Refs #4059 Work in progress: Conversion to use Namespaces: Period*, Metrics, Segment, SegmentExpression, PluginsManager.

Removed some deprecated code.

126 files changed, 738 insertions, 626 deletions

diff --git a/plugins/API/API.php b/plugins/API/API.php
index b93dae7902..e85974fd8e 100644
--- a/plugins/API/API.php
+++ b/plugins/API/API.php
@@ -8,17 +8,23 @@
  * @category Piwik_Plugins
  * @package Piwik_API
  */
+use Piwik\DataTable\Filter\ColumnDelete;
+use Piwik\DataTable\Row;
 use Piwik\Metrics;
 use Piwik\Piwik;
 use Piwik\Common;
 use Piwik\Config;
+use Piwik\Date;
+use Piwik\DataTable;
+use Piwik\Plugin;
+use Piwik\Translate;
 
 require_once PIWIK_INCLUDE_PATH . '/core/Config.php';
 
 /**
  * @package Piwik_API
  */
-class Piwik_API extends Piwik_Plugin
+class Piwik_API extends Plugin
 {
     /**
      * @see Piwik_Plugin::getListHooksRegistered
@@ -385,7 +391,7 @@ class Piwik_API_API
     public function getMetadata($idSite, $apiModule, $apiAction, $apiParameters = array(), $language = false,
                                 $period = false, $date = false, $hideMetricsDoc = false, $showSubtableReports = false)
     {
-        Piwik_Translate::getInstance()->reloadLanguage($language);
+        Translate::getInstance()->reloadLanguage($language);
         $reporter = new Piwik_API_ProcessedReport();
         $metadata =  $reporter->getMetadata($idSite, $apiModule, $apiAction, $apiParameters, $language, $period, $date, $hideMetricsDoc, $showSubtableReports);
         return $metadata;
@@ -397,7 +403,7 @@ class Piwik_API_API
      *
      * @param string $idSites Comma separated list of website Ids
      * @param bool|string $period
-     * @param bool|Piwik_Date $date
+     * @param bool|Date $date
      * @param bool $hideMetricsDoc
      * @param bool $showSubtableReports
      * @return array
@@ -466,13 +472,13 @@ class Piwik_API_API
             $params['columns'] = implode(',', $columns);
             $dataTable = Piwik_API_Proxy::getInstance()->call($className, 'get', $params);
             // make sure the table has all columns
-            $array = ($dataTable instanceof Piwik_DataTable_Array ? $dataTable->getArray() : array($dataTable));
+            $array = ($dataTable instanceof DataTable\Map ? $dataTable->getArray() : array($dataTable));
             foreach ($array as $table) {
                 // we don't support idSites=all&date=DATE1,DATE2
-                if ($table instanceof Piwik_DataTable) {
+                if ($table instanceof DataTable) {
                     $firstRow = $table->getFirstRow();
                     if (!$firstRow) {
-                        $firstRow = new Piwik_DataTable_Row;
+                        $firstRow = new Row;
                         $table->addRow($firstRow);
                     }
                     foreach ($columns as $column) {
@@ -500,7 +506,7 @@ class Piwik_API_API
     private function mergeDataTables($table1, $table2)
     {
         // handle table arrays
-        if ($table1 instanceof Piwik_DataTable_Array && $table2 instanceof Piwik_DataTable_Array) {
+        if ($table1 instanceof DataTable\Map && $table2 instanceof DataTable\Map) {
             $subTables2 = $table2->getArray();
             foreach ($table1->getArray() as $index => $subTable1) {
                 $subTable2 = $subTables2[$index];
@@ -511,7 +517,7 @@ class Piwik_API_API
 
         $firstRow1 = $table1->getFirstRow();
         $firstRow2 = $table2->getFirstRow();
-        if ($firstRow2 instanceof Piwik_DataTable_Row) {
+        if ($firstRow2 instanceof Row) {
             foreach ($firstRow2->getColumns() as $metric => $value) {
                 $firstRow1->setColumn($metric, $value);
             }
@@ -525,7 +531,7 @@ class Piwik_API_API
      *
      * @param int $idSite
      * @param string $period
-     * @param Piwik_Date $date
+     * @param Date $date
      * @param string $apiModule
      * @param string $apiAction
      * @param bool|string $label
@@ -591,7 +597,7 @@ class Piwik_API_API
             throw new Exception("Requested segment not found.");
         }
 
-        $startDate = Piwik_Date::now()->subDay(60)->toString();
+        $startDate = Date::now()->subDay(60)->toString();
         $requestLastVisits = "method=Live.getLastVisitsDetails
             &idSite=$idSite
             &period=range
@@ -622,7 +628,7 @@ class Piwik_API_API
         $values = $table->getColumn($segmentName);
 
         // Select also flattened keys (custom variables "page" scope, page URLs for one visit, page titles for one visit)
-        $valuesBis = $table->getColumnsStartingWith($segmentName . Piwik_DataTable_Filter_ColumnDelete::APPEND_TO_COLUMN_NAME_TO_KEEP);
+        $valuesBis = $table->getColumnsStartingWith($segmentName . ColumnDelete::APPEND_TO_COLUMN_NAME_TO_KEEP);
         $values = array_merge($values, $valuesBis);
 
         // remove false values (while keeping zeros)
diff --git a/plugins/API/ProcessedReport.php b/plugins/API/ProcessedReport.php
index db30a13648..a008c82025 100644
--- a/plugins/API/ProcessedReport.php
+++ b/plugins/API/ProcessedReport.php
@@ -1,8 +1,12 @@
 <?php
+use Piwik\DataTable\Simple;
+use Piwik\DataTable\Row;
 use Piwik\Metrics;
 use Piwik\Period;
 use Piwik\Piwik;
 use Piwik\Common;
+use Piwik\Date;
+use Piwik\DataTable;
 use Piwik\Site;
 
 /**
@@ -60,7 +64,7 @@ class Piwik_API_ProcessedReport
      *
      * @param string $idSites Comma separated list of website Ids
      * @param bool|string $period
-     * @param bool|Piwik_Date $date
+     * @param bool|Date $date
      * @param bool $hideMetricsDoc
      * @param bool $showSubtableReports
      * @return array
@@ -272,7 +276,7 @@ class Piwik_API_ProcessedReport
         $url = Piwik_Url::getQueryStringFromParameters($parameters);
         $request = new Piwik_API_Request($url);
         try {
-            /** @var Piwik_DataTable */
+            /** @var DataTable */
             $dataTable = $request->process();
         } catch (Exception $e) {
             throw new Exception("API returned an error: " . $e->getMessage() . " at " . basename($e->getFile()) . ":" . $e->getLine() . "\n");
@@ -307,14 +311,14 @@ class Piwik_API_ProcessedReport
      * - remove metrics based on $reportMetadata['metrics']
      * - add 0 valued metrics if $dataTable doesn't provide all $reportMetadata['metrics']
      * - format metric values to a 'human readable' format
-     * - extract row metadata to a separate Piwik_DataTable_Simple|Piwik_DataTable_Array : $rowsMetadata
+     * - extract row metadata to a separate Simple|Set : $rowsMetadata
      * - translate metric names to a separate array : $columns
      *
      * @param int $idSite enables monetary value formatting based on site currency
-     * @param Piwik_DataTable|Piwik_DataTable_Array $dataTable
+     * @param \Piwik\DataTable\Set $dataTable
      * @param array $reportMetadata
      * @param bool $showRawMetrics
-     * @return array Piwik_DataTable_Simple|Piwik_DataTable_Array $newReport with human readable format & array $columns list of translated column names & Piwik_DataTable_Simple|Piwik_DataTable_Array $rowsMetadata
+     * @return array Simple|Set $newReport with human readable format & array $columns list of translated column names & Simple|Set $rowsMetadata
      */
     private function handleTableReport($idSite, $dataTable, &$reportMetadata, $showRawMetrics = false)
     {
@@ -356,17 +360,17 @@ class Piwik_API_ProcessedReport
 
         $columns = $this->hideShowMetrics($columns);
 
-        // $dataTable is an instance of Piwik_DataTable_Array when multiple periods requested
-        if ($dataTable instanceof Piwik_DataTable_Array) {
-            // Need a new Piwik_DataTable_Array to store the 'human readable' values
-            $newReport = new Piwik_DataTable_Array();
+        // $dataTable is an instance of Set when multiple periods requested
+        if ($dataTable instanceof DataTable\Map) {
+            // Need a new Set to store the 'human readable' values
+            $newReport = new DataTable\Map();
             $newReport->setKeyName("prettyDate");
 
-            // Need a new Piwik_DataTable_Array to store report metadata
-            $rowsMetadata = new Piwik_DataTable_Array();
+            // Need a new Set to store report metadata
+            $rowsMetadata = new DataTable\Map();
             $rowsMetadata->setKeyName("prettyDate");
 
-            // Process each Piwik_DataTable_Simple entry
+            // Process each Simple entry
             foreach ($dataTable->getArray() as $label => $simpleDataTable) {
                 $this->removeEmptyColumns($columns, $reportMetadata, $simpleDataTable);
 
@@ -395,7 +399,7 @@ class Piwik_API_ProcessedReport
      */
     private function removeEmptyColumns(&$columns, &$reportMetadata, $dataTable)
     {
-        $emptyColumns = $dataTable->getMetadata(Piwik_DataTable::EMPTY_COLUMNS_METADATA_NAME);
+        $emptyColumns = $dataTable->getMetadata(DataTable::EMPTY_COLUMNS_METADATA_NAME);
 
         if (!is_array($emptyColumns)) {
             return;
@@ -473,26 +477,26 @@ class Piwik_API_ProcessedReport
      * - remove metrics based on $reportMetadata['metrics']
      * - add 0 valued metrics if $simpleDataTable doesn't provide all $reportMetadata['metrics']
      * - format metric values to a 'human readable' format
-     * - extract row metadata to a separate Piwik_DataTable_Simple $rowsMetadata
+     * - extract row metadata to a separate Simple $rowsMetadata
      *
      * @param int $idSite enables monetary value formatting based on site currency
-     * @param Piwik_DataTable_Simple $simpleDataTable
+     * @param Simple $simpleDataTable
      * @param array $metadataColumns
      * @param boolean $hasDimension
      * @param bool $returnRawMetrics If set to true, the original metrics will be returned
      *
-     * @return array Piwik_DataTable $enhancedDataTable filtered metrics with human readable format & Piwik_DataTable_Simple $rowsMetadata
+     * @return array DataTable $enhancedDataTable filtered metrics with human readable format & Simple $rowsMetadata
      */
     private function handleSimpleDataTable($idSite, $simpleDataTable, $metadataColumns, $hasDimension, $returnRawMetrics = false)
     {
         // new DataTable to store metadata
-        $rowsMetadata = new Piwik_DataTable();
+        $rowsMetadata = new DataTable();
 
         // new DataTable to store 'human readable' values
         if ($hasDimension) {
-            $enhancedDataTable = new Piwik_DataTable();
+            $enhancedDataTable = new DataTable();
         } else {
-            $enhancedDataTable = new Piwik_DataTable_Simple();
+            $enhancedDataTable = new Simple();
         }
 
         // add missing metrics
@@ -506,7 +510,7 @@ class Piwik_API_ProcessedReport
         }
 
         foreach ($simpleDataTable->getRows() as $row) {
-            $enhancedRow = new Piwik_DataTable_Row();
+            $enhancedRow = new Row();
             $enhancedDataTable->addRow($enhancedRow);
             $rowMetrics = $row->getColumns();
             foreach ($rowMetrics as $columnName => $columnValue) {
@@ -528,7 +532,7 @@ class Piwik_API_ProcessedReport
 
                 // Create a row metadata only if there are metadata to insert
                 if (count($rowMetadata) > 0 || !is_null($idSubDataTable)) {
-                    $metadataRow = new Piwik_DataTable_Row();
+                    $metadataRow = new Row();
                     $rowsMetadata->addRow($metadataRow);
 
                     foreach ($rowMetadata as $metadataKey => $metadataValue) {
diff --git a/plugins/API/RowEvolution.php b/plugins/API/RowEvolution.php
index 13b1250a1c..ec6b3c06fc 100644
--- a/plugins/API/RowEvolution.php
+++ b/plugins/API/RowEvolution.php
@@ -8,9 +8,13 @@
  * @category Piwik_Plugins
  * @package Piwik_API
  */
+use Piwik\DataTable\Filter\CalculateEvolutionFilter;
+use Piwik\DataTable\Filter\SafeDecodeLabel;
+use Piwik\DataTable\Row;
 use Piwik\Period;
 use Piwik\Piwik;
 use Piwik\Common;
+use Piwik\DataTable;
 
 /**
  * This class generates a Row evolution dataset, from input request
@@ -104,7 +108,7 @@ class Piwik_API_RowEvolution
 
     /**
      * Get row evolution for a single label
-     * @param Piwik_DataTable $dataTable
+     * @param DataTable $dataTable
      * @param array $metadata
      * @param string $apiModule
      * @param string $apiAction
@@ -119,10 +123,10 @@ class Piwik_API_RowEvolution
         $logo = $actualLabel = false;
         $urlFound = false;
         foreach ($dataTable->getArray() as $date => $subTable) {
-            /** @var $subTable Piwik_DataTable */
+            /** @var $subTable DataTable */
             $subTable->applyQueuedFilters();
             if ($subTable->getRowsCount() > 0) {
-                /** @var $row Piwik_DataTable_Row */
+                /** @var $row Row */
                 $row = $subTable->getFirstRow();
 
                 if (!$actualLabel) {
@@ -155,7 +159,7 @@ class Piwik_API_RowEvolution
         }
 
         $return = array(
-            'label'      => Piwik_DataTable_Filter_SafeDecodeLabel::safeDecodeLabel($actualLabel),
+            'label'      => SafeDecodeLabel::safeDecodeLabel($actualLabel),
             'reportData' => $dataTable,
             'metadata'   => $metadata
         );
@@ -190,7 +194,7 @@ class Piwik_API_RowEvolution
      * @param $segment
      * @param $idGoal
      * @throws Exception
-     * @return Piwik_DataTable_Array|Piwik_DataTable
+     * @return DataTable\Map|DataTable
      */
     private function loadRowEvolutionDataFromAPI($idSite, $period, $date, $apiModule, $apiAction, $label = false, $segment = false, $idGoal = false)
     {
@@ -289,7 +293,7 @@ class Piwik_API_RowEvolution
      * Given the Row evolution dataTable, and the associated metadata,
      * enriches the metadata with min/max values, and % change between the first period and the last one
      * @param array $metadata
-     * @param Piwik_DataTable_Array $dataTable
+     * @param DataTable\Map $dataTable
      */
     private function enhanceRowEvolutionMetaData(&$metadata, $dataTable)
     {
@@ -345,8 +349,8 @@ class Piwik_API_RowEvolution
                 continue;
             }
 
-            $change = Piwik_DataTable_Filter_CalculateEvolutionFilter::calculate($last, $first, $quotientPrecision = 0);
-            $change = Piwik_DataTable_Filter_CalculateEvolutionFilter::prependPlusSignToNumber($change);
+            $change = CalculateEvolutionFilter::calculate($last, $first, $quotientPrecision = 0);
+            $change = CalculateEvolutionFilter::prependPlusSignToNumber($change);
             $metricsResult[$metric]['change'] = $change;
         }
 
@@ -391,7 +395,7 @@ class Piwik_API_RowEvolution
         // array('label' => $label, 'column' => $value).
         $dataTableMulti = $dataTable->getEmptyClone();
         foreach ($dataTable->getArray() as $tableLabel => $table) {
-            $newRow = new Piwik_DataTable_Row();
+            $newRow = new Row();
 
             foreach ($labels as $labelIdx => $label) {
                 $row = $this->getRowEvolutionRowFromLabelIdx($table, $labelIdx);
@@ -429,7 +433,7 @@ class Piwik_API_RowEvolution
                 $label .= ' (' . $metadata['columns'][$column] . ')';
             }
             $metricName = $column . '_' . $labelIndex;
-            $metadata['metrics'][$metricName] = Piwik_DataTable_Filter_SafeDecodeLabel::safeDecodeLabel($label);
+            $metadata['metrics'][$metricName] = SafeDecodeLabel::safeDecodeLabel($label);
 
             if (!empty($logos[$labelIndex])) {
                 $metadata['logos'][$metricName] = $logos[$labelIndex];
@@ -448,9 +452,9 @@ class Piwik_API_RowEvolution
     /**
      * Returns the row in a datatable by its Piwik_API_DataTableManipulator_LabelFilter::FLAG_IS_ROW_EVOLUTION metadata.
      *
-     * @param Piwik_DataTable $table
+     * @param DataTable $table
      * @param int $labelIdx
-     * @return Piwik_DataTable_Row|false
+     * @return Row|false
      */
     private function getRowEvolutionRowFromLabelIdx($table, $labelIdx)
     {
diff --git a/plugins/Actions/API.php b/plugins/Actions/API.php
index 0262f807e0..b40afb87e2 100644
--- a/plugins/Actions/API.php
+++ b/plugins/Actions/API.php
@@ -12,6 +12,8 @@ use Piwik\Archive;
 use Piwik\Metrics;
 use Piwik\Piwik;
 use Piwik\Common;
+use Piwik\Date;
+use Piwik\DataTable;
 
 /**
  * The Actions API lets you request reports for all your Visitor Actions: Page URLs, Page titles (Piwik Events),
@@ -50,7 +52,7 @@ class Piwik_Actions_API
      * @param string $date
      * @param bool|string $segment
      * @param bool|array $columns
-     * @return Piwik_DataTable
+     * @return DataTable
      */
     public function get($idSite, $period, $date, $segment = false, $columns = false)
     {
@@ -112,12 +114,12 @@ class Piwik_Actions_API
     /**
      * @param int $idSite
      * @param string $period
-     * @param Piwik_Date $date
+     * @param Date $date
      * @param bool $segment
      * @param bool $expanded
      * @param bool $idSubtable
      *
-     * @return Piwik_DataTable|Piwik_DataTable_Array
+     * @return DataTable|DataTable\Map
      */
     public function getPageUrls($idSite, $period, $date, $segment = false, $expanded = false, $idSubtable = false)
     {
@@ -130,12 +132,12 @@ class Piwik_Actions_API
     /**
      * @param int $idSite
      * @param string $period
-     * @param Piwik_Date $date
+     * @param Date $date
      * @param bool $segment
      * @param bool $expanded
      * @param bool $idSubtable
      *
-     * @return Piwik_DataTable|Piwik_DataTable_Array
+     * @return DataTable|DataTable\Map
      */
     public function getPageUrlsFollowingSiteSearch($idSite, $period, $date, $segment = false, $expanded = false, $idSubtable = false)
     {
@@ -147,12 +149,12 @@ class Piwik_Actions_API
     /**
      * @param int $idSite
      * @param string $period
-     * @param Piwik_Date $date
+     * @param Date $date
      * @param bool $segment
      * @param bool $expanded
      * @param bool $idSubtable
      *
-     * @return Piwik_DataTable|Piwik_DataTable_Array
+     * @return DataTable|DataTable\Map
      */
     public function getPageTitlesFollowingSiteSearch($idSite, $period, $date, $segment = false, $expanded = false, $idSubtable = false)
     {
@@ -162,7 +164,7 @@ class Piwik_Actions_API
     }
 
     /**
-     * @param Piwik_DataTable $dataTable
+     * @param DataTable $dataTable
      */
     protected function keepPagesFollowingSearch($dataTable)
     {
@@ -213,7 +215,7 @@ class Piwik_Actions_API
     }
 
     /**
-     * Returns a Piwik_DataTable with analytics information for every unique entry page title
+     * Returns a DataTable with analytics information for every unique entry page title
      * for the given site, time period & segment.
      */
     public function getEntryPageTitles($idSite, $period, $date, $segment = false, $expanded = false,
@@ -225,7 +227,7 @@ class Piwik_Actions_API
     }
 
     /**
-     * Returns a Piwik_DataTable with analytics information for every unique exit page title
+     * Returns a DataTable with analytics information for every unique exit page title
      * for the given site, time period & segment.
      */
     public function getExitPageTitles($idSite, $period, $date, $segment = false, $expanded = false,
@@ -306,7 +308,7 @@ class Piwik_Actions_API
                  Metrics::INDEX_SITE_SEARCH_HAS_NO_RESULT,
                  create_function('$value', 'return $value >= 1;')
             ));
-        $dataTable->deleteRow(Piwik_DataTable::ID_SUMMARY_ROW);
+        $dataTable->deleteRow(DataTable::ID_SUMMARY_ROW);
         $dataTable->deleteColumn(Metrics::INDEX_SITE_SEARCH_HAS_NO_RESULT);
         $this->filterPageDatatable($dataTable);
         $this->filterActionsDataTable($dataTable);
@@ -317,10 +319,10 @@ class Piwik_Actions_API
     /**
      * @param int $idSite
      * @param string $period
-     * @param Piwik_Date $date
+     * @param Date $date
      * @param bool $segment
      *
-     * @return Piwik_DataTable|Piwik_DataTable_Array
+     * @return DataTable|DataTable\Map
      */
     public function getSiteSearchCategories($idSite, $period, $date, $segment = false)
     {
@@ -329,10 +331,10 @@ class Piwik_Actions_API
 
         $customVarNameToLookFor = Piwik_Tracker_Action::CVAR_KEY_SEARCH_CATEGORY;
 
-        $dataTable = new Piwik_DataTable();
+        $dataTable = new DataTable();
         // Handle case where date=last30&period=day
         // FIXMEA: this logic should really be refactored somewhere, this is ugly!
-        if ($customVariables instanceof Piwik_DataTable_Array) {
+        if ($customVariables instanceof DataTable\Map) {
             $dataTable = $customVariables->getEmptyClone();
 
             $customVariableDatatables = $customVariables->getArray();
@@ -349,7 +351,7 @@ class Piwik_Actions_API
                     }
                 }
             }
-        } elseif ($customVariables instanceof Piwik_DataTable) {
+        } elseif ($customVariables instanceof DataTable) {
             $row = $customVariables->getRowFromLabel($customVarNameToLookFor);
             if ($row) {
                 $idSubtable = $row->getIdSubDataTable();
@@ -388,7 +390,7 @@ class Piwik_Actions_API
             // fetch the data table
             $table = call_user_func_array(array('Piwik\Archive', 'getDataTableFromArchive'), $callBackParameters);
 
-            if ($table instanceof Piwik_DataTable_Array) {
+            if ($table instanceof DataTable\Map) {
                 // search an array of tables, e.g. when using date=last30
                 // note that if the root is an array, we filter all children
                 // if an array occurs inside the nested table, we only look for the first match (see below)
@@ -414,7 +416,7 @@ class Piwik_Actions_API
     protected function doFilterPageDatatableSearch($callBackParameters, $table, $searchTree)
     {
         // filter a data table array
-        if ($table instanceof Piwik_DataTable_Array) {
+        if ($table instanceof DataTable\Map) {
             foreach ($table->getArray() as $subTable) {
                 $filteredSubTable = $this->doFilterPageDatatableSearch($callBackParameters, $subTable, $searchTree);
 
@@ -425,24 +427,24 @@ class Piwik_Actions_API
             }
 
             // nothing found in all sub tables
-            return new Piwik_DataTable;
+            return new DataTable;
         }
 
         // filter regular data table
-        if ($table instanceof Piwik_DataTable) {
+        if ($table instanceof DataTable) {
             // search for the first part of the tree search
             $search = array_shift($searchTree);
             $row = $table->getRowFromLabel($search);
             if ($row === false) {
                 // not found
-                $result = new Piwik_DataTable;
+                $result = new DataTable;
                 $result->metadata = $table->metadata;
                 return $result;
             }
 
             // end of tree search reached
             if (count($searchTree) == 0) {
-                $result = new Piwik_DataTable();
+                $result = new DataTable();
                 $result->addRow($row);
                 $result->metadata = $table->metadata;
                 return $result;
@@ -489,8 +491,8 @@ class Piwik_Actions_API
                                                          Metrics::INDEX_PAGE_MAX_TIME_GENERATION
                                                      )));
 
-            if ($dataTable instanceof Piwik_DataTable) {
-                $emptyColumns = $dataTable->getMetadata(Piwik_DataTable::EMPTY_COLUMNS_METADATA_NAME);
+            if ($dataTable instanceof DataTable) {
+                $emptyColumns = $dataTable->getMetadata(DataTable::EMPTY_COLUMNS_METADATA_NAME);
                 if (!is_array($emptyColumns)) {
                     $emptyColumns = array();
                 }
@@ -498,7 +500,7 @@ class Piwik_Actions_API
                 $emptyColumns[] = 'avg_time_generation';
                 $emptyColumns[] = 'min_time_generation';
                 $emptyColumns[] = 'max_time_generation';
-                $dataTable->setMetadata(Piwik_DataTable::EMPTY_COLUMNS_METADATA_NAME, $emptyColumns);
+                $dataTable->setMetadata(DataTable::EMPTY_COLUMNS_METADATA_NAME, $emptyColumns);
             }
         }
     }
@@ -519,7 +521,7 @@ class Piwik_Actions_API
     /**
      * Removes DataTable rows referencing actions that were never the first action of a visit.
      *
-     * @param Piwik_DataTable $dataTable
+     * @param DataTable $dataTable
      */
     private function filterNonEntryActions($dataTable)
     {
@@ -529,7 +531,7 @@ class Piwik_Actions_API
     /**
      * Removes DataTable rows referencing actions that were never the last action of a visit.
      *
-     * @param Piwik_DataTable $dataTable
+     * @param DataTable $dataTable
      */
     private function filterNonExitActions($dataTable)
     {
diff --git a/plugins/Actions/Actions.php b/plugins/Actions/Actions.php
index 03109bfdb9..0906c0cbd3 100644
--- a/plugins/Actions/Actions.php
+++ b/plugins/Actions/Actions.php
@@ -8,8 +8,10 @@
  * @category Piwik_Plugins
  * @package Piwik_Actions
  */
+use Piwik\ArchiveProcessor;
 use Piwik\Piwik;
 use Piwik\Common;
+use Piwik\Plugin;
 use Piwik\SegmentExpression;
 use Piwik\Site;
 
@@ -20,7 +22,7 @@ use Piwik\Site;
  *
  * @package Piwik_Actions
  */
-class Piwik_Actions extends Piwik_Plugin
+class Piwik_Actions extends Plugin
 {
     const ACTIONS_REPORT_ROWS_DISPLAY = 100;
     
@@ -572,7 +574,7 @@ class Piwik_Actions extends Piwik_Plugin
      * For each action we process the "interest statistics" :
      * visits, unique visitors, bounce count, sum visit length.
      */
-    public function archiveDay(Piwik_ArchiveProcessor_Day $archiveProcessor)
+    public function archiveDay(ArchiveProcessor\Day $archiveProcessor)
     {
         $archiving = new Piwik_Actions_Archiver($archiveProcessor);
         if($archiving->shouldArchive()) {
@@ -580,7 +582,7 @@ class Piwik_Actions extends Piwik_Plugin
         }
     }
 
-    function archivePeriod(Piwik_ArchiveProcessor_Period $archiveProcessor)
+    function archivePeriod(ArchiveProcessor\Period $archiveProcessor)
     {
         $archiving = new Piwik_Actions_Archiver($archiveProcessor);
         if($archiving->shouldArchive()) {
@@ -597,7 +599,7 @@ class Piwik_Actions extends Piwik_Plugin
 
     static protected function isCustomVariablesPluginsEnabled()
     {
-        return PluginsManager::getInstance()->isPluginActivated('CustomVariables');
+        return \Piwik\PluginsManager::getInstance()->isPluginActivated('CustomVariables');
     }
 
     /**
@@ -711,7 +713,7 @@ class Piwik_Actions extends Piwik_Plugin
         );
         
         // prettify avg_time_on_page column
-        $getPrettyTimeFromSeconds = array('Piwik', 'getPrettyTimeFromSeconds');
+        $getPrettyTimeFromSeconds = '\Piwik\Piwik::getPrettyTimeFromSeconds';
         $result['filters'][] = array('ColumnCallbackReplace', array('avg_time_on_page', $getPrettyTimeFromSeconds));
         
         // prettify avg_time_generation column
diff --git a/plugins/Actions/Archiver.php b/plugins/Actions/Archiver.php
index f512bd36ea..987bf5104a 100644
--- a/plugins/Actions/Archiver.php
+++ b/plugins/Actions/Archiver.php
@@ -9,14 +9,18 @@
  * @package Piwik_Actions
  */
 use Piwik\Config;
+use Piwik\DataTable\Manager;
+use Piwik\DataTable\Row\DataTableSummaryRow;
 use Piwik\Metrics;
+use Piwik\DataTable;
+use Piwik\PluginsArchiver;
 
 /**
  * Class encapsulating logic to process Day/Period Archiving for the Actions reports
  *
  * @package Piwik_Actions
  */
-class Piwik_Actions_Archiver extends Piwik_PluginsArchiver
+class Piwik_Actions_Archiver extends PluginsArchiver
 {
     const DOWNLOADS_RECORD_NAME = 'Actions_downloads';
     const OUTLINKS_RECORD_NAME = 'Actions_outlink';
@@ -152,7 +156,7 @@ class Piwik_Actions_Archiver extends Piwik_PluginsArchiver
     {
         $this->actionsTablesByType = array();
         foreach (self::$actionTypes as $type) {
-            $dataTable = new Piwik_DataTable();
+            $dataTable = new DataTable();
             $dataTable->setMaximumAllowedRows(Piwik_Actions_ArchivingHelper::$maximumRowsInDataTableLevelZero);
 
             if ($type == Piwik_Tracker_Action::TYPE_ACTION_URL
@@ -212,7 +216,7 @@ class Piwik_Actions_Archiver extends Piwik_PluginsArchiver
         $rankingQuery = false;
         if ($rankingQueryLimit > 0) {
             $rankingQuery = new Piwik_RankingQuery($rankingQueryLimit);
-            $rankingQuery->setOthersLabel(Piwik_DataTable::LABEL_SUMMARY_ROW);
+            $rankingQuery->setOthersLabel(DataTable::LABEL_SUMMARY_ROW);
             $rankingQuery->addLabelColumn(array('idaction', 'name'));
             $rankingQuery->addColumn(array('url_prefix', Metrics::INDEX_NB_UNIQ_VISITORS));
             $rankingQuery->addColumn(array(Metrics::INDEX_PAGE_NB_HITS, Metrics::INDEX_NB_VISITS), 'sum');
@@ -291,7 +295,7 @@ class Piwik_Actions_Archiver extends Piwik_PluginsArchiver
         $rankingQuery = false;
         if ($rankingQueryLimit > 0) {
             $rankingQuery = new Piwik_RankingQuery($rankingQueryLimit);
-            $rankingQuery->setOthersLabel(Piwik_DataTable::LABEL_SUMMARY_ROW);
+            $rankingQuery->setOthersLabel(DataTable::LABEL_SUMMARY_ROW);
             $rankingQuery->addLabelColumn('idaction');
             $rankingQuery->addColumn(Metrics::INDEX_PAGE_ENTRY_NB_UNIQ_VISITORS);
             $rankingQuery->addColumn(array(Metrics::INDEX_PAGE_ENTRY_NB_VISITS,
@@ -342,7 +346,7 @@ class Piwik_Actions_Archiver extends Piwik_PluginsArchiver
         $rankingQuery = false;
         if ($rankingQueryLimit > 0) {
             $rankingQuery = new Piwik_RankingQuery($rankingQueryLimit);
-            $rankingQuery->setOthersLabel(Piwik_DataTable::LABEL_SUMMARY_ROW);
+            $rankingQuery->setOthersLabel(DataTable::LABEL_SUMMARY_ROW);
             $rankingQuery->addLabelColumn('idaction');
             $rankingQuery->addColumn(Metrics::INDEX_PAGE_EXIT_NB_UNIQ_VISITORS);
             $rankingQuery->addColumn(Metrics::INDEX_PAGE_EXIT_NB_VISITS, 'sum');
@@ -388,7 +392,7 @@ class Piwik_Actions_Archiver extends Piwik_PluginsArchiver
         $rankingQuery = false;
         if ($rankingQueryLimit > 0) {
             $rankingQuery = new Piwik_RankingQuery($rankingQueryLimit);
-            $rankingQuery->setOthersLabel(Piwik_DataTable::LABEL_SUMMARY_ROW);
+            $rankingQuery->setOthersLabel(DataTable::LABEL_SUMMARY_ROW);
             $rankingQuery->addLabelColumn('idaction');
             $rankingQuery->addColumn(Metrics::INDEX_PAGE_SUM_TIME_SPENT, 'sum');
             $rankingQuery->partitionResultIntoMultipleGroups('type', array_keys($this->actionsTablesByType));
@@ -454,7 +458,7 @@ class Piwik_Actions_Archiver extends Piwik_PluginsArchiver
 
     /**
      * @param $typeId
-     * @return Piwik_DataTable
+     * @return DataTable
      */
     protected function getDataTable($typeId)
     {
@@ -472,20 +476,20 @@ class Piwik_Actions_Archiver extends Piwik_PluginsArchiver
      * For rows which have subtables (eg. directories with sub pages),
      * deletes columns which don't make sense when all values of sub pages are summed.
      *
-     * @param $dataTable Piwik_DataTable
+     * @param $dataTable DataTable
      */
     static public function deleteInvalidSummedColumnsFromDataTable($dataTable)
     {
         foreach ($dataTable->getRows() as $id => $row) {
             if (($idSubtable = $row->getIdSubDataTable()) !== null
-                || $id === Piwik_DataTable::ID_SUMMARY_ROW
+                || $id === DataTable::ID_SUMMARY_ROW
             ) {
                 if ($idSubtable !== null) {
-                    $subtable = Piwik_DataTable_Manager::getInstance()->getTable($idSubtable);
+                    $subtable = Manager::getInstance()->getTable($idSubtable);
                     self::deleteInvalidSummedColumnsFromDataTable($subtable);
                 }
 
-                if ($row instanceof Piwik_DataTable_Row_DataTableSummary) {
+                if ($row instanceof DataTableSummaryRow) {
                     $row->recalculate();
                 }
 
diff --git a/plugins/Actions/ArchivingHelper.php b/plugins/Actions/ArchivingHelper.php
index 514b75116b..2e885a435e 100644
--- a/plugins/Actions/ArchivingHelper.php
+++ b/plugins/Actions/ArchivingHelper.php
@@ -9,7 +9,9 @@
  * @package Piwik_Actions
  */
 use Piwik\Config;
+use Piwik\DataTable\Row;
 use Piwik\Metrics;
+use Piwik\DataTable;
 
 /**
  * This static class provides:
@@ -55,7 +57,7 @@ class Piwik_Actions_ArchivingHelper
             ) {
                 $url = null;
             } elseif (!empty($row['name'])
-                && $row['name'] != Piwik_DataTable::LABEL_SUMMARY_ROW
+                && $row['name'] != DataTable::LABEL_SUMMARY_ROW
             ) {
                 $url = Piwik_Tracker_Action::reconstructNormalizedUrl((string)$row['name'], $row['url_prefix']);
             }
@@ -70,7 +72,7 @@ class Piwik_Actions_ArchivingHelper
 
                 // in some unknown case, the type field is NULL, as reported in #1082 - we ignore this page view
                 if (empty($actionType)) {
-                    if ($idaction != Piwik_DataTable::LABEL_SUMMARY_ROW) {
+                    if ($idaction != DataTable::LABEL_SUMMARY_ROW) {
                         self::setCachedActionRow($idaction, $actionType, false);
                     }
                     continue;
@@ -97,7 +99,7 @@ class Piwik_Actions_ArchivingHelper
             // This is to ensure that when, different URLs are loaded with the same page name.
             // For example http://piwik.org and http://id.piwik.org are reported in Piwik > Actions > Pages with /index
             // But, we must make sure http://piwik.org is used to link & for transitions
-            // Note: this code is partly duplicated from Piwik_DataTable_Row->sumRowMetadata()
+            // Note: this code is partly duplicated from Row->sumRowMetadata()
             if (!is_null($url)
                 && !$actionRow->isSummaryRow()
             ) {
@@ -220,7 +222,7 @@ class Piwik_Actions_ArchivingHelper
         self::$maximumRowsInDataTableLevelZero = Config::getInstance()->General['datatable_archiving_maximum_rows_actions'];
         self::$maximumRowsInSubDataTable = Config::getInstance()->General['datatable_archiving_maximum_rows_subtable_actions'];
 
-        Piwik_DataTable::setMaximumDepthLevelAllowedAtLeast(self::getSubCategoryLevelLimit() + 1);
+        DataTable::setMaximumDepthLevelAllowedAtLeast(self::getSubCategoryLevelLimit() + 1);
     }
 
 
@@ -229,7 +231,7 @@ class Piwik_Actions_ArchivingHelper
      * there could be pages that have exit/entry hits, but don't yet
      * have a record in the table (or the record was truncated).
      *
-     * @return Piwik_DataTable_Row
+     * @return Row
      */
     static private function getDefaultRow()
     {
@@ -238,8 +240,8 @@ class Piwik_Actions_ArchivingHelper
             // This row is used in the case where an action is know as an exit_action
             // but this action was not properly recorded when it was hit in the first place
             // so we add this fake row information to make sure there is a nb_hits, etc. column for every action
-            $row = new Piwik_DataTable_Row(array(
-                                                Piwik_DataTable_Row::COLUMNS => array(
+            $row = new Row(array(
+                                                Row::COLUMNS => array(
                                                     Metrics::INDEX_NB_VISITS        => 1,
                                                     Metrics::INDEX_NB_UNIQ_VISITORS => 1,
                                                     Metrics::INDEX_PAGE_NB_HITS     => 1,
@@ -256,17 +258,17 @@ class Piwik_Actions_ArchivingHelper
      * @param int $actionType
      * @param int $urlPrefix
      * @param array $actionsTablesByType
-     * @return Piwik_DataTable
+     * @return DataTable
      */
     protected static function getActionRow($actionName, $actionType, $urlPrefix = null, &$actionsTablesByType)
     {
         // we work on the root table of the given TYPE (either ACTION_URL or DOWNLOAD or OUTLINK etc.)
-        /* @var Piwik_DataTable $currentTable */
+        /* @var DataTable $currentTable */
         $currentTable =& $actionsTablesByType[$actionType];
 
         // check for ranking query cut-off
-        if ($actionName == Piwik_DataTable::LABEL_SUMMARY_ROW) {
-            $summaryRow = $currentTable->getRowFromId(Piwik_DataTable::ID_SUMMARY_ROW);
+        if ($actionName == DataTable::LABEL_SUMMARY_ROW) {
+            $summaryRow = $currentTable->getRowFromId(DataTable::ID_SUMMARY_ROW);
             if ($summaryRow === false) {
                 $summaryRow = $currentTable->addSummaryRow(self::createSummaryRow());
             }
@@ -296,11 +298,11 @@ class Piwik_Actions_ArchivingHelper
      *  we explode link http://piwik.org/some/path into an array( 'some', 'path' );
      *
      * for action names:
-     *   we explode name 'Piwik / Category 1 / Category 2' into an array('Piwik', 'Category 1', 'Category 2');
+     *   we explode name 'Piwik / Category 1 / Category 2' into an array('\Piwik\Piwik', 'Category 1', 'Category 2');
      *
-     * @param string action name
-     * @param int action type
-     * @param int url prefix (only used for TYPE_ACTION_URL)
+     * @param string $name action name
+     * @param int $type action type
+     * @param int $urlPrefix url prefix (only used for TYPE_ACTION_URL)
      * @return array of exploded elements from $name
      */
     static public function getActionExplodedNames($name, $type, $urlPrefix = null)
@@ -402,7 +404,7 @@ class Piwik_Actions_ArchivingHelper
      */
     private static function getCachedActionRowKey($idAction, $actionType)
     {
-        return $idAction == Piwik_DataTable::LABEL_SUMMARY_ROW
+        return $idAction == DataTable::LABEL_SUMMARY_ROW
             ? $actionType . '_others'
             : $idAction;
     }
@@ -451,7 +453,7 @@ class Piwik_Actions_ArchivingHelper
      *
      * @param int $idAction
      * @param int $actionType
-     * @return Piwik_DataTable_Row|false
+     * @return Row|false
      */
     private static function getCachedActionRow($idAction, $actionType)
     {
@@ -472,7 +474,7 @@ class Piwik_Actions_ArchivingHelper
      *
      * @param int $idAction
      * @param int $actionType
-     * @param Piwik_DataTable_Row
+     * @param \DataTable\Row
      */
     private static function setCachedActionRow($idAction, $actionType, $actionRow)
     {
@@ -496,13 +498,13 @@ class Piwik_Actions_ArchivingHelper
     /**
      * Creates a summary row for an Actions DataTable.
      *
-     * @return Piwik_DataTable_Row
+     * @return Row
      */
     private static function createSummaryRow()
     {
-        return new Piwik_DataTable_Row(array(
-                                            Piwik_DataTable_Row::COLUMNS =>
-                                            array('label' => Piwik_DataTable::LABEL_SUMMARY_ROW) + self::getDefaultRowColumns()
+        return new Row(array(
+                                            Row::COLUMNS =>
+                                            array('label' => DataTable::LABEL_SUMMARY_ROW) + self::getDefaultRowColumns()
                                        ));
     }
 }
diff --git a/plugins/Actions/Controller.php b/plugins/Actions/Controller.php
index 6044c225d8..f90ad12f28 100644
--- a/plugins/Actions/Controller.php
+++ b/plugins/Actions/Controller.php
@@ -49,7 +49,7 @@ class Piwik_Actions_Controller extends Piwik_Controller
         $view->noResultKeywords = $this->getSiteSearchNoResultKeywords(true);
         $view->pagesUrlsFollowingSiteSearch = $this->getPageUrlsFollowingSiteSearch(true);
 
-        $categoryTrackingEnabled = PluginsManager::getInstance()->isPluginActivated('CustomVariables');
+        $categoryTrackingEnabled = \Piwik\PluginsManager::getInstance()->isPluginActivated('CustomVariables');
         if ($categoryTrackingEnabled) {
             $view->categories = $this->getSiteSearchCategories(true);
         }
diff --git a/plugins/Annotations/API.php b/plugins/Annotations/API.php
index 603cce5431..8e2ec1c167 100755
--- a/plugins/Annotations/API.php
+++ b/plugins/Annotations/API.php
@@ -9,8 +9,9 @@
  * @package Piwik_Annotations
  */
 use Piwik\Period;
-use Piwik\Period_Range;
+use Piwik\Period\Range;
 use Piwik\Piwik;
+use Piwik\Date;
 
 /**
  * @see plugins/Annotations/AnnotationList.php
@@ -248,7 +249,7 @@ class Piwik_Annotations_API
                     && $result[$idSite][$strDate]['count'] == 1
                 ) {
                     $annotationsForSite = $annotations->search(
-                        $date, Piwik_Date::factory($nextDate->getTimestamp() - 1), $idSite);
+                        $date, Date::factory($nextDate->getTimestamp() - 1), $idSite);
                     $annotation = reset($annotationsForSite[$idSite]);
 
                     $result[$idSite][$strDate]['note'] = $annotation['note'];
@@ -318,9 +319,9 @@ class Piwik_Annotations_API
             || $period == 'range'
         ) {
             if ($period == 'range') {
-                $oPeriod = new Period_Range('day', $date);
+                $oPeriod = new Range('day', $date);
             } else {
-                $oPeriod = Period::factory($period, Piwik_Date::factory($date));
+                $oPeriod = Period::factory($period, Date::factory($date));
             }
 
             $startDate = $oPeriod->getDateStart();
@@ -331,8 +332,8 @@ class Piwik_Annotations_API
                 Piwik_ViewDataTable_GenerateGraphHTML_ChartEvolution::getDateRangeAndLastN($period, $date, $lastN);
             list($startDate, $endDate) = explode(',', $date);
 
-            $startDate = Piwik_Date::factory($startDate);
-            $endDate = Piwik_Date::factory($endDate);
+            $startDate = Date::factory($startDate);
+            $endDate = Date::factory($endDate);
         }
         return array($startDate, $endDate);
     }
@@ -361,6 +362,6 @@ class Piwik_Annotations_API
             return;
         }
 
-        Piwik_Date::factory($date);
+        Date::factory($date);
     }
 }
diff --git a/plugins/Annotations/AnnotationList.php b/plugins/Annotations/AnnotationList.php
index 4d15e91e50..0f5ba42ae9 100755
--- a/plugins/Annotations/AnnotationList.php
+++ b/plugins/Annotations/AnnotationList.php
@@ -9,6 +9,7 @@
  * @package Piwik_Annotations
  */
 use Piwik\Piwik;
+use Piwik\Date;
 use Piwik\Site;
 
 /**
@@ -172,7 +173,6 @@ class Piwik_Annotations_AnnotationList
      *
      * @param int $idSite The ID of the site to get an annotation for.
      * @param int $idNote The ID of the note to get.
-     * @param array The annotation.
      * @throws Exception if $idSite is not an ID that was supplied upon construction.
      * @throws Exception if $idNote does not refer to valid note for the site.
      */
@@ -194,8 +194,8 @@ class Piwik_Annotations_AnnotationList
      *
      * @see self::get for info on what attributes stored within annotations.
      *
-     * @param Piwik_Date|bool $startDate The start of the date range.
-     * @param Piwik_Date|bool $endDate The end of the date range.
+     * @param Date|bool $startDate The start of the date range.
+     * @param Date|bool $endDate The end of the date range.
      * @param array|bool|int|string $idSite IDs of the sites whose annotations to
      *                                       search through.
      * @return array Array mapping site IDs with arrays of annotations, eg:
@@ -230,7 +230,7 @@ class Piwik_Annotations_AnnotationList
 
             foreach ($this->annotations[$idSite] as $idNote => $annotation) {
                 if ($startDate !== false) {
-                    $annotationDate = Piwik_Date::factory($annotation['date']);
+                    $annotationDate = Date::factory($annotation['date']);
                     if ($annotationDate->getTimestamp() < $startDate->getTimestamp()
                         || $annotationDate->getTimestamp() > $endDate->getTimestamp()
                     ) {
@@ -266,7 +266,7 @@ class Piwik_Annotations_AnnotationList
         $this->checkIdSiteIsLoaded($idSite);
 
         // search includes end date, and count should not, so subtract one from the timestamp
-        $annotations = $this->search($startDate, Piwik_Date::factory($endDate->getTimestamp() - 1));
+        $annotations = $this->search($startDate, Date::factory($endDate->getTimestamp() - 1));
 
         // count the annotations
         $count = $starred = 0;
diff --git a/plugins/Annotations/Annotations.php b/plugins/Annotations/Annotations.php
index 1ef39eeee6..5b29ec48b5 100755
--- a/plugins/Annotations/Annotations.php
+++ b/plugins/Annotations/Annotations.php
@@ -8,6 +8,7 @@
  * @category Piwik_Plugins
  * @package Piwik_Annotations
  */
+use Piwik\Plugin;
 
 /**
  * Annotations plugins. Provides the ability to attach text notes to
@@ -15,7 +16,7 @@
  *
  * @package Piwik_Annotations
  */
-class Piwik_Annotations extends Piwik_Plugin
+class Piwik_Annotations extends Plugin
 {
     /**
      * @see Piwik_Plugin::getListHooksRegistered
diff --git a/plugins/AnonymizeIP/AnonymizeIP.php b/plugins/AnonymizeIP/AnonymizeIP.php
index a835a91d8a..7d6ce520a9 100644
--- a/plugins/AnonymizeIP/AnonymizeIP.php
+++ b/plugins/AnonymizeIP/AnonymizeIP.php
@@ -10,13 +10,14 @@
  */
 use Piwik\Config;
 use Piwik\Common;
+use Piwik\Plugin;
 
 /**
  * Anonymize visitor IP addresses to comply with the privacy laws/guidelines in countries, such as Germany.
  *
  * @package Piwik_AnonymizeIP
  */
-class Piwik_AnonymizeIP extends Piwik_Plugin
+class Piwik_AnonymizeIP extends Plugin
 {
     /**
      * @see Piwik_Plugin::getInformation
diff --git a/plugins/CoreAdminHome/API.php b/plugins/CoreAdminHome/API.php
index d9bf9b4cee..fe6772fe09 100644
--- a/plugins/CoreAdminHome/API.php
+++ b/plugins/CoreAdminHome/API.php
@@ -8,9 +8,13 @@
  * @category Piwik_Plugins
  * @package Piwik_CoreAdminHome
  */
+use Piwik\DataAccess\ArchiveTableCreator;
 use Piwik\Period;
+use Piwik\Period\Week;
 use Piwik\Piwik;
+use Piwik\Config;
 use Piwik\Common;
+use Piwik\Date;
 use Piwik\Site;
 
 /**
@@ -85,7 +89,7 @@ class Piwik_CoreAdminHome_API
         $dates = array_unique($dates);
         foreach ($dates as $theDate) {
             try {
-                $date = Piwik_Date::factory($theDate);
+                $date = Date::factory($theDate);
             } catch (Exception $e) {
                 $invalidDates[] = $theDate;
                 continue;
@@ -105,13 +109,13 @@ class Piwik_CoreAdminHome_API
         if ($logsDeleteEnabled
             && $logsAreDeletedBeforeThisDate
         ) {
-            $minimumDateWithLogs = Piwik_Date::factory('today')->subDay($logsAreDeletedBeforeThisDate);
+            $minimumDateWithLogs = Date::factory('today')->subDay($logsAreDeletedBeforeThisDate);
         }
 
         // Given the list of dates, process which tables they should be deleted from
         $minDate = false;
         $warningDates = $processedDates = array();
-        /* @var $date Piwik_Date */
+        /* @var $date Date */
         foreach ($toInvalidate as $date) {
             // we should only delete reports for dates that are more recent than N days
             if ($minimumDateWithLogs
@@ -131,7 +135,7 @@ class Piwik_CoreAdminHome_API
             $datesByMonth[$year][] = $date->toString();
 
             // but also weeks overlapping several months stored in the month where the week is starting
-            /* @var $week Piwik_Period_Week */
+            /* @var $week Week */
             $week = Period::factory('week', $date);
             $weekAsString = $week->getDateStart()->toString('Y_m');
             $datesByMonth[$weekAsString][] = $date->toString();
@@ -146,10 +150,10 @@ class Piwik_CoreAdminHome_API
 
         // In each table, invalidate day/week/month/year containing this date
         $sqlIdSites = implode(",", $idSites);
-        $archiveTables = Piwik_DataAccess_ArchiveTableCreator::getTablesArchivesInstalled();
+        $archiveTables = ArchiveTableCreator::getTablesArchivesInstalled();
         foreach ($archiveTables as $table) {
             // Extract Y_m from table name
-            $suffix = Piwik_DataAccess_ArchiveTableCreator::getDateFromTableName($table);
+            $suffix = ArchiveTableCreator::getDateFromTableName($table);
             if (!isset($datesByMonth[$suffix])) {
                 continue;
             }
diff --git a/plugins/CoreAdminHome/Controller.php b/plugins/CoreAdminHome/Controller.php
index 612a9e1c3e..5bae81c756 100644
--- a/plugins/CoreAdminHome/Controller.php
+++ b/plugins/CoreAdminHome/Controller.php
@@ -8,6 +8,7 @@
  * @category Piwik_Plugins
  * @package Piwik_CoreAdminHome
  */
+use Piwik\ArchiveProcessor\Rules;
 use Piwik\Config;
 use Piwik\Piwik;
 use Piwik\Common;
@@ -33,8 +34,8 @@ class Piwik_CoreAdminHome_Controller extends Piwik_Controller_Admin
         $view = new Piwik_View('@CoreAdminHome/generalSettings');
 
         if (Piwik::isUserIsSuperUser()) {
-            $enableBrowserTriggerArchiving = Piwik_ArchiveProcessor_Rules::isBrowserTriggerEnabled();
-            $todayArchiveTimeToLive = Piwik_ArchiveProcessor_Rules::getTodayArchiveTimeToLive();
+            $enableBrowserTriggerArchiving = Rules::isBrowserTriggerEnabled();
+            $todayArchiveTimeToLive = Rules::getTodayArchiveTimeToLive();
             $showWarningCron = false;
             if (!$enableBrowserTriggerArchiving
                 && $todayArchiveTimeToLive < 3600
@@ -83,8 +84,8 @@ class Piwik_CoreAdminHome_Controller extends Piwik_Controller_Admin
             $enableBrowserTriggerArchiving = Common::getRequestVar('enableBrowserTriggerArchiving');
             $todayArchiveTimeToLive = Common::getRequestVar('todayArchiveTimeToLive');
 
-            Piwik_ArchiveProcessor_Rules::setBrowserTriggerArchiving((bool)$enableBrowserTriggerArchiving);
-            Piwik_ArchiveProcessor_Rules::setTodayArchiveTimeToLive($todayArchiveTimeToLive);
+            Rules::setBrowserTriggerArchiving((bool)$enableBrowserTriggerArchiving);
+            Rules::setTodayArchiveTimeToLive($todayArchiveTimeToLive);
 
             // Update email settings
             $mail = array();
diff --git a/plugins/CoreAdminHome/CoreAdminHome.php b/plugins/CoreAdminHome/CoreAdminHome.php
index 110feb03b6..39a4f08199 100644
--- a/plugins/CoreAdminHome/CoreAdminHome.php
+++ b/plugins/CoreAdminHome/CoreAdminHome.php
@@ -8,13 +8,17 @@
  * @category Piwik_Plugins
  * @package Piwik_CoreAdminHome
  */
+use Piwik\DataAccess\ArchiveSelector;
+use Piwik\DataAccess\ArchiveTableCreator;
 use Piwik\Piwik;
+use Piwik\Date;
+use Piwik\Plugin;
 
 /**
  *
  * @package Piwik_CoreAdminHome
  */
-class Piwik_CoreAdminHome extends Piwik_Plugin
+class Piwik_CoreAdminHome extends Plugin
 {
     /**
      * @see Piwik_Plugin::getListHooksRegistered
@@ -72,10 +76,10 @@ class Piwik_CoreAdminHome extends Piwik_Plugin
 
     function addMenu()
     {
-        Piwik_AddAdminSubMenu('CoreAdminHome_MenuManage', NULL, "", Piwik::isUserHasSomeAdminAccess(), $order = 1);
-        Piwik_AddAdminSubMenu('CoreAdminHome_MenuCommunity', NULL, "", Piwik::isUserHasSomeAdminAccess(), $order = 3);
-        Piwik_AddAdminSubMenu('CoreAdminHome_MenuDiagnostic', NULL, "", Piwik::isUserHasSomeAdminAccess(), $order = 20);
-        Piwik_AddAdminSubMenu('General_Settings', NULL, "", Piwik::isUserHasSomeAdminAccess(), $order = 5);
+        Piwik_AddAdminSubMenu('CoreAdminHome_MenuManage', null, "", Piwik::isUserHasSomeAdminAccess(), $order = 1);
+        Piwik_AddAdminSubMenu('CoreAdminHome_MenuCommunity', null, "", Piwik::isUserHasSomeAdminAccess(), $order = 3);
+        Piwik_AddAdminSubMenu('CoreAdminHome_MenuDiagnostic', null, "", Piwik::isUserHasSomeAdminAccess(), $order = 20);
+        Piwik_AddAdminSubMenu('General_Settings', null, "", Piwik::isUserHasSomeAdminAccess(), $order = 5);
         Piwik_AddAdminSubMenu('General_Settings', 'CoreAdminHome_MenuGeneralSettings',
             array('module' => 'CoreAdminHome', 'action' => 'generalSettings'),
             Piwik::isUserHasSomeAdminAccess(),
@@ -89,17 +93,17 @@ class Piwik_CoreAdminHome extends Piwik_Plugin
 
     function purgeOutdatedArchives()
     {
-        $archiveTables = Piwik_DataAccess_ArchiveTableCreator::getTablesArchivesInstalled();
+        $archiveTables = ArchiveTableCreator::getTablesArchivesInstalled();
         foreach ($archiveTables as $table) {
-            $date = Piwik_DataAccess_ArchiveTableCreator::getDateFromTableName($table);
+            $date = ArchiveTableCreator::getDateFromTableName($table);
             list($month, $year) = explode('_', $date);
-            Piwik_DataAccess_ArchiveSelector::purgeOutdatedArchives(Piwik_Date::factory("$year-$month-15"));
+            ArchiveSelector::purgeOutdatedArchives(Date::factory("$year-$month-15"));
         }
     }
 
     function optimizeArchiveTable()
     {
-        $archiveTables = Piwik_DataAccess_ArchiveTableCreator::getTablesArchivesInstalled();
+        $archiveTables = ArchiveTableCreator::getTablesArchivesInstalled();
         Piwik_OptimizeTables($archiveTables);
     }
 }
diff --git a/plugins/CoreHome/Controller.php b/plugins/CoreHome/Controller.php
index 08eabcbf82..c95b5d61ce 100644
--- a/plugins/CoreHome/Controller.php
+++ b/plugins/CoreHome/Controller.php
@@ -10,6 +10,7 @@
  */
 use Piwik\Piwik;
 use Piwik\Common;
+use Piwik\Date;
 use Piwik\Site;
 
 /**
@@ -31,7 +32,7 @@ class Piwik_CoreHome_Controller extends Piwik_Controller
 
         // User preference: default report to load is the All Websites dashboard
         if ($defaultReport == 'MultiSites'
-            && PluginsManager::getInstance()->isPluginActivated('MultiSites')
+            && \Piwik\PluginsManager::getInstance()->isPluginActivated('MultiSites')
         ) {
             $module = 'MultiSites';
         }
@@ -76,8 +77,8 @@ class Piwik_CoreHome_Controller extends Piwik_Controller
         if ($websiteId) {
             $website = new Site($websiteId);
             $datetimeCreationDate = $this->site->getCreationDate()->getDatetime();
-            $creationDateLocalTimezone = Piwik_Date::factory($datetimeCreationDate, $website->getTimezone())->toString('Y-m-d');
-            $todayLocalTimezone = Piwik_Date::factory('now', $website->getTimezone())->toString('Y-m-d');
+            $creationDateLocalTimezone = Date::factory($datetimeCreationDate, $website->getTimezone())->toString('Y-m-d');
+            $todayLocalTimezone = Date::factory('now', $website->getTimezone())->toString('Y-m-d');
             if ($creationDateLocalTimezone == $todayLocalTimezone) {
                 Piwik::redirectToModule('CoreHome', 'index',
                     array('date'   => 'today',
diff --git a/plugins/CoreHome/CoreHome.php b/plugins/CoreHome/CoreHome.php
index 07820ffe01..56c4dbbfd2 100644
--- a/plugins/CoreHome/CoreHome.php
+++ b/plugins/CoreHome/CoreHome.php
@@ -8,12 +8,13 @@
  * @category Piwik_Plugins
  * @package Piwik_CoreHome
  */
+use Piwik\Plugin;
 
 /**
  *
  * @package Piwik_CoreHome
  */
-class Piwik_CoreHome extends Piwik_Plugin
+class Piwik_CoreHome extends Plugin
 {
     /**
      * @see Piwik_Plugin::getListHooksRegistered
diff --git a/plugins/CoreHome/DataTableRowAction/RowEvolution.php b/plugins/CoreHome/DataTableRowAction/RowEvolution.php
index 4d16253e6b..3b3bea686c 100644
--- a/plugins/CoreHome/DataTableRowAction/RowEvolution.php
+++ b/plugins/CoreHome/DataTableRowAction/RowEvolution.php
@@ -10,6 +10,7 @@
  */
 use Piwik\Common;
 use Piwik\Metrics;
+use Piwik\Date;
 
 /**
  * ROW EVOLUTION
@@ -45,7 +46,7 @@ class Piwik_CoreHome_DataTableRowAction_RowEvolution
 
     /**
      * The data
-     * @var Piwik_DataTable_Array
+     * @var DataTable
      */
     protected $dataTable;
 
@@ -68,7 +69,7 @@ class Piwik_CoreHome_DataTableRowAction_RowEvolution
      * The constructor
      * Initialize some local variables from the request
      * @param int $idSite
-     * @param Piwik_Date $date ($this->date from controller)
+     * @param Date $date ($this->date from controller)
      * @param null|string $graphType
      * @throws Exception
      */
diff --git a/plugins/CoreHome/templates/_dataTable.twig b/plugins/CoreHome/templates/_dataTable.twig
index d6b51d34f1..73eb6f1143 100644
--- a/plugins/CoreHome/templates/_dataTable.twig
+++ b/plugins/CoreHome/templates/_dataTable.twig
@@ -1,3 +1,4 @@
+{% set summaryRowId = -1 %}{# ID_SUMMARY_ROW #}
 {% set isSubtable = javascriptVariablesToSet.idSubtable is defined and javascriptVariablesToSet.idSubtable != 0 %}
 <div class="dataTable {{ properties.datatable_css_class }} {% if isSubtable %}subDataTable{% endif %}"
      data-table-type="{{ properties.datatable_js_type|default('dataTable') }}"
@@ -26,7 +27,7 @@
                     <tbody>
                     {% for rowId, row in dataTable.getRows() %}
                         {%- set rowHasSubtable = row.getIdSubDataTable() and javascriptVariablesToSet.controllerActionCalledWhenRequestSubTable is not null -%}
-                        {%- set shouldHighlightRow = rowId == constant("Piwik_DataTable::ID_SUMMARY_ROW") and properties.highlight_summary_row -%}
+                        {%- set shouldHighlightRow = rowId == summaryRowId and properties.highlight_summary_row -%}
                         
                         {# display this row if it doesn't have a subtable or if we don't replace the row with the subtable #}
                         {% if not rowHasSubtable or not properties.show_expanded|default(false) or not properties.replace_row_with_subtable|default(false) %}
diff --git a/plugins/CorePluginsAdmin/Controller.php b/plugins/CorePluginsAdmin/Controller.php
index 64f7be4bb3..ff0900073e 100644
--- a/plugins/CorePluginsAdmin/Controller.php
+++ b/plugins/CorePluginsAdmin/Controller.php
@@ -10,6 +10,7 @@
  */
 use Piwik\Piwik;
 use Piwik\Common;
+use Piwik\Config;
 
 /**
  *
@@ -51,21 +52,21 @@ class Piwik_CorePluginsAdmin_Controller extends Piwik_Controller_Admin
         $plugins = array();
 
         $listPlugins = array_merge(
-            PluginsManager::getInstance()->readPluginsDirectory(),
+            \Piwik\PluginsManager::getInstance()->readPluginsDirectory(),
             Config::getInstance()->Plugins['Plugins']
         );
         $listPlugins = array_unique($listPlugins);
         foreach ($listPlugins as $pluginName) {
-            PluginsManager::getInstance()->loadPlugin($pluginName);
+            \Piwik\PluginsManager::getInstance()->loadPlugin($pluginName);
             $plugins[$pluginName] = array(
-                'activated'       => PluginsManager::getInstance()->isPluginActivated($pluginName),
-                'alwaysActivated' => PluginsManager::getInstance()->isPluginAlwaysActivated($pluginName),
-                'uninstallable'   => PluginsManager::getInstance()->isPluginUninstallable($pluginName),
+                'activated'       => \Piwik\PluginsManager::getInstance()->isPluginActivated($pluginName),
+                'alwaysActivated' => \Piwik\PluginsManager::getInstance()->isPluginAlwaysActivated($pluginName),
+                'uninstallable'   => \Piwik\PluginsManager::getInstance()->isPluginUninstallable($pluginName),
             );
         }
-        PluginsManager::getInstance()->loadPluginTranslations();
+        \Piwik\PluginsManager::getInstance()->loadPluginTranslations();
 
-        $loadedPlugins = PluginsManager::getInstance()->getLoadedPlugins();
+        $loadedPlugins = \Piwik\PluginsManager::getInstance()->getLoadedPlugins();
         foreach ($loadedPlugins as $oPlugin) {
             $pluginName = $oPlugin->getPluginName();
             $plugins[$pluginName]['info'] = $oPlugin->getInformation();
@@ -107,7 +108,7 @@ class Piwik_CorePluginsAdmin_Controller extends Piwik_Controller_Admin
     public function deactivate($redirectAfter = true)
     {
         $pluginName = $this->initPluginModification();
-        PluginsManager::getInstance()->deactivatePlugin($pluginName);
+        \Piwik\PluginsManager::getInstance()->deactivatePlugin($pluginName);
         $this->redirectAfterModification($redirectAfter);
     }
 
@@ -129,14 +130,14 @@ class Piwik_CorePluginsAdmin_Controller extends Piwik_Controller_Admin
     public function activate($redirectAfter = true)
     {
         $pluginName = $this->initPluginModification();
-        PluginsManager::getInstance()->activatePlugin($pluginName);
+        \Piwik\PluginsManager::getInstance()->activatePlugin($pluginName);
         $this->redirectAfterModification($redirectAfter);
     }
 
     public function uninstall($redirectAfter = true)
     {
         $pluginName = $this->initPluginModification();
-        $uninstalled = PluginsManager::getInstance()->uninstallPlugin($pluginName);
+        $uninstalled = \Piwik\PluginsManager::getInstance()->uninstallPlugin($pluginName);
         if(!$uninstalled) {
             $path = Common::getPathToPiwikRoot() . '/plugins/' . $pluginName . '/';
             $messagePermissions = Piwik::getErrorMessageMissingPermissions($path);
diff --git a/plugins/CorePluginsAdmin/CorePluginsAdmin.php b/plugins/CorePluginsAdmin/CorePluginsAdmin.php
index c7e856b91e..fe4e9d8780 100644
--- a/plugins/CorePluginsAdmin/CorePluginsAdmin.php
+++ b/plugins/CorePluginsAdmin/CorePluginsAdmin.php
@@ -9,12 +9,13 @@
  * @package Piwik_CorePluginsAdmin
  */
 use Piwik\Piwik;
+use Piwik\Plugin;
 
 /**
  *
  * @package Piwik_CorePluginsAdmin
  */
-class Piwik_CorePluginsAdmin extends Piwik_Plugin
+class Piwik_CorePluginsAdmin extends Plugin
 {
     /**
      * @see Piwik_Plugin::getListHooksRegistered
diff --git a/plugins/CoreUpdater/Controller.php b/plugins/CoreUpdater/Controller.php
index 87f1beb634..11e0c9c7d1 100644
--- a/plugins/CoreUpdater/Controller.php
+++ b/plugins/CoreUpdater/Controller.php
@@ -8,6 +8,7 @@
  * @category Piwik_Plugins
  * @package Piwik_CoreUpdater
  */
+use Piwik\ArchiveProcessor\Rules;
 use Piwik\Config;
 use Piwik\Piwik;
 use Piwik\Common;
@@ -166,7 +167,7 @@ class Piwik_CoreUpdater_Controller extends Piwik_Controller
         /*
          * Make sure the execute bit is set for this shell script
          */
-        if (!Piwik_ArchiveProcessor_Rules::isBrowserTriggerEnabled()) {
+        if (!Rules::isBrowserTriggerEnabled()) {
             @chmod($this->pathRootExtractedPiwik . '/misc/cron/archive.sh', 0755);
         }
 
@@ -345,7 +346,7 @@ class Piwik_CoreUpdater_Controller extends Piwik_Controller
                     $this->coreError = true;
                     break;
                 } else {
-                    PluginsManager::getInstance()->deactivatePlugin($name);
+                    \Piwik\PluginsManager::getInstance()->deactivatePlugin($name);
                     $this->deactivatedPlugins[] = $name;
                 }
             }
diff --git a/plugins/CoreUpdater/CoreUpdater.php b/plugins/CoreUpdater/CoreUpdater.php
index 4c35b42029..99c7e4029d 100644
--- a/plugins/CoreUpdater/CoreUpdater.php
+++ b/plugins/CoreUpdater/CoreUpdater.php
@@ -10,12 +10,13 @@
  */
 use Piwik\Piwik;
 use Piwik\Common;
+use Piwik\Plugin;
 
 /**
  *
  * @package Piwik_CoreUpdater
  */
-class Piwik_CoreUpdater extends Piwik_Plugin
+class Piwik_CoreUpdater extends Plugin
 {
     /**
      * @see Piwik_Plugin::getListHooksRegistered
@@ -32,7 +33,7 @@ class Piwik_CoreUpdater extends Piwik_Plugin
     public static function getComponentUpdates(Piwik_Updater $updater)
     {
         $updater->addComponentToCheck('core', Piwik_Version::VERSION);
-        $plugins = PluginsManager::getInstance()->getLoadedPlugins();
+        $plugins = \Piwik\PluginsManager::getInstance()->getLoadedPlugins();
         foreach ($plugins as $pluginName => $plugin) {
             $updater->addComponentToCheck($pluginName, $plugin->getVersion());
         }
diff --git a/plugins/CustomVariables/API.php b/plugins/CustomVariables/API.php
index 800b916886..bfe38b7240 100644
--- a/plugins/CustomVariables/API.php
+++ b/plugins/CustomVariables/API.php
@@ -10,6 +10,8 @@
  */
 use Piwik\Archive;
 use Piwik\Metrics;
+use Piwik\Date;
+use Piwik\DataTable;
 
 /**
  * The Custom Variables API lets you access reports for your <a href='http://piwik.org/docs/custom-variables/' target='_blank'>Custom Variables</a> names and values.
@@ -34,12 +36,12 @@ class Piwik_CustomVariables_API
     /**
      * @param int $idSite
      * @param string $period
-     * @param Piwik_Date $date
+     * @param Date $date
      * @param string $segment
      * @param bool $expanded
      * @param int $idSubtable
      *
-     * @return Piwik_DataTable|Piwik_DataTable_Array
+     * @return DataTable|DataTable\Map
      */
     protected function getDataTable($idSite, $period, $date, $segment, $expanded, $idSubtable)
     {
@@ -53,18 +55,18 @@ class Piwik_CustomVariables_API
     /**
      * @param int $idSite
      * @param string $period
-     * @param Piwik_Date $date
+     * @param Date $date
      * @param string|bool $segment
      * @param bool $expanded
      * @param bool $_leavePiwikCoreVariables
      *
-     * @return Piwik_DataTable|Piwik_DataTable_Array
+     * @return DataTable|DataTable\Map
      */
     public function getCustomVariables($idSite, $period, $date, $segment = false, $expanded = false, $_leavePiwikCoreVariables = false)
     {
         $dataTable = $this->getDataTable($idSite, $period, $date, $segment, $expanded, $idSubtable = null);
 
-        if ($dataTable instanceof Piwik_DataTable
+        if ($dataTable instanceof DataTable
             && !$_leavePiwikCoreVariables
         ) {
             $mapping = self::getReservedCustomVariableKeys();
@@ -90,12 +92,12 @@ class Piwik_CustomVariables_API
     /**
      * @param int $idSite
      * @param string $period
-     * @param Piwik_Date $date
+     * @param Date $date
      * @param int $idSubtable
      * @param string|bool $segment
      * @param bool $_leavePriceViewedColumn
      *
-     * @return Piwik_DataTable|Piwik_DataTable_Array
+     * @return DataTable|DataTable\Map
      */
     public function getCustomVariablesValuesFromNameId($idSite, $period, $date, $idSubtable, $segment = false, $_leavePriceViewedColumn = false)
     {
diff --git a/plugins/CustomVariables/Archiver.php b/plugins/CustomVariables/Archiver.php
index 08b15ec865..654cf22835 100644
--- a/plugins/CustomVariables/Archiver.php
+++ b/plugins/CustomVariables/Archiver.php
@@ -1,7 +1,9 @@
 <?php
 use Piwik\Common;
 use Piwik\Config;
+use Piwik\DataAccess\LogAggregator;
 use Piwik\Metrics;
+use Piwik\PluginsArchiver;
 
 /**
  * Piwik - Open source web analytics
@@ -13,7 +15,7 @@ use Piwik\Metrics;
  * @package Piwik_CustomVariables
  */
 
-class Piwik_CustomVariables_Archiver extends Piwik_PluginsArchiver
+class Piwik_CustomVariables_Archiver extends PluginsArchiver
 {
     const LABEL_CUSTOM_VALUE_NOT_DEFINED = "Value not defined";
     const CUSTOM_VARIABLE_RECORD_NAME = 'CustomVariables_valueByName';
@@ -78,7 +80,7 @@ class Piwik_CustomVariables_Archiver extends Piwik_PluginsArchiver
 
     protected function getSelectAveragePrice()
     {
-        return Piwik_DataAccess_LogAggregator::getSqlRevenue("AVG(log_link_visit_action.custom_var_v2)")
+        return LogAggregator::getSqlRevenue("AVG(log_link_visit_action.custom_var_v2)")
             . " as `" . Metrics::INDEX_ECOMMERCE_ITEM_PRICE_VIEWED . "`";
     }
 
diff --git a/plugins/CustomVariables/CustomVariables.php b/plugins/CustomVariables/CustomVariables.php
index 9a402c192f..971a967b8e 100644
--- a/plugins/CustomVariables/CustomVariables.php
+++ b/plugins/CustomVariables/CustomVariables.php
@@ -8,11 +8,13 @@
  * @category Piwik_Plugins
  * @package Piwik_CustomVariables
  */
+use Piwik\ArchiveProcessor;
+use Piwik\Plugin;
 
 /**
  * @package Piwik_CustomVariables
  */
-class Piwik_CustomVariables extends Piwik_Plugin
+class Piwik_CustomVariables extends Plugin
 {
     public function getInformation()
     {
@@ -130,7 +132,7 @@ class Piwik_CustomVariables extends Piwik_Plugin
     /**
      * Hooks on daily archive to trigger various log processing
      */
-    public function archiveDay(Piwik_ArchiveProcessor_Day $archiveProcessor)
+    public function archiveDay(ArchiveProcessor\Day $archiveProcessor)
     {
         $archiving = new Piwik_CustomVariables_Archiver($archiveProcessor);
         if($archiving->shouldArchive()) {
@@ -138,7 +140,7 @@ class Piwik_CustomVariables extends Piwik_Plugin
         }
     }
 
-    public function archivePeriod(Piwik_ArchiveProcessor_Period $archiveProcessor)
+    public function archivePeriod(ArchiveProcessor\Period $archiveProcessor)
     {
         $archiving = new Piwik_CustomVariables_Archiver($archiveProcessor);
         if($archiving->shouldArchive()) {
diff --git a/plugins/DBStats/API.php b/plugins/DBStats/API.php
index 0c4a4d1e53..46b3666c02 100644
--- a/plugins/DBStats/API.php
+++ b/plugins/DBStats/API.php
@@ -10,6 +10,7 @@
  */
 use Piwik\Piwik;
 use Piwik\Common;
+use Piwik\DataTable;
 
 /**
  * @see plugins/DBStats/MySQLMetadataProvider.php
@@ -100,7 +101,7 @@ class Piwik_DBStats_API
      * This function will group tracker tables, numeric archive tables, blob archive tables
      * and other tables together so only four rows are shown.
      *
-     * @return Piwik_DataTable A datatable with three columns: 'data_size', 'index_size', 'row_count'.
+     * @return DataTable A datatable with three columns: 'data_size', 'index_size', 'row_count'.
      */
     public function getDatabaseUsageSummary()
     {
@@ -130,13 +131,13 @@ class Piwik_DBStats_API
             $rowToAddTo['row_count'] += $status['Rows'];
         }
 
-        return Piwik_DataTable::makeFromIndexedArray($rows);
+        return DataTable::makeFromIndexedArray($rows);
     }
 
     /**
      * Returns a datatable describing how much space is taken up by each log table.
      *
-     * @return Piwik_DataTable A datatable with three columns: 'data_size', 'index_size', 'row_count'.
+     * @return DataTable A datatable with three columns: 'data_size', 'index_size', 'row_count'.
      */
     public function getTrackerDataSummary()
     {
@@ -148,7 +149,7 @@ class Piwik_DBStats_API
      * Returns a datatable describing how much space is taken up by each numeric
      * archive table.
      *
-     * @return Piwik_DataTable A datatable with three columns: 'data_size', 'index_size', 'row_count'.
+     * @return DataTable A datatable with three columns: 'data_size', 'index_size', 'row_count'.
      */
     public function getMetricDataSummary()
     {
@@ -160,7 +161,7 @@ class Piwik_DBStats_API
      * Returns a datatable describing how much space is taken up by each numeric
      * archive table, grouped by year.
      *
-     * @return Piwik_DataTable A datatable with three columns: 'data_size', 'index_size', 'row_count'.
+     * @return DataTable A datatable with three columns: 'data_size', 'index_size', 'row_count'.
      */
     public function getMetricDataSummaryByYear()
     {
@@ -178,7 +179,7 @@ class Piwik_DBStats_API
      * Returns a datatable describing how much space is taken up by each blob
      * archive table.
      *
-     * @return Piwik_DataTable A datatable with three columns: 'data_size', 'index_size', 'row_count'.
+     * @return DataTable A datatable with three columns: 'data_size', 'index_size', 'row_count'.
      */
     public function getReportDataSummary()
     {
@@ -190,7 +191,7 @@ class Piwik_DBStats_API
      * Returns a datatable describing how much space is taken up by each blob
      * archive table, grouped by year.
      *
-     * @return Piwik_DataTable A datatable with three columns: 'data_size', 'index_size', 'row_count'.
+     * @return DataTable A datatable with three columns: 'data_size', 'index_size', 'row_count'.
      */
     public function getReportDataSummaryByYear()
     {
@@ -210,7 +211,7 @@ class Piwik_DBStats_API
      * An 'admin' table is a table that is not central to analytics functionality.
      * So any table that isn't an archive table or a log table is an 'admin' table.
      *
-     * @return Piwik_DataTable A datatable with three columns: 'data_size', 'index_size', 'row_count'.
+     * @return DataTable A datatable with three columns: 'data_size', 'index_size', 'row_count'.
      */
     public function getAdminDataSummary()
     {
@@ -226,7 +227,7 @@ class Piwik_DBStats_API
      *
      * @param bool $forceCache false to use the cached result, true to run the queries again and
      *                         cache the result.
-     * @return Piwik_DataTable A datatable with three columns: 'data_size', 'index_size', 'row_count'.
+     * @return DataTable A datatable with three columns: 'data_size', 'index_size', 'row_count'.
      */
     public function getIndividualReportsSummary($forceCache = false)
     {
@@ -242,7 +243,7 @@ class Piwik_DBStats_API
      *
      * @param bool $forceCache false to use the cached result, true to run the queries again and
      *                         cache the result.
-     * @return Piwik_DataTable A datatable with three columns: 'data_size', 'index_size', 'row_count'.
+     * @return DataTable A datatable with three columns: 'data_size', 'index_size', 'row_count'.
      */
     public function getIndividualMetricsSummary($forceCache = false)
     {
@@ -254,11 +255,11 @@ class Piwik_DBStats_API
      * Returns a datatable representation of a set of table statuses.
      *
      * @param array $statuses The table statuses to summarize.
-     * @return Piwik_DataTable
+     * @return DataTable
      */
     private function getTablesSummary($statuses)
     {
-        $dataTable = new Piwik_DataTable();
+        $dataTable = new DataTable();
         foreach ($statuses as $status) {
             $dataTable->addRowFromSimpleArray(array(
                                                    'label'      => $status['Name'],
diff --git a/plugins/DBStats/Controller.php b/plugins/DBStats/Controller.php
index caf2241e14..7596dc4106 100644
--- a/plugins/DBStats/Controller.php
+++ b/plugins/DBStats/Controller.php
@@ -313,7 +313,7 @@ class Piwik_DBStats_Controller extends Piwik_Controller_Admin
             }
         }
 
-        $getPrettySize = array('Piwik', 'getPrettySizeFromBytes');
+        $getPrettySize = '\Piwik\Piwik::getPrettySizeFromBytes';
         $params = $fixedMemoryUnit === false ? array() : array($fixedMemoryUnit);
         $view->queueFilter(
             'ColumnCallbackReplace', array($sizeColumns, $getPrettySize, $params), $runPrettySizeFilterBeforeGeneric);
@@ -324,8 +324,7 @@ class Piwik_DBStats_Controller extends Piwik_Controller_Admin
             $view->queueFilter('ColumnCallbackReplace', array($sizeColumns, $replaceSpaces));
         }
 
-        $getPrettyNumber = array('Piwik', 'getPrettyNumber');
-        $view->queueFilter('ColumnCallbackReplace', array(array('row_count'), $getPrettyNumber));
+        $view->queueFilter('ColumnCallbackReplace', array(array('row_count'), '\Piwik\Piwik::getPrettyNumber'));
 
         return $view;
     }
diff --git a/plugins/DBStats/DBStats.php b/plugins/DBStats/DBStats.php
index fd649d5b1e..770e00f0ed 100644
--- a/plugins/DBStats/DBStats.php
+++ b/plugins/DBStats/DBStats.php
@@ -9,12 +9,14 @@
  * @package Piwik_DBStats
  */
 use Piwik\Piwik;
+use Piwik\Date;
+use Piwik\Plugin;
 
 /**
  *
  * @package Piwik_DBStats
  */
-class Piwik_DBStats extends Piwik_Plugin
+class Piwik_DBStats extends Plugin
 {
     const TIME_OF_LAST_TASK_RUN_OPTION = 'dbstats_time_of_last_cache_task_run';
 
@@ -63,7 +65,7 @@ class Piwik_DBStats extends Piwik_Plugin
         $api->getIndividualReportsSummary(true);
         $api->getIndividualMetricsSummary(true);
 
-        $now = Piwik_Date::now()->getLocalized("%longYear%, %shortMonth% %day%");
+        $now = Date::now()->getLocalized("%longYear%, %shortMonth% %day%");
         Piwik_SetOption(self::TIME_OF_LAST_TASK_RUN_OPTION, $now);
     }
 
diff --git a/plugins/DBStats/MySQLMetadataProvider.php b/plugins/DBStats/MySQLMetadataProvider.php
index 9641d2d788..c7701e6023 100755
--- a/plugins/DBStats/MySQLMetadataProvider.php
+++ b/plugins/DBStats/MySQLMetadataProvider.php
@@ -10,6 +10,8 @@
  */
 use Piwik\Piwik;
 use Piwik\Common;
+use Piwik\Config;
+use Piwik\DataTable;
 
 /**
  * Utility class that provides general information about databases, including the size of
@@ -175,7 +177,7 @@ class Piwik_DBStats_MySQLMetadataProvider
      *
      * @param bool $forceCache false to use the cached result, true to run the queries again and
      *                         cache the result.
-     * @return Piwik_DataTable
+     * @return DataTable
      */
     public function getRowCountsAndSizeByBlobName($forceCache = false)
     {
@@ -194,7 +196,7 @@ class Piwik_DBStats_MySQLMetadataProvider
      *
      * @param bool $forceCache false to use the cached result, true to run the queries again and
      *                         cache the result.
-     * @return Piwik_DataTable
+     * @return DataTable
      */
     public function getRowCountsAndSizeByMetricName($forceCache = false)
     {
@@ -216,20 +218,20 @@ class Piwik_DBStats_MySQLMetadataProvider
 
         $cols = array_merge(array('row_count'), $otherDataTableColumns);
 
-        $dataTable = new Piwik_DataTable();
+        $dataTable = new DataTable();
         foreach ($statuses as $status) {
             $dataTableOptionName = $this->getCachedOptionName($status['Name'], 'byArchiveName');
 
             // if option exists && !$forceCache, use the cached data, otherwise create the
             $cachedData = Piwik_GetOption($dataTableOptionName);
             if ($cachedData !== false && !$forceCache) {
-                $table = new Piwik_DataTable();
+                $table = new DataTable();
                 $table->addRowsFromSerializedArray($cachedData);
             } else {
                 // otherwise, create data table & cache it
                 $sql = "SELECT name as 'label', COUNT(*) as 'row_count'$extraCols FROM {$status['Name']} GROUP BY name";
 
-                $table = new Piwik_DataTable();
+                $table = new DataTable();
                 $table->addRowsFromSimpleArray(Piwik_FetchAll($sql));
 
                 $reduceArchiveRowName = array($this, 'reduceArchiveRowName');
diff --git a/plugins/Dashboard/Controller.php b/plugins/Dashboard/Controller.php
index f91718d097..0f6cca6d00 100644
--- a/plugins/Dashboard/Controller.php
+++ b/plugins/Dashboard/Controller.php
@@ -7,6 +7,7 @@
  * @category Piwik_Plugins
  * @package  Piwik_Dashboard
  */
+use Piwik\DataTable\Renderer\Json;
 use Piwik\Piwik;
 use Piwik\Common;
 
@@ -66,7 +67,7 @@ class Piwik_Dashboard_Controller extends Piwik_Controller
     {
         $this->checkTokenInUrl();
 
-        Piwik_DataTable_Renderer_Json::sendHeaderJSON();
+        Json::sendHeaderJSON();
         echo Common::json_encode(Piwik_GetWidgetsList());
     }
 
@@ -157,7 +158,7 @@ class Piwik_Dashboard_Controller extends Piwik_Controller
         $this->checkTokenInUrl();
         
         if (Piwik::isUserIsAnonymous()) {
-            Piwik_DataTable_Renderer_Json::sendHeaderJSON();
+            Json::sendHeaderJSON();
             echo '[]';
             
             return;
@@ -166,7 +167,7 @@ class Piwik_Dashboard_Controller extends Piwik_Controller
         $login      = Piwik::getCurrentUserLogin();
         $dashboards = $this->dashboard->getAllDashboards($login);
 
-        Piwik_DataTable_Renderer_Json::sendHeaderJSON();
+        Json::sendHeaderJSON();
         echo Common::json_encode($dashboards);
     }
 
@@ -197,7 +198,7 @@ class Piwik_Dashboard_Controller extends Piwik_Controller
             Common::prefixTable('user_dashboard'));
         Piwik_Query($query, array($user, $nextId, $name, $layout));
 
-        Piwik_DataTable_Renderer_Json::sendHeaderJSON();
+        Json::sendHeaderJSON();
         echo Common::json_encode($nextId);
     }
 
@@ -235,7 +236,7 @@ class Piwik_Dashboard_Controller extends Piwik_Controller
                 Common::prefixTable('user_dashboard'));
             Piwik_Query($query, array($user, $nextId, $name, $layout));
 
-            Piwik_DataTable_Renderer_Json::sendHeaderJSON();
+            Json::sendHeaderJSON();
             echo Common::json_encode($nextId);
             return;
         }
diff --git a/plugins/Dashboard/Dashboard.php b/plugins/Dashboard/Dashboard.php
index 7548104be9..25fb766226 100644
--- a/plugins/Dashboard/Dashboard.php
+++ b/plugins/Dashboard/Dashboard.php
@@ -10,12 +10,13 @@
  */
 use Piwik\Piwik;
 use Piwik\Common;
+use Piwik\Plugin;
 use Piwik\Site;
 
 /**
  * @package Piwik_Dashboard
  */
-class Piwik_Dashboard extends Piwik_Plugin
+class Piwik_Dashboard extends Plugin
 {
     /**
      * @see Piwik_Plugin::getListHooksRegistered
diff --git a/plugins/DevicesDetection/API.php b/plugins/DevicesDetection/API.php
index 3117122c96..1800849fcf 100644
--- a/plugins/DevicesDetection/API.php
+++ b/plugins/DevicesDetection/API.php
@@ -12,6 +12,7 @@
 use Piwik\Archive;
 use Piwik\Metrics;
 use Piwik\Piwik;
+use Piwik\DataTable;
 
 /**
  * The DevicesDetection API lets you access reports on your visitors devices, brands, models, Operating system, Browsers.
@@ -58,7 +59,7 @@ class Piwik_DevicesDetection_API
      * @param string $period
      * @param string $date
      * @param bool|string $segment
-     * @return Piwik_DataTable
+     * @return DataTable
      */
     public function getType($idSite, $period, $date, $segment = false)
     {
@@ -75,7 +76,7 @@ class Piwik_DevicesDetection_API
      * @param string $period
      * @param string $date
      * @param bool|string $segment
-     * @return Piwik_DataTable
+     * @return DataTable
      */
     public function getBrand($idSite, $period, $date, $segment = false)
     {
@@ -91,7 +92,7 @@ class Piwik_DevicesDetection_API
      * @param string $period
      * @param string $date
      * @param bool|string $segment
-     * @return Piwik_DataTable
+     * @return DataTable
      */
     public function getModel($idSite, $period, $date, $segment = false)
     {
@@ -106,7 +107,7 @@ class Piwik_DevicesDetection_API
      * @param string $period
      * @param string $date
      * @param bool|string $segment
-     * @return Piwik_DataTable
+     * @return DataTable
      */
     public function getOsFamilies($idSite, $period, $date, $segment = false)
     {
@@ -122,7 +123,7 @@ class Piwik_DevicesDetection_API
      * @param string $period
      * @param string $date
      * @param bool|string $segment
-     * @return Piwik_DataTable
+     * @return DataTable
      */
     public function getOsVersions($idSite, $period, $date, $segment = false)
     {
@@ -139,7 +140,7 @@ class Piwik_DevicesDetection_API
      * @param string $period
      * @param string $date
      * @param bool|string $segment
-     * @return Piwik_DataTable
+     * @return DataTable
      */
     public function getBrowserFamilies($idSite, $period, $date, $segment = false)
     {
@@ -155,7 +156,7 @@ class Piwik_DevicesDetection_API
      * @param string $period
      * @param string $date
      * @param bool|string $segment
-     * @return Piwik_DataTable
+     * @return DataTable
      */
     public function getBrowserVersions($idSite, $period, $date, $segment = false)
     {
diff --git a/plugins/DevicesDetection/Archiver.php b/plugins/DevicesDetection/Archiver.php
index 6bf0288894..73a66fb67d 100644
--- a/plugins/DevicesDetection/Archiver.php
+++ b/plugins/DevicesDetection/Archiver.php
@@ -10,8 +10,9 @@
  */
 
 use Piwik\Metrics;
+use Piwik\PluginsArchiver;
 
-class Piwik_DevicesDetection_Archiver extends Piwik_PluginsArchiver
+class Piwik_DevicesDetection_Archiver extends PluginsArchiver
 {
     const DEVICE_TYPE_RECORD_NAME = 'DevicesDetection_types';
     const DEVICE_BRAND_RECORD_NAME = 'DevicesDetection_brands';
diff --git a/plugins/DevicesDetection/DevicesDetection.php b/plugins/DevicesDetection/DevicesDetection.php
index 2a734b24e4..7129ee581b 100644
--- a/plugins/DevicesDetection/DevicesDetection.php
+++ b/plugins/DevicesDetection/DevicesDetection.php
@@ -9,13 +9,15 @@
  * @category Piwik_Plugins
  * @package Piwik_DevicesDetection
  */
+use Piwik\ArchiveProcessor;
 use Piwik\Config;
 use Piwik\Common;
+use Piwik\Plugin;
 
 require_once PIWIK_INCLUDE_PATH . "/plugins/DevicesDetection/UserAgentParserEnhanced/UserAgentParserEnhanced.php";
 require_once PIWIK_INCLUDE_PATH . '/plugins/DevicesDetection/functions.php';
 
-class Piwik_DevicesDetection extends Piwik_Plugin
+class Piwik_DevicesDetection extends Plugin
 {
     /**
      * @see Piwik_Plugin::getInformation
@@ -229,7 +231,7 @@ class Piwik_DevicesDetection extends Piwik_Plugin
         Common::printDebug($deviceInfo);
     }
 
-    public function archiveDay(Piwik_ArchiveProcessor_Day $archiveProcessor)
+    public function archiveDay(ArchiveProcessor\Day $archiveProcessor)
     {
         $archiving = new Piwik_DevicesDetection_Archiver($archiveProcessor);
         if($archiving->shouldArchive()) {
@@ -237,7 +239,7 @@ class Piwik_DevicesDetection extends Piwik_Plugin
         }
     }
 
-    public function archivePeriod(Piwik_ArchiveProcessor_Period $archiveProcessor)
+    public function archivePeriod(ArchiveProcessor\Period $archiveProcessor)
     {
         $archiving = new Piwik_DevicesDetection_Archiver($archiveProcessor);
         if($archiving->shouldArchive()) {
diff --git a/plugins/DoNotTrack/DoNotTrack.php b/plugins/DoNotTrack/DoNotTrack.php
index 2b8409d394..2ea56e3d0f 100644
--- a/plugins/DoNotTrack/DoNotTrack.php
+++ b/plugins/DoNotTrack/DoNotTrack.php
@@ -8,6 +8,8 @@
  * @category Piwik_Plugins
  * @package Piwik_DoNotTrack
  */
+use Piwik\Plugin;
+use Piwik\Common;
 
 /**
  * Ignore visits where user agent's request contains either:
@@ -16,7 +18,7 @@
  *
  * @package Piwik_DoNotTrack
  */
-class Piwik_DoNotTrack extends Piwik_Plugin
+class Piwik_DoNotTrack extends Plugin
 {
     /**
      * @see Piwik_Plugin::getListHooksRegistered
diff --git a/plugins/ExampleAPI/API.php b/plugins/ExampleAPI/API.php
index 163d265c27..d4a0febccf 100644
--- a/plugins/ExampleAPI/API.php
+++ b/plugins/ExampleAPI/API.php
@@ -8,7 +8,9 @@
  * @category Piwik_Plugins
  * @package Piwik_ExampleAPI
  */
+use Piwik\DataTable\Row;
 use Piwik\Piwik;
+use Piwik\DataTable;
 
 /**
  * The ExampleAPI is useful to developers building a custom Piwik plugin.
@@ -126,13 +128,13 @@ class Piwik_ExampleAPI_API
      * This data table will be converted to all available formats
      * when requested in the API request.
      *
-     * @return Piwik_DataTable
+     * @return DataTable
      */
     public function getCompetitionDatatable()
     {
-        $dataTable = new Piwik_DataTable();
+        $dataTable = new DataTable();
 
-        $row1 = new Piwik_DataTable_Row();
+        $row1 = new Row();
         $row1->setColumns(array('name' => 'piwik', 'license' => 'GPL'));
 
         // Rows Metadata is useful to store non stats data for example (logos, urls, etc.)
diff --git a/plugins/ExampleAPI/ExampleAPI.php b/plugins/ExampleAPI/ExampleAPI.php
index 7c96f96c19..da1c3f4c52 100644
--- a/plugins/ExampleAPI/ExampleAPI.php
+++ b/plugins/ExampleAPI/ExampleAPI.php
@@ -8,12 +8,13 @@
  * @category Piwik_Plugins
  * @package Piwik_ExampleAPI
  */
+use Piwik\Plugin;
 
 /**
  * ExampleAPI plugin
  *
  * @package Piwik_ExampleAPI
  */
-class Piwik_ExampleAPI extends Piwik_Plugin
+class Piwik_ExampleAPI extends Plugin
 {
 }
diff --git a/plugins/ExamplePlugin/Controller.php b/plugins/ExamplePlugin/Controller.php
index 7ff7a79042..3e6c557130 100644
--- a/plugins/ExamplePlugin/Controller.php
+++ b/plugins/ExamplePlugin/Controller.php
@@ -73,7 +73,7 @@ class Piwik_ExamplePlugin_Controller extends Piwik_Controller
         $out .= '<h2>General</h2>';
         $out .= '<h3>Accessible from your plugin controller</h3>';
 
-        $out .= '<code>$this->date</code> = current selected <b>Piwik_Date</b> object (<a href="https://github.com/piwik/piwik/blob/master/core/Date.php">class</a>)<br />';
+        $out .= '<code>$this->date</code> = current selected <b>Date</b> object (<a href="https://github.com/piwik/piwik/blob/master/core/Date.php">class</a>)<br />';
         $out .= '<code>$period = Common::getRequestVar("period");</code> - Get the current selected period<br />';
         $out .= '<code>$idSite = Common::getRequestVar("idSite");</code> - Get the selected idSite<br />';
         $out .= '<code>$site = new Site($idSite);</code> - Build the Site object (<a href="https://github.com/piwik/piwik/tree/master/core/Site.php">class</a>)<br />';
diff --git a/plugins/ExamplePlugin/ExamplePlugin.php b/plugins/ExamplePlugin/ExamplePlugin.php
index a3143b34bb..7fc7a2cc09 100644
--- a/plugins/ExamplePlugin/ExamplePlugin.php
+++ b/plugins/ExamplePlugin/ExamplePlugin.php
@@ -8,12 +8,13 @@
  * @category Piwik_Plugins
  * @package Piwik_ExamplePlugin
  */
+use Piwik\Plugin;
 
 /**
  *
  * @package Piwik_ExamplePlugin
  */
-class Piwik_ExamplePlugin extends Piwik_Plugin
+class Piwik_ExamplePlugin extends Plugin
 {
     /**
      * @see Piwik_Plugin::getListHooksRegistered
diff --git a/plugins/ExampleRssWidget/ExampleRssWidget.php b/plugins/ExampleRssWidget/ExampleRssWidget.php
index eeb4d78157..72831e6d0b 100644
--- a/plugins/ExampleRssWidget/ExampleRssWidget.php
+++ b/plugins/ExampleRssWidget/ExampleRssWidget.php
@@ -8,12 +8,13 @@
  * @category Piwik_Plugins
  * @package Piwik_ExampleRssWidget
  */
+use Piwik\Plugin;
 
 /**
  *
  * @package Piwik_ExampleRssWidget
  */
-class Piwik_ExampleRssWidget extends Piwik_Plugin
+class Piwik_ExampleRssWidget extends Plugin
 {
     /**
      * @see Piwik_Plugin::getListHooksRegistered
diff --git a/plugins/ExampleUI/API.php b/plugins/ExampleUI/API.php
index 87bc64a88c..5857ef112b 100644
--- a/plugins/ExampleUI/API.php
+++ b/plugins/ExampleUI/API.php
@@ -8,7 +8,8 @@
  * @category Piwik_Plugins
  * @package Piwik_ExampleUI
  */
-use Piwik\Period_Range;
+use Piwik\Period\Range;
+use Piwik\DataTable;
 
 /**
  * ExampleUI API is also an example API useful if you are developing a Piwik plugin.
@@ -32,7 +33,7 @@ class Piwik_ExampleUI_API
 
     public function getTemperaturesEvolution($date, $period)
     {
-        $period = new Period_Range($period, 'last30');
+        $period = new Range($period, 'last30');
         $dateStart = $period->getDateStart()->toString('Y-m-d'); // eg. "2009-04-01"
         $dateEnd = $period->getDateEnd()->toString('Y-m-d'); // eg. "2009-04-30"
 
@@ -51,7 +52,7 @@ class Piwik_ExampleUI_API
             $value = array('server1' => $server1, 'server2' => $server2);
             $temperatures[$subPeriod->getLocalizedShortString()] = $value;
         }
-        return Piwik_DataTable::makeFromIndexedArray($temperatures);
+        return DataTable::makeFromIndexedArray($temperatures);
     }
 
     // we generate an array of random server temperatures
@@ -68,7 +69,7 @@ class Piwik_ExampleUI_API
             $temperatures[$xAxisLabel] = $temperatureValues[$i];
         }
 
-        return Piwik_DataTable::makeFromIndexedArray($temperatures);
+        return DataTable::makeFromIndexedArray($temperatures);
     }
 
     public function getPlanetRatios()
@@ -84,7 +85,7 @@ class Piwik_ExampleUI_API
             'Neptune' => 3.883,
         );
         // convert this array to a DataTable object
-        return Piwik_DataTable::makeFromIndexedArray($planetRatios);
+        return DataTable::makeFromIndexedArray($planetRatios);
     }
 
     public function getPlanetRatiosWithLogos()
diff --git a/plugins/ExampleUI/ExampleUI.php b/plugins/ExampleUI/ExampleUI.php
index 6808be9109..4e1210cf14 100644
--- a/plugins/ExampleUI/ExampleUI.php
+++ b/plugins/ExampleUI/ExampleUI.php
@@ -18,12 +18,13 @@
 - without all columns icon
 + update http://piwik.org/participate/user-interface
 */
+use Piwik\Plugin;
 
 /**
  *
  * @package Piwik_ExampleUI
  */
-class Piwik_ExampleUI extends Piwik_Plugin
+class Piwik_ExampleUI extends Plugin
 {
     /**
      * @see Piwik_Plugin::getListHooksRegistered
diff --git a/plugins/Feedback/Feedback.php b/plugins/Feedback/Feedback.php
index 5217def3d4..522c09fe96 100644
--- a/plugins/Feedback/Feedback.php
+++ b/plugins/Feedback/Feedback.php
@@ -8,12 +8,13 @@
  * @category Piwik_Plugins
  * @package Piwik_Feedback
  */
+use Piwik\Plugin;
 
 /**
  *
  * @package Piwik_Feedback
  */
-class Piwik_Feedback extends Piwik_Plugin
+class Piwik_Feedback extends Plugin
 {
 
     /**
diff --git a/plugins/Goals/API.php b/plugins/Goals/API.php
index 5d0d0eab5c..db754b3bb3 100644
--- a/plugins/Goals/API.php
+++ b/plugins/Goals/API.php
@@ -12,6 +12,7 @@ use Piwik\Archive;
 use Piwik\Metrics;
 use Piwik\Piwik;
 use Piwik\Common;
+use Piwik\DataTable;
 use Piwik\Site;
 
 /**
@@ -249,11 +250,11 @@ class Piwik_Goals_API
         $customVarNameToLookFor = $mapping[$recordName];
 
         // Handle case where date=last30&period=day
-        if ($customVariables instanceof Piwik_DataTable_Array) {
+        if ($customVariables instanceof DataTable\Map) {
             $customVariableDatatables = $customVariables->getArray();
             $dataTables = $dataTable->getArray();
             foreach ($customVariableDatatables as $key => $customVariableTableForDate) {
-                $dataTableForDate = isset($dataTables[$key]) ? $dataTables[$key] : new Piwik_DataTable();
+                $dataTableForDate = isset($dataTables[$key]) ? $dataTables[$key] : new DataTable();
 
                 // we do not enter the IF
                 // if case idSite=1,3 AND period=day&date=datefrom,dateto,
@@ -268,7 +269,7 @@ class Piwik_Goals_API
                 }
                 $this->renameNotDefinedRow($dataTableForDate, $notDefinedStringPretty);
             }
-        } elseif ($customVariables instanceof Piwik_DataTable) {
+        } elseif ($customVariables instanceof DataTable) {
             $row = $customVariables->getRowFromLabel($customVarNameToLookFor);
             if ($row) {
                 $idSubtable = $row->getIdSubDataTable();
@@ -285,7 +286,7 @@ class Piwik_Goals_API
 
     protected function renameNotDefinedRow($dataTable, $notDefinedStringPretty)
     {
-        if ($dataTable instanceof Piwik_DataTable_Array) {
+        if ($dataTable instanceof DataTable\Map) {
             foreach ($dataTable->getArray() as $table) {
                 $this->renameNotDefinedRow($table, $notDefinedStringPretty);
             }
@@ -369,7 +370,7 @@ class Piwik_Goals_API
      * @param bool $segment
      * @param bool|int $idGoal
      * @param array $columns Array of metrics to fetch: nb_conversions, conversion_rate, revenue
-     * @return Piwik_DataTable
+     * @return DataTable
      */
     public function get($idSite, $period, $date, $segment = false, $idGoal = false, $columns = array())
     {
@@ -404,7 +405,7 @@ class Piwik_Goals_API
             $dataTable->renameColumn($oldName, $columns[$id]);
         }
         if ($idGoal == Piwik::LABEL_ID_GOAL_IS_ECOMMERCE_ORDER) {
-            if ($dataTable instanceof Piwik_DataTable_Array) {
+            if ($dataTable instanceof DataTable\Map) {
                 foreach ($dataTable->getArray() as $row) {
                     $this->enrichTable($row);
                 }
@@ -482,7 +483,7 @@ class Piwik_Goals_API
      * @param string $segment The segment.
      * @param int|bool $idGoal The id of the goal to get data for. If this is set to false,
      *                         data for every goal that belongs to $idSite is returned.
-     * @return false|Piwik_DataTable
+     * @return false|DataTable
      */
     protected function getGoalSpecificDataTable($recordName, $idSite, $period, $date, $segment, $idGoal)
     {
@@ -510,7 +511,7 @@ class Piwik_Goals_API
      * @param string|bool $segment The segment.
      * @param int|bool $idGoal The id of the goal to get data for. If this is set to false,
      *                         data for every goal that belongs to $idSite is returned.
-     * @return false|Piwik_DataTable
+     * @return false|DataTable
      */
     public function getDaysToConversion($idSite, $period, $date, $segment = false, $idGoal = false)
     {
@@ -534,7 +535,7 @@ class Piwik_Goals_API
      * @param string|bool $segment The segment.
      * @param int|bool $idGoal The id of the goal to get data for. If this is set to false,
      *                         data for every goal that belongs to $idSite is returned.
-     * @return bool|Piwik_DataTable
+     * @return bool|DataTable
      */
     public function getVisitsUntilConversion($idSite, $period, $date, $segment = false, $idGoal = false)
     {
diff --git a/plugins/Goals/Archiver.php b/plugins/Goals/Archiver.php
index a22cc9ef98..96792174c1 100644
--- a/plugins/Goals/Archiver.php
+++ b/plugins/Goals/Archiver.php
@@ -9,9 +9,12 @@
  * @package Piwik_Goals
  */
 
+use Piwik\DataAccess\LogAggregator;
 use Piwik\Metrics;
+use Piwik\DataTable;
+use Piwik\PluginsArchiver;
 
-class Piwik_Goals_Archiver extends Piwik_PluginsArchiver
+class Piwik_Goals_Archiver extends PluginsArchiver
 {
     const VISITS_UNTIL_RECORD_NAME = 'visits_until_conv';
     const DAYS_UNTIL_CONV_RECORD_NAME = 'days_until_conv';
@@ -96,7 +99,7 @@ class Piwik_Goals_Archiver extends Piwik_PluginsArchiver
         );
         $selects = array();
         foreach ($aggregatesMetadata as $aggregateMetadata) {
-            $selects = array_merge($selects, Piwik_DataAccess_LogAggregator::getSelectsFromRangedColumn($aggregateMetadata));
+            $selects = array_merge($selects, LogAggregator::getSelectsFromRangedColumn($aggregateMetadata));
         }
 
         $query = $this->getLogAggregator()->queryConversionsByDimension(array(), false, $selects);
@@ -121,16 +124,16 @@ class Piwik_Goals_Archiver extends Piwik_PluginsArchiver
             $goals->sumMetrics($idGoal, $values);
 
             if (empty($visitsToConversions[$idGoal])) {
-                $visitsToConversions[$idGoal] = new Piwik_DataTable();
+                $visitsToConversions[$idGoal] = new DataTable();
             }
-            $array = Piwik_DataAccess_LogAggregator::makeArrayOneColumn($row, Metrics::INDEX_NB_CONVERSIONS, $prefixes[self::VISITS_UNTIL_RECORD_NAME]);
-            $visitsToConversions[$idGoal]->addDataTable(Piwik_DataTable::makeFromIndexedArray($array));
+            $array = LogAggregator::makeArrayOneColumn($row, Metrics::INDEX_NB_CONVERSIONS, $prefixes[self::VISITS_UNTIL_RECORD_NAME]);
+            $visitsToConversions[$idGoal]->addDataTable(DataTable::makeFromIndexedArray($array));
 
             if (empty($daysToConversions[$idGoal])) {
-                $daysToConversions[$idGoal] = new Piwik_DataTable();
+                $daysToConversions[$idGoal] = new DataTable();
             }
-            $array = Piwik_DataAccess_LogAggregator::makeArrayOneColumn($row, Metrics::INDEX_NB_CONVERSIONS, $prefixes[self::DAYS_UNTIL_CONV_RECORD_NAME]);
-            $daysToConversions[$idGoal]->addDataTable(Piwik_DataTable::makeFromIndexedArray($array));
+            $array = LogAggregator::makeArrayOneColumn($row, Metrics::INDEX_NB_CONVERSIONS, $prefixes[self::DAYS_UNTIL_CONV_RECORD_NAME]);
+            $daysToConversions[$idGoal]->addDataTable(DataTable::makeFromIndexedArray($array));
 
             // We don't want to sum Abandoned cart metrics in the overall revenue/conversions/converted visits
             // since it is a "negative conversion"
@@ -209,7 +212,7 @@ class Piwik_Goals_Archiver extends Piwik_PluginsArchiver
 
     protected function getOverviewFromGoalTables($tableByGoal)
     {
-        $overview = new Piwik_DataTable();
+        $overview = new DataTable();
         foreach ($tableByGoal as $idGoal => $table) {
             if ($this->isStandardGoal($idGoal)) {
                 $overview->addDataTable($table);
diff --git a/plugins/Goals/Controller.php b/plugins/Goals/Controller.php
index d659959ab3..64ab750b6b 100644
--- a/plugins/Goals/Controller.php
+++ b/plugins/Goals/Controller.php
@@ -8,8 +8,10 @@
  * @category Piwik_Plugins
  * @package Piwik_Goals
  */
+use Piwik\DataTable\Filter\AddColumnsProcessedMetricsGoal;
 use Piwik\Piwik;
 use Piwik\Common;
+use Piwik\DataTable;
 
 /**
  *
@@ -35,7 +37,7 @@ class Piwik_Goals_Controller extends Piwik_Controller
 
     private function formatConversionRate($conversionRate)
     {
-        if ($conversionRate instanceof Piwik_DataTable) {
+        if ($conversionRate instanceof DataTable) {
             if ($conversionRate->getRowsCount() == 0) {
                 $conversionRate = 0;
             } else {
@@ -75,7 +77,7 @@ class Piwik_Goals_Controller extends Piwik_Controller
 
     public function ecommerceReport()
     {
-        if (!PluginsManager::getInstance()->isPluginActivated('CustomVariables')) {
+        if (!\Piwik\PluginsManager::getInstance()->isPluginActivated('CustomVariables')) {
             throw new Exception("Ecommerce Tracking requires that the plugin Custom Variables is enabled. Please enable the plugin CustomVariables (or ask your admin).");
         }
 
@@ -294,14 +296,14 @@ class Piwik_Goals_Controller extends Piwik_Controller
 
         $topDimensionsToLoad = array();
 
-        if (PluginsManager::getInstance()->isPluginActivated('UserCountry')) {
+        if (\Piwik\PluginsManager::getInstance()->isPluginActivated('UserCountry')) {
             $topDimensionsToLoad += array(
                 'country' => 'UserCountry.getCountry',
             );
         }
 
         $keywordNotDefinedString = '';
-        if (PluginsManager::getInstance()->isPluginActivated('Referers')) {
+        if (\Piwik\PluginsManager::getInstance()->isPluginActivated('Referers')) {
             $keywordNotDefinedString = Piwik_Referers_API::getKeywordNotDefinedString();
             $topDimensionsToLoad += array(
                 'keyword' => 'Referers.getKeywords',
@@ -313,7 +315,7 @@ class Piwik_Goals_Controller extends Piwik_Controller
             $request = new Piwik_API_Request("method=$apiMethod
 								&format=original
 								&filter_update_columns_when_show_all_goals=1
-								&idGoal=" . Piwik_DataTable_Filter_AddColumnsProcessedMetricsGoal::GOALS_FULL_TABLE . "
+								&idGoal=" . AddColumnsProcessedMetricsGoal::GOALS_FULL_TABLE . "
 								&filter_sort_order=desc
 								&filter_sort_column=$columnNbConversions" .
                 // select a couple more in case some are not valid (ie. conversions==0 or they are "Keyword not defined")
diff --git a/plugins/Goals/Goals.php b/plugins/Goals/Goals.php
index dc3445cb88..cd9857e3fd 100644
--- a/plugins/Goals/Goals.php
+++ b/plugins/Goals/Goals.php
@@ -8,15 +8,17 @@
  * @category Piwik_Plugins
  * @package Piwik_Goals
  */
+use Piwik\ArchiveProcessor;
 use Piwik\Piwik;
 use Piwik\Common;
+use Piwik\Plugin;
 use Piwik\Site;
 
 /**
  *
  * @package Piwik_Goals
  */
-class Piwik_Goals extends Piwik_Plugin
+class Piwik_Goals extends Plugin
 {
     protected $ecommerceReports = array(
         array('Goals_ProductSKU', 'Goals', 'getItemsSku'),
@@ -479,7 +481,7 @@ class Piwik_Goals extends Piwik_Plugin
      * Will process Goal stats overall and for each Goal.
      * Also processes the New VS Returning visitors conversion stats.
      */
-    public function archiveDay(Piwik_ArchiveProcessor_Day $archiveProcessor)
+    public function archiveDay(ArchiveProcessor\Day $archiveProcessor)
     {
         $archiving = new Piwik_Goals_Archiver($archiveProcessor);
         if($archiving->shouldArchive()) {
@@ -491,7 +493,7 @@ class Piwik_Goals extends Piwik_Plugin
      * Hooks on Period archiving.
      * Sums up Goal conversions stats, and processes overall conversion rate
      */
-    public function archivePeriod(Piwik_ArchiveProcessor_Period $archiveProcessor)
+    public function archivePeriod(ArchiveProcessor\Period $archiveProcessor)
     {
         $archiving = new Piwik_Goals_Archiver($archiveProcessor);
         if($archiving->shouldArchive()) {
@@ -575,7 +577,7 @@ class Piwik_Goals extends Piwik_Plugin
         
         $moneyColumns = array('revenue', 'avg_price');
         $prettifyMoneyColumns = array(
-            'ColumnCallbackReplace', array($moneyColumns, array("Piwik", "getPrettyMoney"), array($idSite)));
+            'ColumnCallbackReplace', array($moneyColumns, '\Piwik\Piwik::getPrettyMoney', array($idSite)));
         
         $result = array(
             'show_ecommerce' => true,
diff --git a/plugins/ImageGraph/API.php b/plugins/ImageGraph/API.php
index dd6967b56b..b2811772f0 100644
--- a/plugins/ImageGraph/API.php
+++ b/plugins/ImageGraph/API.php
@@ -11,6 +11,7 @@
 use Piwik\Period;
 use Piwik\Piwik;
 use Piwik\Common;
+use Piwik\Translate;
 
 /**
  * The ImageGraph.get API call lets you generate beautiful static PNG Graphs for any existing Piwik report.
@@ -145,7 +146,7 @@ class Piwik_ImageGraph_API
         $useUnicodeFont = array(
             'am', 'ar', 'el', 'fa', 'fi', 'he', 'ja', 'ka', 'ko', 'te', 'th', 'zh-cn', 'zh-tw',
         );
-        $languageLoaded = Piwik_Translate::getInstance()->getLanguageLoaded();
+        $languageLoaded = Translate::getInstance()->getLanguageLoaded();
         $font = self::getFontPath(self::DEFAULT_FONT);
         if (in_array($languageLoaded, $useUnicodeFont)) {
             $unicodeFontPath = self::getFontPath(self::UNICODE_FONT);
@@ -378,10 +379,10 @@ class Piwik_ImageGraph_API
                 $reportMetadata = $processedReport['reportMetadata']->getRows();
 
                 $i = 0;
-                // $reportData instanceof Piwik_DataTable
-                foreach ($reportData->getRows() as $row) // Piwik_DataTable_Row[]
+                // $reportData instanceof DataTable
+                foreach ($reportData->getRows() as $row) // Row[]
                 {
-                    // $row instanceof Piwik_DataTable_Row
+                    // $row instanceof Row
                     $rowData = $row->getColumns(); // Associative Array
                     $abscissaSeries[] = Common::unsanitizeInputValue($rowData['label']);
 
@@ -408,13 +409,13 @@ class Piwik_ImageGraph_API
                 }
             } else // if the report has no dimension we have multiple reports each with only one row within the reportData
             {
-                // $periodsData instanceof Piwik_DataTable_Simple[]
+                // $periodsData instanceof Simple[]
                 $periodsData = array_values($reportData->getArray());
                 $periodsCount = count($periodsData);
 
                 for ($i = 0; $i < $periodsCount; $i++) {
-                    // $periodsData[$i] instanceof Piwik_DataTable_Simple
-                    // $rows instanceof Piwik_DataTable_Row[]
+                    // $periodsData[$i] instanceof Simple
+                    // $rows instanceof Row[]
                     if (empty($periodsData[$i])) {
                         continue;
                     }
diff --git a/plugins/ImageGraph/ImageGraph.php b/plugins/ImageGraph/ImageGraph.php
index 73743ccbba..3a2f56bb58 100644
--- a/plugins/ImageGraph/ImageGraph.php
+++ b/plugins/ImageGraph/ImageGraph.php
@@ -1,7 +1,9 @@
 <?php
 use Piwik\Common;
 use Piwik\Period;
+use Piwik\Plugin;
 use Piwik\Site;
+use Piwik\Config;
 
 /**
  * Piwik - Open source web analytics
@@ -13,7 +15,7 @@ use Piwik\Site;
  * @package Piwik_ImageGraph
  */
 
-class Piwik_ImageGraph extends Piwik_Plugin
+class Piwik_ImageGraph extends Plugin
 {
     static private $CONSTANT_ROW_COUNT_REPORT_EXCEPTIONS = array(
         'Referers_getRefererType',
diff --git a/plugins/ImageGraph/StaticGraph.php b/plugins/ImageGraph/StaticGraph.php
index 4fe0523e2a..85778163e0 100644
--- a/plugins/ImageGraph/StaticGraph.php
+++ b/plugins/ImageGraph/StaticGraph.php
@@ -9,6 +9,8 @@
  * @package Piwik_ImageGraph
  */
 
+use Piwik\Loader;
+
 require_once PIWIK_INCLUDE_PATH . "/libs/pChart2.1.3/class/pDraw.class.php";
 require_once PIWIK_INCLUDE_PATH . "/libs/pChart2.1.3/class/pImage.class.php";
 require_once PIWIK_INCLUDE_PATH . "/libs/pChart2.1.3/class/pData.class.php";
@@ -77,7 +79,7 @@ abstract class Piwik_ImageGraph_StaticGraph
         if (isset(self::$availableStaticGraphTypes[$graphType])) {
 
             $className = self::$availableStaticGraphTypes[$graphType];
-            Piwik_Loader::loadClass($className);
+            Loader::loadClass($className);
             return new $className;
         } else {
             throw new Exception(
@@ -108,7 +110,7 @@ abstract class Piwik_ImageGraph_StaticGraph
     }
 
     /**
-     * @return rendered static graph
+     * @return Image rendered static graph
      */
     public function getRenderedImage()
     {
diff --git a/plugins/Installation/Controller.php b/plugins/Installation/Controller.php
index 05d3913043..5fcfcbe39a 100644
--- a/plugins/Installation/Controller.php
+++ b/plugins/Installation/Controller.php
@@ -8,7 +8,9 @@
  * @category Piwik_Plugins
  * @package Piwik_Installation
  */
+use Piwik\DataAccess\ArchiveTableCreator;
 use Piwik\Piwik;
+use Piwik\Config;
 use Piwik\Common;
 use Piwik\Access;
 
@@ -261,7 +263,7 @@ class Piwik_Installation_Controller extends Piwik_Controller_Admin
             $view->someTablesInstalled = true;
 
             // remove monthly archive tables
-            $archiveTables = Piwik_DataAccess_ArchiveTableCreator::getTablesArchivesInstalled();
+            $archiveTables = ArchiveTableCreator::getTablesArchivesInstalled();
             $baseTablesInstalled = count($tablesInstalled) - count($archiveTables);
             $minimumCountPiwikTables = 17;
 
diff --git a/plugins/Installation/Installation.php b/plugins/Installation/Installation.php
index 1d81de1393..8017e4e535 100644
--- a/plugins/Installation/Installation.php
+++ b/plugins/Installation/Installation.php
@@ -10,12 +10,14 @@
  */
 use Piwik\Piwik;
 use Piwik\Common;
+use Piwik\Plugin;
+use Piwik\Translate;
 
 /**
  *
  * @package Piwik_Installation
  */
-class Piwik_Installation extends Piwik_Plugin
+class Piwik_Installation extends Plugin
 {
     protected $installationControllerName = 'Piwik_Installation_Controller';
 
@@ -51,7 +53,7 @@ class Piwik_Installation extends Piwik_Plugin
             $message = '';
         }
 
-        Piwik_Translate::getInstance()->loadCoreTranslation();
+        Translate::getInstance()->loadCoreTranslation();
 
         Piwik_PostEvent('Installation.startInstallation', array($this));
 
diff --git a/plugins/LanguagesManager/LanguagesManager.php b/plugins/LanguagesManager/LanguagesManager.php
index da096266b5..1d0bc24ed9 100644
--- a/plugins/LanguagesManager/LanguagesManager.php
+++ b/plugins/LanguagesManager/LanguagesManager.php
@@ -12,12 +12,14 @@
 use Piwik\Config;
 use Piwik\Piwik;
 use Piwik\Common;
+use Piwik\Plugin;
+use Piwik\Translate;
 
 /**
  *
  * @package Piwik_LanguagesManager
  */
-class Piwik_LanguagesManager extends Piwik_Plugin
+class Piwik_LanguagesManager extends Plugin
 {
     /**
      * @see Piwik_Plugin::getListHooksRegistered
@@ -82,7 +84,7 @@ class Piwik_LanguagesManager extends Piwik_Plugin
             $language = self::getLanguageCodeForCurrentUser();
         }
         if (!Piwik_LanguagesManager_API::getInstance()->isLanguageAvailable($language)) {
-            $language = Piwik_Translate::getInstance()->getLanguageDefault();
+            $language = Translate::getInstance()->getLanguageDefault();
         }
     }
 
@@ -131,7 +133,7 @@ class Piwik_LanguagesManager extends Piwik_Plugin
             $languageCode = Common::extractLanguageCodeFromBrowserLanguage(Common::getBrowserLanguage(), Piwik_LanguagesManager_API::getInstance()->getAvailableLanguages());
         }
         if (!Piwik_LanguagesManager_API::getInstance()->isLanguageAvailable($languageCode)) {
-            $languageCode = Piwik_Translate::getInstance()->getLanguageDefault();
+            $languageCode = Translate::getInstance()->getLanguageDefault();
         }
         return $languageCode;
     }
diff --git a/plugins/Live/API.php b/plugins/Live/API.php
index a9fd58a6f6..8a739a0b17 100644
--- a/plugins/Live/API.php
+++ b/plugins/Live/API.php
@@ -9,10 +9,15 @@
  * @package Piwik_Live
  */
 use Piwik\Config;
+use Piwik\DataAccess\LogAggregator;
+use Piwik\DataTable\Filter\ColumnDelete;
+use Piwik\DataTable\Row;
 use Piwik\Period;
-use Piwik\Period_Range;
+use Piwik\Period\Range;
 use Piwik\Piwik;
 use Piwik\Common;
+use Piwik\Date;
+use Piwik\DataTable;
 use Piwik\Segment;
 use Piwik\Site;
 
@@ -82,7 +87,7 @@ class Piwik_Live_API
 
         $bind = array(
             $idSite,
-            Piwik_Date::factory(time() - $lastMinutes * 60)->toString('Y-m-d H:i:s')
+            Date::factory(time() - $lastMinutes * 60)->toString('Y-m-d H:i:s')
         );
 
         $segment = new Segment($segment, $idSite);
@@ -110,7 +115,7 @@ class Piwik_Live_API
      * @param int $filter_limit
      * @param bool $flat Whether to flatten the visitor details array
      *
-     * @return Piwik_DataTable
+     * @return DataTable
      */
     public function getLastVisitsForVisitor($visitorId, $idSite, $filter_limit = 10, $flat = false)
     {
@@ -133,7 +138,7 @@ class Piwik_Live_API
      * @param bool|int $minTimestamp (optional) Minimum timestamp to restrict the query to (useful when paginating or refreshing visits)
      * @param bool $flat
      * @param bool $doNotFetchActions
-     * @return Piwik_DataTable
+     * @return DataTable
      */
     public function getLastVisitsDetails($idSite, $period, $date, $segment = false, $filter_limit = false, $filter_offset = false, $minTimestamp = false, $flat = false, $doNotFetchActions = false)
     {
@@ -162,13 +167,13 @@ class Piwik_Live_API
      * @param bool $flat whether to flatten the array (eg. 'customVariables' names/values will appear in the root array rather than in 'customVariables' key
      * @param bool $doNotFetchActions If set to true, we only fetch visit info and not actions (much faster)
      *
-     * @return Piwik_DataTable
+     * @return DataTable
      */
     private function getCleanedVisitorsFromDetails($visitorDetails, $idSite, $flat = false, $doNotFetchActions = false)
     {
         $actionsLimit = (int)Config::getInstance()->General['visitor_log_maximum_actions_per_visit'];
 
-        $table = new Piwik_DataTable();
+        $table = new DataTable();
 
         $site = new Site($idSite);
         $timezone = $site->getTimezone();
@@ -181,11 +186,11 @@ class Piwik_Live_API
             $visitorDetailsArray['siteCurrency'] = $site->getCurrency();
             $visitorDetailsArray['siteCurrencySymbol'] = @$currencies[$site->getCurrency()];
             $visitorDetailsArray['serverTimestamp'] = $visitorDetailsArray['lastActionTimestamp'];
-            $dateTimeVisit = Piwik_Date::factory($visitorDetailsArray['lastActionTimestamp'], $timezone);
+            $dateTimeVisit = Date::factory($visitorDetailsArray['lastActionTimestamp'], $timezone);
             $visitorDetailsArray['serverTimePretty'] = $dateTimeVisit->getLocalized('%time%');
             $visitorDetailsArray['serverDatePretty'] = $dateTimeVisit->getLocalized(Piwik_Translate('CoreHome_ShortDateFormat'));
 
-            $dateTimeVisitFirstAction = Piwik_Date::factory($visitorDetailsArray['firstActionTimestamp'], $timezone);
+            $dateTimeVisitFirstAction = Date::factory($visitorDetailsArray['firstActionTimestamp'], $timezone);
             $visitorDetailsArray['serverDatePrettyFirstAction'] = $dateTimeVisitFirstAction->getLocalized(Piwik_Translate('CoreHome_ShortDateFormat'));
             $visitorDetailsArray['serverTimePrettyFirstAction'] = $dateTimeVisitFirstAction->getLocalized('%time%');
 
@@ -197,7 +202,7 @@ class Piwik_Live_API
             if($flat) {
                 $visitorDetailsArray = $this->flattenVisitorDetailsArray($visitorDetailsArray);
             }
-            $table->addRowFromArray(array(Piwik_DataTable_Row::COLUMNS => $visitorDetailsArray));
+            $table->addRowFromArray(array(Row::COLUMNS => $visitorDetailsArray));
         }
         return $table;
     }
@@ -240,7 +245,7 @@ class Piwik_Live_API
             if (!empty($action['customVariables'])) {
                 foreach ($action['customVariables'] as $thisCustomVar) {
                     foreach ($thisCustomVar as $cvKey => $cvValue) {
-                        $flattenedKeyName = $cvKey . Piwik_DataTable_Filter_ColumnDelete::APPEND_TO_COLUMN_NAME_TO_KEEP . $count;
+                        $flattenedKeyName = $cvKey . ColumnDelete::APPEND_TO_COLUMN_NAME_TO_KEEP . $count;
                         $visitorDetailsArray[$flattenedKeyName] = $cvValue;
                         $count++;
                     }
@@ -252,7 +257,7 @@ class Piwik_Live_API
         $count = 1;
         foreach($visitorDetailsArray['actionDetails'] as $action) {
             if(!empty($action['goalId'])) {
-                $flattenedKeyName = 'visitConvertedGoalId' . Piwik_DataTable_Filter_ColumnDelete::APPEND_TO_COLUMN_NAME_TO_KEEP . $count;
+                $flattenedKeyName = 'visitConvertedGoalId' . ColumnDelete::APPEND_TO_COLUMN_NAME_TO_KEEP . $count;
                 $visitorDetailsArray[$flattenedKeyName] = $action['goalId'];
                 $count++;
             }
@@ -262,17 +267,17 @@ class Piwik_Live_API
         $count = 1;
         foreach($visitorDetailsArray['actionDetails'] as $action) {
             if(!empty($action['url'])) {
-                $flattenedKeyName = 'pageUrl' . Piwik_DataTable_Filter_ColumnDelete::APPEND_TO_COLUMN_NAME_TO_KEEP . $count;
+                $flattenedKeyName = 'pageUrl' . ColumnDelete::APPEND_TO_COLUMN_NAME_TO_KEEP . $count;
                 $visitorDetailsArray[$flattenedKeyName] = $action['url'];
             }
 
             if(!empty($action['pageTitle'])) {
-                $flattenedKeyName = 'pageTitle' . Piwik_DataTable_Filter_ColumnDelete::APPEND_TO_COLUMN_NAME_TO_KEEP . $count;
+                $flattenedKeyName = 'pageTitle' . ColumnDelete::APPEND_TO_COLUMN_NAME_TO_KEEP . $count;
                 $visitorDetailsArray[$flattenedKeyName] = $action['pageTitle'];
             }
 
             if(!empty($action['siteSearchKeyword'])) {
-                $flattenedKeyName = 'siteSearchKeyword' . Piwik_DataTable_Filter_ColumnDelete::APPEND_TO_COLUMN_NAME_TO_KEEP . $count;
+                $flattenedKeyName = 'siteSearchKeyword' . ColumnDelete::APPEND_TO_COLUMN_NAME_TO_KEEP . $count;
                 $visitorDetailsArray[$flattenedKeyName] = $action['siteSearchKeyword'];
             }
             $count++;
@@ -354,15 +359,15 @@ class Piwik_Live_API
 
             $dateString = $date;
             if ($period == 'range') {
-                $processedPeriod = new Period_Range('range', $date);
-                if ($parsedDate = Period_Range::parseDateRange($date)) {
+                $processedPeriod = new Range('range', $date);
+                if ($parsedDate = Range::parseDateRange($date)) {
                     $dateString = $parsedDate[2];
                 }
             } else {
-                $processedDate = Piwik_Date::factory($date);
+                $processedDate = Date::factory($date);
                 if ($date == 'today'
                     || $date == 'now'
-                    || $processedDate->toString() == Piwik_Date::factory('now', $currentTimezone)->toString()
+                    || $processedDate->toString() == Date::factory('now', $currentTimezone)->toString()
                 ) {
                     $processedDate = $processedDate->subDay(1);
                 }
@@ -375,7 +380,7 @@ class Piwik_Live_API
             if (!in_array($date, array('now', 'today', 'yesterdaySameTime'))
                 && strpos($date, 'last') === false
                 && strpos($date, 'previous') === false
-                && Piwik_Date::factory($dateString)->toString('Y-m-d') != Piwik_Date::factory('now', $currentTimezone)->toString()
+                && Date::factory($dateString)->toString('Y-m-d') != Date::factory('now', $currentTimezone)->toString()
             ) {
                 $dateEnd = $processedPeriod->getDateEnd()->setTimezone($currentTimezone);
                 $where[] = " log_visit.visit_last_action_time <= ?";
@@ -551,11 +556,11 @@ class Piwik_Live_API
         $sql = "SELECT
 						case idgoal when " . Piwik_Tracker_GoalManager::IDGOAL_CART . " then '" . Piwik::LABEL_ID_GOAL_IS_ECOMMERCE_CART . "' else '" . Piwik::LABEL_ID_GOAL_IS_ECOMMERCE_ORDER . "' end as type,
 						idorder as orderId,
-						" . Piwik_DataAccess_LogAggregator::getSqlRevenue('revenue') . " as revenue,
-						" . Piwik_DataAccess_LogAggregator::getSqlRevenue('revenue_subtotal') . " as revenueSubTotal,
-						" . Piwik_DataAccess_LogAggregator::getSqlRevenue('revenue_tax') . " as revenueTax,
-						" . Piwik_DataAccess_LogAggregator::getSqlRevenue('revenue_shipping') . " as revenueShipping,
-						" . Piwik_DataAccess_LogAggregator::getSqlRevenue('revenue_discount') . " as revenueDiscount,
+						" . LogAggregator::getSqlRevenue('revenue') . " as revenue,
+						" . LogAggregator::getSqlRevenue('revenue_subtotal') . " as revenueSubTotal,
+						" . LogAggregator::getSqlRevenue('revenue_tax') . " as revenueTax,
+						" . LogAggregator::getSqlRevenue('revenue_shipping') . " as revenueShipping,
+						" . LogAggregator::getSqlRevenue('revenue_discount') . " as revenueDiscount,
 						items as items,
 
 						log_conversion.server_time as serverTimePretty
@@ -592,7 +597,7 @@ class Piwik_Live_API
 							log_action_sku.name as itemSKU,
 							log_action_name.name as itemName,
 							log_action_category.name as itemCategory,
-							" . Piwik_DataAccess_LogAggregator::getSqlRevenue('price') . " as price,
+							" . LogAggregator::getSqlRevenue('price') . " as price,
 							quantity as quantity
 						FROM " . Common::prefixTable('log_conversion_item') . "
 							INNER JOIN " . Common::prefixTable('log_action') . " AS log_action_sku
@@ -652,7 +657,7 @@ class Piwik_Live_API
                     break;
             }
             // Convert datetimes to the site timezone
-            $dateTimeVisit = Piwik_Date::factory($details['serverTimePretty'], $timezone);
+            $dateTimeVisit = Date::factory($details['serverTimePretty'], $timezone);
             $details['serverTimePretty'] = $dateTimeVisit->getLocalized(Piwik_Translate('CoreHome_ShortDateFormat') . ' %time%');
 
         }
diff --git a/plugins/Live/Controller.php b/plugins/Live/Controller.php
index bad3a1bcbf..69c94fdf87 100644
--- a/plugins/Live/Controller.php
+++ b/plugins/Live/Controller.php
@@ -8,8 +8,9 @@
  * @category Piwik_Plugins
  * @package Piwik_Live
  */
-use Piwik\Piwik;
 use Piwik\Common;
+use Piwik\Piwik;
+use Piwik\Config;
 
 /**
  * @package Piwik_Live
@@ -67,7 +68,7 @@ class Piwik_Live_Controller extends Piwik_Controller
         return $this->render($view, $fetch);
     }
 
-    private function render($view, $fetch)
+    private function render(Piwik_View $view, $fetch)
     {
         $rendered = $view->render();
         if ($fetch) {
@@ -102,7 +103,7 @@ class Piwik_Live_Controller extends Piwik_Controller
 
         // disable the tag cloud,  pie charts, bar chart icons
         $view->disableShowAllViewsIcons();
-        // disable the button "show more datas"
+        // disable the button "show more data"
         $view->disableShowAllColumns();
         // disable the RSS feed
         $view->disableShowExportAsRssFeed();
diff --git a/plugins/Live/Live.php b/plugins/Live/Live.php
index d4bd504204..ba6bf5b219 100644
--- a/plugins/Live/Live.php
+++ b/plugins/Live/Live.php
@@ -8,12 +8,13 @@
  * @category Piwik_Plugins
  * @package Piwik_Live
  */
+use Piwik\Plugin;
 
 /**
  *
  * @package Piwik_Live
  */
-class Piwik_Live extends Piwik_Plugin
+class Piwik_Live extends Plugin
 {
     /**
      * @see Piwik_Plugin::getListHooksRegistered
diff --git a/plugins/Live/Visitor.php b/plugins/Live/Visitor.php
index 1c8ec26952..df7edf761d 100644
--- a/plugins/Live/Visitor.php
+++ b/plugins/Live/Visitor.php
@@ -343,7 +343,7 @@ class Piwik_Live_Visitor
     function getKeyword()
     {
         $keyword = $this->details['referer_keyword'];
-        if (PluginsManager::getInstance()->isPluginActivated('Referers')
+        if (\Piwik\PluginsManager::getInstance()->isPluginActivated('Referers')
             && $this->getRefererType() == 'search'
         ) {
             $keyword = Piwik_Referers_API::getCleanKeyword($keyword);
@@ -354,7 +354,7 @@ class Piwik_Live_Visitor
     function getRefererUrl()
     {
         if ($this->getRefererType() == 'search') {
-            if (PluginsManager::getInstance()->isPluginActivated('Referers')
+            if (\Piwik\PluginsManager::getInstance()->isPluginActivated('Referers')
                 && $this->details['referer_keyword'] == Piwik_Referers_API::LABEL_KEYWORD_NOT_DEFINED
             ) {
                 return 'http://piwik.org/faq/general/#faq_144';
@@ -512,7 +512,7 @@ class Piwik_Live_Visitor
 
     function getDeviceType()
     {
-        if(PluginsManager::getInstance()->isPluginActivated('DevicesDetection')) {
+        if(\Piwik\PluginsManager::getInstance()->isPluginActivated('DevicesDetection')) {
             return Piwik_getDeviceTypeLabel($this->details['config_device_type']);
         }
         return false;
diff --git a/plugins/Login/Controller.php b/plugins/Login/Controller.php
index 013658b419..28aa0e285c 100644
--- a/plugins/Login/Controller.php
+++ b/plugins/Login/Controller.php
@@ -10,6 +10,7 @@
  */
 use Piwik\Config;
 use Piwik\Piwik;
+use Piwik\Common;
 
 require_once PIWIK_INCLUDE_PATH . '/core/Config.php';
 
@@ -315,7 +316,7 @@ class Piwik_Login_Controller extends Piwik_Controller
 
         if (is_null($errorMessage)) // if success, show login w/ success message
         {
-            $this->redirectToIndex('Login', 'resetPasswordSuccess');
+            return $this->redirectToIndex('Login', 'resetPasswordSuccess');
         } else {
             // show login page w/ error. this will keep the token in the URL
             return $this->login($errorMessage);
@@ -392,7 +393,7 @@ class Piwik_Login_Controller extends Piwik_Controller
     /**
      * Generate a password reset token.  Expires in (roughly) 24 hours.
      *
-     * @param array user information
+     * @param array $user user information
      * @param int $timestamp Unix timestamp
      * @return string generated token
      */
diff --git a/plugins/Login/Login.php b/plugins/Login/Login.php
index a46bf6e387..7208328074 100644
--- a/plugins/Login/Login.php
+++ b/plugins/Login/Login.php
@@ -10,12 +10,13 @@
  */
 use Piwik\Config;
 use Piwik\Piwik;
+use Piwik\Plugin;
 
 /**
  *
  * @package Piwik_Login
  */
-class Piwik_Login extends Piwik_Plugin
+class Piwik_Login extends Plugin
 {
     /**
      * @see Piwik_Plugin::getListHooksRegistered
diff --git a/plugins/Login/templates/resetPassword.twig b/plugins/Login/templates/resetPassword.twig
index eaa5be0a8d..bd9cf4accc 100755
--- a/plugins/Login/templates/resetPassword.twig
+++ b/plugins/Login/templates/resetPassword.twig
@@ -1,8 +1,8 @@
-{% if infoMessage is defined %}
+{% if infoMessage is defined and infoMessage is not empty %}
     <p class="message">{{ infoMessage }}</p>
 {% endif %}
 {% if formErrors is defined %}
-    <p id="login_error">
+    <p class="message_error">
         {% for data in formErrors %}
             <strong>{{ 'General_Error'|translate }}</strong>
             : {{ data }}
diff --git a/plugins/MobileMessaging/MobileMessaging.php b/plugins/MobileMessaging/MobileMessaging.php
index 941d753fa7..840ae48abc 100644
--- a/plugins/MobileMessaging/MobileMessaging.php
+++ b/plugins/MobileMessaging/MobileMessaging.php
@@ -9,12 +9,13 @@
  * @package Piwik_MobileMessaging
  */
 use Piwik\Piwik;
+use Piwik\Plugin;
 
 /**
  *
  * @package Piwik_MobileMessaging
  */
-class Piwik_MobileMessaging extends Piwik_Plugin
+class Piwik_MobileMessaging extends Plugin
 {
     const DELEGATED_MANAGEMENT_OPTION = 'MobileMessaging_DelegatedManagement';
     const PROVIDER_OPTION = 'Provider';
@@ -158,7 +159,7 @@ class Piwik_MobileMessaging extends Piwik_Plugin
     public function getRendererInstance(&$reportRenderer, $info)
     {
         if (self::manageEvent($info)) {
-            if (PluginsManager::getInstance()->isPluginActivated('MultiSites')) {
+            if (\Piwik\PluginsManager::getInstance()->isPluginActivated('MultiSites')) {
                 $reportRenderer = new Piwik_MobileMessaging_ReportRenderer_Sms();
             } else {
                 $reportRenderer = new Piwik_MobileMessaging_ReportRenderer_Exception(
diff --git a/plugins/MobileMessaging/SMSProvider.php b/plugins/MobileMessaging/SMSProvider.php
index 6abc527dcb..402c135b48 100644
--- a/plugins/MobileMessaging/SMSProvider.php
+++ b/plugins/MobileMessaging/SMSProvider.php
@@ -8,6 +8,7 @@
  * @category Piwik_Plugins
  * @package Piwik_MobileMessaging
  */
+use Piwik\Loader;
 
 /**
  * The Piwik_MobileMessaging_SMSProvider abstract class is used as a base class for SMS provider implementations.
@@ -49,7 +50,7 @@ abstract class Piwik_MobileMessaging_SMSProvider
         $className = 'Piwik_MobileMessaging_SMSProvider_' . $providerName;
 
         try {
-            Piwik_Loader::loadClass($className);
+            Loader::loadClass($className);
             return new $className;
         } catch (Exception $e) {
             throw new Exception(
diff --git a/plugins/MultiSites/API.php b/plugins/MultiSites/API.php
index 0c75406004..2906edc981 100755
--- a/plugins/MultiSites/API.php
+++ b/plugins/MultiSites/API.php
@@ -9,9 +9,11 @@
  * @package Piwik_MultiSites
  */
 use Piwik\Archive;
-use Piwik\Period_Range;
+use Piwik\DataTable\Filter\CalculateEvolutionFilter;
+use Piwik\Period\Range;
 use Piwik\Piwik;
 use Piwik\Common;
+use Piwik\DataTable;
 use Piwik\Site;
 
 /**
@@ -95,7 +97,7 @@ class Piwik_MultiSites_API
      *                                        Only used when a scheduled task is running
      * @param bool|string $enhanced When true, return additional goal & ecommerce metrics
      * @param bool|string $pattern If specified, only the website which names (or site ID) match the pattern will be returned using SitesManager.getPatternMatchSites
-     * @return Piwik_DataTable
+     * @return DataTable
      */
     public function getAll($period, $date, $segment = false, $_restrictSitesToLogin = false, $enhanced = false, $pattern = false)
     {
@@ -104,7 +106,7 @@ class Piwik_MultiSites_API
         $idSites = $this->getSitesIdFromPattern($pattern);
 
         if(empty($idSites)) {
-            return new Piwik_DataTable();
+            return new DataTable();
         }
         return $this->buildDataTable(
             $idSites,
@@ -154,7 +156,7 @@ class Piwik_MultiSites_API
      * @param bool|string $_restrictSitesToLogin Hack used to enforce we restrict the returned data to the specified username
      *                                        Only used when a scheduled task is running
      * @param bool|string $enhanced When true, return additional goal & ecommerce metrics
-     * @return Piwik_DataTable
+     * @return DataTable
      */
     public function getOne($idSite, $period, $date, $segment = false, $_restrictSitesToLogin = false, $enhanced = false)
     {
@@ -214,16 +216,16 @@ class Piwik_MultiSites_API
         }
 
         // get the data
-        // $dataTable instanceOf Piwik_DataTable_Array
+        // $dataTable instanceOf Set
         $dataTable = $archive->getDataTableFromNumeric($fieldsToGet);
 
         // get rid of the DataTable_Array that is created by the IndexedBySite archive type
-        if ($dataTable instanceof Piwik_DataTable_Array
+        if ($dataTable instanceof DataTable\Map
             && $multipleWebsitesRequested
         ) {
             $dataTable = $dataTable->mergeChildren();
         } else {
-            if (!($dataTable instanceof Piwik_DataTable_Array)
+            if (!($dataTable instanceof DataTable\Map)
                 && $dataTable->getRowsCount() > 0
             ) {
                 $firstSite = is_array($sites) ? reset($sites) : $sites;
@@ -238,18 +240,18 @@ class Piwik_MultiSites_API
 
         // if the period isn't a range & a lastN/previousN date isn't used, we get the same
         // data for the last period to show the evolution of visits/actions/revenue
-        list($strLastDate, $lastPeriod) = Period_Range::getLastDate($date, $period);
+        list($strLastDate, $lastPeriod) = Range::getLastDate($date, $period);
         if ($strLastDate !== false) {
             if ($lastPeriod !== false) {
                 // NOTE: no easy way to set last period date metadata when range of dates is requested.
                 //       will be easier if DataTable_Array::metadata is removed, and metadata that is
-                //       put there is put directly in Piwik_DataTable::metadata.
+                //       put there is put directly in DataTable::metadata.
                 $dataTable->setMetadata(self::getLastPeriodMetadataName('date'), $lastPeriod);
             }
             $pastArchive = Archive::build($sites, $period, $strLastDate, $segment, $_restrictSitesToLogin);
             $pastData = $pastArchive->getDataTableFromNumeric($fieldsToGet);
             
-            if ($pastData instanceof Piwik_DataTable_Array
+            if ($pastData instanceof DataTable\Map
                 && $multipleWebsitesRequested
             ) {
                 $pastData = $pastData->mergeChildren();
@@ -264,7 +266,7 @@ class Piwik_MultiSites_API
         // remove eCommerce related metrics on non eCommerce Piwik sites
         // note: this is not optimal in terms of performance: those metrics should not be retrieved in the first place
         if ($enhanced) {
-            // $dataTableRows instanceOf Piwik_DataTable_Row[]
+            // $dataTableRows instanceOf Row[]
             $dataTableRows = $dataTable->getRows();
 
             foreach ($dataTableRows as $dataTableRow) {
@@ -283,8 +285,7 @@ class Piwik_MultiSites_API
 
         // set the label of each row to the site name
         if ($multipleWebsitesRequested) {
-            $getNameFor = array('Site', 'getNameFor');
-            $dataTable->filter('ColumnCallbackReplace', array('label', $getNameFor));
+            $dataTable->filter('ColumnCallbackReplace', array('label', '\Piwik\Site::getNameFor'));
         } else {
             $dataTable->filter('ColumnDelete', array('label'));
         }
@@ -317,8 +318,8 @@ class Piwik_MultiSites_API
      * Performs a binary filter of two
      * DataTables in order to correctly calculate evolution metrics.
      *
-     * @param Piwik_DataTable|Piwik_DataTable_Array $currentData
-     * @param Piwik_DataTable|Piwik_DataTable_Array $pastData
+     * @param DataTable|DataTable\Map $currentData
+     * @param DataTable|DataTable\Map $pastData
      * @param array $apiMetrics The array of string fields to calculate evolution
      *                          metrics for.
      * @throws Exception
@@ -330,7 +331,7 @@ class Piwik_MultiSites_API
                                . get_class($pastData).".");
         }
         
-        if ($currentData instanceof Piwik_DataTable_Array) {
+        if ($currentData instanceof DataTable\Map) {
             $pastArray = $pastData->getArray();
             foreach ($currentData->getArray() as $subTable) {
                 $this->calculateEvolutionPercentages($subTable, current($pastArray), $apiMetrics);
@@ -354,13 +355,13 @@ class Piwik_MultiSites_API
      * Sets the total visits, actions & revenue for a DataTable returned by
      * $this->buildDataTable.
      *
-     * @param Piwik_DataTable $dataTable
+     * @param DataTable $dataTable
      * @param array $apiMetrics Metrics info.
      * @return array Array of three values: total visits, total actions, total revenue
      */
     private function setMetricsTotalsMetadata($dataTable, $apiMetrics)
     {
-        if ($dataTable instanceof Piwik_DataTable_Array) {
+        if ($dataTable instanceof DataTable\Map) {
             foreach ($dataTable->getArray() as $table) {
                 $this->setMetricsTotalsMetadata($table, $apiMetrics);
             }
@@ -393,13 +394,13 @@ class Piwik_MultiSites_API
      * Sets the total evolution metadata for a datatable returned by $this->buildDataTable
      * given data for the last period.
      *
-     * @param Piwik_DataTable $dataTable
-     * @param Piwik_DataTable $pastData
+     * @param DataTable $dataTable
+     * @param DataTable $pastData
      * @param array $apiMetrics Metrics info.
      */
     private function setPastDataMetadata($dataTable, $pastData, $apiMetrics)
     {
-        if ($dataTable instanceof Piwik_DataTable_Array) {
+        if ($dataTable instanceof DataTable\Map) {
             $pastArray = $pastData->getArray();
             foreach ($dataTable->getArray() as $subTable) {
                 $this->setPastDataMetadata($subTable, current($pastArray), $apiMetrics);
@@ -422,7 +423,7 @@ class Piwik_MultiSites_API
 
                 // calculate & set evolution
                 $currentTotal = $dataTable->getMetadata($totalMetadataName);
-                $evolution = Piwik_DataTable_Filter_CalculateEvolutionFilter::calculate($currentTotal, $pastTotal);
+                $evolution = CalculateEvolutionFilter::calculate($currentTotal, $pastTotal);
                 $dataTable->setMetadata($totalEvolutionMetadataName, $evolution);
             }
         }
diff --git a/plugins/MultiSites/Controller.php b/plugins/MultiSites/Controller.php
index 992cfa6be0..4986ba1abc 100644
--- a/plugins/MultiSites/Controller.php
+++ b/plugins/MultiSites/Controller.php
@@ -12,6 +12,7 @@ use Piwik\Period;
 use Piwik\Piwik;
 use Piwik\Common;
 use Piwik\Config;
+use Piwik\Date;
 use Piwik\Site;
 
 /**
@@ -153,8 +154,8 @@ class Piwik_MultiSites_Controller extends Piwik_Controller
         // if the current date is today, or yesterday,
         // in case the website is set to UTC-12), or today in UTC+14, we refresh the page every 5min
         if (in_array($date, array('today', date('Y-m-d'),
-                                  'yesterday', Piwik_Date::factory('yesterday')->toString('Y-m-d'),
-                                  Piwik_Date::factory('now', 'UTC+14')->toString('Y-m-d')))
+                                  'yesterday', Date::factory('yesterday')->toString('Y-m-d'),
+                                  Date::factory('now', 'UTC+14')->toString('Y-m-d')))
         ) {
 
             $view->autoRefreshTodayReport = Config::getInstance()->General['multisites_refresh_after_seconds'];
@@ -171,32 +172,32 @@ class Piwik_MultiSites_Controller extends Piwik_Controller
      * The Multisites reports displays the first calendar date as the earliest day available for all websites.
      * Also, today is the later "today" available across all timezones.
      * @param array $siteIds Array of IDs for each site being displayed.
-     * @return array of two Piwik_Date instances. First is the min-date & the second
+     * @return array of two Date instances. First is the min-date & the second
      *               is the max date.
      */
     private function getMinMaxDateAcrossWebsites($siteIds)
     {
-        $now = Piwik_Date::now();
+        $now = Date::now();
 
         $minDate = null;
         $maxDate = $now->subDay(1)->getTimestamp();
         foreach ($siteIds as $idsite) {
             // look for 'now' in the website's timezone
             $timezone = Site::getTimezoneFor($idsite);
-            $date = Piwik_Date::adjustForTimezone($now->getTimestamp(), $timezone);
+            $date = Date::adjustForTimezone($now->getTimestamp(), $timezone);
             if ($date > $maxDate) {
                 $maxDate = $date;
             }
 
             // look for the absolute minimum date
             $creationDate = Site::getCreationDateFor($idsite);
-            $date = Piwik_Date::adjustForTimezone(strtotime($creationDate), $timezone);
+            $date = Date::adjustForTimezone(strtotime($creationDate), $timezone);
             if (is_null($minDate) || $date < $minDate) {
                 $minDate = $date;
             }
         }
 
-        return array(Piwik_Date::factory($minDate), Piwik_Date::factory($maxDate));
+        return array(Date::factory($minDate), Date::factory($maxDate));
     }
 
     protected function applyPrettyMoney(&$sites)
diff --git a/plugins/MultiSites/MultiSites.php b/plugins/MultiSites/MultiSites.php
index a8ccc1ffcf..96f14fabce 100644
--- a/plugins/MultiSites/MultiSites.php
+++ b/plugins/MultiSites/MultiSites.php
@@ -8,12 +8,13 @@
  * @category Piwik_Plugins
  * @package Piwik_MultiSites
  */
+use Piwik\Plugin;
 
 /**
  *
  * @package Piwik_MultiSites
  */
-class Piwik_MultiSites extends Piwik_Plugin
+class Piwik_MultiSites extends Plugin
 {
     public function getInformation()
     {
diff --git a/plugins/Overlay/API.php b/plugins/Overlay/API.php
index 9db64023c8..26cf98a5c5 100644
--- a/plugins/Overlay/API.php
+++ b/plugins/Overlay/API.php
@@ -2,6 +2,7 @@
 use Piwik\Config;
 use Piwik\Piwik;
 use Piwik\Access;
+use Piwik\DataTable;
 
 /**
  * Piwik - Open source web analytics
@@ -81,7 +82,7 @@ class Piwik_Overlay_API
         $url = Piwik_Tracker_Action::excludeQueryParametersFromUrl($url, $idSite);
         // we don't unsanitize $url here. it will be done in the Transitions plugin.
 
-        $resultDataTable = new Piwik_DataTable;
+        $resultDataTable = new DataTable;
 
         try {
             $limitBeforeGrouping = Config::getInstance()->General['overlay_following_pages_limit'];
diff --git a/plugins/Overlay/Controller.php b/plugins/Overlay/Controller.php
index 6f7c00caf9..d3bd8ab3b0 100644
--- a/plugins/Overlay/Controller.php
+++ b/plugins/Overlay/Controller.php
@@ -1,6 +1,7 @@
 <?php
 use Piwik\Metrics;
 use Piwik\Piwik;
+use Piwik\Config;
 use Piwik\Common;
 
 /**
@@ -22,7 +23,7 @@ class Piwik_Overlay_Controller extends Piwik_Controller
         Piwik::checkUserHasViewAccess($this->idSite);
 
         $template = '@Overlay/index';
-        if (Piwik_Config::getInstance()->General['overlay_disable_framed_mode']) {
+        if (Config::getInstance()->General['overlay_disable_framed_mode']) {
             $template = '@Overlay/index_noframe';
         }
 
diff --git a/plugins/Overlay/Overlay.php b/plugins/Overlay/Overlay.php
index 5c6d072be5..72a08d5046 100644
--- a/plugins/Overlay/Overlay.php
+++ b/plugins/Overlay/Overlay.php
@@ -9,7 +9,9 @@
  * @package Piwik_Overlay
  */
 
-class Piwik_Overlay extends Piwik_Plugin
+use Piwik\Plugin;
+
+class Piwik_Overlay extends Plugin
 {
     public function getInformation()
     {
diff --git a/plugins/PDFReports/API.php b/plugins/PDFReports/API.php
index c3eea2e13d..4826fe8c80 100644
--- a/plugins/PDFReports/API.php
+++ b/plugins/PDFReports/API.php
@@ -10,7 +10,9 @@
  */
 use Piwik\Piwik;
 use Piwik\Common;
+use Piwik\Date;
 use Piwik\Site;
+use Piwik\Translate;
 
 /**
  * The PDFReports API lets you manage Scheduled Email reports, as well as generate, download or email any existing report.
@@ -119,7 +121,7 @@ class Piwik_PDFReports_API
                  'format'      => $reportFormat,
                  'parameters'  => $parameters,
                  'reports'     => $reports,
-                 'ts_created'  => Piwik_Date::now()->getDatetime(),
+                 'ts_created'  => Date::now()->getDatetime(),
                  'deleted'     => 0,
             ));
 
@@ -294,10 +296,10 @@ class Piwik_PDFReports_API
 
         // load specified language
         if (empty($language)) {
-            $language = Piwik_Translate::getInstance()->getLanguageDefault();
+            $language = Translate::getInstance()->getLanguageDefault();
         }
 
-        Piwik_Translate::getInstance()->reloadLanguage($language);
+        Translate::getInstance()->reloadLanguage($language);
 
         $reports = $this->getReports($idSite = false, $_period = false, $idReport);
         $report = reset($reports);
@@ -496,7 +498,7 @@ class Piwik_PDFReports_API
         }
 
         if (empty($date)) {
-            $date = Piwik_Date::now()->subPeriod(1, $report['period'])->toString();
+            $date = Date::now()->subPeriod(1, $report['period'])->toString();
         }
 
         $language = Piwik_LanguagesManager_API::getInstance()->getLanguageForUser($report['login']);
@@ -538,7 +540,7 @@ class Piwik_PDFReports_API
 
         // Update flag in DB
         Zend_Registry::get('db')->update(Common::prefixTable('report'),
-            array('ts_last_sent' => Piwik_Date::now()->getDatetime()),
+            array('ts_last_sent' => Date::now()->getDatetime()),
             "idreport = " . $report['idreport']
         );
 
@@ -798,6 +800,6 @@ class Piwik_PDFReports_API
      */
     public static function isSegmentEditorActivated()
     {
-        return PluginsManager::getInstance()->isPluginActivated('SegmentEditor');
+        return \Piwik\PluginsManager::getInstance()->isPluginActivated('SegmentEditor');
     }
 }
diff --git a/plugins/PDFReports/PDFReports.php b/plugins/PDFReports/PDFReports.php
index 5d93ed38cb..69ddb3d498 100644
--- a/plugins/PDFReports/PDFReports.php
+++ b/plugins/PDFReports/PDFReports.php
@@ -10,13 +10,16 @@
  */
 use Piwik\Piwik;
 use Piwik\Common;
+use Piwik\Config;
+use Piwik\Date;
+use Piwik\Plugin;
 use Piwik\Site;
 
 /**
  *
  * @package Piwik_PDFReports
  */
-class Piwik_PDFReports extends Piwik_Plugin
+class Piwik_PDFReports extends Plugin
 {
     const MOBILE_MESSAGING_TOP_MENU_TRANSLATION_KEY = 'MobileMessaging_TopMenu';
     const PDF_REPORTS_TOP_MENU_TRANSLATION_KEY = 'PDFReports_EmailReports';
@@ -204,7 +207,7 @@ class Piwik_PDFReports extends Piwik_Plugin
                         :
                         $displayFormat != self::DISPLAY_FORMAT_TABLES_ONLY)
                         && Piwik::isGdExtensionEnabled()
-                        && PluginsManager::getInstance()->isPluginActivated('ImageGraph')
+                        && \Piwik\PluginsManager::getInstance()->isPluginActivated('ImageGraph')
                         && !empty($metadata['imageGraphUrl']);
 
                 $processedReport['evolutionGraph'] = $evolutionGraph;
@@ -409,13 +412,13 @@ class Piwik_PDFReports extends Piwik_Plugin
 
     public function getScheduledTasks(&$tasks)
     {
-        $arbitraryDateInUTC = Piwik_Date::factory('2011-01-01');
+        $arbitraryDateInUTC = Date::factory('2011-01-01');
         foreach (Piwik_PDFReports_API::getInstance()->getReports() as $report) {
             if (!$report['deleted'] && $report['period'] != Piwik_ScheduledTime::PERIOD_NEVER) {
                 $midnightInSiteTimezone =
                     date(
                         'H',
-                        Piwik_Date::factory(
+                        Date::factory(
                             $arbitraryDateInUTC,
                             Site::getTimezoneFor($report['idsite'])
                         )->getTimestamp()
@@ -461,7 +464,7 @@ class Piwik_PDFReports extends Piwik_Plugin
             13,
             $isHTML = false,
             $tooltip = Piwik_Translate(
-                PluginsManager::getInstance()->isPluginActivated('MobileMessaging')
+                \Piwik\PluginsManager::getInstance()->isPluginActivated('MobileMessaging')
                     ? 'MobileMessaging_TopLinkTooltip' : 'PDFReports_TopLinkTooltip'
             )
         );
@@ -470,7 +473,7 @@ class Piwik_PDFReports extends Piwik_Plugin
     function getTopMenuTranslationKey()
     {
         // if MobileMessaging is not activated, display 'Email reports'
-        if (!PluginsManager::getInstance()->isPluginActivated('MobileMessaging'))
+        if (!\Piwik\PluginsManager::getInstance()->isPluginActivated('MobileMessaging'))
             return self::PDF_REPORTS_TOP_MENU_TRANSLATION_KEY;
 
         if (Piwik::isUserIsAnonymous()) {
diff --git a/plugins/PleineLune/PleineLune.php b/plugins/PleineLune/PleineLune.php
index 133cbbfea2..12b581bdc1 100644
--- a/plugins/PleineLune/PleineLune.php
+++ b/plugins/PleineLune/PleineLune.php
@@ -8,12 +8,13 @@
  * @category Piwik_Plugins
  * @package Piwik_PleineLune
  */
+use Piwik\Plugin;
 
 /**
  *
  * @package Piwik_PleineLune
  */
-class Piwik_PleineLune extends Piwik_Plugin
+class Piwik_PleineLune extends Plugin
 {
     public function getListHooksRegistered()
     {
diff --git a/plugins/PrivacyManager/Controller.php b/plugins/PrivacyManager/Controller.php
index a6770ae74a..a3af0246be 100644
--- a/plugins/PrivacyManager/Controller.php
+++ b/plugins/PrivacyManager/Controller.php
@@ -11,6 +11,7 @@
 use Piwik\Config;
 use Piwik\Piwik;
 use Piwik\Common;
+use Piwik\Date;
 
 /**
  *
@@ -105,7 +106,7 @@ class Piwik_PrivacyManager_Controller extends Piwik_Controller_Admin
      */
     public static function isDntSupported()
     {
-        return PluginsManager::getInstance()->isPluginActivated('DoNotTrack');
+        return \Piwik\PluginsManager::getInstance()->isPluginActivated('DoNotTrack');
     }
 
     public function privacySettings()
@@ -214,12 +215,12 @@ class Piwik_PrivacyManager_Controller extends Piwik_Controller_Admin
         Piwik::checkUserIsSuperUser();
         $anonymizeIP = array();
 
-        PluginsManager::getInstance()->loadPlugin(self::ANONYMIZE_IP_PLUGIN_NAME);
+        \Piwik\PluginsManager::getInstance()->loadPlugin(self::ANONYMIZE_IP_PLUGIN_NAME);
 
         $anonymizeIP["name"] = self::ANONYMIZE_IP_PLUGIN_NAME;
-        $anonymizeIP["enabled"] = PluginsManager::getInstance()->isPluginActivated(self::ANONYMIZE_IP_PLUGIN_NAME);
+        $anonymizeIP["enabled"] = \Piwik\PluginsManager::getInstance()->isPluginActivated(self::ANONYMIZE_IP_PLUGIN_NAME);
         $anonymizeIP["maskLength"] = Config::getInstance()->Tracker['ip_address_mask_length'];
-        $anonymizeIP["info"] = PluginsManager::getInstance()->getLoadedPlugin(self::ANONYMIZE_IP_PLUGIN_NAME)->getInformation();
+        $anonymizeIP["info"] = \Piwik\PluginsManager::getInstance()->getLoadedPlugin(self::ANONYMIZE_IP_PLUGIN_NAME)->getInformation();
 
         return $anonymizeIP;
     }
@@ -241,7 +242,7 @@ class Piwik_PrivacyManager_Controller extends Piwik_Controller_Admin
         if (!empty($scheduleTimetable) && ($scheduleTimetable - time() > 0)) {
             $nextPossibleSchedule = (int)$scheduleTimetable;
         } else {
-            $date = Piwik_Date::factory("today");
+            $date = Date::factory("today");
             $nextPossibleSchedule = $date->addDay(1)->getTimestamp();
         }
 
@@ -250,11 +251,11 @@ class Piwik_PrivacyManager_Controller extends Piwik_Controller_Admin
             $deleteDataInfos["lastRun"] = false;
 
             //next run ASAP (with next schedule run)
-            $date = Piwik_Date::factory("today");
+            $date = Date::factory("today");
             $deleteDataInfos["nextScheduleTime"] = $nextPossibleSchedule;
         } else {
             $deleteDataInfos["lastRun"] = $optionTable;
-            $deleteDataInfos["lastRunPretty"] = Piwik_Date::factory((int)$optionTable)->getLocalized('%day% %shortMonth% %longYear%');
+            $deleteDataInfos["lastRunPretty"] = Date::factory((int)$optionTable)->getLocalized('%day% %shortMonth% %longYear%');
 
             //Calculate next run based on last run + interval
             $nextScheduleRun = (int)($deleteDataInfos["lastRun"] + $deleteDataInfos["config"]["delete_logs_schedule_lowest_interval"] * 24 * 60 * 60);
@@ -276,9 +277,9 @@ class Piwik_PrivacyManager_Controller extends Piwik_Controller_Admin
     {
         $pluginController = new Piwik_CorePluginsAdmin_Controller();
 
-        if ($state == 1 && !PluginsManager::getInstance()->isPluginActivated(self::ANONYMIZE_IP_PLUGIN_NAME)) {
+        if ($state == 1 && !\Piwik\PluginsManager::getInstance()->isPluginActivated(self::ANONYMIZE_IP_PLUGIN_NAME)) {
             $pluginController->activate($redirectAfter = false);
-        } elseif ($state == 0 && PluginsManager::getInstance()->isPluginActivated(self::ANONYMIZE_IP_PLUGIN_NAME)) {
+        } elseif ($state == 0 && \Piwik\PluginsManager::getInstance()->isPluginActivated(self::ANONYMIZE_IP_PLUGIN_NAME)) {
             $pluginController->deactivate($redirectAfter = false);
         } else {
             //nothing to do
diff --git a/plugins/PrivacyManager/LogDataPurger.php b/plugins/PrivacyManager/LogDataPurger.php
index ac899a6ce4..6d7a06b951 100755
--- a/plugins/PrivacyManager/LogDataPurger.php
+++ b/plugins/PrivacyManager/LogDataPurger.php
@@ -10,6 +10,7 @@
  */
 use Piwik\Piwik;
 use Piwik\Common;
+use Piwik\Date;
 
 /**
  * Purges the log_visit, log_conversion and related tables of old visit data.
@@ -155,7 +156,7 @@ class Piwik_PrivacyManager_LogDataPurger
         }
 
         // select highest idvisit to delete from
-        $dateStart = Piwik_Date::factory("today")->subDay($this->deleteLogsOlderThan);
+        $dateStart = Date::factory("today")->subDay($this->deleteLogsOlderThan);
         $sql = "SELECT idvisit
 		          FROM $logVisit
 		         WHERE '" . $dateStart->toString('Y-m-d H:i:s') . "' > visit_last_action_time
diff --git a/plugins/PrivacyManager/PrivacyManager.php b/plugins/PrivacyManager/PrivacyManager.php
index dcbc12814d..710232001b 100644
--- a/plugins/PrivacyManager/PrivacyManager.php
+++ b/plugins/PrivacyManager/PrivacyManager.php
@@ -12,6 +12,8 @@ use Piwik\Config;
 use Piwik\Metrics;
 use Piwik\Piwik;
 use Piwik\Common;
+use Piwik\Date;
+use Piwik\Plugin;
 
 /**
  * @see plugins/PrivacyManager/LogDataPurger.php
@@ -27,7 +29,7 @@ require_once PIWIK_INCLUDE_PATH . '/plugins/PrivacyManager/ReportsPurger.php';
  *
  * @package Piwik_PrivacyManager
  */
-class Piwik_PrivacyManager extends Piwik_Plugin
+class Piwik_PrivacyManager extends Plugin
 {
     const OPTION_LAST_DELETE_PIWIK_LOGS = "lastDelete_piwik_logs";
     const OPTION_LAST_DELETE_PIWIK_REPORTS = 'lastDelete_piwik_reports';
@@ -146,7 +148,7 @@ class Piwik_PrivacyManager extends Piwik_Plugin
      */
     public static function savePurgeDataSettings($settings)
     {
-        $plugin = PluginsManager::getInstance()->getLoadedPlugin('PrivacyManager');
+        $plugin = \Piwik\PluginsManager::getInstance()->getLoadedPlugin('PrivacyManager');
 
         foreach (self::$defaultPurgeDataOptions as $optionName => $defaultValue) {
             if (isset($settings[$optionName])) {
@@ -189,7 +191,7 @@ class Piwik_PrivacyManager extends Piwik_Plugin
         }
 
         // set last run time
-        Piwik_SetOption(self::OPTION_LAST_DELETE_PIWIK_REPORTS, Piwik_Date::factory('today')->getTimestamp());
+        Piwik_SetOption(self::OPTION_LAST_DELETE_PIWIK_REPORTS, Date::factory('today')->getTimestamp());
 
         Piwik_PrivacyManager_ReportsPurger::make($settings, self::getAllMetricsToKeep())->purgeData();
     }
@@ -226,7 +228,7 @@ class Piwik_PrivacyManager extends Piwik_Plugin
          * If deletion / table optimization exceeds execution time, other tasks maybe prevented of being executed
          * every time, when the schedule is triggered.
          */
-        $lastDeleteDate = Piwik_Date::factory("today")->getTimestamp();
+        $lastDeleteDate = Date::factory("today")->getTimestamp();
         Piwik_SetOption(self::OPTION_LAST_DELETE_PIWIK_LOGS, $lastDeleteDate);
 
         // execute the purge
@@ -274,7 +276,7 @@ class Piwik_PrivacyManager extends Piwik_Plugin
      *
      * @param int $reportDateYear The year of the report in question.
      * @param int $reportDateMonth The month of the report in question.
-     * @param int|Piwik_Date $reportsOlderThan If an int, the number of months a report must be older than
+     * @param int|Date $reportsOlderThan If an int, the number of months a report must be older than
      *                                         in order to be purged. If a date, the date a report must be
      *                                         older than in order to be purged.
      * @return bool
@@ -293,8 +295,8 @@ class Piwik_PrivacyManager extends Piwik_Plugin
         }
 
         // if a integer was supplied, assume it is the number of months a report must be older than
-        if (!($reportsOlderThan instanceof Piwik_Date)) {
-            $reportsOlderThan = Piwik_Date::factory('today')->subMonth(1 + $reportsOlderThan);
+        if (!($reportsOlderThan instanceof Date)) {
+            $reportsOlderThan = Date::factory('today')->subMonth(1 + $reportsOlderThan);
         }
 
         return Piwik_PrivacyManager_ReportsPurger::shouldReportBePurged(
diff --git a/plugins/PrivacyManager/ReportsPurger.php b/plugins/PrivacyManager/ReportsPurger.php
index db4e5cafe3..a8ed8c3bfa 100755
--- a/plugins/PrivacyManager/ReportsPurger.php
+++ b/plugins/PrivacyManager/ReportsPurger.php
@@ -8,7 +8,9 @@
  * @category Piwik_Plugins
  * @package Piwik_PrivacyManager
  */
+use Piwik\DataAccess\ArchiveTableCreator;
 use Piwik\Piwik;
+use Piwik\Date;
 
 /**
  * Purges archived reports and metrics that are considered old.
@@ -203,21 +205,21 @@ class Piwik_PrivacyManager_ReportsPurger
         // get month for which reports as old or older than, should be deleted
         // reports whose creation date <= this month will be deleted
         // (NOTE: we ignore how far we are in the current month)
-        $toRemoveDate = Piwik_Date::factory('today')->subMonth(1 + $this->deleteReportsOlderThan);
+        $toRemoveDate = Date::factory('today')->subMonth(1 + $this->deleteReportsOlderThan);
 
         // find all archive tables that are older than N months
         $oldNumericTables = array();
         $oldBlobTables = array();
         foreach (Piwik::getTablesInstalled() as $table) {
-            $type = Piwik_DataAccess_ArchiveTableCreator::getTypeFromTableName($table);
+            $type = ArchiveTableCreator::getTypeFromTableName($table);
             if($type === false) {
                 continue;
             }
-            $date = Piwik_DataAccess_ArchiveTableCreator::getDateFromTableName($table);
+            $date = ArchiveTableCreator::getDateFromTableName($table);
             list($year, $month) = explode('_', $date);
 
             if (self::shouldReportBePurged($year, $month, $toRemoveDate)) {
-                if ($type == Piwik_DataAccess_ArchiveTableCreator::NUMERIC_TABLE) {
+                if ($type == ArchiveTableCreator::NUMERIC_TABLE) {
                     $oldNumericTables[] = $table;
                 } else {
                     $oldBlobTables[] = $table;
@@ -233,7 +235,7 @@ class Piwik_PrivacyManager_ReportsPurger
      *
      * @param int $reportDateYear The year of the report in question.
      * @param int $reportDateMonth The month of the report in question.
-     * @param Piwik_Date $toRemoveDate The date a report must be older than in order to be purged.
+     * @param Date $toRemoveDate The date a report must be older than in order to be purged.
      * @return bool
      */
     public static function shouldReportBePurged($reportDateYear, $reportDateMonth, $toRemoveDate)
@@ -285,7 +287,7 @@ class Piwik_PrivacyManager_ReportsPurger
             // if not keeping segments make sure segments w/ kept periods are also deleted
             if (!$this->keepSegmentReports) {
                 $this->findSegmentArchives($oldNumericTables);
-                $archiveIds = $this->segmentArchiveIds[Piwik_DataAccess_ArchiveTableCreator::getDateFromTableName($table)];
+                $archiveIds = $this->segmentArchiveIds[ArchiveTableCreator::getDateFromTableName($table)];
 
                 if (!empty($archiveIds)) {
                     $where .= " OR idarchive IN (" . implode(',', $archiveIds) . ")";
@@ -308,7 +310,7 @@ class Piwik_PrivacyManager_ReportsPurger
         }
 
         foreach ($numericTables as $table) {
-            $tableDate = Piwik_DataAccess_ArchiveTableCreator::getDateFromTableName($table);
+            $tableDate = ArchiveTableCreator::getDateFromTableName($table);
 
             $maxIdArchive = Piwik_FetchOne("SELECT MAX(idarchive) FROM $table");
 
diff --git a/plugins/Provider/Archiver.php b/plugins/Provider/Archiver.php
index ce782f9342..bd9a4fa456 100644
--- a/plugins/Provider/Archiver.php
+++ b/plugins/Provider/Archiver.php
@@ -9,8 +9,9 @@
  * @package Piwik_Provider
  */
 use Piwik\Metrics;
+use Piwik\PluginsArchiver;
 
-class Piwik_Provider_Archiver extends Piwik_PluginsArchiver
+class Piwik_Provider_Archiver extends PluginsArchiver
 {
     const PROVIDER_RECORD_NAME = 'Provider_hostnameExt';
     const PROVIDER_FIELD = "location_provider";
diff --git a/plugins/Provider/Provider.php b/plugins/Provider/Provider.php
index ca7c05ae8d..fe448e7395 100644
--- a/plugins/Provider/Provider.php
+++ b/plugins/Provider/Provider.php
@@ -9,12 +9,14 @@
  * @package Piwik_Provider
  */
 use Piwik\Common;
+use Piwik\Plugin;
+use Piwik\ArchiveProcessor;
 
 /**
  *
  * @package Piwik_Provider
  */
-class Piwik_Provider extends Piwik_Plugin
+class Piwik_Provider extends Plugin
 {
     /**
      * @see Piwik_Plugin::getListHooksRegistered
@@ -192,7 +194,7 @@ class Piwik_Provider extends Piwik_Plugin
     /**
      * Daily archive: processes the report Visits by Provider
      */
-    public function archiveDay(Piwik_ArchiveProcessor_Day $archiveProcessor)
+    public function archiveDay(ArchiveProcessor\Day $archiveProcessor)
     {
         $archiving = new Piwik_Provider_Archiver($archiveProcessor);
         if($archiving->shouldArchive()) {
@@ -200,7 +202,7 @@ class Piwik_Provider extends Piwik_Plugin
         }
     }
 
-    public function archivePeriod(Piwik_ArchiveProcessor_Period $archiveProcessor)
+    public function archivePeriod(ArchiveProcessor\Period $archiveProcessor)
     {
         $archiving = new Piwik_Provider_Archiver($archiveProcessor);
         if($archiving->shouldArchive()) {
diff --git a/plugins/Provider/functions.php b/plugins/Provider/functions.php
index a09ec1ab36..540060db4b 100644
--- a/plugins/Provider/functions.php
+++ b/plugins/Provider/functions.php
@@ -9,6 +9,7 @@
  * @package Piwik_Provider
  */
 use Piwik\Common;
+use Piwik\DataTable;
 
 /**
  * Return hostname portion of a domain name
@@ -38,7 +39,7 @@ function Piwik_getHostnameName($in)
  */
 function Piwik_getHostnameUrl($in)
 {
-    if ($in == Piwik_DataTable::LABEL_SUMMARY_ROW) {
+    if ($in == DataTable::LABEL_SUMMARY_ROW) {
         return false;
     }
     if (empty($in)
diff --git a/plugins/Proxy/Controller.php b/plugins/Proxy/Controller.php
index f7f71bb8a8..9f49505e97 100644
--- a/plugins/Proxy/Controller.php
+++ b/plugins/Proxy/Controller.php
@@ -21,73 +21,6 @@ class Piwik_Proxy_Controller extends Piwik_Controller
     const TRANSPARENT_PNG_PIXEL = 'iVBORw0KGgoAAAANSUhEUgAAAAEAAAABAQMAAAAl21bKAAAAA1BMVEUAAACnej3aAAAAAXRSTlMAQObYZgAAAApJREFUCNdjYAAAAAIAAeIhvDMAAAAASUVORK5CYII=';
 
     /**
-     * Display the "Export Image" window.
-     *
-     * @deprecated 1.5.1
-     *
-     * @internal param string $imageData Base-64 encoded image data (via $_POST)
-     */
-    static public function exportImageWindow()
-    {
-        Piwik::checkUserHasSomeViewAccess();
-
-        $view = new Piwik_View('@Proxy/exportImageWindow');
-        $view->imageData = 'data:image/png;base64,' . Common::getRequestVar('imageData', self::TRANSPARENT_PNG_PIXEL, 'string', $_POST);
-        echo $view->render();
-    }
-
-    function exportImage()
-    {
-        self::exportImageWindow();
-    }
-
-    /**
-     * Output binary image from base-64 encoded data.
-     *
-     * @deprecated 1.5.1
-     *
-     * @internal param string $imageData Base-64 encoded image data (via $_POST)
-     */
-    static public function outputBinaryImage()
-    {
-        Piwik::checkUserHasSomeViewAccess();
-
-        $rawData = Common::getRequestVar('imageData', '', 'string', $_POST);
-
-        // returns false if any illegal characters in input
-        $data = base64_decode($rawData);
-        if ($data !== false) {
-            // check for PNG header
-            if (Common::substr($data, 0, 8) === "\x89\x50\x4e\x47\x0d\x0a\x1a\x0a") {
-                header('Content-Type: image/png');
-
-                // more robust validation (if available)
-                if (function_exists('imagecreatefromstring')) {
-                    // validate image data
-                    $imgResource = @imagecreatefromstring($data);
-                    if ($imgResource !== false) {
-                        // output image and clean-up
-                        imagepng($imgResource);
-                        imagedestroy($imgResource);
-                        exit;
-                    }
-                } else {
-                    echo $data;
-                    exit;
-                }
-            }
-        }
-
-        Piwik::setHttpStatus('400 Bad Request');
-        exit;
-    }
-
-    function outputImage()
-    {
-        self::outputBinaryImage();
-    }
-
-    /**
      * Output the merged CSS file.
      * This method is called when the asset manager is enabled.
      *
diff --git a/plugins/Proxy/Proxy.php b/plugins/Proxy/Proxy.php
index c669215411..fc404bfd2e 100644
--- a/plugins/Proxy/Proxy.php
+++ b/plugins/Proxy/Proxy.php
@@ -8,13 +8,14 @@
  * @category Piwik_Plugins
  * @package Piwik_Proxy
  */
+use Piwik\Plugin;
 
 /**
  * Proxy services for the UI
  *
  * @package Piwik_Proxy
  */
-class Piwik_Proxy extends Piwik_Plugin
+class Piwik_Proxy extends Plugin
 {
     /**
      * Return information about this plugin.
diff --git a/plugins/Proxy/templates/exportImageWindow.twig b/plugins/Proxy/templates/exportImageWindow.twig
deleted file mode 100644
index 0145a6589f..0000000000
--- a/plugins/Proxy/templates/exportImageWindow.twig
+++ /dev/null
@@ -1,12 +0,0 @@
-<!DOCTYPE html>
-<html>
-<head>
-    <meta charset="utf-8">
-    <title>{{ 'General_ExportAsImage_js'|translate }}</title>
-</head>
-<body>
-<img title="Piwik Graph" src="{{ imageData }}"/><br/><br/>
-
-<p>{{ 'General_SaveImageOnYourComputer_js'|translate }}</p>
-</body>
-</html>
diff --git a/plugins/Referers/API.php b/plugins/Referers/API.php
index 16168b532a..a8dba84e0d 100644
--- a/plugins/Referers/API.php
+++ b/plugins/Referers/API.php
@@ -9,9 +9,12 @@
  * @package Piwik_Referers
  */
 use Piwik\Archive;
+use Piwik\DataTable\Row;
 use Piwik\Metrics;
 use Piwik\Piwik;
 use Piwik\Common;
+use Piwik\Date;
+use Piwik\DataTable;
 
 /**
  * The Referrers API lets you access reports about Websites, Search engines, Keywords, Campaigns used to access your website.
@@ -39,11 +42,11 @@ class Piwik_Referers_API
      * @param string $name
      * @param int $idSite
      * @param string $period
-     * @param Piwik_Date $date
+     * @param Date $date
      * @param string $segment
      * @param bool $expanded
      * @param int|null $idSubtable
-     * @return Piwik_DataTable
+     * @return DataTable
      */
     protected function getDataTable($name, $idSite, $period, $date, $segment, $expanded = false, $idSubtable = null)
     {
@@ -71,7 +74,7 @@ class Piwik_Referers_API
      *                        subtable ID. The result when using this parameter will be the
      *                        specific report for the given referrer type.
      * @param bool $expanded Whether to get report w/ subtables loaded or not.
-     * @return Piwik_DataTable
+     * @return DataTable
      */
     public function  getRefererType($idSite, $period, $date, $segment = false, $typeReferer = false,
                                    $idSubtable = false, $expanded = false)
@@ -108,7 +111,7 @@ class Piwik_Referers_API
 
         // set subtable IDs for each row to the label (which holds the int referrer type)
         // NOTE: not yet possible to do this w/ DataTable_Array instances
-        if (!($dataTable instanceof Piwik_DataTable_Array)) {
+        if (!($dataTable instanceof DataTable\Map)) {
             $this->setGetReferrerTypeSubtables($dataTable, $idSite, $period, $date, $segment, $expanded);
         }
 
@@ -125,7 +128,7 @@ class Piwik_Referers_API
     {
         $dataTable = $this->getRefererType($idSite, $period, $date, $segment, $typeReferer = false, $idSubtable = false, $expanded = true);
 
-        if ($dataTable instanceof Piwik_DataTable_Array) {
+        if ($dataTable instanceof DataTable\Map) {
             throw new Exception("Referrers.getAll with multiple sites or dates is not supported (yet).");
         }
 
@@ -190,11 +193,11 @@ class Piwik_Referers_API
     }
 
     /**
-     * @param Piwik_Datatable $table
+     * @param DataTable $table
      */
     private function filterOutKeywordNotDefined($table)
     {
-        if ($table instanceof Piwik_Datatable) {
+        if ($table instanceof DataTable) {
             $row = $table->getRowIdFromLabel('');
             if ($row) {
                 $table->deleteRow($row);
@@ -212,7 +215,7 @@ class Piwik_Referers_API
         $table = $response->getResponse($table);
 
         // If period=lastX we only keep the first resultset as we want to return a plain list
-        if ($table instanceof Piwik_DataTable_Array) {
+        if ($table instanceof DataTable\Map) {
             $tables = $table->getArray();
             $table = current($tables);
         }
@@ -253,7 +256,7 @@ class Piwik_Referers_API
         $searchEngines = $this->getSearchEngines($idSite, $period, $date, $segment);
         $searchEngines->applyQueuedFilters();
 
-        if ($searchEngines instanceof Piwik_DataTable_Array) {
+        if ($searchEngines instanceof DataTable\Map) {
             $dataTables = $searchEngines->getArray();
 
             // find first datatable containing data
@@ -313,7 +316,7 @@ class Piwik_Referers_API
      * @param string $date
      * @param string|bool $segment
      * @param bool $expanded
-     * @return Piwik_DataTable
+     * @return DataTable
      */
     public function getSocials($idSite, $period, $date, $segment = false, $expanded = false)
     {
@@ -346,7 +349,7 @@ class Piwik_Referers_API
      *                              is the array index of an item in the /core/DataFiles/Socials.php file.
      *                              The urls are filtered by the social network at this index.
      *                              If false, no filtering is done and every social URL is returned.
-     * @return Piwik_DataTable
+     * @return DataTable
      */
     public function getUrlsForSocial($idSite, $period, $date, $segment = false, $idSubtable = false)
     {
@@ -420,11 +423,11 @@ class Piwik_Referers_API
      * Removes idsubdatatable_in_db metadata from a DataTable. Used by Social tables since
      * they use fake subtable IDs.
      *
-     * @param Piwik_DataTable $dataTable
+     * @param DataTable $dataTable
      */
     private function removeSubtableMetadata($dataTable)
     {
-        if ($dataTable instanceof Piwik_DataTable_Array) {
+        if ($dataTable instanceof DataTable\Map) {
             foreach ($dataTable->getArray() as $childTable) {
                 $this->removeSubtableMetadata($childTable);
             }
@@ -440,11 +443,11 @@ class Piwik_Referers_API
      *
      * The IDs are int indexes into the array in /core/DataFiles/Socials.php.
      *
-     * @param Piwik_DataTable $dataTable
+     * @param DataTable $dataTable
      */
     private function setSocialIdSubtables($dataTable)
     {
-        if ($dataTable instanceof Piwik_DataTable_Array) {
+        if ($dataTable instanceof DataTable\Map) {
             foreach ($dataTable->getArray() as $childTable) {
                 $this->setSocialIdSubtables($childTable);
             }
@@ -455,7 +458,7 @@ class Piwik_Referers_API
                 $i = 1; // start at one because idSubtable=0 is equivalent to idSubtable=false
                 foreach ($GLOBALS['Piwik_socialUrl'] as $domain => $name) {
                     if ($name == $socialName) {
-                        $row->c[Piwik_DataTable_Row::DATATABLE_ASSOCIATED] = $i;
+                        $row->c[Row::DATATABLE_ASSOCIATED] = $i;
                         break;
                     }
 
@@ -471,12 +474,12 @@ class Piwik_Referers_API
      * the grandchildren of the report will be the original report, and it will
      * recurse when trying to get a flat report).
      *
-     * @param Piwik_DataTable $table
-     * @return Piwik_DataTable Returns $table for convenience.
+     * @param DataTable $table
+     * @return DataTable Returns $table for convenience.
      */
     private function removeSubtableIds($table)
     {
-        if ($table instanceof Piwik_DataTable_Array) {
+        if ($table instanceof DataTable\Map) {
             foreach ($table->getArray() as $childTable) {
                 $this->removeSubtableIds($childTable);
             }
@@ -498,7 +501,7 @@ class Piwik_Referers_API
      * If we are getting an expanded datatable, the datatable for the row's referrer
      * type is loaded and attached to the appropriate row in the getRefererType report.
      *
-     * @param Piwik_DataTable $dataTable
+     * @param DataTable $dataTable
      * @param string $idSite
      * @param string $period
      * @param string $date
@@ -512,7 +515,7 @@ class Piwik_Referers_API
             if ($typeReferrer != Common::REFERER_TYPE_DIRECT_ENTRY) {
                 if (!$expanded) // if we don't want the expanded datatable, then don't do any extra queries
                 {
-                    $row->c[Piwik_DataTable_Row::DATATABLE_ASSOCIATED] = $typeReferrer;
+                    $row->c[Row::DATATABLE_ASSOCIATED] = $typeReferrer;
                 } else // otherwise, we have to get the othe datatables
                 {
                     $subtable = $this->getRefererType($idSite, $period, $date, $segment, $type = false,
diff --git a/plugins/Referers/Archiver.php b/plugins/Referers/Archiver.php
index 7c7b484f02..dd7a795e9e 100644
--- a/plugins/Referers/Archiver.php
+++ b/plugins/Referers/Archiver.php
@@ -2,6 +2,7 @@
 use Piwik\Common;
 use Piwik\Config;
 use Piwik\Metrics;
+use Piwik\PluginsArchiver;
 
 /**
  * Piwik - Open source web analytics
@@ -13,7 +14,7 @@ use Piwik\Metrics;
  * @package Piwik_Referers
  */
 
-class Piwik_Referers_Archiver extends Piwik_PluginsArchiver
+class Piwik_Referers_Archiver extends PluginsArchiver
 {
     const SEARCH_ENGINES_RECORD_NAME = 'Referers_keywordBySearchEngine';
     const KEYWORDS_RECORD_NAME = 'Referers_searchEngineByKeyword';
diff --git a/plugins/Referers/Controller.php b/plugins/Referers/Controller.php
index 06f2c1ca71..97d920e175 100644
--- a/plugins/Referers/Controller.php
+++ b/plugins/Referers/Controller.php
@@ -9,7 +9,7 @@
  * @package Piwik_Referers
  */
 use Piwik\Metrics;
-use Piwik\Period_Range;
+use Piwik\Period\Range;
 use Piwik\Piwik;
 use Piwik\Common;
 
@@ -51,7 +51,7 @@ class Piwik_Referers_Controller extends Piwik_Controller
         }
 
         // calculate evolution for visit metrics & distinct metrics
-        list($lastPeriodDate, $ignore) = Period_Range::getLastDate();
+        list($lastPeriodDate, $ignore) = Range::getLastDate();
         if ($lastPeriodDate !== false) {
             $date = Common::getRequestVar('date');
             $period = Common::getRequestVar('period');
diff --git a/plugins/Referers/Referers.php b/plugins/Referers/Referers.php
index c96ca7927d..449bc0ce41 100644
--- a/plugins/Referers/Referers.php
+++ b/plugins/Referers/Referers.php
@@ -8,7 +8,9 @@
  * @category Piwik_Plugins
  * @package Piwik_Referers
  */
+use Piwik\ArchiveProcessor;
 use Piwik\Piwik;
+use Piwik\Plugin;
 
 /**
  * @see plugins/Referers/functions.php
@@ -18,7 +20,7 @@ require_once PIWIK_INCLUDE_PATH . '/plugins/Referers/functions.php';
 /**
  * @package Piwik_Referers
  */
-class Piwik_Referers extends Piwik_Plugin
+class Piwik_Referers extends Plugin
 {
     /**
      * @see Piwik_Plugin::getListHooksRegistered
@@ -267,7 +269,7 @@ class Piwik_Referers extends Piwik_Plugin
     /**
      * Hooks on daily archive to trigger various log processing
      */
-    public function archiveDay(Piwik_ArchiveProcessor_Day $archiveProcessor)
+    public function archiveDay(ArchiveProcessor\Day $archiveProcessor)
     {
         $archiving = new Piwik_Referers_Archiver($archiveProcessor);
         if ($archiving->shouldArchive()) {
@@ -279,7 +281,7 @@ class Piwik_Referers extends Piwik_Plugin
      * Period archiving: sums up daily stats and sums report tables,
      * making sure that tables are still truncated.
      */
-    public function archivePeriod(Piwik_ArchiveProcessor_Period $archiveProcessor)
+    public function archivePeriod(ArchiveProcessor\Period $archiveProcessor)
     {
         $archiving = new Piwik_Referers_Archiver($archiveProcessor);
         if($archiving->shouldArchive()) {
diff --git a/plugins/SEO/API.php b/plugins/SEO/API.php
index b7826f30d5..185561df44 100644
--- a/plugins/SEO/API.php
+++ b/plugins/SEO/API.php
@@ -9,6 +9,7 @@
  * @package Piwik_SEO
  */
 use Piwik\Piwik;
+use Piwik\DataTable;
 
 /**
  * @see plugins/Referers/functions.php
@@ -40,7 +41,7 @@ class Piwik_SEO_API
      * Returns SEO statistics for a URL.
      *
      * @param string $url URL to request SEO stats for
-     * @return Piwik_DataTable
+     * @return DataTable
      */
     public function getRank($url)
     {
@@ -101,6 +102,6 @@ class Piwik_SEO_API
             $data[Piwik_Translate('SEO_Dmoz')] = $dmozRank;
         }
 
-        return Piwik_DataTable::makeFromIndexedArray($data);
+        return DataTable::makeFromIndexedArray($data);
     }
 }
diff --git a/plugins/SEO/Controller.php b/plugins/SEO/Controller.php
index b33aac8986..b509264871 100644
--- a/plugins/SEO/Controller.php
+++ b/plugins/SEO/Controller.php
@@ -9,6 +9,7 @@
  * @package Piwik_SEO
  */
 use Piwik\Common;
+use Piwik\DataTable\Renderer;
 use Piwik\Site;
 
 /**
@@ -36,7 +37,7 @@ class Piwik_SEO_Controller extends Piwik_Controller
         $view = new Piwik_View('@SEO/getRank');
         $view->urlToRank = Piwik_SEO_RankChecker::extractDomainFromUrl($url);
 
-        $renderer = Piwik_DataTable_Renderer::factory('php');
+        $renderer = Renderer::factory('php');
         $renderer->setSerialize(false);
         $view->ranks = $renderer->render($dataTable);
         echo $view->render();
diff --git a/plugins/SEO/SEO.php b/plugins/SEO/SEO.php
index 4ff22fdabb..e41c93385c 100644
--- a/plugins/SEO/SEO.php
+++ b/plugins/SEO/SEO.php
@@ -8,11 +8,12 @@
  * @category Piwik_Plugins
  * @package Piwik_SEO
  */
+use Piwik\Plugin;
 
 /**
  * @package Piwik_SEO
  */
-class Piwik_SEO extends Piwik_Plugin
+class Piwik_SEO extends Plugin
 {
     /**
      * @see Piwik_Plugin::getInformation
diff --git a/plugins/SecurityInfo/PhpSecInfo/Test/Core/upload_tmp_dir.php b/plugins/SecurityInfo/PhpSecInfo/Test/Core/upload_tmp_dir.php
index 4a83e0f7cd..588b5f096f 100644
--- a/plugins/SecurityInfo/PhpSecInfo/Test/Core/upload_tmp_dir.php
+++ b/plugins/SecurityInfo/PhpSecInfo/Test/Core/upload_tmp_dir.php
@@ -45,7 +45,7 @@ class PhpSecInfo_Test_Core_Upload_Tmp_Dir extends PhpSecInfo_Test_Core
      * We are disabling this function on Windows OSes right now until
      * we can be certain of the proper way to check world-readability
      *
-     * @return unknown
+     * @return bool
      */
     function isTestable()
     {
diff --git a/plugins/SecurityInfo/SecurityInfo.php b/plugins/SecurityInfo/SecurityInfo.php
index ecd8d2e5f6..785247d2a2 100644
--- a/plugins/SecurityInfo/SecurityInfo.php
+++ b/plugins/SecurityInfo/SecurityInfo.php
@@ -9,12 +9,13 @@
  * @package Piwik_SecurityInfo
  */
 use Piwik\Piwik;
+use Piwik\Plugin;
 
 /**
  *
  * @package Piwik_SecurityInfo
  */
-class Piwik_SecurityInfo extends Piwik_Plugin
+class Piwik_SecurityInfo extends Plugin
 {
     /**
      * @see Piwik_Plugin::getListHooksRegistered
diff --git a/plugins/SegmentEditor/API.php b/plugins/SegmentEditor/API.php
index 855affb5e6..884c206e78 100644
--- a/plugins/SegmentEditor/API.php
+++ b/plugins/SegmentEditor/API.php
@@ -10,6 +10,7 @@
  */
 use Piwik\Piwik;
 use Piwik\Common;
+use Piwik\Date;
 use Piwik\Segment;
 
 /**
@@ -142,9 +143,9 @@ class Piwik_SegmentEditor_API
     /**
      * Modifies an existing stored segment.
      *
-     * @param $idSegment The ID of the stored segment to modify.
-     * @param $name  The new name of the segment.
-     * @param $definition  The new definition of the segment.
+     * @param int $idSegment The ID of the stored segment to modify.
+     * @param string $name  The new name of the segment.
+     * @param string $definition  The new definition of the segment.
      * @param bool $idSite  If supplied, associates the stored segment with as single site.
      * @param bool $autoArchive Whether to automatically archive data with the segment or not.
      * @param bool $enabledAllUsers Whether the stored segment is viewable by all users or just the one that created it.
@@ -168,7 +169,7 @@ class Piwik_SegmentEditor_API
             'enable_all_users'   => $enabledAllUsers,
             'enable_only_idsite' => $idSite,
             'auto_archive'       => $autoArchive,
-            'ts_last_edit'       => Piwik_Date::now()->getDatetime(),
+            'ts_last_edit'       => Date::now()->getDatetime(),
         );
 
         $db = Zend_Registry::get('db');
@@ -182,8 +183,8 @@ class Piwik_SegmentEditor_API
     /**
      * Adds a new stored segment.
      *
-     * @param $name  The new name of the segment.
-     * @param $definition  The new definition of the segment.
+     * @param string $name  The new name of the segment.
+     * @param string $definition  The new definition of the segment.
      * @param bool $idSite  If supplied, associates the stored segment with as single site.
      * @param bool $autoArchive Whether to automatically archive data with the segment or not.
      * @param bool $enabledAllUsers Whether the stored segment is viewable by all users or just the one that created it.
@@ -207,7 +208,7 @@ class Piwik_SegmentEditor_API
             'enable_all_users'   => $enabledAllUsers,
             'enable_only_idsite' => $idSite,
             'auto_archive'       => $autoArchive,
-            'ts_created'         => Piwik_Date::now()->getDatetime(),
+            'ts_created'         => Date::now()->getDatetime(),
             'deleted'            => 0,
         );
         $db->insert(Common::prefixTable("segment"), $bind);
diff --git a/plugins/SegmentEditor/SegmentEditor.php b/plugins/SegmentEditor/SegmentEditor.php
index 94eefc117d..a4f54d01e7 100644
--- a/plugins/SegmentEditor/SegmentEditor.php
+++ b/plugins/SegmentEditor/SegmentEditor.php
@@ -9,11 +9,12 @@
  * @package Piwik_SegmentEditor
  */
 use Piwik\Common;
+use Piwik\Plugin;
 
 /**
  * @package Piwik_SegmentEditor
  */
-class Piwik_SegmentEditor extends Piwik_Plugin
+class Piwik_SegmentEditor extends Plugin
 {
     /**
      * @see Piwik_Plugin::getInformation
diff --git a/plugins/SitesManager/API.php b/plugins/SitesManager/API.php
index c9a12e710c..edc66625e6 100644
--- a/plugins/SitesManager/API.php
+++ b/plugins/SitesManager/API.php
@@ -11,6 +11,7 @@
 use Piwik\Piwik;
 use Piwik\Common;
 use Piwik\Access;
+use Piwik\Date;
 use Piwik\Site;
 
 /**
@@ -223,7 +224,7 @@ class Piwik_SitesManager_API
 
         if (empty($timestamp)) $timestamp = time();
 
-        $time = Piwik_Date::factory((int)$timestamp)->getDatetime();
+        $time = Date::factory((int)$timestamp)->getDatetime();
         $result = Piwik_FetchAll("
             SELECT
                 idsite
@@ -236,7 +237,7 @@ class Piwik_SitesManager_API
                 AND visit_last_action_time > ?
                 AND visit_last_action_time <= ?
                 LIMIT 1)
-        ", array($time, $now = Piwik_Date::now()->addHour(1)->getDatetime()));
+        ", array($time, $now = Date::now()->addHour(1)->getDatetime()));
         $idSites = array();
         foreach ($result as $idSite) {
             $idSites[] = $idSite['idsite'];
@@ -516,8 +517,8 @@ class Piwik_SitesManager_API
         $bind['sitesearch_keyword_parameters'] = $searchKeywordParameters;
         $bind['sitesearch_category_parameters'] = $searchCategoryParameters;
         $bind['ts_created'] = !is_null($startDate)
-            ? Piwik_Date::factory($startDate)->getDatetime()
-            : Piwik_Date::now()->getDatetime();
+            ? Date::factory($startDate)->getDatetime()
+            : Date::now()->getDatetime();
 
         if (!empty($group)
             && Piwik::isUserIsSuperUser()
@@ -692,7 +693,7 @@ class Piwik_SitesManager_API
      * Sets IPs to be excluded from all websites. IPs can contain wildcards.
      * Will also apply to websites created in the future.
      *
-     * @param string Comma separated list of IPs to exclude from being tracked (allows wildcards)
+     * @param string $excludedIps Comma separated list of IPs to exclude from being tracked (allows wildcards)
      * @return bool
      */
     public function setGlobalExcludedIps($excludedIps)
@@ -853,7 +854,7 @@ class Piwik_SitesManager_API
      * Sets list of URL query parameters to be excluded on all websites.
      * Will also apply to websites created in the future.
      *
-     * @param string Comma separated list of URL query parameters to exclude from URLs
+     * @param string $excludedQueryParameters Comma separated list of URL query parameters to exclude from URLs
      * @return bool
      */
     public function setGlobalExcludedQueryParameters($excludedQueryParameters)
@@ -1015,7 +1016,7 @@ class Piwik_SitesManager_API
             $bind['ecommerce'] = (int)(bool)$ecommerce;
         }
         if (!is_null($startDate)) {
-            $bind['ts_created'] = Piwik_Date::factory($startDate)->getDatetime();
+            $bind['ts_created'] = Date::factory($startDate)->getDatetime();
         }
         $bind['excluded_ips'] = $this->checkAndReturnExcludedIps($excludedIps);
         $bind['excluded_parameters'] = $this->checkAndReturnCommaSeparatedStringList($excludedQueryParameters);
diff --git a/plugins/SitesManager/Controller.php b/plugins/SitesManager/Controller.php
index d5dd1c8be0..afbd9d21ed 100644
--- a/plugins/SitesManager/Controller.php
+++ b/plugins/SitesManager/Controller.php
@@ -8,8 +8,10 @@
  * @category Piwik_Plugins
  * @package Piwik_SitesManager
  */
+use Piwik\DataTable\Renderer\Json;
 use Piwik\Piwik;
 use Piwik\Common;
+use Piwik\Date;
 use Piwik\Site;
 
 /**
@@ -51,7 +53,7 @@ class Piwik_SitesManager_Controller extends Piwik_Controller_Admin
         $view->currencies = Common::json_encode(Piwik_SitesManager_API::getInstance()->getCurrencyList());
         $view->defaultCurrency = Piwik_SitesManager_API::getInstance()->getDefaultCurrency();
 
-        $view->utcTime = Piwik_Date::now()->getDatetime();
+        $view->utcTime = Date::now()->getDatetime();
         $excludedIpsGlobal = Piwik_SitesManager_API::getInstance()->getExcludedIpsGlobal();
         $view->globalExcludedIps = str_replace(',', "\n", $excludedIpsGlobal);
         $excludedQueryParametersGlobal = Piwik_SitesManager_API::getInstance()->getExcludedQueryParametersGlobal();
@@ -62,7 +64,7 @@ class Piwik_SitesManager_Controller extends Piwik_Controller_Admin
 
         $view->globalSearchKeywordParameters = Piwik_SitesManager_API::getInstance()->getSearchKeywordParametersGlobal();
         $view->globalSearchCategoryParameters = Piwik_SitesManager_API::getInstance()->getSearchCategoryParametersGlobal();
-        $view->isSearchCategoryTrackingEnabled = PluginsManager::getInstance()->isPluginActivated('CustomVariables');
+        $view->isSearchCategoryTrackingEnabled = \Piwik\PluginsManager::getInstance()->isPluginActivated('CustomVariables');
         $view->allowSiteSpecificUserAgentExclude =
             Piwik_SitesManager_API::getInstance()->isSiteSpecificUserAgentExcludeEnabled();
 
@@ -187,7 +189,7 @@ class Piwik_SitesManager_Controller extends Piwik_Controller_Admin
             }
         }
 
-        Piwik_DataTable_Renderer_Json::sendHeaderJSON();
+        Json::sendHeaderJSON();
         print Common::json_encode($results);
     }
 }
diff --git a/plugins/SitesManager/SitesManager.php b/plugins/SitesManager/SitesManager.php
index 8fbad87b00..7b21bbafd1 100644
--- a/plugins/SitesManager/SitesManager.php
+++ b/plugins/SitesManager/SitesManager.php
@@ -9,12 +9,13 @@
  * @package Piwik_SitesManager
  */
 use Piwik\Piwik;
+use Piwik\Plugin;
 
 /**
  *
  * @package Piwik_SitesManager
  */
-class Piwik_SitesManager extends Piwik_Plugin
+class Piwik_SitesManager extends Plugin
 {
     const KEEP_URL_FRAGMENT_USE_DEFAULT = 0;
     const KEEP_URL_FRAGMENT_YES = 1;
diff --git a/plugins/Transitions/API.php b/plugins/Transitions/API.php
index fe84b328cb..ac04dac368 100644
--- a/plugins/Transitions/API.php
+++ b/plugins/Transitions/API.php
@@ -8,10 +8,17 @@
  * @category Piwik_Plugins
  * @package Piwik_Transitions
  */
+
+use Piwik\ArchiveProcessor;
+use Piwik\DataAccess\LogAggregator;
+use Piwik\DataTable\Manager;
+use Piwik\DataTable\Row;
 use Piwik\Metrics;
 use Piwik\Period;
+use Piwik\Period\Day;
 use Piwik\Piwik;
 use Piwik\Common;
+use Piwik\DataTable;
 use Piwik\Segment;
 use Piwik\SegmentExpression;
 use Piwik\Site;
@@ -72,11 +79,11 @@ class Piwik_Transitions_API
         $segment = new Segment($segment, $idSite);
         $site = new Site($idSite);
         $period = Period::advancedFactory($period, $date);
-        $archiveProcessor = new Piwik_ArchiveProcessor_Day($period, $site, $segment);
+        $archiveProcessor = new ArchiveProcessor\Day($period, $site, $segment);
         $logAggregator = $archiveProcessor->getLogAggregator();
         // prepare the report
         $report = array(
-            'date' => Piwik_Period_Day::advancedFactory($period->getLabel(), $date)->getLocalizedShortString()
+            'date' => Day::advancedFactory($period->getLabel(), $date)->getLocalizedShortString()
         );
 
         // add data to the report
@@ -167,7 +174,7 @@ class Piwik_Transitions_API
      * Add the internal referrers to the report:
      * previous pages and previous site searches
      *
-     * @param Piwik_DataAccess_LogAggregator $logAggregator
+     * @param LogAggregator $logAggregator
      * @param $report
      * @param $idaction
      * @param string $actionType
@@ -193,7 +200,7 @@ class Piwik_Transitions_API
      * Add the following actions to the report:
      * following pages, downloads, outlinks
      *
-     * @param Piwik_DataAccess_LogAggregator $logAggregator
+     * @param LogAggregator $logAggregator
      * @param $report
      * @param $idaction
      * @param string $actionType
@@ -218,12 +225,12 @@ class Piwik_Transitions_API
      *
      * @param $idaction
      * @param $actionType
-     * @param Piwik_DataAccess_LogAggregator  $logAggregator
+     * @param LogAggregator  $logAggregator
      * @param $limitBeforeGrouping
      * @param $includeLoops
-     * @return array(followingPages:Piwik_DataTable, outlinks:Piwik_DataTable, downloads:Piwik_DataTable)
+     * @return array(followingPages:DataTable, outlinks:DataTable, downloads:DataTable)
      */
-    public function queryFollowingActions($idaction, $actionType, Piwik_DataAccess_LogAggregator $logAggregator,
+    public function queryFollowingActions($idaction, $actionType, LogAggregator $logAggregator,
                                           $limitBeforeGrouping = false, $includeLoops = false)
     {
         $types = array();
@@ -296,12 +303,12 @@ class Piwik_Transitions_API
         $this->totalTransitionsToFollowingActions = 0;
         $dataTables = array();
         foreach ($types as $type => $recordName) {
-            $dataTable = new Piwik_DataTable;
+            $dataTable = new DataTable;
             if (isset($data[$type])) {
                 foreach ($data[$type] as &$record) {
                     $actions = intval($record[Metrics::INDEX_NB_ACTIONS]);
-                    $dataTable->addRow(new Piwik_DataTable_Row(array(
-                                                                    Piwik_DataTable_Row::COLUMNS => array(
+                    $dataTable->addRow(new Row(array(
+                                                                    Row::COLUMNS => array(
                                                                         'label'                         => $this->getPageLabel($record, $isTitle),
                                                                         Metrics::INDEX_NB_ACTIONS => $actions
                                                                     )
@@ -330,9 +337,9 @@ class Piwik_Transitions_API
      *
      * @param $idaction
      * @param $actionType
-     * @param Piwik_ArchiveProcessor_Day $logAggregator
+     * @param Day $logAggregator
      * @param $limitBeforeGrouping
-     * @return Piwik_DataTable
+     * @return DataTable
      */
     public function queryExternalReferrers($idaction, $actionType, $logAggregator, $limitBeforeGrouping = false)
     {
@@ -395,7 +402,7 @@ class Piwik_Transitions_API
 
         //FIXMEA refactor after integration tests written
         $array = new Piwik_DataArray($referrerData, $referrerSubData);
-        return Piwik_ArchiveProcessor_Day::getDataTableFromDataArray($array);
+        return Day::getDataTableFromDataArray($array);
     }
 
     /**
@@ -403,9 +410,9 @@ class Piwik_Transitions_API
      *
      * @param $idaction
      * @param $actionType
-     * @param Piwik_ArchiveProcessor_Day $logAggregator
+     * @param Day $logAggregator
      * @param $limitBeforeGrouping
-     * @return array(previousPages:Piwik_DataTable, loops:integer)
+     * @return array(previousPages:DataTable, loops:integer)
      */
     protected function queryInternalReferrers($idaction, $actionType, $logAggregator, $limitBeforeGrouping = false)
     {
@@ -451,12 +458,12 @@ class Piwik_Transitions_API
 
         $loops = 0;
         $nbPageviews = 0;
-        $previousPagesDataTable = new Piwik_DataTable;
+        $previousPagesDataTable = new DataTable;
         if (isset($data['result'][1])) {
             foreach ($data['result'][1] as &$page) {
                 $nbActions = intval($page[Metrics::INDEX_NB_ACTIONS]);
-                $previousPagesDataTable->addRow(new Piwik_DataTable_Row(array(
-                                                                             Piwik_DataTable_Row::COLUMNS => array(
+                $previousPagesDataTable->addRow(new Row(array(
+                                                                             Row::COLUMNS => array(
                                                                                  'label'                         => $this->getPageLabel($page, $isTitle),
                                                                                  Metrics::INDEX_NB_ACTIONS => $nbActions
                                                                              )
@@ -465,12 +472,12 @@ class Piwik_Transitions_API
             }
         }
 
-        $previousSearchesDataTable = new Piwik_DataTable;
+        $previousSearchesDataTable = new DataTable;
         if (isset($data['result'][2])) {
             foreach ($data['result'][2] as &$search) {
                 $nbActions = intval($search[Metrics::INDEX_NB_ACTIONS]);
-                $previousSearchesDataTable->addRow(new Piwik_DataTable_Row(array(
-                                                                                Piwik_DataTable_Row::COLUMNS => array(
+                $previousSearchesDataTable->addRow(new Row(array(
+                                                                                Row::COLUMNS => array(
                                                                                     'label'                         => $search['name'],
                                                                                     Metrics::INDEX_NB_ACTIONS => $nbActions
                                                                                 )
@@ -542,7 +549,7 @@ class Piwik_Transitions_API
      * Add the external referrers to the report:
      * direct entries, websites, campaigns, search engines
      *
-     * @param Piwik_DataAccess_LogAggregator  $logAggregator
+     * @param LogAggregator  $logAggregator
      * @param $report
      * @param $idaction
      * @param string $actionType
@@ -563,7 +570,7 @@ class Piwik_Transitions_API
                 // load details (i.e. subtables)
                 $details = array();
                 if ($idSubTable = $row->getIdSubDataTable()) {
-                    $subTable = Piwik_DataTable_Manager::getInstance()->getTable($idSubTable);
+                    $subTable = Manager::getInstance()->getTable($idSubTable);
                     foreach ($subTable->getRows() as $subRow) {
                         $details[] = array(
                             'label'     => $subRow->getColumn('label'),
diff --git a/plugins/Transitions/Transitions.php b/plugins/Transitions/Transitions.php
index 90d1ff2839..b47db2e436 100644
--- a/plugins/Transitions/Transitions.php
+++ b/plugins/Transitions/Transitions.php
@@ -8,11 +8,12 @@
  * @category Piwik_Plugins
  * @package Piwik_Transitions
  */
+use Piwik\Plugin;
 
 /**
  * @package Piwik_Transitions
  */
-class Piwik_Transitions extends Piwik_Plugin
+class Piwik_Transitions extends Plugin
 {
     /**
      * @see Piwik_Plugin::getListHooksRegistered
diff --git a/plugins/UserCountry/API.php b/plugins/UserCountry/API.php
index 79aaf191c5..113a1dc6c5 100644
--- a/plugins/UserCountry/API.php
+++ b/plugins/UserCountry/API.php
@@ -11,6 +11,7 @@
 use Piwik\Archive;
 use Piwik\Metrics;
 use Piwik\Piwik;
+use Piwik\DataTable;
 
 /**
  * @see plugins/UserCountry/functions.php
@@ -67,7 +68,7 @@ class Piwik_UserCountry_API
      * @param string $period
      * @param string $date
      * @param string|bool $segment
-     * @return Piwik_DataTable
+     * @return DataTable
      */
     public function getRegion($idSite, $period, $date, $segment = false)
     {
@@ -109,7 +110,7 @@ class Piwik_UserCountry_API
      * @param string $period
      * @param string $date
      * @param string|bool $segment
-     * @return Piwik_DataTable
+     * @return DataTable
      */
     public function getCity($idSite, $period, $date, $segment = false)
     {
diff --git a/plugins/UserCountry/Archiver.php b/plugins/UserCountry/Archiver.php
index 4667e38474..129da79557 100644
--- a/plugins/UserCountry/Archiver.php
+++ b/plugins/UserCountry/Archiver.php
@@ -9,9 +9,12 @@
  * @package Piwik_UserCountry
  */
 
+use Piwik\ArchiveProcessor\Day;
 use Piwik\Metrics;
+use Piwik\DataTable;
+use Piwik\PluginsArchiver;
 
-class Piwik_UserCountry_Archiver extends Piwik_PluginsArchiver
+class Piwik_UserCountry_Archiver extends PluginsArchiver
 {
     const COUNTRY_RECORD_NAME = 'UserCountry_country';
     const REGION_RECORD_NAME = 'UserCountry_region';
@@ -124,15 +127,15 @@ class Piwik_UserCountry_Archiver extends Piwik_PluginsArchiver
 
     protected function recordDayReports()
     {
-        $tableCountry = Piwik_ArchiveProcessor_Day::getDataTableFromDataArray($this->arrays[self::COUNTRY_FIELD]);
+        $tableCountry = Day::getDataTableFromDataArray($this->arrays[self::COUNTRY_FIELD]);
         $this->getProcessor()->insertBlobRecord(self::COUNTRY_RECORD_NAME, $tableCountry->getSerialized());
         $this->getProcessor()->insertNumericRecord(self::DISTINCT_COUNTRIES_METRIC, $tableCountry->getRowsCount());
 
-        $tableRegion = Piwik_ArchiveProcessor_Day::getDataTableFromDataArray($this->arrays[self::REGION_FIELD]);
+        $tableRegion = Day::getDataTableFromDataArray($this->arrays[self::REGION_FIELD]);
         $serialized = $tableRegion->getSerialized($this->maximumRows, $this->maximumRows, Metrics::INDEX_NB_VISITS);
         $this->getProcessor()->insertBlobRecord(self::REGION_RECORD_NAME, $serialized);
 
-        $tableCity = Piwik_ArchiveProcessor_Day::getDataTableFromDataArray($this->arrays[self::CITY_FIELD]);
+        $tableCity = Day::getDataTableFromDataArray($this->arrays[self::CITY_FIELD]);
         $this->setLatitudeLongitude($tableCity);
         $serialized = $tableCity->getSerialized($this->maximumRows, $this->maximumRows, Metrics::INDEX_NB_VISITS);
         $this->getProcessor()->insertBlobRecord(self::CITY_RECORD_NAME, $serialized);
@@ -142,7 +145,7 @@ class Piwik_UserCountry_Archiver extends Piwik_PluginsArchiver
      * Utility method, appends latitude/longitude pairs to city table labels, if that data
      * exists for the city.
      */
-    private function setLatitudeLongitude(Piwik_DataTable $tableCity)
+    private function setLatitudeLongitude(DataTable $tableCity)
     {
         foreach ($tableCity->getRows() as $row) {
             $label = $row->getColumn('label');
diff --git a/plugins/UserCountry/Controller.php b/plugins/UserCountry/Controller.php
index bda89e927b..9c547ee6dc 100644
--- a/plugins/UserCountry/Controller.php
+++ b/plugins/UserCountry/Controller.php
@@ -8,6 +8,7 @@
  * @category Piwik_Plugins
  * @package Piwik_UserCountry
  */
+use Piwik\DataTable\Renderer\Json;
 use Piwik\Piwik;
 use Piwik\Common;
 
@@ -98,7 +99,7 @@ class Piwik_UserCountry_Controller extends Piwik_Controller_Admin
         Piwik::checkUserIsSuperUser();
         if ($_SERVER["REQUEST_METHOD"] == "POST") {
             $this->checkTokenInUrl();
-            Piwik_DataTable_Renderer_Json::sendHeaderJSON();
+            Json::sendHeaderJSON();
             $outputPath = Piwik_UserCountry_LocationProvider_GeoIp::getPathForGeoIpDatabase('GeoIPCity.dat') . '.gz';
             try {
                 $result = Piwik_Http::downloadChunk(
@@ -180,7 +181,7 @@ class Piwik_UserCountry_Controller extends Piwik_Controller_Admin
     {
         Piwik::checkUserIsSuperUser();
         if ($_SERVER["REQUEST_METHOD"] == "POST") {
-            Piwik_DataTable_Renderer_Json::sendHeaderJSON();
+            Json::sendHeaderJSON();
             try {
                 $this->checkTokenInUrl();
 
@@ -225,7 +226,7 @@ class Piwik_UserCountry_Controller extends Piwik_Controller_Admin
             try {
                 $this->checkTokenInUrl();
 
-                Piwik_DataTable_Renderer_Json::sendHeaderJSON();
+                Json::sendHeaderJSON();
 
                 // based on the database type (provided by the 'key' query param) determine the
                 // url & output file name
diff --git a/plugins/UserCountry/GeoIPAutoUpdater.php b/plugins/UserCountry/GeoIPAutoUpdater.php
index 051eeb42d4..dea98daa0f 100755
--- a/plugins/UserCountry/GeoIPAutoUpdater.php
+++ b/plugins/UserCountry/GeoIPAutoUpdater.php
@@ -10,6 +10,7 @@
  */
 use Piwik\Piwik;
 use Piwik\Common;
+use Piwik\Date;
 
 /**
  * Used to automatically update installed GeoIP databases, and manages the updater's
@@ -48,7 +49,7 @@ class Piwik_UserCountry_GeoIPAutoUpdater
     public function update()
     {
         try {
-            Piwik_SetOption(self::LAST_RUN_TIME_OPTION_NAME, Piwik_Date::factory('today')->getTimestamp());
+            Piwik_SetOption(self::LAST_RUN_TIME_OPTION_NAME, Date::factory('today')->getTimestamp());
 
             $locUrl = Piwik_GetOption(self::LOC_URL_OPTION_NAME);
             if (!empty($locUrl)) {
@@ -570,11 +571,11 @@ class Piwik_UserCountry_GeoIPAutoUpdater
     /**
      * Returns the time the auto updater was last run.
      *
-     * @return Piwik_Date|false
+     * @return Date|false
      */
     public static function getLastRunTime()
     {
         $timestamp = Piwik_GetOption(self::LAST_RUN_TIME_OPTION_NAME);
-        return $timestamp === false ? false : Piwik_Date::factory((int)$timestamp);
+        return $timestamp === false ? false : Date::factory((int)$timestamp);
     }
 }
diff --git a/plugins/UserCountry/LocationProvider/GeoIp/ServerBased.php b/plugins/UserCountry/LocationProvider/GeoIp/ServerBased.php
index a26217bac2..382ee9a319 100755
--- a/plugins/UserCountry/LocationProvider/GeoIp/ServerBased.php
+++ b/plugins/UserCountry/LocationProvider/GeoIp/ServerBased.php
@@ -9,6 +9,8 @@
  * @package Piwik_UserCountry
  */
 
+use Piwik\Common;
+
 /**
  * A LocationProvider that uses an GeoIP module installed in an HTTP Server.
  *
diff --git a/plugins/UserCountry/UserCountry.php b/plugins/UserCountry/UserCountry.php
index d6e673e697..72c7cbda9b 100644
--- a/plugins/UserCountry/UserCountry.php
+++ b/plugins/UserCountry/UserCountry.php
@@ -8,8 +8,10 @@
  * @category Piwik_Plugins
  * @package Piwik_UserCountry
  */
-use Piwik\Piwik;
+use Piwik\ArchiveProcessor;
 use Piwik\Common;
+use Piwik\Piwik;
+use Piwik\Plugin;
 
 /**
  * @see plugins/UserCountry/GeoIPAutoUpdater.php
@@ -20,7 +22,7 @@ require_once PIWIK_INCLUDE_PATH . '/plugins/UserCountry/GeoIPAutoUpdater.php';
  *
  * @package Piwik_UserCountry
  */
-class Piwik_UserCountry extends Piwik_Plugin
+class Piwik_UserCountry extends Plugin
 {
     /**
      * @see Piwik_Plugin::getListHooksRegistered
@@ -244,7 +246,7 @@ class Piwik_UserCountry extends Piwik_Plugin
                                                ));
     }
 
-    public function archivePeriod(Piwik_ArchiveProcessor_Period $archiveProcessor)
+    public function archivePeriod(ArchiveProcessor\Period $archiveProcessor)
     {
         $archiving = new Piwik_UserCountry_Archiver($archiveProcessor);
         if($archiving->shouldArchive()) {
@@ -252,7 +254,7 @@ class Piwik_UserCountry extends Piwik_Plugin
         }
     }
 
-    public function archiveDay(Piwik_ArchiveProcessor_Day $archiveProcessor)
+    public function archiveDay(ArchiveProcessor\Day $archiveProcessor)
     {
         $archiving = new Piwik_UserCountry_Archiver($archiveProcessor);
         if($archiving->shouldArchive()) {
diff --git a/plugins/UserCountry/functions.php b/plugins/UserCountry/functions.php
index 9db8a85d78..35919cdf2d 100644
--- a/plugins/UserCountry/functions.php
+++ b/plugins/UserCountry/functions.php
@@ -8,6 +8,7 @@
  * @category Piwik_Plugins
  * @package Piwik_UserCountry
  */
+use Piwik\DataTable;
 
 /**
  * Return the flag image path for a given country
@@ -67,7 +68,7 @@ function Piwik_CountryTranslate($label)
  */
 function Piwik_UserCountry_getElementFromStringArray($label, $separator, $index, $emptyValue = false)
 {
-    if ($label == Piwik_DataTable::LABEL_SUMMARY_ROW) {
+    if ($label == DataTable::LABEL_SUMMARY_ROW) {
         return false; // so no metadata/column is added
     }
 
@@ -80,11 +81,11 @@ function Piwik_UserCountry_getElementFromStringArray($label, $separator, $index,
  *
  * @param string $label A label containing a region code followed by '|' and a country code, eg,
  *                      'P3|GB'.
- * @return string|false The region name or false if $label == Piwik_DataTable::LABEL_SUMMARY_ROW.
+ * @return string|false The region name or false if $label == DataTable::LABEL_SUMMARY_ROW.
  */
 function Piwik_UserCountry_getRegionName($label)
 {
-    if ($label == Piwik_DataTable::LABEL_SUMMARY_ROW) {
+    if ($label == DataTable::LABEL_SUMMARY_ROW) {
         return false; // so no metadata/column is added
     }
 
@@ -102,11 +103,11 @@ function Piwik_UserCountry_getRegionName($label)
  *
  * @param string $label A label containing a region code followed by '|' and a country code, eg,
  *                      'P3|GB'.
- * @return string|false eg. 'Ile de France, France' or false if $label == Piwik_DataTable::LABEL_SUMMARY_ROW.
+ * @return string|false eg. 'Ile de France, France' or false if $label == DataTable::LABEL_SUMMARY_ROW.
  */
 function Piwik_UserCountry_getPrettyRegionName($label)
 {
-    if ($label == Piwik_DataTable::LABEL_SUMMARY_ROW) {
+    if ($label == DataTable::LABEL_SUMMARY_ROW) {
         return $label;
     }
 
@@ -130,11 +131,11 @@ function Piwik_UserCountry_getPrettyRegionName($label)
  * @param string $label A label containing a city name, region code + country code,
  *                      separated by two '|' chars: 'Paris|A8|FR'
  * @return string|false eg. 'Paris, Ile de France, France' or false if $label ==
- *                      Piwik_DataTable::LABEL_SUMMARY_ROW.
+ *                      DataTable::LABEL_SUMMARY_ROW.
  */
 function Piwik_UserCountry_getPrettyCityName($label)
 {
-    if ($label == Piwik_DataTable::LABEL_SUMMARY_ROW) {
+    if ($label == DataTable::LABEL_SUMMARY_ROW) {
         return $label;
     }
 
diff --git a/plugins/UserCountryMap/Controller.php b/plugins/UserCountryMap/Controller.php
index 50b2986ae1..f9f52e8233 100644
--- a/plugins/UserCountryMap/Controller.php
+++ b/plugins/UserCountryMap/Controller.php
@@ -11,6 +11,7 @@
 use Piwik\Piwik;
 use Piwik\Common;
 use Piwik\Site;
+use Piwik\Config;
 
 /**
  *
@@ -163,7 +164,7 @@ class Piwik_UserCountryMap_Controller extends Piwik_Controller
 
     private function checkUserCountryPluginEnabled()
     {
-        if (!PluginsManager::getInstance()->isPluginActivated('UserCountry')) {
+        if (!\Piwik\PluginsManager::getInstance()->isPluginActivated('UserCountry')) {
             throw new Exception(Piwik_Translate('General_Required', 'Plugin UserCountry'));
         }
     }
diff --git a/plugins/UserCountryMap/UserCountryMap.php b/plugins/UserCountryMap/UserCountryMap.php
index 0b3d3298f4..1659288d1c 100644
--- a/plugins/UserCountryMap/UserCountryMap.php
+++ b/plugins/UserCountryMap/UserCountryMap.php
@@ -8,12 +8,13 @@
  * @category Piwik_Plugins
  * @package Piwik_UserCountryMap
  */
+use Piwik\Plugin;
 
 /**
  *
  * @package Piwik_UserCountryMap
  */
-class Piwik_UserCountryMap extends Piwik_Plugin
+class Piwik_UserCountryMap extends Plugin
 {
     /**
      * @see Piwik_Plugin::getInformation
diff --git a/plugins/UserSettings/API.php b/plugins/UserSettings/API.php
index 7a9f5b6dda..c1c5535c1c 100644
--- a/plugins/UserSettings/API.php
+++ b/plugins/UserSettings/API.php
@@ -11,6 +11,7 @@
 use Piwik\Archive;
 use Piwik\Metrics;
 use Piwik\Piwik;
+use Piwik\DataTable;
 
 /**
  * @see plugins/UserSettings/functions.php
@@ -111,7 +112,7 @@ class Piwik_UserSettings_API
         );
 
         $dataTables = array($dataTable);
-        if ($dataTable instanceof Piwik_DataTable_Array) {
+        if ($dataTable instanceof DataTable\Map) {
             $dataTables = $dataTable->getArray();
         }
         foreach ($dataTables AS $table) {
@@ -180,7 +181,7 @@ class Piwik_UserSettings_API
         $visitsSums = $archive->getDataTableFromNumeric('nb_visits');
 
         // check whether given tables are arrays
-        if ($dataTable instanceof Piwik_DataTable_Array) {
+        if ($dataTable instanceof DataTable\Map) {
             $tableArray = $dataTable->getArray();
             $browserTypesArray = $browserTypes->getArray();
             $visitSumsArray = $visitsSums->getArray();
diff --git a/plugins/UserSettings/Archiver.php b/plugins/UserSettings/Archiver.php
index 0c53938257..40f6b94eb3 100644
--- a/plugins/UserSettings/Archiver.php
+++ b/plugins/UserSettings/Archiver.php
@@ -10,11 +10,14 @@
  */
 
 use Piwik\Common;
+use Piwik\DataAccess\LogAggregator;
 use Piwik\Metrics;
+use Piwik\DataTable;
+use Piwik\PluginsArchiver;
 
 require_once PIWIK_INCLUDE_PATH . '/plugins/UserSettings/functions.php';
 
-class Piwik_UserSettings_Archiver extends Piwik_PluginsArchiver
+class Piwik_UserSettings_Archiver extends PluginsArchiver
 {
     const LANGUAGE_RECORD_NAME = 'UserSettings_language';
     const PLUGIN_RECORD_NAME = 'UserSettings_plugin';
@@ -69,7 +72,7 @@ class Piwik_UserSettings_Archiver extends Piwik_PluginsArchiver
         return $tableBrowser;
     }
 
-    protected function aggregateByBrowserType(Piwik_DataTable $tableBrowser)
+    protected function aggregateByBrowserType(DataTable $tableBrowser)
     {
         $tableBrowser->filter('GroupBy', array('label', 'Piwik_getBrowserFamily'));
         $this->insertTable(self::BROWSER_TYPE_RECORD_NAME, $tableBrowser);
@@ -90,7 +93,7 @@ class Piwik_UserSettings_Archiver extends Piwik_PluginsArchiver
         return $table;
     }
 
-    protected function aggregateByScreenType(Piwik_DataTable $resolutions)
+    protected function aggregateByScreenType(DataTable $resolutions)
     {
         $resolutions->filter('GroupBy', array('label', 'Piwik_getScreenTypeFromResolution'));
         $this->insertTable(self::SCREEN_TYPE_RECORD_NAME, $resolutions);
@@ -113,8 +116,8 @@ class Piwik_UserSettings_Archiver extends Piwik_PluginsArchiver
 
         $query = $this->getLogAggregator()->queryVisitsByDimension(array(), false, $selects, $metrics = array());
         $data = $query->fetch();
-        $cleanRow = Piwik_DataAccess_LogAggregator::makeArrayOneColumn($data, Metrics::INDEX_NB_VISITS);
-        $table = Piwik_DataTable::makeFromIndexedArray($cleanRow);
+        $cleanRow = LogAggregator::makeArrayOneColumn($data, Metrics::INDEX_NB_VISITS);
+        $table = DataTable::makeFromIndexedArray($cleanRow);
         $this->insertTable(self::PLUGIN_RECORD_NAME, $table);
     }
 
@@ -132,7 +135,7 @@ class Piwik_UserSettings_Archiver extends Piwik_PluginsArchiver
         $this->insertTable(self::LANGUAGE_RECORD_NAME, $tableLanguage);
     }
 
-    protected function insertTable($recordName, Piwik_DataTable $table)
+    protected function insertTable($recordName, DataTable $table)
     {
         return $this->getProcessor()->insertBlobRecord($recordName, $table->getSerialized($this->maximumRows, null, Metrics::INDEX_NB_VISITS));
     }
diff --git a/plugins/UserSettings/UserSettings.php b/plugins/UserSettings/UserSettings.php
index ad0e5d9316..ce5a37f707 100644
--- a/plugins/UserSettings/UserSettings.php
+++ b/plugins/UserSettings/UserSettings.php
@@ -8,12 +8,14 @@
  * @category Piwik_Plugins
  * @package Piwik_UserSettings
  */
+use Piwik\ArchiveProcessor;
+use Piwik\Plugin;
 
 /**
  *
  * @package Piwik_UserSettings
  */
-class Piwik_UserSettings extends Piwik_Plugin
+class Piwik_UserSettings extends Plugin
 {
     /**
      * Mapping between the browser family shortcode and the displayed name
@@ -370,7 +372,7 @@ class Piwik_UserSettings extends Piwik_Plugin
      * by Browser, Browser family, etc. Some reports are built from the logs, some reports
      * are superset of an existing report (eg. Browser family is built from the Browser report)
      */
-    public function archiveDay(Piwik_ArchiveProcessor_Day $archiveProcessor)
+    public function archiveDay(ArchiveProcessor\Day $archiveProcessor)
     {
         $archiving = new Piwik_UserSettings_Archiver($archiveProcessor);
         if($archiving->shouldArchive()) {
@@ -381,7 +383,7 @@ class Piwik_UserSettings extends Piwik_Plugin
     /**
      * Period archiving: simply sums up daily archives
      */
-    public function archivePeriod(Piwik_ArchiveProcessor_Period $archiveProcessor)
+    public function archivePeriod(ArchiveProcessor\Period $archiveProcessor)
     {
         $archiving = new Piwik_UserSettings_Archiver($archiveProcessor);
         if($archiving->shouldArchive()) {
diff --git a/plugins/UsersManager/API.php b/plugins/UsersManager/API.php
index 2337d76d63..c4c8dc0806 100644
--- a/plugins/UsersManager/API.php
+++ b/plugins/UsersManager/API.php
@@ -12,6 +12,7 @@ use Piwik\Config;
 use Piwik\Piwik;
 use Piwik\Common;
 use Piwik\Access;
+use Piwik\Date;
 use Piwik\Site;
 
 /**
@@ -198,7 +199,7 @@ class Piwik_UsersManager_API
      * If a user doesn't have any access to the $idSite ('noaccess'),
      * the user will not be in the returned array.
      *
-     * @param string website ID
+     * @param int website ID
      *
      * @return array    The returned array has the format
      *                    array(
@@ -249,7 +250,7 @@ class Piwik_UsersManager_API
      * this website will not be in the returned array.
      * If the user doesn't have any access, the returned array will be an empty array.
      *
-     * @param string User that has to be valid
+     * @param string $userLogin User that has to be valid
      *
      * @return array    The returned array has the format
      *                    array(
@@ -282,7 +283,7 @@ class Piwik_UsersManager_API
     /**
      * Returns the user information (login, password md5, alias, email, date_registered, etc.)
      *
-     * @param string the user login
+     * @param string $userLogin the user login
      *
      * @return array the user information
      */
@@ -302,7 +303,7 @@ class Piwik_UsersManager_API
     /**
      * Returns the user information (login, password md5, alias, email, date_registered, etc.)
      *
-     * @param string the user email
+     * @param string $userEmail the user email
      *
      * @return array the user information
      */
@@ -385,7 +386,7 @@ class Piwik_UsersManager_API
                                                             'alias'           => $alias,
                                                             'email'           => $email,
                                                             'token_auth'      => $token_auth,
-                                                            'date_registered' => Piwik_Date::now()->getDatetime()
+                                                            'date_registered' => Date::now()->getDatetime()
                                                        )
         );
 
@@ -629,7 +630,7 @@ class Piwik_UsersManager_API
      * Delete a user given its login.
      * The user's access are not deleted.
      *
-     * @param string the user login.
+     * @param string $userLogin the user login.
      *
      */
     private function deleteUserOnly($userLogin)
@@ -645,8 +646,8 @@ class Piwik_UsersManager_API
      * Delete the user access for the given websites.
      * The array of idsite must be either null OR the values must have been checked before for their validity!
      *
-     * @param string the user login
-     * @param array array of idsites on which to delete the access. If null then delete all the access for this user.
+     * @param string $userLogin the user login
+     * @param array $idSites array of idsites on which to delete the access. If null then delete all the access for this user.
      *
      * @return bool true on success
      */
diff --git a/plugins/UsersManager/Controller.php b/plugins/UsersManager/Controller.php
index 29f567757c..506c6e6acc 100644
--- a/plugins/UsersManager/Controller.php
+++ b/plugins/UsersManager/Controller.php
@@ -10,6 +10,7 @@
  */
 use Piwik\Piwik;
 use Piwik\Common;
+use Piwik\Config;
 use Piwik\Site;
 
 /**
diff --git a/plugins/UsersManager/UsersManager.php b/plugins/UsersManager/UsersManager.php
index 58f585da67..8d2aeb7a57 100644
--- a/plugins/UsersManager/UsersManager.php
+++ b/plugins/UsersManager/UsersManager.php
@@ -9,13 +9,14 @@
  * @package Piwik_UsersManager
  */
 use Piwik\Piwik;
+use Piwik\Plugin;
 
 /**
  * Manage Piwik users
  *
  * @package Piwik_UsersManager
  */
-class Piwik_UsersManager extends Piwik_Plugin
+class Piwik_UsersManager extends Plugin
 {
     const PASSWORD_MIN_LENGTH = 6;
     const PASSWORD_MAX_LENGTH = 26;
@@ -100,7 +101,7 @@ class Piwik_UsersManager extends Piwik_Plugin
     /**
      * Returns true if the password is complex enough (at least 6 characters and max 26 characters)
      *
-     * @param string email
+     * @param $input string
      * @return bool
      */
     public static function isValidPasswordString($input)
diff --git a/plugins/VisitFrequency/VisitFrequency.php b/plugins/VisitFrequency/VisitFrequency.php
index ee0def21d1..ee5c0ecd2a 100644
--- a/plugins/VisitFrequency/VisitFrequency.php
+++ b/plugins/VisitFrequency/VisitFrequency.php
@@ -8,12 +8,13 @@
  * @category Piwik_Plugins
  * @package Piwik_VisitFrequency
  */
+use Piwik\Plugin;
 
 /**
  *
  * @package Piwik_VisitFrequency
  */
-class Piwik_VisitFrequency extends Piwik_Plugin
+class Piwik_VisitFrequency extends Plugin
 {
     /**
      * @see Piwik_Plugin::getListHooksRegistered
diff --git a/plugins/VisitTime/API.php b/plugins/VisitTime/API.php
index 9075c65532..186c378f83 100644
--- a/plugins/VisitTime/API.php
+++ b/plugins/VisitTime/API.php
@@ -12,6 +12,8 @@ use Piwik\Archive;
 use Piwik\Metrics;
 use Piwik\Period;
 use Piwik\Piwik;
+use Piwik\Date;
+use Piwik\DataTable;
 use Piwik\Site;
 
 /**
@@ -64,7 +66,7 @@ class Piwik_VisitTime_API
      * @param string $date The start date of the period. Cannot refer to multiple dates.
      * @param bool|string $segment The segment.
      * @throws Exception
-     * @return Piwik_DataTable
+     * @return DataTable
      */
     public function getByDayOfWeek($idSite, $period, $date, $segment = false)
     {
@@ -105,7 +107,7 @@ class Piwik_VisitTime_API
         foreach (array(1, 2, 3, 4, 5, 6, 7) as $day) {
             $rows[] = array('label' => $day, 'nb_visits' => 0);
         }
-        $result = new Piwik_DataTable();
+        $result = new DataTable();
         $result->addRowsFromSimpleArray($rows);
         $result->addDataTable($dataTable);
 
@@ -128,9 +130,9 @@ class Piwik_VisitTime_API
 
         if ($period == 'day'
             && ($date == 'today'
-                || $date == Piwik_Date::factory('now', $site->getTimezone())->toString())
+                || $date == Date::factory('now', $site->getTimezone())->toString())
         ) {
-            $currentHour = Piwik_Date::factory('now', $site->getTimezone())->toString('G');
+            $currentHour = Date::factory('now', $site->getTimezone())->toString('G');
             // If no data for today, this is an exception to the API output rule, as we normally return nothing:
             // we shall return all hours of the day, with nb_visits = 0
             if ($table->getRowsCount() == 0) {
@@ -160,7 +162,7 @@ function Piwik_getTimeLabel($label)
 
 /**
  * Returns the day of the week for a date string, without creating a new
- * Piwik_Date instance.
+ * Date instance.
  *
  * @param string $dateStr
  * @return int The day of the week (1-7)
diff --git a/plugins/VisitTime/Archiver.php b/plugins/VisitTime/Archiver.php
index b695ba4558..fd6c1dcc8b 100644
--- a/plugins/VisitTime/Archiver.php
+++ b/plugins/VisitTime/Archiver.php
@@ -9,7 +9,10 @@
  * @package Piwik_VisitTime
  */
 
-class Piwik_VisitTime_Archiver extends Piwik_PluginsArchiver
+use Piwik\Date;
+use Piwik\PluginsArchiver;
+
+class Piwik_VisitTime_Archiver extends PluginsArchiver
 {
     const SERVER_TIME_RECORD_NAME = 'VisitTime_serverTime';
     const LOCAL_TIME_RECORD_NAME = 'VisitTime_localTime';
@@ -46,13 +49,13 @@ class Piwik_VisitTime_Archiver extends Piwik_PluginsArchiver
 
     protected function convertTimeToLocalTimezone(Piwik_DataArray &$array)
     {
-        $date = Piwik_Date::factory($this->getProcessor()->getDateStart()->getDateStartUTC())->toString();
+        $date = Date::factory($this->getProcessor()->getDateStart()->getDateStartUTC())->toString();
         $timezone = $this->getProcessor()->getSite()->getTimezone();
 
         $converted = array();
         foreach ($array->getDataArray() as $hour => $stats) {
             $datetime = $date . ' ' . $hour . ':00:00';
-            $hourInTz = (int)Piwik_Date::factory($datetime, $timezone)->toString('H');
+            $hourInTz = (int)Date::factory($datetime, $timezone)->toString('H');
             $converted[$hourInTz] = $stats;
         }
         return new Piwik_DataArray($converted);
diff --git a/plugins/VisitTime/VisitTime.php b/plugins/VisitTime/VisitTime.php
index abd69f7809..4d73dd8ae0 100644
--- a/plugins/VisitTime/VisitTime.php
+++ b/plugins/VisitTime/VisitTime.php
@@ -8,15 +8,17 @@
  * @category Piwik_Plugins
  * @package Piwik_VisitTime
  */
+use Piwik\ArchiveProcessor;
 use Piwik\Common;
 use Piwik\Period;
+use Piwik\Plugin;
 use Piwik\Site;
 
 /**
  *
  * @package Piwik_VisitTime
  */
-class Piwik_VisitTime extends Piwik_Plugin
+class Piwik_VisitTime extends Plugin
 {
     /**
      * @see Piwik_Plugin::getListHooksRegistered
@@ -167,7 +169,7 @@ class Piwik_VisitTime extends Piwik_Plugin
         }
     }
 
-    public function archivePeriod(Piwik_ArchiveProcessor_Period $archiveProcessor)
+    public function archivePeriod(ArchiveProcessor\Period $archiveProcessor)
     {
         $archiving = new Piwik_VisitTime_Archiver($archiveProcessor);
         if($archiving->shouldArchive()) {
@@ -176,7 +178,7 @@ class Piwik_VisitTime extends Piwik_Plugin
     }
 
 
-    public function archiveDay(Piwik_ArchiveProcessor_Day $archiveProcessor)
+    public function archiveDay(ArchiveProcessor\Day $archiveProcessor)
     {
         $archiving = new Piwik_VisitTime_Archiver($archiveProcessor);
         if($archiving->shouldArchive()) {
diff --git a/plugins/VisitorGenerator/Controller.php b/plugins/VisitorGenerator/Controller.php
index de621bc6ea..1a4f9facd0 100644
--- a/plugins/VisitorGenerator/Controller.php
+++ b/plugins/VisitorGenerator/Controller.php
@@ -8,8 +8,10 @@
  * @category Piwik_Plugins
  * @package Piwik_VisitorGenerator
  */
+use Piwik\ArchiveProcessor\Rules;
 use Piwik\Piwik;
 use Piwik\Common;
+use Piwik\Date;
 use Piwik\Site;
 
 /**
@@ -78,7 +80,7 @@ class Piwik_VisitorGenerator_Controller extends Piwik_Controller_Admin
         $api = Piwik_CoreAdminHome_API::getInstance();
         $api->invalidateArchivedReports($idSite, implode($dates, ","));
 
-        $browserArchiving = Piwik_ArchiveProcessor_Rules::isBrowserTriggerEnabled();
+        $browserArchiving = Rules::isBrowserTriggerEnabled();
 
         // Init view
         $view = new Piwik_View('@VisitorGenerator/generate');
@@ -126,7 +128,7 @@ class Piwik_VisitorGenerator_Controller extends Piwik_Controller_Admin
 
             $start = strpos($url, 'piwik.php?') + strlen('piwik.php?');
             $url = substr($url, $start, strrpos($url, " ") - $start);
-            $datetime = $date . " " . Piwik_Date::factory($time)->toString("H:i:s");
+            $datetime = $date . " " . Date::factory($time)->toString("H:i:s");
             $ip = strlen($ip) < 10 ? "13.5.111.3" : $ip;
 
             // Force date/ip & authenticate
diff --git a/plugins/VisitorGenerator/VisitorGenerator.php b/plugins/VisitorGenerator/VisitorGenerator.php
index 7423f3a900..9ad4fa3d66 100644
--- a/plugins/VisitorGenerator/VisitorGenerator.php
+++ b/plugins/VisitorGenerator/VisitorGenerator.php
@@ -9,12 +9,13 @@
  * @package Piwik_VisitorGenerator
  */
 use Piwik\Piwik;
+use Piwik\Plugin;
 
 /**
  *
  * @package Piwik_VisitorGenerator
  */
-class Piwik_VisitorGenerator extends Piwik_Plugin
+class Piwik_VisitorGenerator extends Plugin
 {
     /**
      * @see Piwik_Plugin::getListHooksRegistered
diff --git a/plugins/VisitorInterest/API.php b/plugins/VisitorInterest/API.php
index f93abbcb34..55474318db 100644
--- a/plugins/VisitorInterest/API.php
+++ b/plugins/VisitorInterest/API.php
@@ -11,6 +11,7 @@
 use Piwik\Archive;
 use Piwik\Metrics;
 use Piwik\Piwik;
+use Piwik\DataTable;
 
 /**
  * VisitorInterest API lets you access two Visitor Engagement reports: number of visits per number of pages,
@@ -68,7 +69,7 @@ class Piwik_VisitorInterest_API
      * @param string $period The period type.
      * @param string $date The date type.
      * @param string|bool $segment The segment.
-     * @return Piwik_DataTable the archived report data.
+     * @return DataTable the archived report data.
      */
     public function getNumberOfVisitsByDaysSinceLast($idSite, $period, $date, $segment = false)
     {
@@ -89,7 +90,7 @@ class Piwik_VisitorInterest_API
      * @param string $period The period type.
      * @param string $date The date type.
      * @param string|bool $segment The segment.
-     * @return Piwik_DataTable the archived report data.
+     * @return DataTable the archived report data.
      */
     public function getNumberOfVisitsByVisitCount($idSite, $period, $date, $segment = false)
     {
@@ -110,11 +111,11 @@ class Piwik_VisitorInterest_API
      * regardless of whether the data table is an data table array or just
      * a data table.
      *
-     * @param Piwik_DataTable $dataTable The data table to modify.
+     * @param DataTable $dataTable The data table to modify.
      */
     private static function addVisitsPercentColumn($dataTable)
     {
-        if ($dataTable instanceof Piwik_DataTable_Array) {
+        if ($dataTable instanceof DataTable\Map) {
             foreach ($dataTable->getArray() as $table) {
                 self::addVisitsPercentColumn($table);
             }
diff --git a/plugins/VisitorInterest/Archiver.php b/plugins/VisitorInterest/Archiver.php
index 4c38bf1a7f..18449cbf4c 100644
--- a/plugins/VisitorInterest/Archiver.php
+++ b/plugins/VisitorInterest/Archiver.php
@@ -9,9 +9,12 @@
  * @package Piwik_VisitorInterest
  */
 
+use Piwik\DataAccess\LogAggregator;
 use Piwik\Metrics;
+use Piwik\DataTable;
+use Piwik\PluginsArchiver;
 
-class Piwik_VisitorInterest_Archiver extends Piwik_PluginsArchiver
+class Piwik_VisitorInterest_Archiver extends PluginsArchiver
 {
     // third element is unit (s for seconds, default is munutes)
     const TIME_SPENT_RECORD_NAME = 'VisitorInterest_timeGap';
@@ -103,14 +106,14 @@ class Piwik_VisitorInterest_Archiver extends Piwik_PluginsArchiver
         );
         $selects = array();
         foreach($aggregatesMetadata as $aggregateMetadata) {
-            $selectsFromRangedColumn = Piwik_DataAccess_LogAggregator::getSelectsFromRangedColumn($aggregateMetadata);
+            $selectsFromRangedColumn = LogAggregator::getSelectsFromRangedColumn($aggregateMetadata);
             $selects = array_merge( $selects, $selectsFromRangedColumn);
         }
         $query = $this->getLogAggregator()->queryVisitsByDimension(array(), $where = false, $selects, array());
         $row = $query->fetch();
         foreach($prefixes as $recordName => $selectAsPrefix) {
-            $cleanRow = Piwik_DataAccess_LogAggregator::makeArrayOneColumn($row, Metrics::INDEX_NB_VISITS, $selectAsPrefix);
-            $dataTable = Piwik_DataTable::makeFromIndexedArray($cleanRow);
+            $cleanRow = LogAggregator::makeArrayOneColumn($row, Metrics::INDEX_NB_VISITS, $selectAsPrefix);
+            $dataTable = DataTable::makeFromIndexedArray($cleanRow);
             $this->getProcessor()->insertBlobRecord($recordName, $dataTable->getSerialized());
         }
     }
diff --git a/plugins/VisitorInterest/VisitorInterest.php b/plugins/VisitorInterest/VisitorInterest.php
index 10231517e1..a503253e1c 100644
--- a/plugins/VisitorInterest/VisitorInterest.php
+++ b/plugins/VisitorInterest/VisitorInterest.php
@@ -8,12 +8,14 @@
  * @category Piwik_Plugins
  * @package Piwik_VisitorInterest
  */
+use Piwik\ArchiveProcessor;
+use Piwik\Plugin;
 
 /**
  *
  * @package Piwik_VisitorInterest
  */
-class Piwik_VisitorInterest extends Piwik_Plugin
+class Piwik_VisitorInterest extends Plugin
 {
     /**
      * @see Piwik_Plugin::getListHooksRegistered
@@ -111,7 +113,7 @@ class Piwik_VisitorInterest extends Piwik_Plugin
         Piwik_AddAction('template_footerVisitsFrequency', array('Piwik_VisitorInterest', 'footerVisitsFrequency'));
     }
 
-    public function archivePeriod(Piwik_ArchiveProcessor_Period $archiveProcessor)
+    public function archivePeriod(ArchiveProcessor\Period $archiveProcessor)
     {
         $archiving = new Piwik_VisitorInterest_Archiver($archiveProcessor);
         if($archiving->shouldArchive()) {
@@ -119,7 +121,7 @@ class Piwik_VisitorInterest extends Piwik_Plugin
         }
     }
 
-    public function archiveDay(Piwik_ArchiveProcessor_Day $archiveProcessor)
+    public function archiveDay(ArchiveProcessor\Day $archiveProcessor)
     {
         $archiving = new Piwik_VisitorInterest_Archiver($archiveProcessor);
         if($archiving->shouldArchive()) {
diff --git a/plugins/VisitsSummary/API.php b/plugins/VisitsSummary/API.php
index db4355203c..7dbabcf6d9 100644
--- a/plugins/VisitsSummary/API.php
+++ b/plugins/VisitsSummary/API.php
@@ -161,7 +161,7 @@ class Piwik_VisitsSummary_API
         $table = $this->getSumVisitsLength($idSite, $period, $date, $segment);
         if (is_object($table)) {
             $table->filter('ColumnCallbackReplace',
-                array('sum_visit_length', array('Piwik', 'getPrettyTimeFromSeconds')));
+                array('sum_visit_length', '\Piwik\Piwik::getPrettyTimeFromSeconds'));
         } else {
             $table = Piwik::getPrettyTimeFromSeconds($table);
         }
diff --git a/plugins/VisitsSummary/Controller.php b/plugins/VisitsSummary/Controller.php
index 493acaab16..bc30a1e6aa 100644
--- a/plugins/VisitsSummary/Controller.php
+++ b/plugins/VisitsSummary/Controller.php
@@ -8,8 +8,10 @@
  * @category Piwik_Plugins
  * @package Piwik_VisitsSummary
  */
+use Piwik\DataTable\Row;
 use Piwik\Piwik;
 use Piwik\Common;
+use Piwik\DataTable;
 use Piwik\Site;
 
 /**
@@ -98,7 +100,7 @@ class Piwik_VisitsSummary_Controller extends Piwik_Controller
             "&disable_generic_filters=1";
         $request = new Piwik_API_Request($requestString);
         $result = $request->process();
-        return empty($result) ? new Piwik_DataTable() : $result;
+        return empty($result) ? new DataTable() : $result;
     }
 
     static public function getVisits()
@@ -130,11 +132,11 @@ class Piwik_VisitsSummary_Controller extends Piwik_Controller
         $view->displaySiteSearch = $displaySiteSearch;
 
         $dataTableVisit = self::getVisitsSummary();
-        $dataRow = $dataTableVisit->getRowsCount() == 0 ? new Piwik_DataTable_Row() : $dataTableVisit->getFirstRow();
+        $dataRow = $dataTableVisit->getRowsCount() == 0 ? new Row() : $dataTableVisit->getFirstRow();
 
         $dataTableActions = Piwik_Actions_API::getInstance()->get($idSite, Common::getRequestVar('period'), Common::getRequestVar('date'), Piwik_ViewDataTable::getRawSegmentFromRequest());
         $dataActionsRow =
-            $dataTableActions->getRowsCount() == 0 ? new Piwik_DataTable_Row() : $dataTableActions->getFirstRow();
+            $dataTableActions->getRowsCount() == 0 ? new Row() : $dataTableActions->getFirstRow();
 
         $view->nbUniqVisitors = (int)$dataRow->getColumn('nb_uniq_visitors');
         $nbVisits = (int)$dataRow->getColumn('nb_visits');
diff --git a/plugins/VisitsSummary/VisitsSummary.php b/plugins/VisitsSummary/VisitsSummary.php
index daf509753c..fec9352492 100644
--- a/plugins/VisitsSummary/VisitsSummary.php
+++ b/plugins/VisitsSummary/VisitsSummary.php
@@ -8,16 +8,17 @@
  * @category Piwik_Plugins
  * @package Piwik_VisitsSummary
  */
+use Piwik\Plugin;
 
 /**
  * Note: This plugin does not hook on Daily and Period Archiving like other Plugins because it reports the
  * very core metrics (visits, actions, visit duration, etc.) which are processed in the Core
- * Piwik_ArchiveProcessor_Day class directly.
+ * Day class directly.
  * These metrics can be used by other Plugins so they need to be processed up front.
  *
  * @package Piwik_VisitsSummary
  */
-class Piwik_VisitsSummary extends Piwik_Plugin
+class Piwik_VisitsSummary extends Plugin
 {
     /**
      * @see Piwik_Plugin::getListHooksRegistered
diff --git a/plugins/Widgetize/Widgetize.php b/plugins/Widgetize/Widgetize.php
index 62fae7ab4a..7bf8cdb7c1 100644
--- a/plugins/Widgetize/Widgetize.php
+++ b/plugins/Widgetize/Widgetize.php
@@ -9,12 +9,13 @@
  * @category Piwik_Plugins
  * @package Piwik_Widgetize
  */
+use Piwik\Plugin;
 
 /**
  *
  * @package Piwik_Widgetize
  */
-class Piwik_Widgetize extends Piwik_Plugin
+class Piwik_Widgetize extends Plugin
 {
     /**
      * @see Piwik_Plugin::getListHooksRegistered