diff --git a/backend/bin/doctrine.php b/backend/bin/doctrine.php
index 981e1f6..6e417ba 100644
--- a/backend/bin/doctrine.php
+++ b/backend/bin/doctrine.php
@@ -2,6 +2,7 @@
 
 // TODO replace by state class
 const BACKEND_DIR = '/home/steffen/workspace/volkszaehler.org/backend';
+const DEV_ENV = TRUE;
 
 // class autoloading
 require BACKEND_DIR . '/lib/Util/ClassLoader.php';
@@ -28,7 +29,7 @@ $em = Volkszaehler\Dispatcher::createEntityManager();
 $helperSet = new \Symfony\Components\Console\Helper\HelperSet(array('em' => new \Doctrine\ORM\Tools\Console\Helper\EntityManagerHelper($em)));
 
 $cli = new \Symfony\Components\Console\Application('Doctrine Command Line Interface', Doctrine\ORM\Version::VERSION);
-$cli->setCatchExceptions(true);
+$cli->setCatchExceptions(TRUE);
 $cli->setHelperSet($helperSet);
 $cli->addCommands(array(
 	// DBAL Commands
diff --git a/backend/index.php b/backend/index.php
index 0573cb0..ed1f4cd 100644
--- a/backend/index.php
+++ b/backend/index.php
@@ -27,7 +27,7 @@ use Volkszaehler\Controller;
 // TODO replace by state class
 const VERSION = 1.1;
 const BACKEND_DIR = '/home/steffen/workspace/volkszaehler.org/backend';	// TODO realpath(__DIR__)
-const DEV_ENV = true;
+const DEV_ENV = TRUE;
 
 // class autoloading
 require BACKEND_DIR . '/lib/Util/ClassLoader.php';
diff --git a/backend/lib/Controller/Channel.php b/backend/lib/Controller/Channel.php
index df6ddaa..42f4f0c 100644
--- a/backend/lib/Controller/Channel.php
+++ b/backend/lib/Controller/Channel.php
@@ -74,7 +74,7 @@ class Channel extends Controller {
 		$this->em->flush();
 	}
 	
-	// TODO implement ChannelController::edit();
+	// TODO implement Controller\Channel::edit();
 	// TODO authentification/indentification
 	public function edit() {
 		
diff --git a/backend/lib/Controller/Data.php b/backend/lib/Controller/Data.php
index d781470..65542ea 100644
--- a/backend/lib/Controller/Data.php
+++ b/backend/lib/Controller/Data.php
@@ -21,12 +21,14 @@
 
 namespace Volkszaehler\Controller;
 
-// TODO call as subcontroller from Controller\Channel::get()?
+// TODO call via redirect from Controller\Channel
+use Volkszaehler\Util;
+
 class Data extends Controller {
 	
 	// TODO authentification/indentification
 	public function get() {
-		// TODO why not ucids?
+		// TODO use uuids for groups or channels
 		$ids = explode(',', trim($this->view->request->getParameter('ids')));
 		
 		$q = $this->em->createQuery('SELECT c FROM Volkszaehler\Model\Channel c WHERE c.id IN (' . implode(', ', $ids) . ')');
@@ -49,7 +51,7 @@ class Data extends Controller {
 		$value = (float) $this->view->request->getParameter('value');
 		$ts = (int) $this->view->request->getParameter('timestamp');
 		if ($ts == 0) {
-			$ts = microtime(true) * 1000;
+			$ts = microtime(TRUE) * 1000;
 		}
 		
 		$data = new \Volkszaehler\Model\Data($channel, $value, $ts);
@@ -61,9 +63,10 @@ class Data extends Controller {
 	}
 	
 	/*
-	 * prune all data from database
+	 * prune data from database
 	 */
-	public function delete() {	// TODO add user authentification
+	// TODO authentification/indentification
+	public function delete() {
 		$dql = 'DELETE FROM \Volkszaehler\Model\Data WHERE channel_id = ' . $this->id;
 		
 		if ($this->view->request->getParameter('from')) {
diff --git a/backend/lib/Controller/Group.php b/backend/lib/Controller/Group.php
index bd65b21..d443b8c 100644
--- a/backend/lib/Controller/Group.php
+++ b/backend/lib/Controller/Group.php
@@ -43,7 +43,7 @@ class Group extends Controller {
 		$this->view->add($group);
 	}
 	
-	// TODO check for valid user identity
+	// TODO authentification/indentification
 	public function delete() {
 		$group = Group::getByUuid($this->view->request->getParameter('ugid'));
 		
@@ -52,7 +52,7 @@ class Group extends Controller {
 	}
 	
 	public function edit() {
-		// TODO implement GroupController::edit();
+		// TODO implement Controller\Group::edit();
 	}
 }
 
diff --git a/backend/lib/Dispatcher.php b/backend/lib/Dispatcher.php
index df9f8b3..a2dbe8f 100644
--- a/backend/lib/Dispatcher.php
+++ b/backend/lib/Dispatcher.php
@@ -28,7 +28,7 @@ use Volkszaehler\Util;
 /*
  * frontcontroller / dispatcher
  */
-final class Dispatcher {
+class Dispatcher {
 	// MVC
 	protected $em;			// Model (Doctrine EntityManager)
 	protected $view;		// View
@@ -115,7 +115,7 @@ final class Dispatcher {
 		
 		$config->setProxyDir(BACKEND_DIR . '/lib/Model/Proxies');
 		$config->setProxyNamespace('Volkszaehler\Model\Proxies');
-		$config->setAutoGenerateProxyClasses(DEV_ENV == true);
+		$config->setAutoGenerateProxyClasses(DEV_ENV == TRUE);
 		
 		return \Doctrine\ORM\EntityManager::create(Util\Configuration::read('db'), $config);
 	}
diff --git a/backend/lib/Interpreter/Interpreter.php b/backend/lib/Interpreter/Interpreter.php
index e173774..f1848b2 100644
--- a/backend/lib/Interpreter/Interpreter.php
+++ b/backend/lib/Interpreter/Interpreter.php
@@ -74,7 +74,7 @@ abstract class Interpreter implements InterpreterInterface {
 			default:
 				if (is_numeric($groupBy)) {		// lets agrregate it with php
 					$groupBy = (int) $groupBy;
-					$sqlGroupBy = false;
+					$sqlGroupBy = FALSE;
 				}
 				else {
 					throw new \InvalidArgumentException('\'' . $groupBy . '\' is not an unknown grouping mode');
@@ -82,18 +82,18 @@ abstract class Interpreter implements InterpreterInterface {
 		}
 
 		$sql = 'SELECT';
-		$sql .= ($sqlGroupBy === false) ? ' timestamp, value' : ' MAX(timestamp) AS timestamp, SUM(value) AS value, COUNT(timestamp) AS count';
+		$sql .= ($sqlGroupBy === FALSE) ? ' timestamp, value' : ' MAX(timestamp) AS timestamp, SUM(value) AS value, COUNT(timestamp) AS count';
 		$sql .= ' FROM data WHERE channel_id = ' . (int) $this->channel->getId();
 		
-		if (!is_null($from)) {
+		if (isset($from)) {
 			$sql .= ' && timestamp > ' . $from;
 		}
 		
-		if (!is_null($to)) {
+		if (isset($to)) {
 			$sql .= ' && timestamp < ' . $to;
 		}
 
-		if ($sqlGroupBy !== false) {
+		if ($sqlGroupBy !== FALSE) {
 			$sql .= ' GROUP BY ' . $sqlGroupBy;
 		}
 			
@@ -125,7 +125,7 @@ abstract class Interpreter implements InterpreterInterface {
 		for ($i = 1; $i <= $packageCount; $i++) {
 			$package = array('timestamp' => (int) $reading['timestamp'],	// last timestamp in package
 								'value' => (float) $reading['value'],		// sum of values
-								'count' => ($sqlGroupBy === false) ? 1 : $reading['count']);						// total count of values or pulses in the package
+								'count' => ($sqlGroupBy === FALSE) ? 1 : $reading['count']);						// total count of values or pulses in the package
 
 			while ($package['count'] < $packageSize) {
 				$reading = next($result);
diff --git a/backend/lib/Interpreter/Meter.php b/backend/lib/Interpreter/Meter.php
index cf6d9dd..d05cea6 100644
--- a/backend/lib/Interpreter/Meter.php
+++ b/backend/lib/Interpreter/Meter.php
@@ -60,7 +60,8 @@ class Meter extends Interpreter {
 		return $min;
 	}
 	
-	public function getAverage($from = NULL, $to = NULL) {	// TODO calculate timeinterval if no params were given
+	// TODO calculate timeinterval if no params were given
+	public function getAverage($from = NULL, $to = NULL) {	
 		return $this->getConsumption($from, $to) / ($to - $from) / 1000;	// return W
 	}
 	
diff --git a/backend/lib/Model/Channel.php b/backend/lib/Model/Channel.php
index 894ebeb..2ed414d 100644
--- a/backend/lib/Model/Channel.php
+++ b/backend/lib/Model/Channel.php
@@ -42,13 +42,13 @@ class Channel extends Entity {
 	/**
 	 * @OneToMany(targetEntity="Data", mappedBy="channel"), cascade={"remove"}
 	 */
-	private $data = NULL;
+	protected $data = NULL;
 	
 	/** @Column(type="integer") */
-	private $resolution;
+	protected $resolution;
 
 	/** @Column(type="decimal", precision="5", scale="2") */
-	private $cost;
+	protected $cost;
 	
 	/*
 	 * indicator => interpreter, unit mapping
@@ -78,7 +78,7 @@ class Channel extends Entity {
 	
 	/*
 	 * add a new data to the database
-	 * @todo move to logger?
+	 * @todo move to Logger\Logger?
 	 */
 	public function addData(\Volkszaehler\Model\Data $data) {
 		$this->data->add($data);
diff --git a/backend/lib/Model/Data.php b/backend/lib/Model/Data.php
index 6e0d929..e5c0958 100644
--- a/backend/lib/Model/Data.php
+++ b/backend/lib/Model/Data.php
@@ -34,20 +34,20 @@ class Data {
 	 * @Id
 	 * @Column(type="bigint")
 	 */
-	private $timestamp;
+	protected $timestamp;
 
 	/**
 	 * @Column(type="decimal", precision="10", scale="5")
 	 * @todo change to float after DCC-67 has been closed
 	 */
-	private $value;
+	protected $value;
 
 	/**
 	 * @Id
 	 * @ManyToOne(targetEntity="Channel", inversedBy="data")
 	 * @JoinColumn(name="channel_id", referencedColumnName="id")
 	 */
-	private $channel;
+	protected $channel;
 	
 	public function __construct(Channel\Channel $channel, $value, $timestamp) {
 		$this->channel = $channel;
diff --git a/backend/lib/Model/Group.php b/backend/lib/Model/Group.php
index 02e9460..45c0f8a 100644
--- a/backend/lib/Model/Group.php
+++ b/backend/lib/Model/Group.php
@@ -31,10 +31,10 @@ use Doctrine\Common\Collections\ArrayCollection;
  */
 class Group extends Entity {
 	/** @Column(type="string") */
-	private $name;
+	protected $name;
 	
 	/** @Column(type="string") */
-	private $description;
+	protected $description;
 	
 	/**
 	 * @ManyToMany(targetEntity="Channel")
@@ -43,7 +43,7 @@ class Group extends Entity {
 	 * 		inverseJoinColumns={@JoinColumn(name="channel_id", referencedColumnName="id")}
 	 * )
 	 */
-	private $channels = NULL;
+	protected $channels = NULL;
 	
 	/**
 	 * @ManyToMany(targetEntity="Group")
@@ -52,7 +52,7 @@ class Group extends Entity {
 	 * 		inverseJoinColumns={@JoinColumn(name="child_id", referencedColumnName="id")}
 	 * )
 	 */
-	private $children = NULL;
+	protected $children = NULL;
 
 	/*
 	 * construct
diff --git a/backend/lib/Util/ClassLoader.php b/backend/lib/Util/ClassLoader.php
index 9d3f5c3..4439b60 100644
--- a/backend/lib/Util/ClassLoader.php
+++ b/backend/lib/Util/ClassLoader.php
@@ -24,10 +24,10 @@
 namespace Volkszaehler\Util;
 
 class ClassLoader {
-	private $fileExtension = '.php';
-	private $namespace;
-	private $includePath;
-	private $namespaceSeparator = '\\';
+	protected $fileExtension = '.php';
+	protected $namespace;
+	protected $includePath;
+	protected $namespaceSeparator = '\\';
 
 	/**
 	 * Creates a new <tt>ClassLoader</tt> that loads classes of the
@@ -40,7 +40,7 @@ class ClassLoader {
 	 * @param string $ns The namespace of the classes to load.
 	 * @param string $includePath The base include path to use.
 	 */
-	public function __construct($ns = null, $includePath = null) {
+	public function __construct($ns = NULL, $includePath = NULL) {
 		$this->namespace = $ns;
 		$this->includePath = $includePath;
 	}
@@ -102,16 +102,16 @@ class ClassLoader {
 	 * @return boolean TRUE if the class has been successfully loaded, FALSE otherwise.
 	 */
 	public function loadClass($className) {
-		if ($this->namespace !== null && strpos($className, $this->namespace . $this->namespaceSeparator) !== 0) {
-			return false;
+		if ($this->namespace !== NULL && strpos($className, $this->namespace . $this->namespaceSeparator) !== 0) {
+			return FALSE;
 		}
 		
 		$subNamespace = substr($className, strlen($this->namespace));
 		$parts = explode($this->namespaceSeparator, $subNamespace);
 		$path = implode(DIRECTORY_SEPARATOR, $parts);
 
-		require_once ($this->includePath !== null ? $this->includePath : '') . $path . $this->fileExtension;
-		return true;
+		require_once ($this->includePath !== NULL ? $this->includePath : '') . $path . $this->fileExtension;
+		return TRUE;
 	}
 
 	/**
@@ -122,15 +122,15 @@ class ClassLoader {
 	 * @return boolean TRUE if this ClassLoader can load the class, FALSE otherwise.
 	 */
 	public function canLoadClass($className) {
-		if ($this->namespace !== null && strpos($className, $this->namespace . $this->namespaceSeparator) !== 0) {
-			return false;	// TODO handle with exceptions
+		if ($this->namespace !== NULL && strpos($className, $this->namespace . $this->namespaceSeparator) !== 0) {
+			return FALSE;	// TODO handle with exceptions
 		}
 
 		$subNamespace = substr($className, strlen($this->namespace));
 		$parts = explode($this->namespaceSeparator, $subNamespace);
 		$path = implode(DIRECTORY_SEPARATOR, $parts);
 		
-		return file_exists(($this->includePath !== null ? $this->includePath . DIRECTORY_SEPARATOR : '') . $path . $this->fileExtension);
+		return file_exists(($this->includePath !== NULL ? $this->includePath . DIRECTORY_SEPARATOR : '') . $path . $this->fileExtension);
 	}
 
 	/**
@@ -155,8 +155,8 @@ class ClassLoader {
 	 * @return boolean TRUE if the class exists as per the definition given above, FALSE otherwise.
 	 */
 	public static function classExists($className) {
-		if (class_exists($className, false)) {
-			return true;
+		if (class_exists($className, FALSE)) {
+			return TRUE;
 		}
 
 		foreach (spl_autoload_functions() as $loader) {
@@ -164,24 +164,24 @@ class ClassLoader {
 				if (is_object($loader[0])) {
 					if ($loader[0] instanceof ClassLoader) { // array($obj, 'methodName')
 						if ($loader[0]->canLoadClass($className)) {
-							return true;
+							return TRUE;
 						}
 					} else if ($loader[0]->{$loader[1]}($className)) {
-						return true;
+						return TRUE;
 					}
 				} else if ($loader[0]::$loader[1]($className)) { // array('ClassName', 'methodName')
-					return true;
+					return TRUE;
 				}
 			} else if ($loader instanceof \Closure) { // function($className) {..}
 				if ($loader($className)) {
-					return true;
+					return TRUE;
 				}
 			} else if (is_string($loader) && $loader($className)) { // "MyClass::loadClass"
-				return true;
+				return TRUE;
 			}
 		}
 
-		return false;
+		return FALSE;
 	}
 
 	/**
@@ -199,6 +199,6 @@ class ClassLoader {
 			}
 		}
 
-		return null;
+		return NULL;
 	}
 }
\ No newline at end of file
diff --git a/backend/lib/Util/Configuration.php b/backend/lib/Util/Configuration.php
index f0d663d..e43d15c 100644
--- a/backend/lib/Util/Configuration.php
+++ b/backend/lib/Util/Configuration.php
@@ -32,7 +32,7 @@ class Configuration {
 		$values =& self::$values;
 		$tree = explode('.', $var);
 		foreach ($tree as $part) {
-			$values =& $values[$part];	// TODO array_merge_recursive()
+			$values =& $values[$part];	// TODO use array_merge_recursive()
 		}
 		
 		$values = $value;
@@ -81,7 +81,7 @@ class Configuration {
 		
 		$delcaration = '';
 		foreach (self::$values as $key => $value) {
-			$export = var_export($value, true);
+			$export = var_export($value, TRUE);
 			$export = preg_replace('/=>\s+array/', '=> array', $export);
 			$export = str_replace("  ", "\t", $export);
 			
diff --git a/backend/lib/Util/Debug.php b/backend/lib/Util/Debug.php
index b86f8ce..ec12f8d 100644
--- a/backend/lib/Util/Debug.php
+++ b/backend/lib/Util/Debug.php
@@ -37,19 +37,19 @@ class Debug implements Logging\SQLLogger {
 	 */
 	public function __construct($level) {
 		// taking timestamp to stop execution time
-		$this->created = microtime(true);
+		$this->created = microtime(TRUE);
 		
 		$this->level = $level;
 		
-		if (!is_null(self::$instance)) {
+		if (isset(self::$instance)) {
 			throw new \Exception('debugging has already been started. please use the static functions!');
 		}
 		self::$instance = $this;
 		
 		// assert options
-		assert_options(ASSERT_ACTIVE, true);
-		assert_options(ASSERT_BAIL, false);
-		assert_options(ASSERT_WARNING, false);
+		assert_options(ASSERT_ACTIVE, TRUE);
+		assert_options(ASSERT_BAIL, FALSE);
+		assert_options(ASSERT_WARNING, FALSE);
 		assert_options(ASSERT_CALLBACK, array($this, 'assertHandler'));
 		
 		
@@ -58,12 +58,18 @@ class Debug implements Logging\SQLLogger {
 	/*
 	 * interface for doctrine's dbal sql logger
 	 */ 
-	function logSQL($sql, array $params = null) {
-		$this->queries[] = array('sql' => $sql, 'parameter' => $params);
+	function logSQL($sql, array $parameter = NULL) {
+		$query['sql'] = $sql;
+		
+		if (isset($parameter) && !empty($parameter)) {
+			$query['parameters'] = $parameter;
+		}
+		
+		$this->queries[] = $query;
 	}
 	
 	static public function log($message) {
-		if (!is_null(self::$instance)) {
+		if (isset(self::$instance)) {
 			$trace = debug_backtrace();
 			
 			self::$instance->messages[] = array(
@@ -99,9 +105,9 @@ class Debug implements Logging\SQLLogger {
 		);
 	}
 	
-	public static function isActivated() { return !is_null(self::$instance); }
+	public static function isActivated() { return isset(self::$instance); }
 	
-	public function getExecutionTime() { return round((microtime(true) - $this->created), 5); }
+	public function getExecutionTime() { return round((microtime(TRUE) - $this->created), 5); }
 	public function getQueries() { return $this->queries; }
 	public function getMessages() { return $this->messages; }
 }
diff --git a/backend/lib/Util/Uuid.php b/backend/lib/Util/Uuid.php
index 6ab859a..edc1238 100644
--- a/backend/lib/Util/Uuid.php
+++ b/backend/lib/Util/Uuid.php
@@ -92,7 +92,7 @@ class Uuid {
 
 	public static function compare($a, $b) {
 		/* Compares the binary representations of two UUIDs.
-		 The comparison will return true if they are bit-exact,
+		 The comparison will return TRUE if they are bit-exact,
 		 or if neither is valid. */
 		if (self::makeBin($a, 16)==self::makeBin($b, 16))
 		return TRUE;
@@ -239,7 +239,7 @@ class Uuid {
 
 	protected static function makeBin($str, $len) {
 		/* Insure that an input string is either binary or hexadecimal.
-		 Returns binary representation, or false on failure. */
+		 Returns binary representation, or FALSE on failure. */
 		if ($str instanceof self)
 		return $str->bytes;
 		if (strlen($str)==$len)
diff --git a/backend/lib/View/Csv/Csv.php b/backend/lib/View/Csv/Csv.php
index 3b35873..0fe1499 100644
--- a/backend/lib/View/Csv/Csv.php
+++ b/backend/lib/View/Csv/Csv.php
@@ -27,6 +27,9 @@ abstract class Csv extends \Volkszaehler\View\View {
 	protected $csv = array();
 	protected $header = array();
 	protected $footer = array();
+	
+	protected $delimiter = ';';
+	protected $enclosure = '"';
 
 	/*
 	 * constructor
@@ -37,8 +40,8 @@ abstract class Csv extends \Volkszaehler\View\View {
 		$this->header[] = 'source: volkszaehler.org';
 		$this->header[] = 'version: ' . \Volkszaehler\VERSION;
 
-		$this->response->setHeader('Content-type', 'text/plain');
-		//$this->response->setHeader('Content-Disposition', 'attachment; filename="data.csv"');
+		$this->response->setHeader('Content-type', 'text/csv');
+		$this->response->setHeader('Content-Disposition', 'attachment; filename="data.csv"');
 	}
 	
 	public function render() {
@@ -49,7 +52,9 @@ abstract class Csv extends \Volkszaehler\View\View {
 		echo PHP_EOL;
 		
 		foreach ($this->csv as $array) {
-			echo implode(";", $array) . PHP_EOL;
+			$array = array_map(array($this, 'escape'), $array);
+				
+			echo implode($this->delimiter, $array) . PHP_EOL;
 		}
 		
 		echo PHP_EOL;
@@ -61,11 +66,27 @@ abstract class Csv extends \Volkszaehler\View\View {
 		parent::render();
 	}
 	
-	public function addDebug() {
-		$this->footer[] = 'time: ' . $this->getTime();
+	protected function escape($value) {
+		if (is_string($value)) {
+			return $this->enclosure . $value . $this->enclosure;
+		}
+		elseif (is_numeric($value)) {
+			return $value;
+		}
+		else {
+			return (string) $value;
+		}
+	}
+	
+	public function addDebug(Util\Debug $debug) {
+		$this->footer[] = 'time: ' . $debug->getExecutionTime();
 		$this->footer[] = 'database: ' . Util\Configuration::read('db.driver');
 		
-		foreach (\Volkszaehler\Util\Debug::getSQLLogger()->queries as $query) {
+		foreach ($debug->getMessages() as $message) {
+			$this->footer[] = 'message: ' . $message['message'];	// TODO add more information
+		}
+		
+		foreach ($debug->getQueries() as $query) {
 			$this->footer[] = 'query: ' . $query['sql'];
 			$this->footer[] = '  parameters: ' . implode(', ', $query['parameters']);
 		}
diff --git a/backend/lib/View/Http/Response.php b/backend/lib/View/Http/Response.php
index b467ee0..9bbbf3b 100644
--- a/backend/lib/View/Http/Response.php
+++ b/backend/lib/View/Http/Response.php
@@ -103,7 +103,7 @@ class Response {
 	public function getCode() { return $this->code; }
 	public function setCode($code) { $this->code = $code; }
 	static public function getCodeDescription($code) {
-		return (isset(self::$codes[$code])) ? self::$codes[$code] : false;
+		return (isset(self::$codes[$code])) ? self::$codes[$code] : FALSE;
 	}
 }
 
diff --git a/backend/lib/View/JpGraph.php b/backend/lib/View/JpGraph.php
index 88f0515..eb435e1 100644
--- a/backend/lib/View/JpGraph.php
+++ b/backend/lib/View/JpGraph.php
@@ -29,7 +29,6 @@ require_once \Volkszaehler\BACKEND_DIR . '/lib/vendor/JpGraph/jpgraph_date.php';
  * JpGraph plotting
  * 
  * @todo add caching
- * @todo unifiy axes of same unit
  */
 class JpGraph extends View {
 	/*
@@ -60,7 +59,7 @@ class JpGraph extends View {
 		$this->graph->SetScale('datlin');
 		
 		$this->graph->legend->SetPos(0.1,0.02, 'left', 'top');
-		$this->graph->legend->SetShadow(false);
+		$this->graph->legend->SetShadow(FALSE);
 		
 		$this->graph->SetMarginColor('white');
 		$this->graph->SetYDeltaDist(65);
@@ -75,7 +74,7 @@ class JpGraph extends View {
 		//$this->graph->img->SetAntiAliasing(); 
 	}
 	
-	public function add(\Volkszaehler\Model\Channel $obj, $data = NULL) {
+	public function add(\Volkszaehler\Model\Channel $obj, array $data) {
 		$count = count($this->channels);
 		$xData = $yData = array();
 		foreach ($data as $reading) {
@@ -87,7 +86,7 @@ class JpGraph extends View {
 		$plot = new \ScatterPlot($yData, $xData);
 		
 		$plot->setLegend($obj->getName() . ': ' . $obj->getDescription() . ' [' . $obj->getUnit() . ']');
-		$plot->SetLinkPoints(true, self::$colors[$count]);
+		$plot->SetLinkPoints(TRUE, self::$colors[$count]);
 		
 		$plot->mark->SetColor(self::$colors[$count]);
 		$plot->mark->SetFillColor(self::$colors[$count]);
diff --git a/backend/lib/View/Json/Channel.php b/backend/lib/View/Json/Channel.php
index 024f674..95bacfa 100644
--- a/backend/lib/View/Json/Channel.php
+++ b/backend/lib/View/Json/Channel.php
@@ -23,8 +23,7 @@ namespace Volkszaehler\View\Json;
 
 class Channel extends Json {
 	
-	public function add(\Volkszaehler\Model\Channel $obj, $data = NULL) {
-		$channel['id'] = (int) $obj->getId();
+	public function add(\Volkszaehler\Model\Channel $obj, array $data = NULL) {
 		$channel['uuid'] = (string) $obj->getUuid();
 		$channel['indicator'] = $obj->getIndicator();
 		$channel['unit'] = $obj->getUnit();
@@ -37,7 +36,7 @@ class Channel extends Json {
 			$channel['cost'] = (float) $obj->getCost();
 		}
 			
-		if (!is_null($data) && is_array($data)) {
+		if (isset($data)) {
 			$channel['data'] = array();
 			foreach ($data as $reading) {
 				$channel['data'][] = array($reading['timestamp'], $reading['value'], $reading['count']);
diff --git a/backend/lib/View/Json/Group.php b/backend/lib/View/Json/Group.php
index 76a5909..4ebf4de 100644
--- a/backend/lib/View/Json/Group.php
+++ b/backend/lib/View/Json/Group.php
@@ -23,13 +23,12 @@ namespace Volkszaehler\View\Json;
 
 class Group extends Json {
 	
-	public function add(\Volkszaehler\Model\Group $obj, $recursive = false) {
-		$group['id'] = (int) $obj->getId();
+	public function add(\Volkszaehler\Model\Group $obj, $recursive = FALSE) {
 		$group['uuid'] = (string) $obj->getUuid();
 		$group['name'] = $obj->getName();
 		$group['description'] = $obj->getDescription();
 		
-		if ($recursive) {	// TODO add really nested sub groups
+		if ($recursive) {	// TODO add nested groups in json view
 			$children = $obj->getChildren();
 
 			foreach ($children as $child) {
diff --git a/backend/lib/View/Json/Json.php b/backend/lib/View/Json/Json.php
index 9731ae6..ff0ff1c 100644
--- a/backend/lib/View/Json/Json.php
+++ b/backend/lib/View/Json/Json.php
@@ -53,7 +53,7 @@ abstract class Json extends \Volkszaehler\View\View {
 	protected static function format($json) {
 		$formatted = '';
 		$indentLevel = 0;
-		$inString = false;
+		$inString = FALSE;
 
 		$len = strlen($json);
 		for($c = 0; $c < $len; $c++) {
diff --git a/backend/lib/View/Xml/Channel.php b/backend/lib/View/Xml/Channel.php
index d78b2fb..3fb3b6d 100644
--- a/backend/lib/View/Xml/Channel.php
+++ b/backend/lib/View/Xml/Channel.php
@@ -29,7 +29,7 @@ class Channel extends Xml {
 		$this->xml = $this->xmlDoc->createElement('channels');
 	}
 	
-	public function add(\Volkszaehler\Model\Channel $obj, $data = NULL) {
+	public function add(\Volkszaehler\Model\Channel $obj, array $data = NULL) {
 		$xmlChannel = $this->xmlDoc->createElement('channel');
 		$xmlChannel->setAttribute('uuid', $obj->getUuid());
 		
@@ -40,7 +40,7 @@ class Channel extends Xml {
 		$xmlChannel->appendChild($this->xmlDoc->createElement('resolution', (int) $obj->getResolution()));
 		$xmlChannel->appendChild($this->xmlDoc->createElement('cost', (float) $obj->getCost()));
 		
-		if (!is_null($data) && is_array($data)) {
+		if (isset($data)) {
 			$xmlData = $this->xmlDoc->createElement('data');
 			
 			foreach ($data as $reading) {
diff --git a/backend/lib/View/Xml/Group.php b/backend/lib/View/Xml/Group.php
index ed62b06..374e982 100644
--- a/backend/lib/View/Xml/Group.php
+++ b/backend/lib/View/Xml/Group.php
@@ -32,9 +32,9 @@ class Group extends Xml {
 	
 	public function add(\Volkszaehler\Model\Group $obj) {
 		$xmlGroup = $this->xmlDoc->createElement('group');
-		$xmlGroup->setAttribute('id', (int) $obj->id);
-		$xmlGroup->appendChild($this->xmlDoc->createElement('uuid', $obj->uuid));
-		$xmlGroup->appendChild($this->xmlDoc->createElement('description', $obj->description));
+		$xmlGroup->setAttribute('uuid', $obj->getUuid());
+		$xmlGroup->appendChild($this->xmlDoc->createElement('name', $obj->getName()));
+		$xmlGroup->appendChild($this->xmlDoc->createElement('description', $obj->getDescription()));
 			
 		// TODO include sub groups?
 			
diff --git a/backend/lib/View/Xml/Xml.php b/backend/lib/View/Xml/Xml.php
index 0aeff02..d1de547 100644
--- a/backend/lib/View/Xml/Xml.php
+++ b/backend/lib/View/Xml/Xml.php
@@ -21,7 +21,6 @@
 
 namespace Volkszaehler\View\Xml;
 
-// TODO outdated
 use Volkszaehler\Util;
 
 abstract class Xml extends \Volkszaehler\View\View {
@@ -58,13 +57,14 @@ abstract class Xml extends \Volkszaehler\View\View {
 		$this->xmlRoot->appendChild($xmlException);
 	}
 	
-	public function addDebug() {
+	public function addDebug(Util\Debug $debug) {
 		$xmlDebug = $this->xmlDoc->createElement('debug');
 		
-		$xmlDebug->appendChild($this->xmlDoc->createElement('time', $this->getTime()));
+		$xmlDebug->appendChild($this->xmlDoc->createElement('time', $debug->getExecutionTime()));
 		$xmlDebug->appendChild($this->xmlDoc->createElement('database', Util\Configuration::read('db.driver')));
 		
-		// TODO add queries
+		// TODO add queries to xml debug
+		// TODO add messages to xml output
 		
 		$this->xmlRoot->appendChild($xmlDebug);
 	}
@@ -83,7 +83,7 @@ abstract class Xml extends \Volkszaehler\View\View {
 						$xmlArgs = $this->xmlDoc->createElement($key);
 						$xmlTrace->appendChild($xmlArgs);
 						foreach ($value as $arg) {
-							$xmlArgs->appendChild($this->xmlDoc->createElement('arg', print_r($value, true))); // TODO check $value content
+							$xmlArgs->appendChild($this->xmlDoc->createElement('arg', (is_scalar($value)) ? $value : print_r($value, TRUE)));
 						}
 						break;
 							
diff --git a/backend/volkszaehler.conf.default.php b/backend/volkszaehler.conf.default.php
index 91d4737..2bec5bb 100644
--- a/backend/volkszaehler.conf.default.php
+++ b/backend/volkszaehler.conf.default.php
@@ -25,6 +25,6 @@ $config['db']['user']				= 'volkszaehler';
 $config['db']['password']			= '';
 $config['db']['dbname']				= 'volkszaehler';
 
-$config['debug']					= false;
+$config['debug']					= FALSE;
 
 ?>
diff --git a/share/tools/install.php b/share/tools/install.php
index 4ab39b7..b1b547d 100644
--- a/share/tools/install.php
+++ b/share/tools/install.php
@@ -31,6 +31,8 @@
 
 <?php
 
+// TODO complete installer
+
 switch (@$_GET['step']) {
 	case '1':
 		echo 'bla';