diff --git a/apps/dav/appinfo/info.xml b/apps/dav/appinfo/info.xml
index 0024e41e753cd83888817821b7be96d7e3741869..f362c882f97eb4e6f40384669bf74b3bd8389486 100644
--- a/apps/dav/appinfo/info.xml
+++ b/apps/dav/appinfo/info.xml
@@ -31,4 +31,23 @@
 		<command>OCA\DAV\Command\SyncBirthdayCalendar</command>
 		<command>OCA\DAV\Command\SyncSystemAddressBook</command>
 	</commands>
+
+	<activity>
+		<filters>
+			<filter>OCA\DAV\CalDAV\Activity\Filter\Calendar</filter>
+			<filter>OCA\DAV\CalDAV\Activity\Filter\Todo</filter>
+		</filters>
+
+		<settings>
+			<setting>OCA\DAV\CalDAV\Activity\Setting\Calendar</setting>
+			<setting>OCA\DAV\CalDAV\Activity\Setting\Event</setting>
+			<setting>OCA\DAV\CalDAV\Activity\Setting\Todo</setting>
+		</settings>
+
+		<providers>
+			<provider>OCA\DAV\CalDAV\Activity\Provider\Calendar</provider>
+			<provider>OCA\DAV\CalDAV\Activity\Provider\Event</provider>
+			<provider>OCA\DAV\CalDAV\Activity\Provider\Todo</provider>
+		</providers>
+	</activity>
 </info>
diff --git a/apps/dav/lib/AppInfo/Application.php b/apps/dav/lib/AppInfo/Application.php
index 7c32fda8f5a7e98e5b9673aa3da8e95b68ec456c..669c52d1489ae6fd049b8b2ed723c8e1fa6179a4 100644
--- a/apps/dav/lib/AppInfo/Application.php
+++ b/apps/dav/lib/AppInfo/Application.php
@@ -26,6 +26,7 @@ namespace OCA\DAV\AppInfo;
 
 use OCA\DAV\CalDAV\Activity\Backend;
 use OCA\DAV\CalDAV\Activity\Extension;
+use OCA\DAV\CalDAV\Activity\Provider\Event;
 use OCA\DAV\CalDAV\BirthdayService;
 use OCA\DAV\Capabilities;
 use OCA\DAV\CardDAV\ContactsManager;
@@ -146,11 +147,11 @@ class Application extends App {
 			/** @var Backend $backend */
 			$backend = $this->getContainer()->query(Backend::class);
 
-			$subject = Extension::SUBJECT_OBJECT_ADD;
+			$subject = Event::SUBJECT_OBJECT_ADD;
 			if ($eventName === '\OCA\DAV\CalDAV\CalDavBackend::updateCalendarObject') {
-				$subject = Extension::SUBJECT_OBJECT_UPDATE;
+				$subject = Event::SUBJECT_OBJECT_UPDATE;
 			} else if ($eventName === '\OCA\DAV\CalDAV\CalDavBackend::deleteCalendarObject') {
-				$subject = Extension::SUBJECT_OBJECT_DELETE;
+				$subject = Event::SUBJECT_OBJECT_DELETE;
 			}
 			$backend->onTouchCalendarObject(
 				$subject,
@@ -162,11 +163,6 @@ class Application extends App {
 		$dispatcher->addListener('\OCA\DAV\CalDAV\CalDavBackend::createCalendarObject', $listener);
 		$dispatcher->addListener('\OCA\DAV\CalDAV\CalDavBackend::updateCalendarObject', $listener);
 		$dispatcher->addListener('\OCA\DAV\CalDAV\CalDavBackend::deleteCalendarObject', $listener);
-
-		$aM = $this->getContainer()->getServer()->getActivityManager();
-		$aM->registerExtension(function() {
-			return $this->getContainer()->query(Extension::class);
-		});
 	}
 
 	public function getSyncService() {
diff --git a/apps/dav/lib/CalDAV/Activity/Backend.php b/apps/dav/lib/CalDAV/Activity/Backend.php
index 6a557fef7bdba87143084dd04bfc63386ba11418..953fdcea832baa5dbcfec87a8719000940a495e0 100644
--- a/apps/dav/lib/CalDAV/Activity/Backend.php
+++ b/apps/dav/lib/CalDAV/Activity/Backend.php
@@ -22,6 +22,8 @@
 namespace OCA\DAV\CalDAV\Activity;
 
 
+use OCA\DAV\CalDAV\Activity\Provider\Calendar;
+use OCA\DAV\CalDAV\Activity\Provider\Event;
 use OCP\Activity\IEvent;
 use OCP\Activity\IManager as IActivityManager;
 use OCP\IGroup;
@@ -63,7 +65,7 @@ class Backend {
 	 * @param array $calendarData
 	 */
 	public function onCalendarAdd(array $calendarData) {
-		$this->triggerCalendarActivity(Extension::SUBJECT_ADD, $calendarData);
+		$this->triggerCalendarActivity(Calendar::SUBJECT_ADD, $calendarData);
 	}
 
 	/**
@@ -74,7 +76,7 @@ class Backend {
 	 * @param array $properties
 	 */
 	public function onCalendarUpdate(array $calendarData, array $shares, array $properties) {
-		$this->triggerCalendarActivity(Extension::SUBJECT_UPDATE, $calendarData, $shares, $properties);
+		$this->triggerCalendarActivity(Calendar::SUBJECT_UPDATE, $calendarData, $shares, $properties);
 	}
 
 	/**
@@ -84,7 +86,7 @@ class Backend {
 	 * @param array $shares
 	 */
 	public function onCalendarDelete(array $calendarData, array $shares) {
-		$this->triggerCalendarActivity(Extension::SUBJECT_DELETE, $calendarData, $shares);
+		$this->triggerCalendarActivity(Calendar::SUBJECT_DELETE, $calendarData, $shares);
 	}
 
 	/**
@@ -112,8 +114,8 @@ class Backend {
 
 		$event = $this->activityManager->generateEvent();
 		$event->setApp('dav')
-			->setObject(Extension::CALENDAR, (int) $calendarData['id'])
-			->setType(Extension::CALENDAR)
+			->setObject('calendar', (int) $calendarData['id'])
+			->setType('calendar')
 			->setAuthor($currentUser);
 
 		$changedVisibleInformation = array_intersect([
@@ -121,7 +123,7 @@ class Backend {
 			'{http://apple.com/ns/ical/}calendar-color'
 		], array_keys($changedProperties));
 
-		if (empty($shares) || ($action === Extension::SUBJECT_UPDATE && empty($changedVisibleInformation))) {
+		if (empty($shares) || ($action === Calendar::SUBJECT_UPDATE && empty($changedVisibleInformation))) {
 			$users = [$owner];
 		} else {
 			$users = $this->getUsersForShares($shares);
@@ -162,8 +164,8 @@ class Backend {
 
 		$event = $this->activityManager->generateEvent();
 		$event->setApp('dav')
-			->setObject(Extension::CALENDAR, (int) $calendarData['id'])
-			->setType(Extension::CALENDAR)
+			->setObject('calendar', (int) $calendarData['id'])
+			->setType('calendar')
 			->setAuthor($currentUser);
 
 		foreach ($remove as $principal) {
@@ -179,8 +181,8 @@ class Backend {
 					$principal[2],
 					$event,
 					$calendarData,
-					Extension::SUBJECT_UNSHARE_USER,
-					Extension::SUBJECT_DELETE . '_self'
+					Calendar::SUBJECT_UNSHARE_USER,
+					Calendar::SUBJECT_DELETE . '_self'
 				);
 
 				if ($owner !== $principal[2]) {
@@ -190,15 +192,15 @@ class Backend {
 					];
 
 					if ($owner === $event->getAuthor()) {
-						$subject = Extension::SUBJECT_UNSHARE_USER . '_you';
+						$subject = Calendar::SUBJECT_UNSHARE_USER . '_you';
 					} else if ($principal[2] === $event->getAuthor()) {
-						$subject = Extension::SUBJECT_UNSHARE_USER . '_self';
+						$subject = Calendar::SUBJECT_UNSHARE_USER . '_self';
 					} else {
 						$event->setAffectedUser($event->getAuthor())
-							->setSubject(Extension::SUBJECT_UNSHARE_USER . '_you', $parameters);
+							->setSubject(Calendar::SUBJECT_UNSHARE_USER . '_you', $parameters);
 						$this->activityManager->publish($event);
 
-						$subject = Extension::SUBJECT_UNSHARE_USER . '_by';
+						$subject = Calendar::SUBJECT_UNSHARE_USER . '_by';
 						$parameters[] = $event->getAuthor();
 					}
 
@@ -207,7 +209,7 @@ class Backend {
 					$this->activityManager->publish($event);
 				}
 			} else if ($principal[1] === 'groups') {
-				$this->triggerActivityGroup($principal[2], $event, $calendarData, Extension::SUBJECT_UNSHARE_USER);
+				$this->triggerActivityGroup($principal[2], $event, $calendarData, Calendar::SUBJECT_UNSHARE_USER);
 
 				$parameters = [
 					$principal[2],
@@ -215,13 +217,13 @@ class Backend {
 				];
 
 				if ($owner === $event->getAuthor()) {
-					$subject = Extension::SUBJECT_UNSHARE_GROUP . '_you';
+					$subject = Calendar::SUBJECT_UNSHARE_GROUP . '_you';
 				} else {
 					$event->setAffectedUser($event->getAuthor())
-						->setSubject(Extension::SUBJECT_UNSHARE_GROUP . '_you', $parameters);
+						->setSubject(Calendar::SUBJECT_UNSHARE_GROUP . '_you', $parameters);
 					$this->activityManager->publish($event);
 
-					$subject = Extension::SUBJECT_UNSHARE_GROUP . '_by';
+					$subject = Calendar::SUBJECT_UNSHARE_GROUP . '_by';
 					$parameters[] = $event->getAuthor();
 				}
 
@@ -244,7 +246,7 @@ class Backend {
 			$principal = explode('/', $parts[1]);
 
 			if ($principal[1] === 'users') {
-				$this->triggerActivityUser($principal[2], $event, $calendarData, Extension::SUBJECT_SHARE_USER);
+				$this->triggerActivityUser($principal[2], $event, $calendarData, Calendar::SUBJECT_SHARE_USER);
 
 				if ($owner !== $principal[2]) {
 					$parameters = [
@@ -253,13 +255,13 @@ class Backend {
 					];
 
 					if ($owner === $event->getAuthor()) {
-						$subject = Extension::SUBJECT_SHARE_USER . '_you';
+						$subject = Calendar::SUBJECT_SHARE_USER . '_you';
 					} else {
 						$event->setAffectedUser($event->getAuthor())
-							->setSubject(Extension::SUBJECT_SHARE_USER . '_you', $parameters);
+							->setSubject(Calendar::SUBJECT_SHARE_USER . '_you', $parameters);
 						$this->activityManager->publish($event);
 
-						$subject = Extension::SUBJECT_SHARE_USER . '_by';
+						$subject = Calendar::SUBJECT_SHARE_USER . '_by';
 						$parameters[] = $event->getAuthor();
 					}
 
@@ -268,7 +270,7 @@ class Backend {
 					$this->activityManager->publish($event);
 				}
 			} else if ($principal[1] === 'groups') {
-				$this->triggerActivityGroup($principal[2], $event, $calendarData, Extension::SUBJECT_SHARE_USER);
+				$this->triggerActivityGroup($principal[2], $event, $calendarData, Calendar::SUBJECT_SHARE_USER);
 
 				$parameters = [
 					$principal[2],
@@ -276,13 +278,13 @@ class Backend {
 				];
 
 				if ($owner === $event->getAuthor()) {
-					$subject = Extension::SUBJECT_SHARE_GROUP . '_you';
+					$subject = Calendar::SUBJECT_SHARE_GROUP . '_you';
 				} else {
 					$event->setAffectedUser($event->getAuthor())
-						->setSubject(Extension::SUBJECT_SHARE_GROUP . '_you', $parameters);
+						->setSubject(Calendar::SUBJECT_SHARE_GROUP . '_you', $parameters);
 					$this->activityManager->publish($event);
 
-					$subject = Extension::SUBJECT_SHARE_GROUP . '_by';
+					$subject = Calendar::SUBJECT_SHARE_GROUP . '_by';
 					$parameters[] = $event->getAuthor();
 				}
 
@@ -379,16 +381,16 @@ class Backend {
 		$object = $this->getObjectNameAndType($objectData);
 		$action = $action . '_' . $object['type'];
 
-		if ($object['type'] === 'todo' && strpos($action, Extension::SUBJECT_OBJECT_UPDATE) === 0 && $object['status'] === 'COMPLETED') {
+		if ($object['type'] === 'todo' && strpos($action, Event::SUBJECT_OBJECT_UPDATE) === 0 && $object['status'] === 'COMPLETED') {
 			$action .= '_completed';
-		} else if ($object['type'] === 'todo' && strpos($action, Extension::SUBJECT_OBJECT_UPDATE) === 0 && $object['status'] === 'NEEDS-ACTION') {
+		} else if ($object['type'] === 'todo' && strpos($action, Event::SUBJECT_OBJECT_UPDATE) === 0 && $object['status'] === 'NEEDS-ACTION') {
 			$action .= '_needs_action';
 		}
 
 		$event = $this->activityManager->generateEvent();
 		$event->setApp('dav')
-			->setObject(Extension::CALENDAR, (int) $calendarData['id'])
-			->setType($object['type'] === 'event' ? Extension::CALENDAR_EVENT : Extension::CALENDAR_TODO)
+			->setObject('calendar', (int) $calendarData['id'])
+			->setType($object['type'] === 'event' ? 'calendar_event' : 'calendar_todo')
 			->setAuthor($currentUser);
 
 		$users = $this->getUsersForShares($shares);
@@ -401,7 +403,10 @@ class Backend {
 					[
 						$currentUser,
 						$calendarData['{DAV:}displayname'],
-						$object['name'],
+						[
+							'id' => $object['id'],
+							'name' => $object['name'],
+						],
 					]
 				);
 			$this->activityManager->publish($event);
@@ -428,9 +433,9 @@ class Backend {
 		}
 
 		if ($componentType === 'VEVENT') {
-			return ['name' => (string) $component->SUMMARY, 'type' => 'event'];
+			return ['id' => (string) $component->UID, 'name' => (string) $component->SUMMARY, 'type' => 'event'];
 		}
-		return ['name' => (string) $component->SUMMARY, 'type' => 'todo', 'status' => (string) $component->STATUS];
+		return ['id' => (string) $component->UID, 'name' => (string) $component->SUMMARY, 'type' => 'todo', 'status' => (string) $component->STATUS];
 	}
 
 	/**
diff --git a/apps/dav/lib/CalDAV/Activity/Extension.php b/apps/dav/lib/CalDAV/Activity/Extension.php
deleted file mode 100644
index 29222b90ce8d07942c036c662273c89ec8e630c8..0000000000000000000000000000000000000000
--- a/apps/dav/lib/CalDAV/Activity/Extension.php
+++ /dev/null
@@ -1,378 +0,0 @@
-<?php
-/**
- * @copyright Copyright (c) 2016 Joas Schilling <coding@schilljs.com>
- *
- * @license GNU AGPL version 3 or any later version
- *
- * This program is free software: you can redistribute it and/or modify
- * it under the terms of the GNU Affero General Public License as
- * published by the Free Software Foundation, either version 3 of the
- * License, or (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU Affero General Public License for more details.
- *
- * You should have received a copy of the GNU Affero General Public License
- * along with this program.  If not, see <http://www.gnu.org/licenses/>.
- *
- */
-
-namespace OCA\DAV\CalDAV\Activity;
-
-use OCP\Activity\IExtension;
-use OCP\IURLGenerator;
-use OCP\L10N\IFactory;
-
-class Extension implements IExtension {
-	const APP = 'dav';
-	/**
-	 * Filter with all sharing related activities
-	 */
-	const CALENDAR = 'calendar';
-	const CALENDAR_EVENT = 'calendar_event';
-	const CALENDAR_TODO = 'calendar_todo';
-
-	const SUBJECT_ADD = 'calendar_add';
-	const SUBJECT_UPDATE = 'calendar_update';
-	const SUBJECT_DELETE = 'calendar_delete';
-	const SUBJECT_SHARE_USER = 'calendar_user_share';
-	const SUBJECT_SHARE_GROUP = 'calendar_group_share';
-	const SUBJECT_UNSHARE_USER = 'calendar_user_unshare';
-	const SUBJECT_UNSHARE_GROUP = 'calendar_group_unshare';
-
-	const SUBJECT_OBJECT_ADD = 'object_add';
-	const SUBJECT_OBJECT_UPDATE = 'object_update';
-	const SUBJECT_OBJECT_DELETE = 'object_delete';
-
-	/** @var IFactory */
-	protected $languageFactory;
-
-	/** @var IURLGenerator */
-	protected $URLGenerator;
-
-	/**
-	 * @param IFactory $languageFactory
-	 * @param IURLGenerator $URLGenerator
-	 */
-	public function __construct(IFactory $languageFactory, IURLGenerator $URLGenerator) {
-		$this->languageFactory = $languageFactory;
-		$this->URLGenerator = $URLGenerator;
-	}
-
-	protected function getL10N($languageCode = null) {
-		return $this->languageFactory->get(self::APP, $languageCode);
-	}
-
-	/**
-	 * The extension can return an array of additional notification types.
-	 * If no additional types are to be added false is to be returned
-	 *
-	 * @param string $languageCode
-	 * @return array|false
-	 */
-	public function getNotificationTypes($languageCode) {
-		$l = $this->getL10N($languageCode);
-
-		return array(
-			self::CALENDAR => (string) $l->t('A <strong>calendar</strong> was modified'),
-			self::CALENDAR_EVENT => (string) $l->t('A calendar <strong>event</strong> was modified'),
-			self::CALENDAR_TODO => (string) $l->t('A calendar <strong>todo</strong> was modified'),
-		);
-	}
-
-	/**
-	 * For a given method additional types to be displayed in the settings can be returned.
-	 * In case no additional types are to be added false is to be returned.
-	 *
-	 * @param string $method
-	 * @return array|false
-	 */
-	public function getDefaultTypes($method) {
-		$defaultTypes = [];
-		if ($method === self::METHOD_STREAM) {
-			$defaultTypes[] = self::CALENDAR;
-			$defaultTypes[] = self::CALENDAR_EVENT;
-			$defaultTypes[] = self::CALENDAR_TODO;
-		}
-
-		return $defaultTypes;
-	}
-
-	/**
-	 * A string naming the css class for the icon to be used can be returned.
-	 * If no icon is known for the given type false is to be returned.
-	 *
-	 * @param string $type
-	 * @return string|false
-	 */
-	public function getTypeIcon($type) {
-		switch ($type) {
-			case self::CALENDAR:
-			case self::CALENDAR_EVENT:
-				return 'icon-calendar-dark';
-			case self::CALENDAR_TODO:
-				return 'icon-checkmark';
-		}
-
-		return false;
-	}
-
-	/**
-	 * The extension can translate a given message to the requested languages.
-	 * If no translation is available false is to be returned.
-	 *
-	 * @param string $app
-	 * @param string $text
-	 * @param array $params
-	 * @param boolean $stripPath
-	 * @param boolean $highlightParams
-	 * @param string $languageCode
-	 * @return string|false
-	 */
-	public function translate($app, $text, $params, $stripPath, $highlightParams, $languageCode) {
-		if ($app !== self::APP) {
-			return false;
-		}
-
-		$l = $this->getL10N($languageCode);
-
-		switch ($text) {
-			case self::SUBJECT_ADD:
-				return (string) $l->t('%1$s created calendar %2$s', $params);
-			case self::SUBJECT_ADD . '_self':
-				return (string) $l->t('You created calendar %2$s', $params);
-			case self::SUBJECT_DELETE:
-				return (string) $l->t('%1$s deleted calendar %2$s', $params);
-			case self::SUBJECT_DELETE . '_self':
-				return (string) $l->t('You deleted calendar %2$s', $params);
-			case self::SUBJECT_UPDATE:
-				return (string) $l->t('%1$s updated calendar %2$s', $params);
-			case self::SUBJECT_UPDATE . '_self':
-				return (string) $l->t('You updated calendar %2$s', $params);
-
-			case self::SUBJECT_SHARE_USER:
-				return (string) $l->t('%1$s shared calendar %2$s with you', $params);
-			case self::SUBJECT_SHARE_USER . '_you':
-				return (string) $l->t('You shared calendar %2$s with %1$s', $params);
-			case self::SUBJECT_SHARE_USER . '_by':
-				return (string) $l->t('%3$s shared calendar %2$s with %1$s', $params);
-			case self::SUBJECT_UNSHARE_USER:
-				return (string) $l->t('%1$s unshared calendar %2$s from you', $params);
-			case self::SUBJECT_UNSHARE_USER . '_you':
-				return (string) $l->t('You unshared calendar %2$s from %1$s', $params);
-			case self::SUBJECT_UNSHARE_USER . '_by':
-				return (string) $l->t('%3$s unshared calendar %2$s from %1$s', $params);
-			case self::SUBJECT_UNSHARE_USER . '_self':
-				return (string) $l->t('%1$s unshared calendar %2$s from themselves', $params);
-
-			case self::SUBJECT_SHARE_GROUP . '_you':
-				return (string) $l->t('You shared calendar %2$s with group %1$s', $params);
-			case self::SUBJECT_SHARE_GROUP . '_by':
-				return (string) $l->t('%3$s shared calendar %2$s with group %1$s', $params);
-			case self::SUBJECT_UNSHARE_GROUP . '_you':
-				return (string) $l->t('You unshared calendar %2$s from group %1$s', $params);
-			case self::SUBJECT_UNSHARE_GROUP . '_by':
-				return (string) $l->t('%3$s unshared calendar %2$s from group %1$s', $params);
-
-			case self::SUBJECT_OBJECT_ADD . '_event':
-				return (string) $l->t('%1$s created event %3$s in calendar %2$s', $params);
-			case self::SUBJECT_OBJECT_ADD . '_event_self':
-				return (string) $l->t('You created event %3$s in calendar %2$s', $params);
-			case self::SUBJECT_OBJECT_DELETE . '_event':
-				return (string) $l->t('%1$s deleted event %3$s from calendar %2$s', $params);
-			case self::SUBJECT_OBJECT_DELETE . '_event_self':
-				return (string) $l->t('You deleted event %3$s from calendar %2$s', $params);
-			case self::SUBJECT_OBJECT_UPDATE . '_event':
-				return (string) $l->t('%1$s updated event %3$s in calendar %2$s', $params);
-			case self::SUBJECT_OBJECT_UPDATE . '_event_self':
-				return (string) $l->t('You updated event %3$s in calendar %2$s', $params);
-
-			case self::SUBJECT_OBJECT_ADD . '_todo':
-				return (string) $l->t('%1$s created todo %3$s in list %2$s', $params);
-			case self::SUBJECT_OBJECT_ADD . '_todo_self':
-				return (string) $l->t('You created todo %3$s in list %2$s', $params);
-			case self::SUBJECT_OBJECT_DELETE . '_todo':
-				return (string) $l->t('%1$s deleted todo %3$s from list %2$s', $params);
-			case self::SUBJECT_OBJECT_DELETE . '_todo_self':
-				return (string) $l->t('You deleted todo %3$s from list %2$s', $params);
-			case self::SUBJECT_OBJECT_UPDATE . '_todo':
-				return (string) $l->t('%1$s updated todo %3$s in list %2$s', $params);
-			case self::SUBJECT_OBJECT_UPDATE . '_todo_self':
-				return (string) $l->t('You updated todo %3$s in list %2$s', $params);
-
-			case self::SUBJECT_OBJECT_UPDATE . '_todo_completed':
-				return (string) $l->t('%1$s solved todo %3$s in list %2$s', $params);
-			case self::SUBJECT_OBJECT_UPDATE . '_todo_completed_self':
-				return (string) $l->t('You solved todo %3$s in list %2$s', $params);
-			case self::SUBJECT_OBJECT_UPDATE . '_todo_needs_action':
-				return (string) $l->t('%1$s reopened todo %3$s in list %2$s', $params);
-			case self::SUBJECT_OBJECT_UPDATE . '_todo_needs_action_self':
-				return (string) $l->t('You reopened todo %3$s in list %2$s', $params);
-
-		}
-
-		return false;
-	}
-
-	/**
-	 * The extension can define the type of parameters for translation
-	 *
-	 * Currently known types are:
-	 * * file		=> will strip away the path of the file and add a tooltip with it
-	 * * username	=> will add the avatar of the user
-	 *
-	 * @param string $app
-	 * @param string $text
-	 * @return array|false
-	 */
-	public function getSpecialParameterList($app, $text) {
-		if ($app === self::APP) {
-			switch ($text) {
-				case self::SUBJECT_ADD:
-				case self::SUBJECT_ADD . '_self':
-				case self::SUBJECT_DELETE:
-				case self::SUBJECT_DELETE . '_self':
-				case self::SUBJECT_UPDATE:
-				case self::SUBJECT_UPDATE . '_self':
-				case self::SUBJECT_SHARE_USER:
-				case self::SUBJECT_SHARE_USER . '_you':
-				case self::SUBJECT_UNSHARE_USER:
-				case self::SUBJECT_UNSHARE_USER . '_you':
-				case self::SUBJECT_UNSHARE_USER . '_self':
-					return [
-						0 => 'username',
-						//1 => 'calendar',
-					];
-				case self::SUBJECT_SHARE_USER . '_by':
-				case self::SUBJECT_UNSHARE_USER . '_by':
-					return [
-						0 => 'username',
-						//1 => 'calendar',
-						2 => 'username',
-					];
-				case self::SUBJECT_SHARE_GROUP . '_you':
-				case self::SUBJECT_UNSHARE_GROUP . '_you':
-					return [
-						//0 => 'group',
-						//1 => 'calendar',
-					];
-				case self::SUBJECT_SHARE_GROUP . '_by':
-				case self::SUBJECT_UNSHARE_GROUP . '_by':
-					return [
-						//0 => 'group',
-						//1 => 'calendar',
-						2 => 'username',
-					];
-
-				case self::SUBJECT_OBJECT_ADD . '_event':
-				case self::SUBJECT_OBJECT_ADD . '_event_self':
-				case self::SUBJECT_OBJECT_DELETE . '_event':
-				case self::SUBJECT_OBJECT_DELETE . '_event_self':
-				case self::SUBJECT_OBJECT_UPDATE . '_event':
-				case self::SUBJECT_OBJECT_UPDATE . '_event_self':
-
-				case self::SUBJECT_OBJECT_ADD . '_todo':
-				case self::SUBJECT_OBJECT_ADD . '_todo_self':
-				case self::SUBJECT_OBJECT_DELETE . '_todo':
-				case self::SUBJECT_OBJECT_DELETE . '_todo_self':
-				case self::SUBJECT_OBJECT_UPDATE . '_todo':
-				case self::SUBJECT_OBJECT_UPDATE . '_todo_self':
-
-				case self::SUBJECT_OBJECT_UPDATE . '_todo_completed':
-				case self::SUBJECT_OBJECT_UPDATE . '_todo_completed_self':
-				case self::SUBJECT_OBJECT_UPDATE . '_todo_needs_action':
-				case self::SUBJECT_OBJECT_UPDATE . '_todo_needs_action_self':
-					return [
-						0 => 'username',
-						//1 => 'calendar',
-						//2 => 'object',
-					];
-			}
-		}
-
-		return false;
-	}
-
-	/**
-	 * The extension can define the parameter grouping by returning the index as integer.
-	 * In case no grouping is required false is to be returned.
-	 *
-	 * @param array $activity
-	 * @return integer|false
-	 */
-	public function getGroupParameter($activity) {
-		return false;
-	}
-
-	/**
-	 * The extension can define additional navigation entries. The array returned has to contain two keys 'top'
-	 * and 'apps' which hold arrays with the relevant entries.
-	 * If no further entries are to be added false is no be returned.
-	 *
-	 * @return array|false
-	 */
-	public function getNavigation() {
-		$l = $this->getL10N();
-		return [
-			'apps' => [
-				self::CALENDAR => [
-					'id' => self::CALENDAR,
-					'icon' => 'icon-calendar-dark',
-					'name' => (string) $l->t('Calendar'),
-					'url' => $this->URLGenerator->linkToRoute('activity.Activities.showList', ['filter' => self::CALENDAR]),
-				],
-				self::CALENDAR_TODO => [
-					'id' => self::CALENDAR_TODO,
-					'icon' => 'icon-checkmark',
-					'name' => (string) $l->t('Todos'),
-					'url' => $this->URLGenerator->linkToRoute('activity.Activities.showList', ['filter' => self::CALENDAR_TODO]),
-				],
-			],
-			'top' => [],
-		];
-	}
-
-	/**
-	 * The extension can check if a custom filter (given by a query string like filter=abc) is valid or not.
-	 *
-	 * @param string $filterValue
-	 * @return boolean
-	 */
-	public function isFilterValid($filterValue) {
-		return in_array($filterValue, [self::CALENDAR, self::CALENDAR_TODO]);
-	}
-
-	/**
-	 * The extension can filter the types based on the filter if required.
-	 * In case no filter is to be applied false is to be returned unchanged.
-	 *
-	 * @param array $types
-	 * @param string $filter
-	 * @return array|false
-	 */
-	public function filterNotificationTypes($types, $filter) {
-		switch ($filter) {
-			case self::CALENDAR:
-				return array_intersect([self::CALENDAR, self::CALENDAR_EVENT], $types);
-			case self::CALENDAR_TODO:
-				return array_intersect([self::CALENDAR_TODO], $types);
-		}
-		return false;
-	}
-
-	/**
-	 * For a given filter the extension can specify the sql query conditions including parameters for that query.
-	 * In case the extension does not know the filter false is to be returned.
-	 * The query condition and the parameters are to be returned as array with two elements.
-	 * E.g. return array('`app` = ? and `message` like ?', array('mail', 'ownCloud%'));
-	 *
-	 * @param string $filter
-	 * @return array|false
-	 */
-	public function getQueryForFilter($filter) {
-		return false;
-	}
-
-}
diff --git a/apps/dav/lib/CalDAV/Activity/Filter/Calendar.php b/apps/dav/lib/CalDAV/Activity/Filter/Calendar.php
new file mode 100644
index 0000000000000000000000000000000000000000..a20b8ad544db65a854158ea35422826c32c4c2d2
--- /dev/null
+++ b/apps/dav/lib/CalDAV/Activity/Filter/Calendar.php
@@ -0,0 +1,92 @@
+<?php
+/**
+ * @copyright Copyright (c) 2016 Joas Schilling <coding@schilljs.com>
+ *
+ * @license GNU AGPL version 3 or any later version
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+namespace OCA\DAV\CalDAV\Activity\Filter;
+
+
+use OCP\Activity\IFilter;
+use OCP\IL10N;
+use OCP\IURLGenerator;
+
+class Calendar implements IFilter {
+
+	/** @var IL10N */
+	protected $l;
+
+	/** @var IURLGenerator */
+	protected $url;
+
+	public function __construct(IL10N $l, IURLGenerator $url) {
+		$this->l = $l;
+		$this->url = $url;
+	}
+
+	/**
+	 * @return string Lowercase a-z and underscore only identifier
+	 * @since 11.0.0
+	 */
+	public function getIdentifier() {
+		return 'calendar';
+	}
+
+	/**
+	 * @return string A translated string
+	 * @since 11.0.0
+	 */
+	public function getName() {
+		return $this->l->t('Calendar');
+	}
+
+	/**
+	 * @return int whether the filter should be rather on the top or bottom of
+	 * the admin section. The filters are arranged in ascending order of the
+	 * priority values. It is required to return a value between 0 and 100.
+	 * @since 11.0.0
+	 */
+	public function getPriority() {
+		return 40;
+	}
+
+	/**
+	 * @return string Full URL to an icon, empty string when none is given
+	 * @since 11.0.0
+	 */
+	public function getIcon() {
+		return $this->url->getAbsoluteURL($this->url->imagePath('core', 'places/calendar-dark.svg'));
+	}
+
+	/**
+	 * @param string[] $types
+	 * @return string[] An array of allowed apps from which activities should be displayed
+	 * @since 11.0.0
+	 */
+	public function filterTypes(array $types) {
+		return array_intersect(['calendar', 'calendar_event'], $types);
+	}
+
+	/**
+	 * @return string[] An array of allowed apps from which activities should be displayed
+	 * @since 11.0.0
+	 */
+	public function allowedApps() {
+		return [];
+	}
+}
diff --git a/apps/dav/lib/CalDAV/Activity/Filter/Todo.php b/apps/dav/lib/CalDAV/Activity/Filter/Todo.php
new file mode 100644
index 0000000000000000000000000000000000000000..42ee07408513ccbfe7640e7250fa097a136e67e2
--- /dev/null
+++ b/apps/dav/lib/CalDAV/Activity/Filter/Todo.php
@@ -0,0 +1,92 @@
+<?php
+/**
+ * @copyright Copyright (c) 2016 Joas Schilling <coding@schilljs.com>
+ *
+ * @license GNU AGPL version 3 or any later version
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+namespace OCA\DAV\CalDAV\Activity\Filter;
+
+
+use OCP\Activity\IFilter;
+use OCP\IL10N;
+use OCP\IURLGenerator;
+
+class Todo implements IFilter {
+
+	/** @var IL10N */
+	protected $l;
+
+	/** @var IURLGenerator */
+	protected $url;
+
+	public function __construct(IL10N $l, IURLGenerator $url) {
+		$this->l = $l;
+		$this->url = $url;
+	}
+
+	/**
+	 * @return string Lowercase a-z and underscore only identifier
+	 * @since 11.0.0
+	 */
+	public function getIdentifier() {
+		return 'calendar_todo';
+	}
+
+	/**
+	 * @return string A translated string
+	 * @since 11.0.0
+	 */
+	public function getName() {
+		return $this->l->t('Todos');
+	}
+
+	/**
+	 * @return int whether the filter should be rather on the top or bottom of
+	 * the admin section. The filters are arranged in ascending order of the
+	 * priority values. It is required to return a value between 0 and 100.
+	 * @since 11.0.0
+	 */
+	public function getPriority() {
+		return 40;
+	}
+
+	/**
+	 * @return string Full URL to an icon, empty string when none is given
+	 * @since 11.0.0
+	 */
+	public function getIcon() {
+		return $this->url->getAbsoluteURL($this->url->imagePath('core', 'actions/checkmark.svg'));
+	}
+
+	/**
+	 * @param string[] $types
+	 * @return string[] An array of allowed apps from which activities should be displayed
+	 * @since 11.0.0
+	 */
+	public function filterTypes(array $types) {
+		return array_intersect(['calendar_todo'], $types);
+	}
+
+	/**
+	 * @return string[] An array of allowed apps from which activities should be displayed
+	 * @since 11.0.0
+	 */
+	public function allowedApps() {
+		return [];
+	}
+}
diff --git a/apps/dav/lib/CalDAV/Activity/Provider/Base.php b/apps/dav/lib/CalDAV/Activity/Provider/Base.php
new file mode 100644
index 0000000000000000000000000000000000000000..72fdd681b8a5a2f76e36817aced6f5b04e30796b
--- /dev/null
+++ b/apps/dav/lib/CalDAV/Activity/Provider/Base.php
@@ -0,0 +1,129 @@
+<?php
+/**
+ * @copyright Copyright (c) 2016 Joas Schilling <coding@schilljs.com>
+ *
+ * @license GNU AGPL version 3 or any later version
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+namespace OCA\DAV\CalDAV\Activity\Provider;
+
+use OCP\Activity\IEvent;
+use OCP\Activity\IProvider;
+use OCP\IUser;
+use OCP\IUserManager;
+
+abstract class Base implements IProvider {
+
+	/** @var IUserManager */
+	protected $userManager;
+
+	/** @var string[] cached displayNames - key is the UID and value the displayname */
+	protected $displayNames = [];
+
+	/**
+	 * @param IUserManager $userManager
+	 */
+	public function __construct(IUserManager $userManager) {
+		$this->userManager = $userManager;
+	}
+
+	/**
+	 * @param IEvent $event
+	 * @param string $subject
+	 * @param array $parameters
+	 */
+	protected function setSubjects(IEvent $event, $subject, array $parameters) {
+		$placeholders = $replacements = [];
+		foreach ($parameters as $placeholder => $parameter) {
+			$placeholders[] = '{' . $placeholder . '}';
+			$replacements[] = $parameter['name'];
+		}
+
+		$event->setParsedSubject(str_replace($placeholders, $replacements, $subject))
+			->setRichSubject($subject, $parameters);
+	}
+
+	/**
+	 * @param array $eventData
+	 * @return array
+	 */
+	protected function generateObjectParameter($eventData) {
+		if (!is_array($eventData) || !isset($eventData['id']) || !isset($eventData['name'])) {
+			throw new \InvalidArgumentException();
+		};
+
+		return [
+			'type' => 'calendar-event',
+			'id' => $eventData['id'],
+			'name' => $eventData['name'],
+		];
+	}
+
+	/**
+	 * @param int $id
+	 * @param string $name
+	 * @return array
+	 */
+	protected function generateCalendarParameter($id, $name) {
+		return [
+			'type' => 'calendar',
+			'id' => $id,
+			'name' => $name,
+		];
+	}
+
+	/**
+	 * @param string $id
+	 * @return array
+	 */
+	protected function generateGroupParameter($id) {
+		return [
+			'type' => 'group',
+			'id' => $id,
+			'name' => $id,
+		];
+	}
+
+	/**
+	 * @param string $uid
+	 * @return array
+	 */
+	protected function generateUserParameter($uid) {
+		if (!isset($this->displayNames[$uid])) {
+			$this->displayNames[$uid] = $this->getDisplayName($uid);
+		}
+
+		return [
+			'type' => 'user',
+			'id' => $uid,
+			'name' => $this->displayNames[$uid],
+		];
+	}
+
+	/**
+	 * @param string $uid
+	 * @return string
+	 */
+	protected function getDisplayName($uid) {
+		$user = $this->userManager->get($uid);
+		if ($user instanceof IUser) {
+			return $user->getDisplayName();
+		} else {
+			return $uid;
+		}
+	}
+}
diff --git a/apps/dav/lib/CalDAV/Activity/Provider/Calendar.php b/apps/dav/lib/CalDAV/Activity/Provider/Calendar.php
new file mode 100644
index 0000000000000000000000000000000000000000..2e2ce5bc27ad1dffa505b6511aaaec2eb5671843
--- /dev/null
+++ b/apps/dav/lib/CalDAV/Activity/Provider/Calendar.php
@@ -0,0 +1,192 @@
+<?php
+/**
+ * @copyright Copyright (c) 2016 Joas Schilling <coding@schilljs.com>
+ *
+ * @license GNU AGPL version 3 or any later version
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+namespace OCA\DAV\CalDAV\Activity\Provider;
+
+use OCP\Activity\IEvent;
+use OCP\Activity\IEventMerger;
+use OCP\Activity\IManager;
+use OCP\IL10N;
+use OCP\IURLGenerator;
+use OCP\IUserManager;
+
+class Calendar extends Base {
+
+	const SUBJECT_ADD = 'calendar_add';
+	const SUBJECT_UPDATE = 'calendar_update';
+	const SUBJECT_DELETE = 'calendar_delete';
+	const SUBJECT_SHARE_USER = 'calendar_user_share';
+	const SUBJECT_SHARE_GROUP = 'calendar_group_share';
+	const SUBJECT_UNSHARE_USER = 'calendar_user_unshare';
+	const SUBJECT_UNSHARE_GROUP = 'calendar_group_unshare';
+
+	/** @var IL10N */
+	protected $l;
+
+	/** @var IURLGenerator */
+	protected $url;
+
+	/** @var IManager */
+	protected $activityManager;
+
+	/** @var IEventMerger */
+	protected $eventMerger;
+
+	/**
+	 * @param IL10N $l
+	 * @param IURLGenerator $url
+	 * @param IManager $activityManager
+	 * @param IUserManager $userManager
+	 * @param IEventMerger $eventMerger
+	 */
+	public function __construct(IL10N $l, IURLGenerator $url, IManager $activityManager, IUserManager $userManager, IEventMerger $eventMerger) {
+		parent::__construct($userManager);
+		$this->l = $l;
+		$this->url = $url;
+		$this->activityManager = $activityManager;
+		$this->eventMerger = $eventMerger;
+	}
+
+	/**
+	 * @param IEvent $event
+	 * @param IEvent|null $previousEvent
+	 * @return IEvent
+	 * @throws \InvalidArgumentException
+	 * @since 11.0.0
+	 */
+	public function parse(IEvent $event, IEvent $previousEvent = null) {
+		if ($event->getApp() !== 'dav' || $event->getType() !== 'calendar') {
+			throw new \InvalidArgumentException();
+		}
+
+		$event->setIcon($this->url->getAbsoluteURL($this->url->imagePath('core', 'places/calendar-dark.svg')));
+
+		if ($event->getSubject() === self::SUBJECT_ADD) {
+			$subject = $this->l->t('{actor} created calendar {calendar}');
+		} else if ($event->getSubject() === self::SUBJECT_ADD . '_self') {
+			$subject = $this->l->t('You created calendar {calendar}');
+		} else if ($event->getSubject() === self::SUBJECT_DELETE) {
+			$subject = $this->l->t('{actor} deleted calendar {calendar}');
+		} else if ($event->getSubject() === self::SUBJECT_DELETE . '_self') {
+			$subject = $this->l->t('You deleted calendar {calendar}');
+		} else if ($event->getSubject() === self::SUBJECT_UPDATE) {
+			$subject = $this->l->t('{actor} updated calendar {calendar}');
+		} else if ($event->getSubject() === self::SUBJECT_UPDATE . '_self') {
+			$subject = $this->l->t('You updated calendar {calendar}');
+
+		} else if ($event->getSubject() === self::SUBJECT_SHARE_USER) {
+			$subject = $this->l->t('{actor} shared calendar {calendar} with you');
+		} else if ($event->getSubject() === self::SUBJECT_SHARE_USER . '_you') {
+			$subject = $this->l->t('You shared calendar {calendar} with {user}');
+		} else if ($event->getSubject() === self::SUBJECT_SHARE_USER . '_by') {
+			$subject = $this->l->t('{actor} shared calendar {calendar} with {user}');
+		} else if ($event->getSubject() === self::SUBJECT_UNSHARE_USER) {
+			$subject = $this->l->t('{actor} unshared calendar {calendar} from you');
+		} else if ($event->getSubject() === self::SUBJECT_UNSHARE_USER . '_you') {
+			$subject = $this->l->t('You unshared calendar {calendar} from {user}');
+		} else if ($event->getSubject() === self::SUBJECT_UNSHARE_USER . '_by') {
+			$subject = $this->l->t('{actor} unshared calendar {calendar} from {user}');
+		} else if ($event->getSubject() === self::SUBJECT_UNSHARE_USER . '_self') {
+			$subject = $this->l->t('{actor} unshared calendar {calendar} from themselves');
+
+		} else if ($event->getSubject() === self::SUBJECT_SHARE_GROUP . '_you') {
+			$subject = $this->l->t('You shared calendar {calendar} with group {group}');
+		} else if ($event->getSubject() === self::SUBJECT_SHARE_GROUP . '_by') {
+			$subject = $this->l->t('{actor} shared calendar {calendar} with group {group}');
+		} else if ($event->getSubject() === self::SUBJECT_UNSHARE_GROUP . '_you') {
+			$subject = $this->l->t('You unshared calendar {calendar} from group {group}');
+		} else if ($event->getSubject() === self::SUBJECT_UNSHARE_GROUP . '_by') {
+			$subject = $this->l->t('{actor} unshared calendar {calendar} from group {group}');
+		} else {
+			throw new \InvalidArgumentException();
+		}
+
+		$parsedParameters = $this->getParameters($event);
+		$this->setSubjects($event, $subject, $parsedParameters);
+
+		$event = $this->eventMerger->mergeEvents('calendar', $event, $previousEvent);
+
+		if ($event->getChildEvent() === null) {
+			if (isset($parsedParameters['user'])) {
+				// Couldn't group by calendar, maybe we can group by users
+				$event = $this->eventMerger->mergeEvents('user', $event, $previousEvent);
+			} else if (isset($parsedParameters['group'])) {
+				// Couldn't group by calendar, maybe we can group by groups
+				$event = $this->eventMerger->mergeEvents('group', $event, $previousEvent);
+			}
+		}
+
+		return $event;
+	}
+
+	/**
+	 * @param IEvent $event
+	 * @return array
+	 */
+	protected function getParameters(IEvent $event) {
+		$subject = $event->getSubject();
+		$parameters = $event->getSubjectParameters();
+
+		switch ($subject) {
+			case self::SUBJECT_ADD:
+			case self::SUBJECT_ADD . '_self':
+			case self::SUBJECT_DELETE:
+			case self::SUBJECT_DELETE . '_self':
+			case self::SUBJECT_UPDATE:
+			case self::SUBJECT_UPDATE . '_self':
+			case self::SUBJECT_SHARE_USER:
+			case self::SUBJECT_UNSHARE_USER:
+			case self::SUBJECT_UNSHARE_USER . '_self':
+				return [
+					'actor' => $this->generateUserParameter($parameters[0]),
+					'calendar' => $this->generateCalendarParameter($event->getObjectId(), $parameters[1]),
+				];
+			case self::SUBJECT_SHARE_USER . '_you':
+			case self::SUBJECT_UNSHARE_USER . '_you':
+				return [
+					'user' => $this->generateUserParameter($parameters[0]),
+					'calendar' => $this->generateCalendarParameter($event->getObjectId(), $parameters[1]),
+				];
+			case self::SUBJECT_SHARE_USER . '_by':
+			case self::SUBJECT_UNSHARE_USER . '_by':
+				return [
+					'user' => $this->generateUserParameter($parameters[0]),
+					'calendar' => $this->generateCalendarParameter($event->getObjectId(), $parameters[1]),
+					'actor' => $this->generateUserParameter($parameters[2]),
+				];
+			case self::SUBJECT_SHARE_GROUP . '_you':
+			case self::SUBJECT_UNSHARE_GROUP . '_you':
+				return [
+					'group' => $this->generateGroupParameter($parameters[0]),
+					'calendar' => $this->generateCalendarParameter($event->getObjectId(), $parameters[1]),
+				];
+			case self::SUBJECT_SHARE_GROUP . '_by':
+			case self::SUBJECT_UNSHARE_GROUP . '_by':
+				return [
+					'group' => $this->generateGroupParameter($parameters[0]),
+					'calendar' => $this->generateCalendarParameter($event->getObjectId(), $parameters[1]),
+					'actor' => $this->generateUserParameter($parameters[2]),
+				];
+		}
+
+		throw new \InvalidArgumentException();
+	}
+}
diff --git a/apps/dav/lib/CalDAV/Activity/Provider/Event.php b/apps/dav/lib/CalDAV/Activity/Provider/Event.php
new file mode 100644
index 0000000000000000000000000000000000000000..11c8d901ac9ea0a38af3fc302c208a22ec5c37c2
--- /dev/null
+++ b/apps/dav/lib/CalDAV/Activity/Provider/Event.php
@@ -0,0 +1,130 @@
+<?php
+/**
+ * @copyright Copyright (c) 2016 Joas Schilling <coding@schilljs.com>
+ *
+ * @license GNU AGPL version 3 or any later version
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+namespace OCA\DAV\CalDAV\Activity\Provider;
+
+use OCP\Activity\IEvent;
+use OCP\Activity\IEventMerger;
+use OCP\Activity\IManager;
+use OCP\IL10N;
+use OCP\IURLGenerator;
+use OCP\IUserManager;
+
+class Event extends Base {
+
+	const SUBJECT_OBJECT_ADD = 'object_add';
+	const SUBJECT_OBJECT_UPDATE = 'object_update';
+	const SUBJECT_OBJECT_DELETE = 'object_delete';
+
+	/** @var IL10N */
+	protected $l;
+
+	/** @var IURLGenerator */
+	protected $url;
+
+	/** @var IManager */
+	protected $activityManager;
+
+	/** @var IEventMerger */
+	protected $eventMerger;
+
+	/**
+	 * @param IL10N $l
+	 * @param IURLGenerator $url
+	 * @param IManager $activityManager
+	 * @param IUserManager $userManager
+	 * @param IEventMerger $eventMerger
+	 */
+	public function __construct(IL10N $l, IURLGenerator $url, IManager $activityManager, IUserManager $userManager, IEventMerger $eventMerger) {
+		parent::__construct($userManager);
+		$this->l = $l;
+		$this->url = $url;
+		$this->activityManager = $activityManager;
+		$this->eventMerger = $eventMerger;
+	}
+
+	/**
+	 * @param IEvent $event
+	 * @param IEvent|null $previousEvent
+	 * @return IEvent
+	 * @throws \InvalidArgumentException
+	 * @since 11.0.0
+	 */
+	public function parse(IEvent $event, IEvent $previousEvent = null) {
+		if ($event->getApp() !== 'dav' || $event->getType() !== 'calendar_event') {
+			throw new \InvalidArgumentException();
+		}
+
+		$event->setIcon($this->url->getAbsoluteURL($this->url->imagePath('core', 'places/calendar-dark.svg')));
+
+		if ($event->getSubject() === self::SUBJECT_OBJECT_ADD . '_event') {
+			$subject = $this->l->t('{actor} created event {event} in calendar {calendar}');
+		} else if ($event->getSubject() === self::SUBJECT_OBJECT_ADD . '_event_self') {
+			$subject = $this->l->t('You created event {event} in calendar {calendar}');
+		} else if ($event->getSubject() === self::SUBJECT_OBJECT_DELETE . '_event') {
+			$subject = $this->l->t('{actor} deleted event {event} from calendar {calendar}');
+		} else if ($event->getSubject() === self::SUBJECT_OBJECT_DELETE . '_event_self') {
+			$subject = $this->l->t('You deleted event {event} from calendar {calendar}');
+		} else if ($event->getSubject() === self::SUBJECT_OBJECT_UPDATE . '_event') {
+			$subject = $this->l->t('{actor} updated event {event} in calendar {calendar}');
+		} else if ($event->getSubject() === self::SUBJECT_OBJECT_UPDATE . '_event_self') {
+			$subject = $this->l->t('You updated event {event} in calendar {calendar}');
+		} else {
+			throw new \InvalidArgumentException();
+		}
+
+		$parsedParameters = $this->getParameters($event);
+		$this->setSubjects($event, $subject, $parsedParameters);
+
+		$event = $this->eventMerger->mergeEvents('event', $event, $previousEvent);
+
+		return $event;
+	}
+
+	/**
+	 * @param IEvent $event
+	 * @return array
+	 */
+	protected function getParameters(IEvent $event) {
+		$subject = $event->getSubject();
+		$parameters = $event->getSubjectParameters();
+
+		switch ($subject) {
+			case self::SUBJECT_OBJECT_ADD . '_event':
+			case self::SUBJECT_OBJECT_DELETE . '_event':
+			case self::SUBJECT_OBJECT_UPDATE . '_event':
+				return [
+					'actor' => $this->generateUserParameter($parameters[0]),
+					'calendar' => $this->generateCalendarParameter($event->getObjectId(), $parameters[1]),
+					'event' => $this->generateObjectParameter($parameters[2]),
+				];
+			case self::SUBJECT_OBJECT_ADD . '_event_self':
+			case self::SUBJECT_OBJECT_DELETE . '_event_self':
+			case self::SUBJECT_OBJECT_UPDATE . '_event_self':
+				return [
+					'calendar' => $this->generateCalendarParameter($event->getObjectId(), $parameters[1]),
+					'event' => $this->generateObjectParameter($parameters[2]),
+				];
+		}
+
+		throw new \InvalidArgumentException();
+	}
+}
diff --git a/apps/dav/lib/CalDAV/Activity/Provider/Todo.php b/apps/dav/lib/CalDAV/Activity/Provider/Todo.php
new file mode 100644
index 0000000000000000000000000000000000000000..43ab9e9c448d0d2757423167c4ccecd981462177
--- /dev/null
+++ b/apps/dav/lib/CalDAV/Activity/Provider/Todo.php
@@ -0,0 +1,107 @@
+<?php
+/**
+ * @copyright Copyright (c) 2016 Joas Schilling <coding@schilljs.com>
+ *
+ * @license GNU AGPL version 3 or any later version
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+namespace OCA\DAV\CalDAV\Activity\Provider;
+
+use OCP\Activity\IEvent;
+
+class Todo extends Event {
+
+	/**
+	 * @param IEvent $event
+	 * @param IEvent|null $previousEvent
+	 * @return IEvent
+	 * @throws \InvalidArgumentException
+	 * @since 11.0.0
+	 */
+	public function parse(IEvent $event, IEvent $previousEvent = null) {
+		if ($event->getApp() !== 'dav' || $event->getType() !== 'calendar_todo') {
+			throw new \InvalidArgumentException();
+		}
+
+		$event->setIcon($this->url->getAbsoluteURL($this->url->imagePath('core', 'actions/checkmark.svg')));
+
+		if ($event->getSubject() === self::SUBJECT_OBJECT_ADD . '_todo') {
+			$subject = $this->l->t('{actor} created todo {todo} in list {calendar}');
+		} else if ($event->getSubject() === self::SUBJECT_OBJECT_ADD . '_todo_self') {
+			$subject = $this->l->t('You created todo {todo} in list {calendar}');
+		} else if ($event->getSubject() === self::SUBJECT_OBJECT_DELETE . '_todo') {
+			$subject = $this->l->t('{actor} deleted todo {todo} from list {calendar}');
+		} else if ($event->getSubject() === self::SUBJECT_OBJECT_DELETE . '_todo_self') {
+			$subject = $this->l->t('You deleted todo {todo} from list {calendar}');
+		} else if ($event->getSubject() === self::SUBJECT_OBJECT_UPDATE . '_todo') {
+			$subject = $this->l->t('{actor} updated todo {todo} in list {calendar}');
+		} else if ($event->getSubject() === self::SUBJECT_OBJECT_UPDATE . '_todo_self') {
+			$subject = $this->l->t('You updated todo {todo} in list {calendar}');
+
+		} else if ($event->getSubject() === self::SUBJECT_OBJECT_UPDATE . '_todo_completed') {
+			$subject = $this->l->t('{actor} solved todo {todo} in list {calendar}');
+		} else if ($event->getSubject() === self::SUBJECT_OBJECT_UPDATE . '_todo_completed_self') {
+			$subject = $this->l->t('You solved todo {todo} in list {calendar}');
+		} else if ($event->getSubject() === self::SUBJECT_OBJECT_UPDATE . '_todo_needs_action') {
+			$subject = $this->l->t('{actor} reopened todo {todo} in list {calendar}');
+		} else if ($event->getSubject() === self::SUBJECT_OBJECT_UPDATE . '_todo_needs_action_self') {
+			$subject = $this->l->t('You reopened todo {todo} in list {calendar}');
+		} else {
+			throw new \InvalidArgumentException();
+		}
+
+		$parsedParameters = $this->getParameters($event);
+		$this->setSubjects($event, $subject, $parsedParameters);
+
+		$event = $this->eventMerger->mergeEvents('todo', $event, $previousEvent);
+
+		return $event;
+	}
+
+	/**
+	 * @param IEvent $event
+	 * @return array
+	 */
+	protected function getParameters(IEvent $event) {
+		$subject = $event->getSubject();
+		$parameters = $event->getSubjectParameters();
+
+		switch ($subject) {
+			case self::SUBJECT_OBJECT_ADD . '_todo':
+			case self::SUBJECT_OBJECT_DELETE . '_todo':
+			case self::SUBJECT_OBJECT_UPDATE . '_todo':
+			case self::SUBJECT_OBJECT_UPDATE . '_todo_completed':
+			case self::SUBJECT_OBJECT_UPDATE . '_todo_needs_action':
+				return [
+					'actor' => $this->generateUserParameter($parameters[0]),
+					'calendar' => $this->generateCalendarParameter($event->getObjectId(), $parameters[1]),
+					'todo' => $this->generateObjectParameter($parameters[2]),
+				];
+			case self::SUBJECT_OBJECT_ADD . '_todo_self':
+			case self::SUBJECT_OBJECT_DELETE . '_todo_self':
+			case self::SUBJECT_OBJECT_UPDATE . '_todo_self':
+			case self::SUBJECT_OBJECT_UPDATE . '_todo_completed_self':
+			case self::SUBJECT_OBJECT_UPDATE . '_todo_needs_action_self':
+				return [
+					'calendar' => $this->generateCalendarParameter($event->getObjectId(), $parameters[1]),
+					'todo' => $this->generateObjectParameter($parameters[2]),
+				];
+		}
+
+		throw new \InvalidArgumentException();
+	}
+}
diff --git a/apps/dav/lib/CalDAV/Activity/Setting/Calendar.php b/apps/dav/lib/CalDAV/Activity/Setting/Calendar.php
new file mode 100644
index 0000000000000000000000000000000000000000..608ee266bb94e8bc353224a73b6d70cd8d2cff9b
--- /dev/null
+++ b/apps/dav/lib/CalDAV/Activity/Setting/Calendar.php
@@ -0,0 +1,98 @@
+<?php
+/**
+ * @copyright Copyright (c) 2016 Joas Schilling <coding@schilljs.com>
+ *
+ * @license GNU AGPL version 3 or any later version
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+namespace OCA\DAV\CalDAV\Activity\Setting;
+
+
+use OCP\Activity\ISetting;
+use OCP\IL10N;
+
+class Calendar implements ISetting {
+
+	/** @var IL10N */
+	protected $l;
+
+	/**
+	 * @param IL10N $l
+	 */
+	public function __construct(IL10N $l) {
+		$this->l = $l;
+	}
+
+	/**
+	 * @return string Lowercase a-z and underscore only identifier
+	 * @since 11.0.0
+	 */
+	public function getIdentifier() {
+		return 'calendar';
+	}
+
+	/**
+	 * @return string A translated string
+	 * @since 11.0.0
+	 */
+	public function getName() {
+		return $this->l->t('A <strong>calendar</strong> was modified');
+	}
+
+	/**
+	 * @return int whether the filter should be rather on the top or bottom of
+	 * the admin section. The filters are arranged in ascending order of the
+	 * priority values. It is required to return a value between 0 and 100.
+	 * @since 11.0.0
+	 */
+	public function getPriority() {
+		return 50;
+	}
+
+	/**
+	 * @return bool True when the option can be changed for the stream
+	 * @since 11.0.0
+	 */
+	public function canChangeStream() {
+		return true;
+	}
+
+	/**
+	 * @return bool True when the option can be changed for the stream
+	 * @since 11.0.0
+	 */
+	public function isDefaultEnabledStream() {
+		return true;
+	}
+
+	/**
+	 * @return bool True when the option can be changed for the mail
+	 * @since 11.0.0
+	 */
+	public function canChangeMail() {
+		return true;
+	}
+
+	/**
+	 * @return bool True when the option can be changed for the stream
+	 * @since 11.0.0
+	 */
+	public function isDefaultEnabledMail() {
+		return false;
+	}
+}
+
diff --git a/apps/dav/lib/CalDAV/Activity/Setting/Event.php b/apps/dav/lib/CalDAV/Activity/Setting/Event.php
new file mode 100644
index 0000000000000000000000000000000000000000..887cd22afadef91aa67b4c229765769a77ba7fad
--- /dev/null
+++ b/apps/dav/lib/CalDAV/Activity/Setting/Event.php
@@ -0,0 +1,98 @@
+<?php
+/**
+ * @copyright Copyright (c) 2016 Joas Schilling <coding@schilljs.com>
+ *
+ * @license GNU AGPL version 3 or any later version
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+namespace OCA\DAV\CalDAV\Activity\Setting;
+
+
+use OCP\Activity\ISetting;
+use OCP\IL10N;
+
+class Event implements ISetting {
+
+	/** @var IL10N */
+	protected $l;
+
+	/**
+	 * @param IL10N $l
+	 */
+	public function __construct(IL10N $l) {
+		$this->l = $l;
+	}
+
+	/**
+	 * @return string Lowercase a-z and underscore only identifier
+	 * @since 11.0.0
+	 */
+	public function getIdentifier() {
+		return 'calendar_event';
+	}
+
+	/**
+	 * @return string A translated string
+	 * @since 11.0.0
+	 */
+	public function getName() {
+		return $this->l->t('A calendar <strong>event</strong> was modified');
+	}
+
+	/**
+	 * @return int whether the filter should be rather on the top or bottom of
+	 * the admin section. The filters are arranged in ascending order of the
+	 * priority values. It is required to return a value between 0 and 100.
+	 * @since 11.0.0
+	 */
+	public function getPriority() {
+		return 50;
+	}
+
+	/**
+	 * @return bool True when the option can be changed for the stream
+	 * @since 11.0.0
+	 */
+	public function canChangeStream() {
+		return true;
+	}
+
+	/**
+	 * @return bool True when the option can be changed for the stream
+	 * @since 11.0.0
+	 */
+	public function isDefaultEnabledStream() {
+		return true;
+	}
+
+	/**
+	 * @return bool True when the option can be changed for the mail
+	 * @since 11.0.0
+	 */
+	public function canChangeMail() {
+		return true;
+	}
+
+	/**
+	 * @return bool True when the option can be changed for the stream
+	 * @since 11.0.0
+	 */
+	public function isDefaultEnabledMail() {
+		return false;
+	}
+}
+
diff --git a/apps/dav/lib/CalDAV/Activity/Setting/Todo.php b/apps/dav/lib/CalDAV/Activity/Setting/Todo.php
new file mode 100644
index 0000000000000000000000000000000000000000..0c8215f4843de1269b46a4e0fb922bce883814ed
--- /dev/null
+++ b/apps/dav/lib/CalDAV/Activity/Setting/Todo.php
@@ -0,0 +1,98 @@
+<?php
+/**
+ * @copyright Copyright (c) 2016 Joas Schilling <coding@schilljs.com>
+ *
+ * @license GNU AGPL version 3 or any later version
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+namespace OCA\DAV\CalDAV\Activity\Setting;
+
+
+use OCP\Activity\ISetting;
+use OCP\IL10N;
+
+class Todo implements ISetting {
+
+	/** @var IL10N */
+	protected $l;
+
+	/**
+	 * @param IL10N $l
+	 */
+	public function __construct(IL10N $l) {
+		$this->l = $l;
+	}
+
+	/**
+	 * @return string Lowercase a-z and underscore only identifier
+	 * @since 11.0.0
+	 */
+	public function getIdentifier() {
+		return 'calendar_todos';
+	}
+
+	/**
+	 * @return string A translated string
+	 * @since 11.0.0
+	 */
+	public function getName() {
+		return $this->l->t('A calendar <strong>todo</strong> was modified');
+	}
+
+	/**
+	 * @return int whether the filter should be rather on the top or bottom of
+	 * the admin section. The filters are arranged in ascending order of the
+	 * priority values. It is required to return a value between 0 and 100.
+	 * @since 11.0.0
+	 */
+	public function getPriority() {
+		return 50;
+	}
+
+	/**
+	 * @return bool True when the option can be changed for the stream
+	 * @since 11.0.0
+	 */
+	public function canChangeStream() {
+		return true;
+	}
+
+	/**
+	 * @return bool True when the option can be changed for the stream
+	 * @since 11.0.0
+	 */
+	public function isDefaultEnabledStream() {
+		return true;
+	}
+
+	/**
+	 * @return bool True when the option can be changed for the mail
+	 * @since 11.0.0
+	 */
+	public function canChangeMail() {
+		return true;
+	}
+
+	/**
+	 * @return bool True when the option can be changed for the stream
+	 * @since 11.0.0
+	 */
+	public function isDefaultEnabledMail() {
+		return false;
+	}
+}
+
diff --git a/apps/dav/tests/unit/CalDAV/Activity/BackendTest.php b/apps/dav/tests/unit/CalDAV/Activity/BackendTest.php
index 3585d69bad32ce199f73ebfadff32b01c003b7ed..d8d15e8f1f764b534344394319906a44703ab3ba 100644
--- a/apps/dav/tests/unit/CalDAV/Activity/BackendTest.php
+++ b/apps/dav/tests/unit/CalDAV/Activity/BackendTest.php
@@ -22,7 +22,7 @@
 namespace OCA\DAV\Tests\unit\CalDAV\Activity;
 
 use OCA\DAV\CalDAV\Activity\Backend;
-use OCA\DAV\CalDAV\Activity\Extension;
+use OCA\DAV\CalDAV\Activity\Provider\Calendar;
 use OCP\Activity\IEvent;
 use OCP\Activity\IManager;
 use OCP\IGroup;
@@ -74,9 +74,9 @@ class BackendTest extends TestCase {
 
 	public function dataCallTriggerCalendarActivity() {
 		return [
-			['onCalendarAdd', [['data']], Extension::SUBJECT_ADD, [['data'], [], []]],
-			['onCalendarUpdate', [['data'], ['shares'], ['changed-properties']], Extension::SUBJECT_UPDATE, [['data'], ['shares'], ['changed-properties']]],
-			['onCalendarDelete', [['data'], ['shares']], Extension::SUBJECT_DELETE, [['data'], ['shares'], []]],
+			['onCalendarAdd', [['data']], Calendar::SUBJECT_ADD, [['data'], [], []]],
+			['onCalendarUpdate', [['data'], ['shares'], ['changed-properties']], Calendar::SUBJECT_UPDATE, [['data'], ['shares'], ['changed-properties']]],
+			['onCalendarDelete', [['data'], ['shares']], Calendar::SUBJECT_DELETE, [['data'], ['shares'], []]],
 		];
 	}
 
@@ -104,51 +104,51 @@ class BackendTest extends TestCase {
 	public function dataTriggerCalendarActivity() {
 		return [
 			// Add calendar
-			[Extension::SUBJECT_ADD, [], [], [], '', '', null, []],
-			[Extension::SUBJECT_ADD, [
+			[Calendar::SUBJECT_ADD, [], [], [], '', '', null, []],
+			[Calendar::SUBJECT_ADD, [
 				'principaluri' => 'principal/user/admin',
 				'id' => 42,
 				'{DAV:}displayname' => 'Name of calendar',
 			], [], [], '', 'admin', null, ['admin']],
-			[Extension::SUBJECT_ADD, [
+			[Calendar::SUBJECT_ADD, [
 				'principaluri' => 'principal/user/admin',
 				'id' => 42,
 				'{DAV:}displayname' => 'Name of calendar',
 			], [], [], 'test2', 'test2', null, ['admin']],
 
 			// Update calendar
-			[Extension::SUBJECT_UPDATE, [], [], [], '', '', null, []],
+			[Calendar::SUBJECT_UPDATE, [], [], [], '', '', null, []],
 			// No visible change - owner only
-			[Extension::SUBJECT_UPDATE, [
+			[Calendar::SUBJECT_UPDATE, [
 				'principaluri' => 'principal/user/admin',
 				'id' => 42,
 				'{DAV:}displayname' => 'Name of calendar',
 			], ['shares'], [], '', 'admin', null, ['admin']],
 			// Visible change
-			[Extension::SUBJECT_UPDATE, [
+			[Calendar::SUBJECT_UPDATE, [
 				'principaluri' => 'principal/user/admin',
 				'id' => 42,
 				'{DAV:}displayname' => 'Name of calendar',
 			], ['shares'], ['{DAV:}displayname' => 'Name'], '', 'admin', ['user1'], ['user1', 'admin']],
-			[Extension::SUBJECT_UPDATE, [
+			[Calendar::SUBJECT_UPDATE, [
 				'principaluri' => 'principal/user/admin',
 				'id' => 42,
 				'{DAV:}displayname' => 'Name of calendar',
 			], ['shares'], ['{DAV:}displayname' => 'Name'], 'test2', 'test2', ['user1'], ['user1', 'admin']],
 
 			// Delete calendar
-			[Extension::SUBJECT_DELETE, [], [], [], '', '', null, []],
-			[Extension::SUBJECT_DELETE, [
+			[Calendar::SUBJECT_DELETE, [], [], [], '', '', null, []],
+			[Calendar::SUBJECT_DELETE, [
 				'principaluri' => 'principal/user/admin',
 				'id' => 42,
 				'{DAV:}displayname' => 'Name of calendar',
 			], ['shares'], [], '', 'admin', [], ['admin']],
-			[Extension::SUBJECT_DELETE, [
+			[Calendar::SUBJECT_DELETE, [
 				'principaluri' => 'principal/user/admin',
 				'id' => 42,
 				'{DAV:}displayname' => 'Name of calendar',
 			], ['shares'], [], '', 'admin', ['user1'], ['user1', 'admin']],
-			[Extension::SUBJECT_DELETE, [
+			[Calendar::SUBJECT_DELETE, [
 				'principaluri' => 'principal/user/admin',
 				'id' => 42,
 				'{DAV:}displayname' => 'Name of calendar',
@@ -202,11 +202,11 @@ class BackendTest extends TestCase {
 				->willReturnSelf();
 			$event->expects($this->once())
 				->method('setObject')
-				->with(Extension::CALENDAR, $data['id'])
+				->with('calendar', $data['id'])
 				->willReturnSelf();
 			$event->expects($this->once())
 				->method('setType')
-				->with(Extension::CALENDAR)
+				->with('calendar')
 				->willReturnSelf();
 			$event->expects($this->once())
 				->method('setAuthor')
diff --git a/apps/dav/tests/unit/CalDAV/Activity/Filter/CalendarTest.php b/apps/dav/tests/unit/CalDAV/Activity/Filter/CalendarTest.php
new file mode 100644
index 0000000000000000000000000000000000000000..895a404acf555f2d4e6f905f2fa8dd8fd29f1200
--- /dev/null
+++ b/apps/dav/tests/unit/CalDAV/Activity/Filter/CalendarTest.php
@@ -0,0 +1,84 @@
+<?php
+/**
+ * @copyright Copyright (c) 2016 Joas Schilling <coding@schilljs.com>
+ *
+ * @license GNU AGPL version 3 or any later version
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+namespace OCA\DAV\Tests\unit\CalDAV\Activity\Filter;
+
+use OCA\DAV\CalDAV\Activity\Filter\Calendar;
+use OCP\Activity\IFilter;
+use OCP\IL10N;
+use OCP\IURLGenerator;
+use Test\TestCase;
+
+class CalendarTest extends TestCase {
+
+	/** @var IURLGenerator|\PHPUnit_Framework_MockObject_MockObject */
+	protected $url;
+
+	/** @var IFilter|\PHPUnit_Framework_MockObject_MockObject */
+	protected $filter;
+
+	protected function setUp() {
+		parent::setUp();
+		$this->url = $this->createMock(IURLGenerator::class);
+		$l = $this->createMock(IL10N::class);
+		$l->expects($this->any())
+			->method('t')
+			->willReturnCallback(function($string, $args) {
+				return vsprintf($string, $args);
+			});
+
+		$this->filter = new Calendar(
+			$l, $this->url
+		);
+	}
+
+	public function testGetIcon() {
+		$this->url->expects($this->once())
+			->method('imagePath')
+			->with('core', 'places/calendar-dark.svg')
+			->willReturn('path-to-icon');
+
+		$this->url->expects($this->once())
+			->method('getAbsoluteURL')
+			->with('path-to-icon')
+			->willReturn('absolute-path-to-icon');
+
+		$this->assertEquals('absolute-path-to-icon', $this->filter->getIcon());
+	}
+
+	public function dataFilterTypes() {
+		return [
+			[[], []],
+			[['calendar', 'calendar_event'], ['calendar', 'calendar_event']],
+			[['calendar', 'calendar_event', 'calendar_todo'], ['calendar', 'calendar_event']],
+			[['calendar', 'calendar_event', 'files'], ['calendar', 'calendar_event']],
+		];
+	}
+
+	/**
+	 * @dataProvider dataFilterTypes
+	 * @param string[] $types
+	 * @param string[] $expected
+	 */
+	public function testFilterTypes($types, $expected) {
+		$this->assertEquals($expected, $this->filter->filterTypes($types));
+	}
+}
diff --git a/apps/dav/tests/unit/CalDAV/Activity/Filter/GenericTest.php b/apps/dav/tests/unit/CalDAV/Activity/Filter/GenericTest.php
new file mode 100644
index 0000000000000000000000000000000000000000..533f88747cd35528ee56bafe91d6a6d9c814631f
--- /dev/null
+++ b/apps/dav/tests/unit/CalDAV/Activity/Filter/GenericTest.php
@@ -0,0 +1,110 @@
+<?php
+/**
+ * @copyright Copyright (c) 2016 Joas Schilling <coding@schilljs.com>
+ *
+ * @license GNU AGPL version 3 or any later version
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+namespace OCA\DAV\Tests\unit\CalDAV\Activity\Filter;
+
+use OCA\DAV\CalDAV\Activity\Filter\Calendar;
+use OCA\DAV\CalDAV\Activity\Filter\Todo;
+use OCP\Activity\IFilter;
+use Test\TestCase;
+
+class GenericTest extends TestCase {
+
+	public function dataFilters() {
+		return [
+			[Calendar::class],
+			[Todo::class],
+		];
+	}
+
+	/**
+	 * @dataProvider dataFilters
+	 * @param string $filterClass
+	 */
+	public function testImplementsInterface($filterClass) {
+		$filter = \OC::$server->query($filterClass);
+		$this->assertInstanceOf(IFilter::class, $filter);
+	}
+
+	/**
+	 * @dataProvider dataFilters
+	 * @param string $filterClass
+	 */
+	public function testGetIdentifier($filterClass) {
+		/** @var IFilter $filter */
+		$filter = \OC::$server->query($filterClass);
+		$this->assertInternalType('string', $filter->getIdentifier());
+	}
+
+	/**
+	 * @dataProvider dataFilters
+	 * @param string $filterClass
+	 */
+	public function testGetName($filterClass) {
+		/** @var IFilter $filter */
+		$filter = \OC::$server->query($filterClass);
+		$this->assertInternalType('string', $filter->getName());
+	}
+
+	/**
+	 * @dataProvider dataFilters
+	 * @param string $filterClass
+	 */
+	public function testGetPriority($filterClass) {
+		/** @var IFilter $filter */
+		$filter = \OC::$server->query($filterClass);
+		$priority = $filter->getPriority();
+		$this->assertInternalType('int', $filter->getPriority());
+		$this->assertGreaterThanOrEqual(0, $priority);
+		$this->assertLessThanOrEqual(100, $priority);
+	}
+
+	/**
+	 * @dataProvider dataFilters
+	 * @param string $filterClass
+	 */
+	public function testGetIcon($filterClass) {
+		/** @var IFilter $filter */
+		$filter = \OC::$server->query($filterClass);
+		$this->assertInternalType('string', $filter->getIcon());
+		$this->assertStringStartsWith('http', $filter->getIcon());
+	}
+
+	/**
+	 * @dataProvider dataFilters
+	 * @param string $filterClass
+	 */
+	public function testFilterTypes($filterClass) {
+		/** @var IFilter $filter */
+		$filter = \OC::$server->query($filterClass);
+		$this->assertInternalType('array', $filter->filterTypes([]));
+	}
+
+	/**
+	 * @dataProvider dataFilters
+	 * @param string $filterClass
+	 */
+	public function testAllowedApps($filterClass) {
+		/** @var IFilter $filter */
+		$filter = \OC::$server->query($filterClass);
+		$this->assertInternalType('array', $filter->allowedApps());
+	}
+}
diff --git a/apps/dav/tests/unit/CalDAV/Activity/Filter/TodoTest.php b/apps/dav/tests/unit/CalDAV/Activity/Filter/TodoTest.php
new file mode 100644
index 0000000000000000000000000000000000000000..54a5a6f5f9d6c04173439ad9afe471644dd14f61
--- /dev/null
+++ b/apps/dav/tests/unit/CalDAV/Activity/Filter/TodoTest.php
@@ -0,0 +1,84 @@
+<?php
+/**
+ * @copyright Copyright (c) 2016 Joas Schilling <coding@schilljs.com>
+ *
+ * @license GNU AGPL version 3 or any later version
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+namespace OCA\DAV\Tests\unit\CalDAV\Activity\Filter;
+
+use OCA\DAV\CalDAV\Activity\Filter\Todo;
+use OCP\Activity\IFilter;
+use OCP\IL10N;
+use OCP\IURLGenerator;
+use Test\TestCase;
+
+class TodoTest extends TestCase {
+
+	/** @var IURLGenerator|\PHPUnit_Framework_MockObject_MockObject */
+	protected $url;
+
+	/** @var IFilter|\PHPUnit_Framework_MockObject_MockObject */
+	protected $filter;
+
+	protected function setUp() {
+		parent::setUp();
+		$this->url = $this->createMock(IURLGenerator::class);
+		$l = $this->createMock(IL10N::class);
+		$l->expects($this->any())
+			->method('t')
+			->willReturnCallback(function($string, $args) {
+				return vsprintf($string, $args);
+			});
+
+		$this->filter = new Todo(
+			$l, $this->url
+		);
+	}
+
+	public function testGetIcon() {
+		$this->url->expects($this->once())
+			->method('imagePath')
+			->with('core', 'actions/checkmark.svg')
+			->willReturn('path-to-icon');
+
+		$this->url->expects($this->once())
+			->method('getAbsoluteURL')
+			->with('path-to-icon')
+			->willReturn('absolute-path-to-icon');
+
+		$this->assertEquals('absolute-path-to-icon', $this->filter->getIcon());
+	}
+
+	public function dataFilterTypes() {
+		return [
+			[[], []],
+			[['calendar_todo'], ['calendar_todo']],
+			[['calendar', 'calendar_event', 'calendar_todo'], ['calendar_todo']],
+			[['calendar', 'calendar_todo', 'files'], ['calendar_todo']],
+		];
+	}
+
+	/**
+	 * @dataProvider dataFilterTypes
+	 * @param string[] $types
+	 * @param string[] $expected
+	 */
+	public function testFilterTypes($types, $expected) {
+		$this->assertEquals($expected, $this->filter->filterTypes($types));
+	}
+}
diff --git a/apps/dav/tests/unit/CalDAV/Activity/Provider/BaseTest.php b/apps/dav/tests/unit/CalDAV/Activity/Provider/BaseTest.php
new file mode 100644
index 0000000000000000000000000000000000000000..85eb439f100587328369922e48f075d691b58f9e
--- /dev/null
+++ b/apps/dav/tests/unit/CalDAV/Activity/Provider/BaseTest.php
@@ -0,0 +1,189 @@
+<?php
+/**
+ * @copyright Copyright (c) 2016 Joas Schilling <coding@schilljs.com>
+ *
+ * @license GNU AGPL version 3 or any later version
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+namespace OCA\DAV\Tests\unit\CalDAV\Activity\Provider;
+
+use OCA\DAV\CalDAV\Activity\Provider\Base;
+use OCP\Activity\IEvent;
+use OCP\Activity\IProvider;
+use OCP\IUser;
+use OCP\IUserManager;
+use Test\TestCase;
+
+class BaseTest extends TestCase {
+
+	/** @var IUserManager|\PHPUnit_Framework_MockObject_MockObject */
+	protected $userManager;
+
+	/** @var IProvider|Base|\PHPUnit_Framework_MockObject_MockObject */
+	protected $provider;
+
+	protected function setUp() {
+		parent::setUp();
+		$this->userManager = $this->createMock(IUserManager::class);
+		$this->provider = $this->getMockBuilder(Base::class)
+			->setConstructorArgs([
+				$this->userManager
+			])
+			->setMethods(['parse'])
+			->getMock();
+	}
+
+	public function dataSetSubjects() {
+		return [
+			['abc', [], 'abc'],
+			['{actor} created {calendar}', ['actor' => ['name' => 'abc'], 'calendar' => ['name' => 'xyz']], 'abc created xyz'],
+		];
+	}
+
+	/**
+	 * @dataProvider dataSetSubjects
+	 * @param string $subject
+	 * @param array $parameters
+	 * @param string $parsedSubject
+	 */
+	public function testSetSubjects($subject, array $parameters, $parsedSubject) {
+		$event = $this->createMock(IEvent::class);
+		$event->expects($this->once())
+			->method('setRichSubject')
+			->with($subject, $parameters)
+			->willReturnSelf();
+		$event->expects($this->once())
+			->method('setParsedSubject')
+			->with($parsedSubject)
+			->willReturnSelf();
+
+		$this->invokePrivate($this->provider, 'setSubjects', [$event, $subject, $parameters]);
+	}
+
+	public function dataGenerateObjectParameter() {
+		return [
+			[23, 'c1'],
+			[42, 'c2'],
+		];
+	}
+
+	/**
+	 * @dataProvider dataGenerateObjectParameter
+	 * @param int $id
+	 * @param string $name
+	 */
+	public function testGenerateObjectParameter($id, $name) {
+		$this->assertEquals([
+			'type' => 'calendar-event',
+			'id' => $id,
+			'name' => $name,
+		], $this->invokePrivate($this->provider, 'generateObjectParameter', [['id' => $id, 'name' => $name]]));
+	}
+
+	public function dataGenerateObjectParameterThrows() {
+		return [
+			['event'],
+			[['name' => 'event']],
+			[['id' => 42]],
+		];
+	}
+
+	/**
+	 * @dataProvider dataGenerateObjectParameterThrows
+	 * @expectedException \InvalidArgumentException
+	 * @param mixed $eventData
+	 */
+	public function testGenerateObjectParameterThrows($eventData) {
+		$this->invokePrivate($this->provider, 'generateObjectParameter', [$eventData]);
+	}
+
+	public function dataGenerateCalendarParameter() {
+		return [
+			[23, 'c1'],
+			[42, 'c2'],
+		];
+	}
+
+	/**
+	 * @dataProvider dataGenerateCalendarParameter
+	 * @param int $id
+	 * @param string $name
+	 */
+	public function testGenerateCalendarParameter($id, $name) {
+		$this->assertEquals([
+			'type' => 'calendar',
+			'id' => $id,
+			'name' => $name,
+		], $this->invokePrivate($this->provider, 'generateCalendarParameter', [$id, $name]));
+	}
+
+	public function dataGenerateGroupParameter() {
+		return [
+			['g1'],
+			['g2'],
+		];
+	}
+
+	/**
+	 * @dataProvider dataGenerateGroupParameter
+	 * @param string $gid
+	 */
+	public function testGenerateGroupParameter($gid) {
+		$this->assertEquals([
+			'type' => 'group',
+			'id' => $gid,
+			'name' => $gid,
+		], $this->invokePrivate($this->provider, 'generateGroupParameter', [$gid]));
+	}
+
+	public function dataGenerateUserParameter() {
+		$u1 = $this->createMock(IUser::class);
+		$u1->expects($this->any())
+			->method('getDisplayName')
+			->willReturn('User 1');
+		return [
+			['u1', 'User 1', $u1],
+			['u2', 'u2', null],
+		];
+	}
+
+	/**
+	 * @dataProvider dataGenerateUserParameter
+	 * @param string $uid
+	 * @param string $displayName
+	 * @param IUser|null $user
+	 */
+	public function testGenerateUserParameter($uid, $displayName, $user) {
+		$this->userManager->expects($this->once())
+			->method('get')
+			->with($uid)
+			->willReturn($user);
+
+		$this->assertEquals([
+			'type' => 'user',
+			'id' => $uid,
+			'name' => $displayName,
+		], $this->invokePrivate($this->provider, 'generateUserParameter', [$uid]));
+
+		// Test caching (only 1 user manager invocation allowed)
+		$this->assertEquals([
+			'type' => 'user',
+			'id' => $uid,
+			'name' => $displayName,
+		], $this->invokePrivate($this->provider, 'generateUserParameter', [$uid]));
+	}
+}
diff --git a/apps/dav/tests/unit/CalDAV/Activity/Setting/GenericTest.php b/apps/dav/tests/unit/CalDAV/Activity/Setting/GenericTest.php
new file mode 100644
index 0000000000000000000000000000000000000000..54c7a54baf75f33c807fe47790f0fb5b047f7a63
--- /dev/null
+++ b/apps/dav/tests/unit/CalDAV/Activity/Setting/GenericTest.php
@@ -0,0 +1,121 @@
+<?php
+/**
+ * @copyright Copyright (c) 2016 Joas Schilling <coding@schilljs.com>
+ *
+ * @license GNU AGPL version 3 or any later version
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+namespace OCA\DAV\Tests\unit\CalDAV\Activity\Setting;
+
+use OCA\DAV\CalDAV\Activity\Setting\Calendar;
+use OCA\DAV\CalDAV\Activity\Setting\Event;
+use OCA\DAV\CalDAV\Activity\Setting\Todo;
+use OCP\Activity\ISetting;
+use Test\TestCase;
+
+class GenericTest extends TestCase {
+
+	public function dataSettings() {
+		return [
+			[Calendar::class],
+			[Event::class],
+			[Todo::class],
+		];
+	}
+
+	/**
+	 * @dataProvider dataSettings
+	 * @param string $settingClass
+	 */
+	public function testImplementsInterface($settingClass) {
+		$setting = \OC::$server->query($settingClass);
+		$this->assertInstanceOf(ISetting::class, $setting);
+	}
+
+	/**
+	 * @dataProvider dataSettings
+	 * @param string $settingClass
+	 */
+	public function testGetIdentifier($settingClass) {
+		/** @var ISetting $setting */
+		$setting = \OC::$server->query($settingClass);
+		$this->assertInternalType('string', $setting->getIdentifier());
+	}
+
+	/**
+	 * @dataProvider dataSettings
+	 * @param string $settingClass
+	 */
+	public function testGetName($settingClass) {
+		/** @var ISetting $setting */
+		$setting = \OC::$server->query($settingClass);
+		$this->assertInternalType('string', $setting->getName());
+	}
+
+	/**
+	 * @dataProvider dataSettings
+	 * @param string $settingClass
+	 */
+	public function testGetPriority($settingClass) {
+		/** @var ISetting $setting */
+		$setting = \OC::$server->query($settingClass);
+		$priority = $setting->getPriority();
+		$this->assertInternalType('int', $setting->getPriority());
+		$this->assertGreaterThanOrEqual(0, $priority);
+		$this->assertLessThanOrEqual(100, $priority);
+	}
+
+	/**
+	 * @dataProvider dataSettings
+	 * @param string $settingClass
+	 */
+	public function testCanChangeStream($settingClass) {
+		/** @var ISetting $setting */
+		$setting = \OC::$server->query($settingClass);
+		$this->assertInternalType('bool', $setting->canChangeStream());
+	}
+
+	/**
+	 * @dataProvider dataSettings
+	 * @param string $settingClass
+	 */
+	public function testIsDefaultEnabledStream($settingClass) {
+		/** @var ISetting $setting */
+		$setting = \OC::$server->query($settingClass);
+		$this->assertInternalType('bool', $setting->isDefaultEnabledStream());
+	}
+
+	/**
+	 * @dataProvider dataSettings
+	 * @param string $settingClass
+	 */
+	public function testCanChangeMail($settingClass) {
+		/** @var ISetting $setting */
+		$setting = \OC::$server->query($settingClass);
+		$this->assertInternalType('bool', $setting->canChangeMail());
+	}
+
+	/**
+	 * @dataProvider dataSettings
+	 * @param string $settingClass
+	 */
+	public function testIsDefaultEnabledMail($settingClass) {
+		/** @var ISetting $setting */
+		$setting = \OC::$server->query($settingClass);
+		$this->assertInternalType('bool', $setting->isDefaultEnabledMail());
+	}
+}
diff --git a/core/img/places/calendar-dark.svg b/core/img/places/calendar-dark.svg
index 06d2a8efca3cbc657920c6e4d4cb87d8b0030faf..9290ef60f68413637024403816f29879cf3112b1 100644
--- a/core/img/places/calendar-dark.svg
+++ b/core/img/places/calendar-dark.svg
@@ -1 +1 @@
-<svg xmlns="http://www.w3.org/2000/svg" height="32" width="32"><path d="M8 2c-1.108 0-2 .892-2 2v4c0 1.108.892 2 2 2s2-.892 2-2V4c0-1.108-.892-2-2-2zm16 0c-1.108 0-2 .892-2 2v4c0 1.108.892 2 2 2s2-.892 2-2V4c0-1.108-.892-2-2-2zM11 6v2c0 1.662-1.338 3-3 3S5 9.662 5 8V6.125A3.993 3.993 0 0 0 2 10v16c0 2.216 1.784 4 4 4h20c2.216 0 4-1.784 4-4V10a3.993 3.993 0 0 0-3-3.875V8c0 1.662-1.338 3-3 3s-3-1.338-3-3V6zM6.094 16h19.812a.09.09 0 0 1 .094.094v9.812a.09.09 0 0 1-.094.094H6.094A.09.09 0 0 1 6 25.906v-9.812A.09.09 0 0 1 6.094 16z"/></svg>
\ No newline at end of file
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diff --git a/core/img/places/contacts-dark.svg b/core/img/places/contacts-dark.svg
index c819521a254f9e3984aa6c2e3980f83e8adff00d..714cfef1dbb7f44fa9b65a6dbbd01999f9096eee 100644
--- a/core/img/places/contacts-dark.svg
+++ b/core/img/places/contacts-dark.svg
@@ -1 +1 @@
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