev/null
+++ b/framework/yii/web/ResponseFormatter.php
@@ -0,0 +1,25 @@
+<?php
+/**
+ * @link http://www.yiiframework.com/
+ * @copyright Copyright (c) 2008 Yii Software LLC
+ * @license http://www.yiiframework.com/license/
+ */
+
+namespace yii\web;
+
+/**
+ * ResponseFormatter specifies the interface needed to format data for a Web response object.
+ *
+ * @author Qiang Xue <qiang.xue@gmail.com>
+ * @since 2.0
+ */
+interface ResponseFormatter
+{
+	/**
+	 * Formats the given data for the response.
+	 * @param Response $response the response object that will accept the formatted result
+	 * @param mixed $data the data to be formatted
+	 * @return string the formatted result
+	 */
+	function format($response, $data);
+}
diff --git a/framework/yii/web/XmlResponseFormatter.php b/framework/yii/web/XmlResponseFormatter.php
new file mode 100644
index 0000000..32b7213
--- /dev/null
+++ b/framework/yii/web/XmlResponseFormatter.php
@@ -0,0 +1,99 @@
+<?php
+/**
+ * @link http://www.yiiframework.com/
+ * @copyright Copyright (c) 2008 Yii Software LLC
+ * @license http://www.yiiframework.com/license/
+ */
+
+namespace yii\web;
+
+use DOMDocument;
+use DOMElement;
+use DOMText;
+use yii\base\Arrayable;
+use yii\base\Component;
+use yii\helpers\StringHelper;
+
+
+/**
+ * XmlResponseFormatter formats the given data into an XML response content.
+ *
+ * @author Qiang Xue <qiang.xue@gmail.com>
+ * @since 2.0
+ */
+class XmlResponseFormatter extends Component implements ResponseFormatter
+{
+	/**
+	 * @var string the Content-Type header for the response
+	 */
+	public $contentType = 'application/xml';
+	/**
+	 * @var string the XML version
+	 */
+	public $version = '1.0';
+	/**
+	 * @var string the XML encoding. If not set, it will use the value of [[Response::charset]].
+	 */
+	public $encoding;
+	/**
+	 * @var string the name of the root element.
+	 */
+	public $rootTag = 'response';
+	/**
+	 * @var string the name of the elements that represent the array elements with numeric keys.
+	 */
+	public $itemTag = 'item';
+
+	/**
+	 * Formats the given data for the response.
+	 * @param Response $response the response object that will accept the formatted result
+	 * @param mixed $data the data to be formatted
+	 * @return string the formatted result
+	 */
+	public function format($response, $data)
+	{
+		$response->getHeaders()->set('Content-Type', $this->contentType);
+		$dom = new DOMDocument($this->version, $this->encoding === null ? $response->charset : $this->encoding);
+		$root = new DOMElement($this->rootTag);
+		$dom->appendChild($root);
+		$this->buildXml($root, $data);
+		return $dom->saveXML();
+	}
+
+	/**
+	 * @param DOMElement $element
+	 * @param mixed $data
+	 */
+	protected function buildXml($element, $data)
+	{
+		if (is_object($data)) {
+			$child = new DOMElement(StringHelper::basename(get_class($data)));
+			$element->appendChild($child);
+			if ($data instanceof Arrayable) {
+				$this->buildXml($child, $data->toArray());
+			} else {
+				$array = array();
+				foreach ($data as $name => $value) {
+					$array[$name] = $value;
+				}
+				$this->buildXml($child, $array);
+			}
+		} elseif (is_array($data)) {
+			foreach ($data as $name => $value) {
+				if (is_int($name) && is_object($value)) {
+					$this->buildXml($element, $value);
+				} elseif (is_array($value) || is_object($value)) {
+					$child = new DOMElement(is_int($name) ? $this->itemTag : $name);
+					$element->appendChild($child);
+					$this->buildXml($child, $value);
+				} else {
+					$child = new DOMElement(is_int($name) ? $this->itemTag : $name);
+					$element->appendChild($child);
+					$child->appendChild(new DOMText((string)$value));
+				}
+			}
+		} else {
+			$element->appendChild(new DOMText((string)$data));
+		}
+	}
+}
diff --git a/tests/unit/framework/web/XmlResponseFormatterTest.php b/tests/unit/framework/web/XmlResponseFormatterTest.php
new file mode 100644
index 0000000..f39d474
--- /dev/null
+++ b/tests/unit/framework/web/XmlResponseFormatterTest.php
@@ -0,0 +1,117 @@
+<?php
+/**
+ * @link http://www.yiiframework.com/
+ * @copyright Copyright (c) 2008 Yii Software LLC
+ * @license http://www.yiiframework.com/license/
+ */
+
+namespace yiiunit\framework\web;
+
+use yii\base\Object;
+use yii\web\Response;
+use yii\web\XmlResponseFormatter;
+
+class Post extends Object
+{
+	public $id;
+	public $title;
+
+	public function __construct($id, $title)
+	{
+		$this->id = $id;
+		$this->title = $title;
+	}
+}
+
+/**
+ * @author Qiang Xue <qiang.xue@gmail.com>
+ * @since 2.0
+ */
+class XmlResponseFormatterTest extends \yiiunit\TestCase
+{
+	/**
+	 * @var Response
+	 */
+	public $response;
+	/**
+	 * @var XmlResponseFormatter
+	 */
+	public $formatter;
+
+	protected function setUp()
+	{
+		$this->mockApplication();
+		$this->response = new Response;
+		$this->formatter = new XmlResponseFormatter;
+	}
+
+	public function testFormatScalars()
+	{
+		$head = "<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n";
+
+		$xml = $head . "<response></response>\n";
+		$this->assertEquals($xml, $this->formatter->format($this->response, null));
+
+		$xml = $head . "<response>1</response>\n";
+		$this->assertEquals($xml, $this->formatter->format($this->response, 1));
+
+		$xml = $head . "<response>abc</response>\n";
+		$this->assertEquals($xml, $this->formatter->format($this->response, 'abc'));
+
+		$xml = $head . "<response>1</response>\n";
+		$this->assertEquals($xml, $this->formatter->format($this->response, true));
+	}
+
+	public function testFormatArrays()
+	{
+		$head = "<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n";
+
+		$xml = $head . "<response/>\n";
+		$this->assertEquals($xml, $this->formatter->format($this->response, array()));
+
+		$xml = $head . "<response><item>1</item><item>abc</item></response>\n";
+		$this->assertEquals($xml, $this->formatter->format($this->response, array(1, 'abc')));
+
+		$xml = $head . "<response><a>1</a><b>abc</b></response>\n";
+		$this->assertEquals($xml, $this->formatter->format($this->response, array(
+			'a' => 1,
+			'b' => 'abc',
+		)));
+
+		$xml = $head . "<response><item>1</item><item>abc</item><item><item>2</item><item>def</item></item><item>1</item></response>\n";
+		$this->assertEquals($xml, $this->formatter->format($this->response, array(
+			1,
+			'abc',
+			array(2, 'def'),
+			true,
+		)));
+
+		$xml = $head . "<response><a>1</a><b>abc</b><c><item>2</item><item>def</item></c><item>1</item></response>\n";
+		$this->assertEquals($xml, $this->formatter->format($this->response, array(
+			'a' => 1,
+			'b' => 'abc',
+			'c' => array(2, 'def'),
+			true,
+		)));
+	}
+
+	public function testFormatObjects()
+	{
+		$head = "<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n";
+
+		$xml = $head . "<response><Post><id>123</id><title>abc</title></Post></response>\n";
+		$this->assertEquals($xml, $this->formatter->format($this->response, new Post(123, 'abc')));
+
+		$xml = $head . "<response><Post><id>123</id><title>abc</title></Post><Post><id>456</id><title>def</title></Post></response>\n";
+		$this->assertEquals($xml, $this->formatter->format($this->response, array(
+			new Post(123, 'abc'),
+			new Post(456, 'def'),
+		)));
+
+		$xml = $head . "<response><Post><id>123</id><title>abc</title></Post><a><Post><id>456</id><title>def</title></Post></a></response>\n";
+		$this->assertEquals($xml, $this->formatter->format($this->response, array(
+			new Post(123, 'abc'),
+			'a' => new Post(456, 'def'),
+		)));
+	}
+}