diff --git a/apps/dav/appinfo/app.php b/apps/dav/appinfo/app.php
index 4f4fbe6e12624..089aaeb6c7841 100644
--- a/apps/dav/appinfo/app.php
+++ b/apps/dav/appinfo/app.php
@@ -48,6 +48,19 @@ function(GenericEvent $event) use ($app) {
 	}
 );
 
+$eventHandler = function() use ($app) {
+	try {
+		$job = $app->getContainer()->query(\OCA\DAV\BackgroundJob\UpdateCalendarResourcesRoomsBackgroundJob::class);
+		$job->run([]);
+		$app->getContainer()->getServer()->getJobList()->setLastRun($job);
+	} catch(\Exception $ex) {
+		$app->getContainer()->getServer()->getLogger()->logException($ex);
+	}
+};
+
+$eventDispatcher->addListener('\OCP\Calendar\Resource\ForceRefreshEvent', $eventHandler);
+$eventDispatcher->addListener('\OCP\Calendar\Room\ForceRefreshEvent', $eventHandler);
+
 $cm = \OC::$server->getContactsManager();
 $cm->register(function() use ($cm, $app) {
 	$user = \OC::$server->getUserSession()->getUser();
diff --git a/apps/dav/appinfo/info.xml b/apps/dav/appinfo/info.xml
index 2dcb986c841a1..d1f9a823fd746 100644
--- a/apps/dav/appinfo/info.xml
+++ b/apps/dav/appinfo/info.xml
@@ -5,7 +5,7 @@
 	<name>WebDAV</name>
 	<summary>WebDAV endpoint</summary>
 	<description>WebDAV endpoint</description>
-	<version>1.5.3</version>
+	<version>1.5.4</version>
 	<licence>agpl</licence>
 	<author>owncloud.org</author>
 	<namespace>DAV</namespace>
@@ -21,6 +21,7 @@
 
 	<background-jobs>
 		<job>OCA\DAV\BackgroundJob\CleanupDirectLinksJob</job>
+		<job>OCA\DAV\BackgroundJob\UpdateCalendarResourcesRoomsBackgroundJob</job>
 	</background-jobs>
 
 	<repair-steps>
diff --git a/apps/dav/composer/composer/autoload_classmap.php b/apps/dav/composer/composer/autoload_classmap.php
index e9736f26a5be7..93a5a5ef2d4b5 100644
--- a/apps/dav/composer/composer/autoload_classmap.php
+++ b/apps/dav/composer/composer/autoload_classmap.php
@@ -13,6 +13,7 @@
     'OCA\\DAV\\Avatars\\RootCollection' => $baseDir . '/../lib/Avatars/RootCollection.php',
     'OCA\\DAV\\BackgroundJob\\CleanupDirectLinksJob' => $baseDir . '/../lib/BackgroundJob/CleanupDirectLinksJob.php',
     'OCA\\DAV\\BackgroundJob\\GenerateBirthdayCalendarBackgroundJob' => $baseDir . '/../lib/BackgroundJob/GenerateBirthdayCalendarBackgroundJob.php',
+    'OCA\\DAV\\BackgroundJob\\UpdateCalendarResourcesRoomsBackgroundJob' => $baseDir . '/../lib/BackgroundJob/UpdateCalendarResourcesRoomsBackgroundJob.php',
     'OCA\\DAV\\CalDAV\\Activity\\Backend' => $baseDir . '/../lib/CalDAV/Activity/Backend.php',
     'OCA\\DAV\\CalDAV\\Activity\\Filter\\Calendar' => $baseDir . '/../lib/CalDAV/Activity/Filter/Calendar.php',
     'OCA\\DAV\\CalDAV\\Activity\\Filter\\Todo' => $baseDir . '/../lib/CalDAV/Activity/Filter/Todo.php',
@@ -40,6 +41,9 @@
     'OCA\\DAV\\CalDAV\\PublicCalendarRoot' => $baseDir . '/../lib/CalDAV/PublicCalendarRoot.php',
     'OCA\\DAV\\CalDAV\\Publishing\\PublishPlugin' => $baseDir . '/../lib/CalDAV/Publishing/PublishPlugin.php',
     'OCA\\DAV\\CalDAV\\Publishing\\Xml\\Publisher' => $baseDir . '/../lib/CalDAV/Publishing/Xml/Publisher.php',
+    'OCA\\DAV\\CalDAV\\ResourceBooking\\AbstractPrincipalBackend' => $baseDir . '/../lib/CalDAV/ResourceBooking/AbstractPrincipalBackend.php',
+    'OCA\\DAV\\CalDAV\\ResourceBooking\\ResourcePrincipalBackend' => $baseDir . '/../lib/CalDAV/ResourceBooking/ResourcePrincipalBackend.php',
+    'OCA\\DAV\\CalDAV\\ResourceBooking\\RoomPrincipalBackend' => $baseDir . '/../lib/CalDAV/ResourceBooking/RoomPrincipalBackend.php',
     'OCA\\DAV\\CalDAV\\Schedule\\IMipPlugin' => $baseDir . '/../lib/CalDAV/Schedule/IMipPlugin.php',
     'OCA\\DAV\\CalDAV\\Schedule\\Plugin' => $baseDir . '/../lib/CalDAV/Schedule/Plugin.php',
     'OCA\\DAV\\CalDAV\\Search\\SearchPlugin' => $baseDir . '/../lib/CalDAV/Search/SearchPlugin.php',
@@ -144,6 +148,7 @@
     'OCA\\DAV\\Migration\\Version1004Date20170924124212' => $baseDir . '/../lib/Migration/Version1004Date20170924124212.php',
     'OCA\\DAV\\Migration\\Version1004Date20170926103422' => $baseDir . '/../lib/Migration/Version1004Date20170926103422.php',
     'OCA\\DAV\\Migration\\Version1005Date20180413093149' => $baseDir . '/../lib/Migration/Version1005Date20180413093149.php',
+    'OCA\\DAV\\Migration\\Version1005Date20180530124431' => $baseDir . '/../lib/Migration/Version1005Date20180530124431.php',
     'OCA\\DAV\\RootCollection' => $baseDir . '/../lib/RootCollection.php',
     'OCA\\DAV\\Server' => $baseDir . '/../lib/Server.php',
     'OCA\\DAV\\Settings\\CalDAVSettings' => $baseDir . '/../lib/Settings/CalDAVSettings.php',
diff --git a/apps/dav/composer/composer/autoload_static.php b/apps/dav/composer/composer/autoload_static.php
index b8b0411f18b47..0c45b5c0a93ef 100644
--- a/apps/dav/composer/composer/autoload_static.php
+++ b/apps/dav/composer/composer/autoload_static.php
@@ -28,6 +28,7 @@ class ComposerStaticInitDAV
         'OCA\\DAV\\Avatars\\RootCollection' => __DIR__ . '/..' . '/../lib/Avatars/RootCollection.php',
         'OCA\\DAV\\BackgroundJob\\CleanupDirectLinksJob' => __DIR__ . '/..' . '/../lib/BackgroundJob/CleanupDirectLinksJob.php',
         'OCA\\DAV\\BackgroundJob\\GenerateBirthdayCalendarBackgroundJob' => __DIR__ . '/..' . '/../lib/BackgroundJob/GenerateBirthdayCalendarBackgroundJob.php',
+        'OCA\\DAV\\BackgroundJob\\UpdateCalendarResourcesRoomsBackgroundJob' => __DIR__ . '/..' . '/../lib/BackgroundJob/UpdateCalendarResourcesRoomsBackgroundJob.php',
         'OCA\\DAV\\CalDAV\\Activity\\Backend' => __DIR__ . '/..' . '/../lib/CalDAV/Activity/Backend.php',
         'OCA\\DAV\\CalDAV\\Activity\\Filter\\Calendar' => __DIR__ . '/..' . '/../lib/CalDAV/Activity/Filter/Calendar.php',
         'OCA\\DAV\\CalDAV\\Activity\\Filter\\Todo' => __DIR__ . '/..' . '/../lib/CalDAV/Activity/Filter/Todo.php',
@@ -55,6 +56,9 @@ class ComposerStaticInitDAV
         'OCA\\DAV\\CalDAV\\PublicCalendarRoot' => __DIR__ . '/..' . '/../lib/CalDAV/PublicCalendarRoot.php',
         'OCA\\DAV\\CalDAV\\Publishing\\PublishPlugin' => __DIR__ . '/..' . '/../lib/CalDAV/Publishing/PublishPlugin.php',
         'OCA\\DAV\\CalDAV\\Publishing\\Xml\\Publisher' => __DIR__ . '/..' . '/../lib/CalDAV/Publishing/Xml/Publisher.php',
+        'OCA\\DAV\\CalDAV\\ResourceBooking\\AbstractPrincipalBackend' => __DIR__ . '/..' . '/../lib/CalDAV/ResourceBooking/AbstractPrincipalBackend.php',
+        'OCA\\DAV\\CalDAV\\ResourceBooking\\ResourcePrincipalBackend' => __DIR__ . '/..' . '/../lib/CalDAV/ResourceBooking/ResourcePrincipalBackend.php',
+        'OCA\\DAV\\CalDAV\\ResourceBooking\\RoomPrincipalBackend' => __DIR__ . '/..' . '/../lib/CalDAV/ResourceBooking/RoomPrincipalBackend.php',
         'OCA\\DAV\\CalDAV\\Schedule\\IMipPlugin' => __DIR__ . '/..' . '/../lib/CalDAV/Schedule/IMipPlugin.php',
         'OCA\\DAV\\CalDAV\\Schedule\\Plugin' => __DIR__ . '/..' . '/../lib/CalDAV/Schedule/Plugin.php',
         'OCA\\DAV\\CalDAV\\Search\\SearchPlugin' => __DIR__ . '/..' . '/../lib/CalDAV/Search/SearchPlugin.php',
@@ -159,6 +163,7 @@ class ComposerStaticInitDAV
         'OCA\\DAV\\Migration\\Version1004Date20170924124212' => __DIR__ . '/..' . '/../lib/Migration/Version1004Date20170924124212.php',
         'OCA\\DAV\\Migration\\Version1004Date20170926103422' => __DIR__ . '/..' . '/../lib/Migration/Version1004Date20170926103422.php',
         'OCA\\DAV\\Migration\\Version1005Date20180413093149' => __DIR__ . '/..' . '/../lib/Migration/Version1005Date20180413093149.php',
+        'OCA\\DAV\\Migration\\Version1005Date20180530124431' => __DIR__ . '/..' . '/../lib/Migration/Version1005Date20180530124431.php',
         'OCA\\DAV\\RootCollection' => __DIR__ . '/..' . '/../lib/RootCollection.php',
         'OCA\\DAV\\Server' => __DIR__ . '/..' . '/../lib/Server.php',
         'OCA\\DAV\\Settings\\CalDAVSettings' => __DIR__ . '/..' . '/../lib/Settings/CalDAVSettings.php',
diff --git a/apps/dav/lib/BackgroundJob/UpdateCalendarResourcesRoomsBackgroundJob.php b/apps/dav/lib/BackgroundJob/UpdateCalendarResourcesRoomsBackgroundJob.php
new file mode 100644
index 0000000000000..a01540a62921a
--- /dev/null
+++ b/apps/dav/lib/BackgroundJob/UpdateCalendarResourcesRoomsBackgroundJob.php
@@ -0,0 +1,337 @@
+<?php
+/**
+ * @copyright 2018, Georg Ehrke <oc.list@georgehrke.com>
+ *
+ * @author Georg Ehrke <oc.list@georgehrke.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\BackgroundJob;
+
+use OC\BackgroundJob\TimedJob;
+use OCA\DAV\CalDAV\CalDavBackend;
+use OCP\Calendar\BackendTemporarilyUnavailableException;
+use OCP\Calendar\Resource\IManager as IResourceManager;
+use OCP\Calendar\Resource\IResource;
+use OCP\Calendar\Room\IManager as IRoomManager;
+use OCP\Calendar\Room\IRoom;
+use OCP\IDBConnection;
+
+class UpdateCalendarResourcesRoomsBackgroundJob extends TimedJob {
+
+	/** @var IResourceManager */
+	private $resourceManager;
+
+	/** @var IRoomManager */
+	private $roomManager;
+
+	/** @var IDBConnection */
+	private $db;
+
+	/** @var CalDavBackend */
+	private $calDavBackend;
+
+	/** @var string */
+	private $resourceDbTable;
+
+	/** @var string */
+	private $resourcePrincipalUri;
+
+	/** @var string */
+	private $roomDbTable;
+
+	/** @var string */
+	private $roomPrincipalUri;
+
+	/**
+	 * UpdateCalendarResourcesRoomsBackgroundJob constructor.
+	 *
+	 * @param IResourceManager $resourceManager
+	 * @param IRoomManager $roomManager
+	 * @param IDBConnection $dbConnection
+	 * @param CalDavBackend $calDavBackend
+	 */
+	public function __construct(IResourceManager $resourceManager, IRoomManager $roomManager,
+								IDBConnection $dbConnection, CalDavBackend $calDavBackend) {
+		$this->resourceManager = $resourceManager;
+		$this->roomManager = $roomManager;
+		$this->db = $dbConnection;
+		$this->calDavBackend = $calDavBackend;
+		$this->resourceDbTable = 'calendar_resources_cache';
+		$this->resourcePrincipalUri = 'principals/calendar-resources';
+		$this->roomDbTable = 'calendar_rooms_cache';
+		$this->roomPrincipalUri = 'principals/calendar-rooms';
+
+		// run once an hour
+		$this->setInterval(60 * 60);
+	}
+
+	/**
+	 * @param $argument
+	 */
+	public function run($argument) {
+		$this->runResources();
+		$this->runRooms();
+	}
+
+	/**
+	 * run timed job for resources
+	 */
+	private function runResources() {
+		$resourceBackends = $this->resourceManager->getBackends();
+		$cachedResources = $this->getCached($this->resourceDbTable);
+		$cachedResourceIds = $this->getCachedResourceIds($cachedResources);
+
+		$remoteResourceIds = [];
+		foreach($resourceBackends as $resourceBackend) {
+			try {
+				$remoteResourceIds[$resourceBackend->getBackendIdentifier()] =
+					$resourceBackend->listAllResources();
+			} catch(BackendTemporarilyUnavailableException $ex) {
+				// If the backend is temporarily unavailable
+				// ignore this backend in this execution
+				unset($cachedResourceIds[$resourceBackend->getBackendIdentifier()]);
+			}
+		}
+
+		$sortedResources = $this->sortByNewDeletedExisting($cachedResourceIds, $remoteResourceIds);
+
+		foreach($sortedResources['new'] as $backendId => $newResources) {
+			foreach ($newResources as $newResource) {
+				$resource = $this->resourceManager->getBackend($backendId)
+					->getResource($newResource);
+				$this->addToCache($this->resourceDbTable, $resource);
+			}
+		}
+		foreach($sortedResources['deleted'] as $backendId => $deletedResources) {
+			foreach ($deletedResources as $deletedResource) {
+				$this->deleteFromCache($this->resourceDbTable,
+					$this->resourcePrincipalUri, $backendId, $deletedResource);
+			}
+		}
+		foreach($sortedResources['edited'] as $backendId => $editedResources) {
+			foreach ($editedResources as $editedResource) {
+				$resource = $this->resourceManager->getBackend($backendId)
+					->getResource($editedResource);
+				$this->updateCache($this->resourceDbTable, $resource);
+			}
+		}
+	}
+
+	/**
+	 * run timed job for rooms
+	 */
+	private function runRooms() {
+		$roomBackends = $this->roomManager->getBackends();
+		$cachedRooms = $this->getCached($this->roomDbTable);
+		$cachedRoomIds = $this->getCachedRoomIds($cachedRooms);
+
+		$remoteRoomIds = [];
+		foreach($roomBackends as $roomBackend) {
+			try {
+				$remoteRoomIds[$roomBackend->getBackendIdentifier()] =
+					$roomBackend->listAllRooms();
+			} catch(BackendTemporarilyUnavailableException $ex) {
+				// If the backend is temporarily unavailable
+				// ignore this backend in this execution
+				unset($cachedRoomIds[$roomBackend->getBackendIdentifier()]);
+			}
+		}
+
+		$sortedRooms = $this->sortByNewDeletedExisting($cachedRoomIds, $remoteRoomIds);
+
+		foreach($sortedRooms['new'] as $backendId => $newRooms) {
+			foreach ($newRooms as $newRoom) {
+				$resource = $this->roomManager->getBackend($backendId)
+					->getRoom($newRoom);
+				$this->addToCache($this->roomDbTable, $resource);
+			}
+		}
+		foreach($sortedRooms['deleted'] as $backendId => $deletedRooms) {
+			foreach ($deletedRooms as $deletedRoom) {
+				$this->deleteFromCache($this->roomDbTable,
+					$this->roomPrincipalUri, $backendId, $deletedRoom);
+			}
+		}
+		foreach($sortedRooms['edited'] as $backendId => $editedRooms) {
+			foreach ($editedRooms as $editedRoom) {
+				$resource = $this->roomManager->getBackend($backendId)
+					->getRoom($editedRoom);
+				$this->updateCache($this->roomDbTable, $resource);
+			}
+		}
+	}
+
+	/**
+	 * get cached db rows for resources / rooms
+	 * @param string $tableName
+	 * @return array
+	 */
+	private function getCached($tableName):array {
+		$query = $this->db->getQueryBuilder();
+		$query->select('*')->from($tableName);
+
+		$rows = [];
+		$stmt = $query->execute();
+		while($row = $stmt->fetch(\PDO::FETCH_ASSOC)) {
+			$rows[] = $row;
+		}
+
+		return $rows;
+	}
+
+	/**
+	 * @param array $cachedResources
+	 * @return array
+	 */
+	private function getCachedResourceIds(array $cachedResources):array {
+		$cachedResourceIds = [];
+		foreach ($cachedResources as $cachedResource) {
+			if (!isset($cachedResourceIds[$cachedResource['backend_id']])) {
+				$cachedResourceIds[$cachedResource['backend_id']] = [];
+			}
+
+			$cachedResourceIds[$cachedResource['backend_id']][] =
+				$cachedResource['resource_id'];
+		}
+
+		return $cachedResourceIds;
+	}
+
+	/**
+	 * @param array $cachedRooms
+	 * @return array
+	 */
+	private function getCachedRoomIds(array $cachedRooms):array {
+		$cachedRoomIds = [];
+		foreach ($cachedRooms as $cachedRoom) {
+			if (!isset($cachedRoomIds[$cachedRoom['backend_id']])) {
+				$cachedRoomIds[$cachedRoom['backend_id']] = [];
+			}
+
+			$cachedRoomIds[$cachedRoom['backend_id']][] =
+				$cachedRoom['resource_id'];
+		}
+
+		return $cachedRoomIds;
+	}
+
+	/**
+	 * sort list of ids by whether they appear only in the backend /
+	 * only in the cache / in both
+	 *
+	 * @param array $cached
+	 * @param array $remote
+	 * @return array
+	 */
+	private function sortByNewDeletedExisting(array $cached, array $remote):array {
+		$sorted = [
+			'new' => [],
+			'deleted' => [],
+			'edited' => [],
+		];
+
+		$backendIds = array_merge(array_keys($cached), array_keys($remote));
+		foreach($backendIds as $backendId) {
+			if (!isset($cached[$backendId])) {
+				$sorted['new'][$backendId] = $remote[$backendId];
+			} elseif (!isset($remote[$backendId])) {
+				$sorted['deleted'][$backendId] = $cached[$backendId];
+			} else {
+				$sorted['new'][$backendId] = array_diff($remote[$backendId], $cached[$backendId]);
+				$sorted['deleted'][$backendId] = array_diff($cached[$backendId], $remote[$backendId]);
+				$sorted['edited'][$backendId] = array_intersect($remote[$backendId], $cached[$backendId]);
+			}
+		}
+
+		return $sorted;
+	}
+
+	/**
+	 * add entry to cache that exists remotely but not yet in cache
+	 *
+	 * @param string $table
+	 * @param IResource|IRoom $remote
+	 */
+	private function addToCache($table, $remote) {
+		$query = $this->db->getQueryBuilder();
+		$query->insert($table)
+			->values([
+				'backend_id' => $query->createNamedParameter($remote->getBackend()->getBackendIdentifier()),
+				'resource_id' => $query->createNamedParameter($remote->getId()),
+				'email' => $query->createNamedParameter($remote->getEMail()),
+				'displayname' => $query->createNamedParameter($remote->getDisplayName()),
+				'group_restrictions' => $query->createNamedParameter(
+					$this->serializeGroupRestrictions(
+						$remote->getGroupRestrictions()
+					))
+			])
+			->execute();
+	}
+
+	/**
+	 * delete entry from cache that does not exist anymore remotely
+	 *
+	 * @param string $table
+	 * @param string $principalUri
+	 * @param string $backendId
+	 * @param string $resourceId
+	 */
+	private function deleteFromCache($table, $principalUri, $backendId, $resourceId) {
+		$query = $this->db->getQueryBuilder();
+		$query->delete($table)
+			->where($query->expr()->eq('backend_id', $query->createNamedParameter($backendId)))
+			->andWhere($query->expr()->eq('resource_id', $query->createNamedParameter($resourceId)))
+			->execute();
+
+		$calendar = $this->calDavBackend->getCalendarByUri($principalUri, implode('-', [$backendId, $resourceId]));
+		if ($calendar !== null) {
+			$this->calDavBackend->deleteCalendar($calendar['id']);
+		}
+	}
+
+	/**
+	 * update an existing entry in cache
+	 *
+	 * @param string $table
+	 * @param IResource|IRoom $remote
+	 */
+	private function updateCache($table, $remote) {
+		$query = $this->db->getQueryBuilder();
+		$query->update($table)
+			->set('email', $query->createNamedParameter($remote->getEMail()))
+			->set('displayname', $query->createNamedParameter($remote->getDisplayName()))
+			->set('group_restrictions', $query->createNamedParameter(
+				$this->serializeGroupRestrictions(
+					$remote->getGroupRestrictions()
+				)))
+			->where($query->expr()->eq('backend_id', $query->createNamedParameter($remote->getBackend()->getBackendIdentifier())))
+			->andWhere($query->expr()->eq('resource_id', $query->createNamedParameter($remote->getId())))
+			->execute();
+	}
+
+	/**
+	 * serialize array of group restrictions to store them in database
+	 *
+	 * @param array $groups
+	 * @return string
+	 */
+	private function serializeGroupRestrictions(array $groups):string {
+		return \json_encode($groups);
+	}
+}
diff --git a/apps/dav/lib/CalDAV/CalDavBackend.php b/apps/dav/lib/CalDAV/CalDavBackend.php
index b28c8534aaa28..de46dfeb244ee 100644
--- a/apps/dav/lib/CalDAV/CalDavBackend.php
+++ b/apps/dav/lib/CalDAV/CalDavBackend.php
@@ -76,6 +76,9 @@ class CalDavBackend extends AbstractBackend implements SyncSupport, Subscription
 	const PERSONAL_CALENDAR_URI = 'personal';
 	const PERSONAL_CALENDAR_NAME = 'Personal';
 
+	const RESOURCE_BOOKING_CALENDAR_URI = 'calendar';
+	const RESOURCE_BOOKING_CALENDAR_NAME = 'Calendar';
+
 	/**
 	 * We need to specify a max date, because we need to stop *somewhere*
 	 *
diff --git a/apps/dav/lib/CalDAV/CalendarRoot.php b/apps/dav/lib/CalDAV/CalendarRoot.php
index 2c1c8bb4ef27d..f84e8a9678013 100644
--- a/apps/dav/lib/CalDAV/CalendarRoot.php
+++ b/apps/dav/lib/CalDAV/CalendarRoot.php
@@ -27,4 +27,15 @@ class CalendarRoot extends \Sabre\CalDAV\CalendarRoot {
 	function getChildForPrincipal(array $principal) {
 		return new CalendarHome($this->caldavBackend, $principal);
 	}
+
+	function getName() {
+		if ($this->principalPrefix === 'principals/calendar-resources' ||
+			$this->principalPrefix === 'principals/calendar-rooms') {
+			$parts = explode('/', $this->principalPrefix);
+
+			return $parts[1];
+		}
+
+		return parent::getName();
+	}
 }
\ No newline at end of file
diff --git a/apps/dav/lib/CalDAV/Plugin.php b/apps/dav/lib/CalDAV/Plugin.php
index 4aa9762899fd9..f37d9c571a023 100644
--- a/apps/dav/lib/CalDAV/Plugin.php
+++ b/apps/dav/lib/CalDAV/Plugin.php
@@ -25,15 +25,27 @@
 
 class Plugin extends \Sabre\CalDAV\Plugin {
 
+	const SYSTEM_CALENDAR_ROOT = 'system-calendars';
+
 	/**
 	 * @inheritdoc
 	 */
-	function getCalendarHomeForPrincipal($principalUrl) {
+	function getCalendarHomeForPrincipal($principalUrl):string {
 
 		if (strrpos($principalUrl, 'principals/users', -strlen($principalUrl)) !== false) {
 			list(, $principalId) = \Sabre\Uri\split($principalUrl);
-			return self::CALENDAR_ROOT .'/' . $principalId;
+			return self::CALENDAR_ROOT . '/' . $principalId;
+		}
+		if (strrpos($principalUrl, 'principals/calendar-resources', -strlen($principalUrl)) !== false) {
+			list(, $principalId) = \Sabre\Uri\split($principalUrl);
+			return self::SYSTEM_CALENDAR_ROOT . '/calendar-resources/' . $principalId;
 		}
+		if (strrpos($principalUrl, 'principals/calendar-rooms', -strlen($principalUrl)) !== false) {
+			list(, $principalId) = \Sabre\Uri\split($principalUrl);
+			return self::SYSTEM_CALENDAR_ROOT . '/calendar-rooms/' . $principalId;
+		}
+
+		throw new \LogicException('This is not supposed to happen');
 	}
 
 }
diff --git a/apps/dav/lib/CalDAV/ResourceBooking/AbstractPrincipalBackend.php b/apps/dav/lib/CalDAV/ResourceBooking/AbstractPrincipalBackend.php
new file mode 100644
index 0000000000000..135bbe5827e8a
--- /dev/null
+++ b/apps/dav/lib/CalDAV/ResourceBooking/AbstractPrincipalBackend.php
@@ -0,0 +1,361 @@
+<?php
+/**
+ * @copyright 2018, Georg Ehrke <oc.list@georgehrke.com>
+ *
+ * @author Georg Ehrke <oc.list@georgehrke.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\ResourceBooking;
+
+use OCP\IDBConnection;
+use OCP\IGroupManager;
+use OCP\ILogger;
+use OCP\IUserSession;
+use Sabre\DAVACL\PrincipalBackend\BackendInterface;
+use Sabre\DAV\Exception;
+use \Sabre\DAV\PropPatch;
+
+abstract class AbstractPrincipalBackend implements BackendInterface {
+
+	/** @var IDBConnection */
+	private $db;
+
+	/** @var IUserSession */
+	private $userSession;
+
+	/** @var IGroupManager */
+	private $groupManager;
+
+	/** @var ILogger */
+	private $logger;
+
+	/** @var string */
+	private $principalPrefix;
+
+	/** @var string */
+	private $dbTableName;
+
+	/**
+	 * @param IDBConnection $dbConnection
+	 * @param IUserSession $userSession
+	 * @param IGroupManager $groupManager
+	 * @param ILogger $logger
+	 * @param string $principalPrefix
+	 * @param string $dbPrefix
+	 */
+	public function __construct(IDBConnection $dbConnection,
+								IUserSession $userSession,
+								IGroupManager $groupManager,
+								ILogger $logger,
+								$principalPrefix, $dbPrefix) {
+		$this->db = $dbConnection;
+		$this->userSession = $userSession;
+		$this->groupManager = $groupManager;
+		$this->logger = $logger;
+		$this->principalPrefix = $principalPrefix;
+		$this->dbTableName = 'calendar_' . $dbPrefix . '_cache';
+	}
+
+	/**
+	 * Returns a list of principals based on a prefix.
+	 *
+	 * This prefix will often contain something like 'principals'. You are only
+	 * expected to return principals that are in this base path.
+	 *
+	 * You are expected to return at least a 'uri' for every user, you can
+	 * return any additional properties if you wish so. Common properties are:
+	 *   {DAV:}displayname
+	 *
+	 * @param string $prefixPath
+	 * @return string[]
+	 */
+	public function getPrincipalsByPrefix($prefixPath) {
+		$principals = [];
+
+		if ($prefixPath === $this->principalPrefix) {
+			$query = $this->db->getQueryBuilder();
+			$query->select(['id', 'backend_id', 'resource_id', 'email', 'displayname'])
+				->from($this->dbTableName);
+			$stmt = $query->execute();
+
+			while($row = $stmt->fetch(\PDO::FETCH_ASSOC)) {
+				$principals[] = $this->rowToPrincipal($row);
+			}
+
+			$stmt->closeCursor();
+		}
+
+		return $principals;
+	}
+
+	/**
+	 * Returns a specific principal, specified by it's path.
+	 * The returned structure should be the exact same as from
+	 * getPrincipalsByPrefix.
+	 *
+	 * @param string $path
+	 * @return array
+	 */
+	public function getPrincipalByPath($path) {
+		if (strpos($path, $this->principalPrefix) !== 0) {
+			return null;
+		}
+		list(, $name) = \Sabre\Uri\split($path);
+
+		list($backendId, $resourceId) = explode('-',  $name, 2);
+
+		$query = $this->db->getQueryBuilder();
+		$query->select(['id', 'backend_id', 'resource_id', 'email', 'displayname'])
+			->from($this->dbTableName)
+			->where($query->expr()->eq('backend_id', $query->createNamedParameter($backendId)))
+			->andWhere($query->expr()->eq('resource_id', $query->createNamedParameter($resourceId)));
+		$stmt = $query->execute();
+		$row = $stmt->fetch(\PDO::FETCH_ASSOC);
+
+		if(!$row) {
+			return null;
+		}
+
+		return $this->rowToPrincipal($row);
+	}
+
+	/**
+	 * Returns the list of members for a group-principal
+	 *
+	 * @param string $principal
+	 * @return string[]
+	 */
+	public function getGroupMemberSet($principal) {
+		return [];
+	}
+
+	/**
+	 * Returns the list of groups a principal is a member of
+	 *
+	 * @param string $principal
+	 * @return array
+	 */
+	public function getGroupMembership($principal) {
+		return [];
+	}
+
+	/**
+	 * Updates the list of group members for a group principal.
+	 *
+	 * The principals should be passed as a list of uri's.
+	 *
+	 * @param string $principal
+	 * @param string[] $members
+	 * @throws Exception
+	 */
+	public function setGroupMemberSet($principal, array $members) {
+		throw new Exception('Setting members of the group is not supported yet');
+	}
+
+	/**
+	 * @param string $path
+	 * @param PropPatch $propPatch
+	 * @return int
+	 */
+	function updatePrincipal($path, PropPatch $propPatch) {
+		return 0;
+	}
+
+	/**
+	 * @param string $prefixPath
+	 * @param array $searchProperties
+	 * @param string $test
+	 * @return array
+	 */
+	function searchPrincipals($prefixPath, array $searchProperties, $test = 'allof') {
+		$results = [];
+		if (\count($searchProperties) === 0) {
+			return [];
+		}
+		if ($prefixPath !== $this->principalPrefix) {
+			return [];
+		}
+
+		$user = $this->userSession->getUser();
+		if (!$user) {
+			return [];
+		}
+		$usersGroups = $this->groupManager->getUserGroupIds($user);
+
+		foreach ($searchProperties as $prop => $value) {
+			switch ($prop) {
+				case '{http://sabredav.org/ns}email-address':
+					$query = $this->db->getQueryBuilder();
+					$query->select(['id', 'backend_id', 'resource_id', 'email', 'displayname', 'group_restrictions'])
+						->from($this->dbTableName)
+						->where($query->expr()->iLike('email', $query->createNamedParameter('%' . $this->db->escapeLikeParameter($value) . '%')));
+
+					$stmt = $query->execute();
+					$principals = [];
+					while($row = $stmt->fetch(\PDO::FETCH_ASSOC)) {
+						if (!$this->isAllowedToAccessResource($row, $usersGroups)) {
+							continue;
+						}
+						$principals[] = $this->rowToPrincipal($row)['uri'];
+					}
+					$results[] = $principals;
+
+					$stmt->closeCursor();
+					break;
+
+				case '{DAV:}displayname':
+					$query = $this->db->getQueryBuilder();
+					$query->select(['id', 'backend_id', 'resource_id', 'email', 'displayname', 'group_restrictions'])
+						->from($this->dbTableName)
+						->where($query->expr()->iLike('displayname', $query->createNamedParameter('%' . $this->db->escapeLikeParameter($value) . '%')));
+
+					$stmt = $query->execute();
+					$principals = [];
+					while($row = $stmt->fetch(\PDO::FETCH_ASSOC)) {
+						if (!$this->isAllowedToAccessResource($row, $usersGroups)) {
+							continue;
+						}
+						$principals[] = $this->rowToPrincipal($row)['uri'];
+					}
+					$results[] = $principals;
+
+					$stmt->closeCursor();
+					break;
+
+				default:
+					$results[] = [];
+					break;
+			}
+		}
+
+		// results is an array of arrays, so this is not the first search result
+		// but the results of the first searchProperty
+		if (count($results) === 1) {
+			return $results[0];
+		}
+
+		switch ($test) {
+			case 'anyof':
+				return array_values(array_unique(array_merge(...$results)));
+
+			case 'allof':
+			default:
+				return array_values(array_intersect(...$results));
+		}
+	}
+
+	/**
+	 * @param string $uri
+	 * @param string $principalPrefix
+	 * @return null|string
+	 */
+	function findByUri($uri, $principalPrefix) {
+		$user = $this->userSession->getUser();
+		if (!$user) {
+			return null;
+		}
+		$usersGroups = $this->groupManager->getUserGroupIds($user);
+
+		if (strpos($uri, 'mailto:') === 0) {
+			$email = substr($uri, 7);
+			$query = $this->db->getQueryBuilder();
+			$query->select(['id', 'backend_id', 'resource_id', 'email', 'displayname', 'group_restrictions'])
+				->from($this->dbTableName)
+				->where($query->expr()->eq('email', $query->createNamedParameter($email)));
+
+			$stmt = $query->execute();
+			$row = $stmt->fetch(\PDO::FETCH_ASSOC);
+
+			if(!$row) {
+				return null;
+			}
+			if (!$this->isAllowedToAccessResource($row, $usersGroups)) {
+				return null;
+			}
+
+			return $this->rowToPrincipal($row)['uri'];
+		}
+
+		if (strpos($uri, 'principal:') === 0) {
+			$path = substr($uri, 10);
+			if (strpos($path, $this->principalPrefix) !== 0) {
+				return null;
+			}
+
+			list(, $name) = \Sabre\Uri\split($path);
+			list($backendId, $resourceId) = explode('-',  $name, 2);
+
+			$query = $this->db->getQueryBuilder();
+			$query->select(['id', 'backend_id', 'resource_id', 'email', 'displayname', 'group_restrictions'])
+				->from($this->dbTableName)
+				->where($query->expr()->eq('backend_id', $query->createNamedParameter($backendId)))
+				->andWhere($query->expr()->eq('resource_id', $query->createNamedParameter($resourceId)));
+			$stmt = $query->execute();
+			$row = $stmt->fetch(\PDO::FETCH_ASSOC);
+
+			if(!$row) {
+				return null;
+			}
+			if (!$this->isAllowedToAccessResource($row, $usersGroups)) {
+				return null;
+			}
+
+			return $this->rowToPrincipal($row)['uri'];
+		}
+
+		return null;
+	}
+
+	/**
+	 * convert database row to principal
+	 */
+	private function rowToPrincipal($row) {
+		return [
+			'uri' => $this->principalPrefix . '/' . $row['backend_id'] . '-' . $row['resource_id'],
+			'{DAV:}displayname' => $row['displayname'],
+			'{http://sabredav.org/ns}email-address' => $row['email']
+		];
+	}
+
+	/**
+	 * @param $row
+	 * @param $userGroups
+	 * @return bool
+	 */
+	private function isAllowedToAccessResource($row, $userGroups) {
+		if (!isset($row['group_restrictions']) ||
+			$row['group_restrictions'] === null ||
+			$row['group_restrictions'] === '') {
+			return true;
+		}
+
+		// group restrictions contains something, but not parsable, deny access and log warning
+		$json = json_decode($row['group_restrictions']);
+		if (!\is_array($json)) {
+			$this->logger->info('group_restrictions field could not be parsed for ' . $this->dbTableName . '::' . $row['id'] . ', denying access to resource');
+			return false;
+		}
+
+		// empty array => no group restrictions
+		if (empty($json)) {
+			return true;
+		}
+
+		return !empty(array_intersect($json, $userGroups));
+	}
+}
diff --git a/apps/dav/lib/CalDAV/ResourceBooking/ResourcePrincipalBackend.php b/apps/dav/lib/CalDAV/ResourceBooking/ResourcePrincipalBackend.php
new file mode 100644
index 0000000000000..a1030376c11be
--- /dev/null
+++ b/apps/dav/lib/CalDAV/ResourceBooking/ResourcePrincipalBackend.php
@@ -0,0 +1,45 @@
+<?php
+/**
+ * @copyright 2018, Georg Ehrke <oc.list@georgehrke.com>
+ *
+ * @author Georg Ehrke <oc.list@georgehrke.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\ResourceBooking;
+
+use OCP\IDBConnection;
+use OCP\IGroupManager;
+use OCP\ILogger;
+use OCP\IUserSession;
+
+class ResourcePrincipalBackend extends AbstractPrincipalBackend {
+
+	/**
+	 * @param IDBConnection $dbConnection
+	 * @param IUserSession $userSession
+	 * @param IGroupManager $groupManager
+	 * @param ILogger $logger
+	 */
+	public function __construct(IDBConnection $dbConnection,
+								IUserSession $userSession,
+								IGroupManager $groupManager,
+								ILogger $logger) {
+		parent::__construct($dbConnection, $userSession, $groupManager, $logger,
+			'principals/calendar-resources', 'resources');
+	}
+}
diff --git a/apps/dav/lib/CalDAV/ResourceBooking/RoomPrincipalBackend.php b/apps/dav/lib/CalDAV/ResourceBooking/RoomPrincipalBackend.php
new file mode 100644
index 0000000000000..1d22299515f9c
--- /dev/null
+++ b/apps/dav/lib/CalDAV/ResourceBooking/RoomPrincipalBackend.php
@@ -0,0 +1,45 @@
+<?php
+/**
+ * @copyright 2018, Georg Ehrke <oc.list@georgehrke.com>
+ *
+ * @author Georg Ehrke <oc.list@georgehrke.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\ResourceBooking;
+
+use OCP\IDBConnection;
+use OCP\IGroupManager;
+use OCP\ILogger;
+use OCP\IUserSession;
+
+class RoomPrincipalBackend extends AbstractPrincipalBackend {
+
+	/**
+	 * @param IDBConnection $dbConnection
+	 * @param IUserSession $userSession
+	 * @param IGroupManager $groupManager
+	 * @param ILogger $logger
+	 */
+	public function __construct(IDBConnection $dbConnection,
+								IUserSession $userSession,
+								IGroupManager $groupManager,
+								ILogger $logger) {
+		parent::__construct($dbConnection, $userSession, $groupManager, $logger,
+			'principals/calendar-rooms', 'rooms');
+	}
+}
diff --git a/apps/dav/lib/CalDAV/Schedule/Plugin.php b/apps/dav/lib/CalDAV/Schedule/Plugin.php
index faf495a4de68b..b3f7232c2fefc 100644
--- a/apps/dav/lib/CalDAV/Schedule/Plugin.php
+++ b/apps/dav/lib/CalDAV/Schedule/Plugin.php
@@ -80,20 +80,32 @@ function propFindDefaultCalendarUrl(PropFind $propFind, INode $node) {
 				$principalUrl = $node->getPrincipalUrl();
 
 				$calendarHomePath = $caldavPlugin->getCalendarHomeForPrincipal($principalUrl);
-
 				if (!$calendarHomePath) {
 					return null;
 				}
 
+				if (strpos($principalUrl, 'principals/users') === 0) {
+					$uri = CalDavBackend::PERSONAL_CALENDAR_URI;
+					$displayname = CalDavBackend::PERSONAL_CALENDAR_NAME;
+				} elseif (strpos($principalUrl, 'principals/calendar-resources') === 0 ||
+						  strpos($principalUrl, 'principals/calendar-rooms') === 0) {
+					$uri = CalDavBackend::RESOURCE_BOOKING_CALENDAR_URI;
+					$displayname = CalDavBackend::RESOURCE_BOOKING_CALENDAR_NAME;
+				} else {
+					// How did we end up here?
+					// TODO - throw exception or just ignore?
+					return null;
+				}
+
 				/** @var CalendarHome $calendarHome */
 				$calendarHome = $this->server->tree->getNodeForPath($calendarHomePath);
-				if (!$calendarHome->childExists(CalDavBackend::PERSONAL_CALENDAR_URI)) {
-					$calendarHome->getCalDAVBackend()->createCalendar($principalUrl, CalDavBackend::PERSONAL_CALENDAR_URI, [
-						'{DAV:}displayname' => CalDavBackend::PERSONAL_CALENDAR_NAME,
+				if (!$calendarHome->childExists($uri)) {
+					$calendarHome->getCalDAVBackend()->createCalendar($principalUrl, $uri, [
+						'{DAV:}displayname' => $displayname,
 					]);
 				}
 
-				$result = $this->server->getPropertiesForPath($calendarHomePath . '/' . CalDavBackend::PERSONAL_CALENDAR_URI, [], 1);
+				$result = $this->server->getPropertiesForPath($calendarHomePath . '/' . $uri, [], 1);
 				if (empty($result)) {
 					return null;
 				}
diff --git a/apps/dav/lib/Migration/Version1005Date20180530124431.php b/apps/dav/lib/Migration/Version1005Date20180530124431.php
new file mode 100644
index 0000000000000..ae9a40dc5b254
--- /dev/null
+++ b/apps/dav/lib/Migration/Version1005Date20180530124431.php
@@ -0,0 +1,87 @@
+<?php
+/**
+ * @copyright 2017 Georg Ehrke <oc.list@georgehrke.com>
+ *
+ * @author Georg Ehrke <oc.list@georgehrke.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\Migration;
+
+use Doctrine\DBAL\Types\Type;
+use OCP\DB\ISchemaWrapper;
+use OCP\Migration\SimpleMigrationStep;
+use OCP\Migration\IOutput;
+
+/**
+ * Auto-generated migration step: Please modify to your needs!
+ */
+class Version1005Date20180530124431 extends SimpleMigrationStep {
+
+	/**
+	 * @param IOutput $output
+	 * @param \Closure $schemaClosure The `\Closure` returns a `ISchemaWrapper`
+	 * @param array $options
+	 * @return null|ISchemaWrapper
+	 * @since 13.0.0
+	 */
+	public function changeSchema(IOutput $output, \Closure $schemaClosure, array $options) {
+		/** @var ISchemaWrapper $schema */
+		$schema = $schemaClosure();
+
+		$types = ['resources', 'rooms'];
+		foreach($types as $type) {
+			if (!$schema->hasTable('calendar_' . $type . '_cache')) {
+				$table = $schema->createTable('calendar_' . $type . '_cache');
+
+				$table->addColumn('id', Type::BIGINT, [
+					'autoincrement' => true,
+					'notnull' => true,
+					'length' => 11,
+					'unsigned' => true,
+				]);
+				$table->addColumn('backend_id', Type::STRING, [
+					'notnull' => false,
+					'length' => 64,
+				]);
+				$table->addColumn('resource_id', Type::STRING, [
+					'notnull' => false,
+					'length' => 64,
+				]);
+				$table->addColumn('email', Type::STRING, [
+					'notnull' => false,
+					'length' => 255,
+				]);
+				$table->addColumn('displayname', Type::STRING, [
+					'notnull' => false,
+					'length' => 255,
+				]);
+				$table->addColumn('group_restrictions', Type::STRING, [
+					'notnull' => false,
+					'length' => 4000,
+				]);
+
+				$table->setPrimaryKey(['id'], 'calendar_' . $type . '_cache_id_idx');
+				$table->addIndex(['backend_id', 'resource_id'], 'calendar_' . $type . '_cache_backendresource_idx');
+				$table->addIndex(['email'], 'calendar_' . $type . '_cache_email_idx');
+				$table->addIndex(['displayname'], 'calendar_' . $type . '_cache_displayname_idx');
+			}
+		}
+
+		return $schema;
+	}
+}
diff --git a/apps/dav/lib/RootCollection.php b/apps/dav/lib/RootCollection.php
index b9f381b4b9260..9a3261c388c65 100644
--- a/apps/dav/lib/RootCollection.php
+++ b/apps/dav/lib/RootCollection.php
@@ -27,6 +27,8 @@
 use OCA\DAV\CalDAV\CalDavBackend;
 use OCA\DAV\CalDAV\CalendarRoot;
 use OCA\DAV\CalDAV\PublicCalendarRoot;
+use OCA\DAV\CalDAV\ResourceBooking\ResourcePrincipalBackend;
+use OCA\DAV\CalDAV\ResourceBooking\RoomPrincipalBackend;
 use OCA\DAV\CardDAV\AddressBookRoot;
 use OCA\DAV\CardDAV\CardDavBackend;
 use OCA\DAV\Connector\Sabre\Principal;
@@ -43,6 +45,7 @@ public function __construct() {
 		$random = \OC::$server->getSecureRandom();
 		$logger = \OC::$server->getLogger();
 		$userManager = \OC::$server->getUserManager();
+		$userSession = \OC::$server->getUserSession();
 		$groupManager = \OC::$server->getGroupManager();
 		$shareManager = \OC::$server->getShareManager();
 		$db = \OC::$server->getDatabaseConnection();
@@ -55,6 +58,8 @@ public function __construct() {
 			$config
 		);
 		$groupPrincipalBackend = new GroupPrincipalBackend($groupManager);
+		$calendarResourcePrincipalBackend = new ResourcePrincipalBackend($db, $userSession, $groupManager, $logger);
+		$calendarRoomPrincipalBackend = new RoomPrincipalBackend($db, $userSession, $groupManager, $logger);
 		// as soon as debug mode is enabled we allow listing of principals
 		$disableListing = !$config->getSystemValue('debug', false);
 
@@ -65,11 +70,25 @@ public function __construct() {
 		$groupPrincipals->disableListing = $disableListing;
 		$systemPrincipals = new Collection(new SystemPrincipalBackend(), 'principals/system');
 		$systemPrincipals->disableListing = $disableListing;
+		$calendarResourcePrincipals = new Collection($calendarResourcePrincipalBackend, 'principals/calendar-resources');
+		$calendarResourcePrincipals->disableListing = $disableListing;
+		$calendarRoomPrincipals = new Collection($calendarRoomPrincipalBackend, 'principals/calendar-rooms');
+		$calendarRoomPrincipals->disableListing = $disableListing;
+
+
 		$filesCollection = new Files\RootCollection($userPrincipalBackend, 'principals/users');
 		$filesCollection->disableListing = $disableListing;
 		$caldavBackend = new CalDavBackend($db, $userPrincipalBackend, $userManager, $groupManager, $random, $logger, $dispatcher);
-		$calendarRoot = new CalendarRoot($userPrincipalBackend, $caldavBackend, 'principals/users');
-		$calendarRoot->disableListing = $disableListing;
+		$userCalendarRoot = new CalendarRoot($userPrincipalBackend, $caldavBackend, 'principals/users');
+		$userCalendarRoot->disableListing = $disableListing;
+
+		$resourceCalendarCaldavBackend = new CalDavBackend($db, $userPrincipalBackend, $userManager, $groupManager, $random, $logger, $dispatcher);
+		$resourceCalendarRoot = new CalendarRoot($calendarResourcePrincipalBackend, $caldavBackend, 'principals/calendar-resources');
+		$resourceCalendarRoot->disableListing = $disableListing;
+		$roomCalendarCaldavBackend = new CalDavBackend($db, $userPrincipalBackend, $userManager, $groupManager, $random, $logger, $dispatcher);
+		$roomCalendarRoot = new CalendarRoot($calendarRoomPrincipalBackend, $roomCalendarCaldavBackend, 'principals/calendar-rooms');
+		$roomCalendarRoot->disableListing = $disableListing;
+
 		$publicCalendarRoot = new PublicCalendarRoot($caldavBackend, $l10n, $config);
 		$publicCalendarRoot->disableListing = $disableListing;
 
@@ -111,9 +130,15 @@ public function __construct() {
 				new SimpleCollection('principals', [
 						$userPrincipals,
 						$groupPrincipals,
-						$systemPrincipals]),
+						$systemPrincipals,
+						$calendarResourcePrincipals,
+						$calendarRoomPrincipals]),
 				$filesCollection,
-				$calendarRoot,
+				$userCalendarRoot,
+				new SimpleCollection('system-calendars', [
+					$resourceCalendarRoot,
+					$roomCalendarRoot,
+				]),
 				$publicCalendarRoot,
 				new SimpleCollection('addressbooks', [
 						$usersAddressBookRoot,
diff --git a/apps/dav/lib/Server.php b/apps/dav/lib/Server.php
index a401fb5704514..231ab9131957b 100644
--- a/apps/dav/lib/Server.php
+++ b/apps/dav/lib/Server.php
@@ -132,13 +132,15 @@ public function __construct(IRequest $request, $baseUri) {
 		// acl
 		$acl = new DavAclPlugin();
 		$acl->principalCollectionSet = [
-			'principals/users', 'principals/groups'
+			'principals/users', 'principals/groups',
+			'principals/calendar-resources',
+			'principals/calendar-rooms',
 		];
 		$acl->defaultUsernamePath = 'principals/users';
 		$this->server->addPlugin($acl);
 
 		// calendar plugins
-		if ($this->requestIsForSubtree(['calendars', 'public-calendars', 'principals'])) {
+		if ($this->requestIsForSubtree(['calendars', 'public-calendars', 'system-calendars', 'principals'])) {
 			$this->server->addPlugin(new \OCA\DAV\CalDAV\Plugin());
 			$this->server->addPlugin(new \Sabre\CalDAV\ICSExportPlugin());
 			$this->server->addPlugin(new \OCA\DAV\CalDAV\Schedule\Plugin());
diff --git a/apps/dav/tests/unit/BackgroundJob/UpdateCalendarResourcesRoomsBackgroundJobTest.php b/apps/dav/tests/unit/BackgroundJob/UpdateCalendarResourcesRoomsBackgroundJobTest.php
new file mode 100644
index 0000000000000..56f768ceda059
--- /dev/null
+++ b/apps/dav/tests/unit/BackgroundJob/UpdateCalendarResourcesRoomsBackgroundJobTest.php
@@ -0,0 +1,285 @@
+<?php
+/**
+ * @copyright Copyright (c) 2018, Georg Ehrke
+ *
+ * @author Georg Ehrke <oc.list@georgehrke.com>
+ *
+ * @license AGPL-3.0
+ *
+ * This code is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License, version 3,
+ * as published by the Free Software Foundation.
+ *
+ * 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, version 3,
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>
+ *
+ */
+
+namespace OCA\DAV\Tests\unit\BackgroundJob;
+
+use OCA\DAV\BackgroundJob\UpdateCalendarResourcesRoomsBackgroundJob;
+
+use OCA\DAV\CalDAV\CalDavBackend;
+use OCP\Calendar\BackendTemporarilyUnavailableException;
+use OCP\Calendar\Resource\IBackend;
+use OCP\Calendar\Resource\IManager as IResourceManager;
+use OCP\Calendar\Resource\IResource;
+use OCP\Calendar\Room\IManager as IRoomManager;
+use Test\TestCase;
+
+class UpdateCalendarResourcesRoomsBackgroundJobTest extends TestCase {
+
+	/** @var UpdateCalendarResourcesRoomsBackgroundJob */
+	private $backgroundJob;
+
+	/** @var IResourceManager | \PHPUnit_Framework_MockObject_MockObject */
+	private $resourceManager;
+
+	/** @var IRoomManager | \PHPUnit_Framework_MockObject_MockObject */
+	private $roomManager;
+
+	/** @var CalDavBackend | \PHPUnit_Framework_MockObject_MockObject */
+	private $calDavBackend;
+
+	protected function setUp() {
+		parent::setUp();
+
+		$this->resourceManager = $this->createMock(IResourceManager::class);
+		$this->roomManager = $this->createMock(IRoomManager::class);
+		$this->calDavBackend = $this->createMock(CalDavBackend::class);
+
+		$this->backgroundJob = new UpdateCalendarResourcesRoomsBackgroundJob(
+			$this->resourceManager, $this->roomManager, self::$realDatabase,
+			$this->calDavBackend);
+	}
+
+	protected function tearDown() {
+		$query = self::$realDatabase->getQueryBuilder();
+		$query->delete('calendar_resources_cache')->execute();
+		$query->delete('calendar_rooms_cache')->execute();
+	}
+
+	/**
+	 * Data in Cache:
+	 * resources:
+	 *  [backend1, res1, Beamer1, {}]
+	 *  [backend1, res2, TV1, {}]
+	 *  [backend2, res3, Beamer2, {}]
+	 *  [backend2, res4, TV2, {}]
+	 *  [backend3, res5, Beamer3, {}]
+	 *  [backend3, res6, Pointer, {foo, bar}]
+	 *
+	 * Data in Backend:
+	 *  backend1 gone
+	 *  backend2 throws BackendTemporarilyUnavailableException
+	 *  [backend3, res6, Pointer123, {foo, biz}]
+	 *  [backend3, res7, Resource4, {biz}]
+	 *  [backend4, res8, Beamer, {}]
+	 *  [backend4, res9, Beamer2, {}]
+	 *
+	 * Expected after run:
+	 *  [backend2, res3, Beamer2, {}]
+	 *  [backend2, res4, TV2, {}]
+	 *  [backend3, res6, Pointer123, {foo, biz}]
+	 *  [backend3, res7, Resource4, {biz}]
+	 *  [backend4, res8, Beamer, {}]
+	 *  [backend4, res9, Beamer2, {}]
+	 */
+
+	public function testRun() {
+		$this->createTestResourcesInCache();
+
+		$backend2 = $this->createMock(IBackend::class);
+		$backend3 = $this->createMock(IBackend::class);
+		$backend4 = $this->createMock(IBackend::class);
+
+		$res6 = $this->createMock(IResource::class);
+		$res7 = $this->createMock(IResource::class);
+		$res8 = $this->createMock(IResource::class);
+		$res9 = $this->createMock(IResource::class);
+
+		$backend2->method('getBackendIdentifier')
+			->will($this->returnValue('backend2'));
+		$backend2->method('listAllResources')
+			->will($this->throwException(new BackendTemporarilyUnavailableException()));
+		$backend2->method('getResource')
+			->will($this->throwException(new BackendTemporarilyUnavailableException()));
+		$backend2->method('getAllResources')
+			->will($this->throwException(new BackendTemporarilyUnavailableException()));
+		$backend3->method('getBackendIdentifier')
+			->will($this->returnValue('backend3'));
+		$backend3->method('listAllResources')
+			->will($this->returnValue(['res6', 'res7']));
+		$backend3->method('getResource')
+			->will($this->returnValueMap([
+				['res6', $res6],
+				['res7', $res7],
+			]));
+		$backend4->method('getBackendIdentifier')
+			->will($this->returnValue('backend4'));
+		$backend4->method('listAllResources')
+			->will($this->returnValue(['res8', 'res9']));
+		$backend4->method('getResource')
+			->will($this->returnValueMap([
+				['res8', $res8],
+				['res9', $res9],
+			]));
+
+		$res6->method('getId')->will($this->returnValue('res6'));
+		$res6->method('getDisplayName')->will($this->returnValue('Pointer123'));
+		$res6->method('getGroupRestrictions')->will($this->returnValue(['foo', 'biz']));
+		$res6->method('getEMail')->will($this->returnValue('res6@foo.bar'));
+		$res6->method('getBackend')->will($this->returnValue($backend3));
+
+		$res7->method('getId')->will($this->returnValue('res7'));
+		$res7->method('getDisplayName')->will($this->returnValue('Resource4'));
+		$res7->method('getGroupRestrictions')->will($this->returnValue(['biz']));
+		$res7->method('getEMail')->will($this->returnValue('res7@foo.bar'));
+		$res7->method('getBackend')->will($this->returnValue($backend3));
+
+		$res8->method('getId')->will($this->returnValue('res8'));
+		$res8->method('getDisplayName')->will($this->returnValue('Beamer'));
+		$res8->method('getGroupRestrictions')->will($this->returnValue([]));
+		$res8->method('getEMail')->will($this->returnValue('res8@foo.bar'));
+		$res8->method('getBackend')->will($this->returnValue($backend4));
+
+		$res9->method('getId')->will($this->returnValue('res9'));
+		$res9->method('getDisplayName')->will($this->returnValue('Beamer2'));
+		$res9->method('getGroupRestrictions')->will($this->returnValue([]));
+		$res9->method('getEMail')->will($this->returnValue('res9@foo.bar'));
+		$res9->method('getBackend')->will($this->returnValue($backend4));
+
+		$this->resourceManager
+			->method('getBackends')
+			->will($this->returnValue([
+				$backend2, $backend3, $backend4
+			]));
+		$this->resourceManager
+			->method('getBackend')
+			->will($this->returnValueMap([
+				['backend2', $backend2],
+				['backend3', $backend3],
+				['backend4', $backend4],
+			]));
+
+		$this->backgroundJob->run([]);
+
+		$query = self::$realDatabase->getQueryBuilder();
+		$query->select('*')->from('calendar_resources_cache');
+
+		$rows = [];
+		$stmt = $query->execute();
+		while($row = $stmt->fetch(\PDO::FETCH_ASSOC)) {
+			unset($row['id']);
+			$rows[] = $row;
+		}
+
+		$this->assertEquals([
+			[
+				'backend_id' => 'backend2',
+				'resource_id' => 'res3',
+				'displayname' => 'Beamer2',
+				'email' => 'res3@foo.bar',
+				'group_restrictions' => '[]',
+			],
+			[
+				'backend_id' => 'backend2',
+				'resource_id' => 'res4',
+				'displayname' => 'TV2',
+				'email' => 'res4@foo.bar',
+				'group_restrictions' => '[]',
+			],
+			[
+				'backend_id' => 'backend3',
+				'resource_id' => 'res6',
+				'displayname' => 'Pointer123',
+				'email' => 'res6@foo.bar',
+				'group_restrictions' => '["foo","biz"]',
+			],
+			[
+				'backend_id' => 'backend3',
+				'resource_id' => 'res7',
+				'displayname' => 'Resource4',
+				'email' => 'res7@foo.bar',
+				'group_restrictions' => '["biz"]',
+			],
+			[
+				'backend_id' => 'backend4',
+				'resource_id' => 'res8',
+				'displayname' => 'Beamer',
+				'email' => 'res8@foo.bar',
+				'group_restrictions' => '[]',
+			],
+			[
+				'backend_id' => 'backend4',
+				'resource_id' => 'res9',
+				'displayname' => 'Beamer2',
+				'email' => 'res9@foo.bar',
+				'group_restrictions' => '[]',
+			],
+		], $rows);
+	}
+
+	protected function createTestResourcesInCache() {
+		$query = self::$realDatabase->getQueryBuilder();
+		$query->insert('calendar_resources_cache')
+			->values([
+				'backend_id' => $query->createNamedParameter('backend1'),
+				'resource_id' => $query->createNamedParameter('res1'),
+				'email' => $query->createNamedParameter('res1@foo.bar'),
+				'displayname' => $query->createNamedParameter('Beamer1'),
+				'group_restrictions' => $query->createNamedParameter('[]'),
+			])
+			->execute();
+		$query->insert('calendar_resources_cache')
+			->values([
+				'backend_id' => $query->createNamedParameter('backend1'),
+				'resource_id' => $query->createNamedParameter('res2'),
+				'email' => $query->createNamedParameter('res2@foo.bar'),
+				'displayname' => $query->createNamedParameter('TV1'),
+				'group_restrictions' => $query->createNamedParameter('[]'),
+			])
+			->execute();
+		$query->insert('calendar_resources_cache')
+			->values([
+				'backend_id' => $query->createNamedParameter('backend2'),
+				'resource_id' => $query->createNamedParameter('res3'),
+				'email' => $query->createNamedParameter('res3@foo.bar'),
+				'displayname' => $query->createNamedParameter('Beamer2'),
+				'group_restrictions' => $query->createNamedParameter('[]'),
+			])
+			->execute();
+		$query->insert('calendar_resources_cache')
+			->values([
+				'backend_id' => $query->createNamedParameter('backend2'),
+				'resource_id' => $query->createNamedParameter('res4'),
+				'email' => $query->createNamedParameter('res4@foo.bar'),
+				'displayname' => $query->createNamedParameter('TV2'),
+				'group_restrictions' => $query->createNamedParameter('[]'),
+			])
+			->execute();
+		$query->insert('calendar_resources_cache')
+			->values([
+				'backend_id' => $query->createNamedParameter('backend3'),
+				'resource_id' => $query->createNamedParameter('res5'),
+				'email' => $query->createNamedParameter('res5@foo.bar'),
+				'displayname' => $query->createNamedParameter('Beamer3'),
+				'group_restrictions' => $query->createNamedParameter('[]'),
+			])
+			->execute();
+		$query->insert('calendar_resources_cache')
+			->values([
+				'backend_id' => $query->createNamedParameter('backend3'),
+				'resource_id' => $query->createNamedParameter('res6'),
+				'email' => $query->createNamedParameter('res6@foo.bar'),
+				'displayname' => $query->createNamedParameter('Pointer'),
+				'group_restrictions' => $query->createNamedParameter('["foo", "bar"]'),
+			])
+			->execute();
+	}
+}
diff --git a/apps/dav/tests/unit/CalDAV/PluginTest.php b/apps/dav/tests/unit/CalDAV/PluginTest.php
index 7d283b6d1ed35..47190d583f015 100644
--- a/apps/dav/tests/unit/CalDAV/PluginTest.php
+++ b/apps/dav/tests/unit/CalDAV/PluginTest.php
@@ -43,8 +43,12 @@ public function linkProvider() {
 				'calendars/MyUserName',
 			],
 			[
-				'FooFoo',
-				null,
+				'principals/calendar-resources/Resource-ABC',
+				'system-calendars/calendar-resources/Resource-ABC',
+			],
+			[
+				'principals/calendar-rooms/Room-ABC',
+				'system-calendars/calendar-rooms/Room-ABC',
 			],
 		];
 	}
@@ -59,4 +63,11 @@ public function testGetCalendarHomeForPrincipal($input, $expected) {
 		$this->assertSame($expected, $this->plugin->getCalendarHomeForPrincipal($input));
 	}
 
+	/**
+	 * @expectedException        \LogicException
+	 * @expectedExceptionMessage This is not supposed to happen
+	 */
+	public function testGetCalendarHomeForUnknownPrincipal() {
+		$this->plugin->getCalendarHomeForPrincipal('FOO/BAR/BLUB');
+	}
 }
diff --git a/apps/dav/tests/unit/CalDAV/ResourceBooking/AbstractPrincipalBackendTest.php b/apps/dav/tests/unit/CalDAV/ResourceBooking/AbstractPrincipalBackendTest.php
new file mode 100644
index 0000000000000..4dee0220fc840
--- /dev/null
+++ b/apps/dav/tests/unit/CalDAV/ResourceBooking/AbstractPrincipalBackendTest.php
@@ -0,0 +1,930 @@
+<?php
+/**
+ * @copyright Copyright (c) 2018, Georg Ehrke
+ *
+ * @author Georg Ehrke <oc.list@georgehrke.com>
+ *
+ * @license AGPL-3.0
+ *
+ * This code is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License, version 3,
+ * as published by the Free Software Foundation.
+ *
+ * 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, version 3,
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>
+ *
+ */
+namespace OCA\DAV\Tests\unit\CalDAV\ResourceBooking;
+
+use OCP\DB\QueryBuilder\IQueryBuilder;
+use OCP\IDBConnection;
+use OCP\IGroupManager;
+use OCP\ILogger;
+use OCP\IUser;
+use OCP\IUserSession;
+use Sabre\DAV\PropPatch;
+use Test\TestCase;
+
+abstract class AbstractPrincipalBackendTest extends TestCase {
+
+	/** @var \OCA\DAV\CalDAV\ResourceBooking\ResourcePrincipalBackend|\OCA\DAV\CalDAV\ResourceBooking\RoomPrincipalBackend */
+	protected $principalBackend;
+
+	/** @var IDBConnection|\PHPUnit_Framework_MockObject_MockObject */
+	protected $dbConnection;
+
+	/** @var IUserSession|\PHPUnit_Framework_MockObject_MockObject */
+	protected $userSession;
+
+	/** @var IGroupManager|\PHPUnit_Framework_MockObject_MockObject */
+	protected $groupManager;
+
+	/** @var ILogger|\PHPUnit_Framework_MockObject_MockObject */
+	protected $logger;
+
+	/** @var string */
+	protected $expectedDbTable;
+
+	/** @var string */
+	protected $principalPrefix;
+
+	public function setUp() {
+		parent::setUp();
+
+		$this->dbConnection = $this->createMock(IDBConnection::class);
+		$this->userSession = $this->createMock(IUserSession::class);
+		$this->groupManager = $this->createMock(IGroupManager::class);
+		$this->logger = $this->createMock(ILogger::class);
+	}
+
+	public function testGetPrincipalsByPrefix() {
+		$queryBuilder = $this->createMock(IQueryBuilder::class);
+		$stmt = $this->createMock(\Doctrine\DBAL\Driver\Statement::class);
+		$this->dbConnection->expects($this->once())
+			->method('getQueryBuilder')
+			->with()
+			->will($this->returnValue($queryBuilder));
+
+		$queryBuilder->expects($this->at(0))
+			->method('select')
+			->with(['id', 'backend_id', 'resource_id', 'email', 'displayname'])
+			->will($this->returnValue($queryBuilder));
+		$queryBuilder->expects($this->at(1))
+			->method('from')
+			->with($this->expectedDbTable)
+			->will($this->returnValue($queryBuilder));
+		$queryBuilder->expects($this->at(2))
+			->method('execute')
+			->with()
+			->will($this->returnValue($stmt));
+
+		$stmt->expects($this->at(0))
+			->method('fetch')
+			->with(\PDO::FETCH_ASSOC)
+			->will($this->returnValue([
+				'id' => 0,
+				'backend_id' => 'db',
+				'resource_id' => '123',
+				'email' => 'foo@bar.com',
+				'displayname' => 'Resource 123'
+			]));
+		$stmt->expects($this->at(1))
+			->method('fetch')
+			->with(\PDO::FETCH_ASSOC)
+			->will($this->returnValue([
+				'id' => 1,
+				'backend_id' => 'ldap',
+				'resource_id' => '123',
+				'email' => 'ldap@bar.com',
+				'displayname' => 'Resource 123 ldap'
+			]));
+		$stmt->expects($this->at(2))
+			->method('fetch')
+			->with(\PDO::FETCH_ASSOC)
+			->will($this->returnValue([
+				'id' => 2,
+				'backend_id' => 'db',
+				'resource_id' => '456',
+				'email' => 'bli@bar.com',
+				'displayname' => 'Resource 456'
+			]));
+		$stmt->expects($this->at(3))
+			->method('fetch')
+			->with(\PDO::FETCH_ASSOC)
+			->will($this->returnValue(null));
+		$stmt->expects($this->at(4))
+			->method('closeCursor')
+			->with();
+
+		$actual = $this->principalBackend->getPrincipalsByPrefix($this->principalPrefix);
+		$this->assertEquals([
+			[
+				'uri' => $this->principalPrefix . '/db-123',
+				'{DAV:}displayname' => 'Resource 123',
+				'{http://sabredav.org/ns}email-address' => 'foo@bar.com',
+			],
+			[
+				'uri' => $this->principalPrefix . '/ldap-123',
+				'{DAV:}displayname' => 'Resource 123 ldap',
+				'{http://sabredav.org/ns}email-address' => 'ldap@bar.com',
+			],
+			[
+				'uri' => $this->principalPrefix . '/db-456',
+				'{DAV:}displayname' => 'Resource 456',
+				'{http://sabredav.org/ns}email-address' => 'bli@bar.com',
+			],
+		], $actual);
+
+	}
+
+	public function testGetNoPrincipalsByPrefixForWrongPrincipalPrefix() {
+		$this->dbConnection->expects($this->never())
+			->method('getQueryBuilder');
+
+		$actual = $this->principalBackend->getPrincipalsByPrefix('principals/users');
+		$this->assertEquals([], $actual);
+	}
+
+	public function testGetPrincipalByPath() {
+		$queryBuilder = $this->createMock(IQueryBuilder::class);
+		$stmt = $this->createMock(\Doctrine\DBAL\Driver\Statement::class);
+		$expr = $this->createMock(\OCP\DB\QueryBuilder\IExpressionBuilder::class);
+
+		$this->dbConnection->expects($this->at(0))
+			->method('getQueryBuilder')
+			->with()
+			->will($this->returnValue($queryBuilder));
+		$queryBuilder->method('expr')
+			->will($this->returnValue($expr));
+		$expr->method('eq')
+			->will($this->returnValueMap([
+				['backend_id', 'createNamedParameter-1', null, 'WHERE_CLAUSE_1'],
+				['resource_id', 'createNamedParameter-2', null, 'WHERE_CLAUSE_2'],
+			]));
+		$queryBuilder->method('createNamedParameter')
+			->will($this->returnValueMap([
+				['db', \PDO::PARAM_STR, null, 'createNamedParameter-1'],
+				['123', \PDO::PARAM_STR, null, 'createNamedParameter-2'],
+			]));
+
+		$queryBuilder->expects($this->at(0))
+			->method('select')
+			->with(['id', 'backend_id', 'resource_id', 'email', 'displayname'])
+			->will($this->returnValue($queryBuilder));
+		$queryBuilder->expects($this->at(1))
+			->method('from')
+			->with($this->expectedDbTable)
+			->will($this->returnValue($queryBuilder));
+		$queryBuilder->expects($this->at(4))
+			->method('where')
+			->with('WHERE_CLAUSE_1')
+			->will($this->returnValue($queryBuilder));
+		$queryBuilder->expects($this->at(7))
+			->method('andWhere')
+			->with('WHERE_CLAUSE_2')
+			->will($this->returnValue($queryBuilder));
+		$queryBuilder->expects($this->at(8))
+			->method('execute')
+			->with()
+			->will($this->returnValue($stmt));
+
+		$stmt->expects($this->at(0))
+			->method('fetch')
+			->with(\PDO::FETCH_ASSOC)
+			->will($this->returnValue([
+				'id' => 0,
+				'backend_id' => 'db',
+				'resource_id' => '123',
+				'email' => 'foo@bar.com',
+				'displayname' => 'Resource 123'
+			]));
+
+		$actual = $this->principalBackend->getPrincipalByPath($this->principalPrefix . '/db-123');
+		$this->assertEquals([
+			'uri' => $this->principalPrefix . '/db-123',
+			'{DAV:}displayname' => 'Resource 123',
+			'{http://sabredav.org/ns}email-address' => 'foo@bar.com',
+		], $actual);
+	}
+
+	public function testGetPrincipalByPathNotFound() {
+		$queryBuilder = $this->createMock(IQueryBuilder::class);
+		$stmt = $this->createMock(\Doctrine\DBAL\Driver\Statement::class);
+		$expr = $this->createMock(\OCP\DB\QueryBuilder\IExpressionBuilder::class);
+
+		$this->dbConnection->expects($this->at(0))
+			->method('getQueryBuilder')
+			->with()
+			->will($this->returnValue($queryBuilder));
+		$queryBuilder->method('expr')
+			->will($this->returnValue($expr));
+		$expr->method('eq')
+			->will($this->returnValueMap([
+				['backend_id', 'createNamedParameter-1', null, 'WHERE_CLAUSE_1'],
+				['resource_id', 'createNamedParameter-2', null, 'WHERE_CLAUSE_2'],
+			]));
+		$queryBuilder->method('createNamedParameter')
+			->will($this->returnValueMap([
+				['db', \PDO::PARAM_STR, null, 'createNamedParameter-1'],
+				['123', \PDO::PARAM_STR, null, 'createNamedParameter-2'],
+			]));
+
+		$queryBuilder->expects($this->at(0))
+			->method('select')
+			->with(['id', 'backend_id', 'resource_id', 'email', 'displayname'])
+			->will($this->returnValue($queryBuilder));
+		$queryBuilder->expects($this->at(1))
+			->method('from')
+			->with($this->expectedDbTable)
+			->will($this->returnValue($queryBuilder));
+		$queryBuilder->expects($this->at(4))
+			->method('where')
+			->with('WHERE_CLAUSE_1')
+			->will($this->returnValue($queryBuilder));
+		$queryBuilder->expects($this->at(7))
+			->method('andWhere')
+			->with('WHERE_CLAUSE_2')
+			->will($this->returnValue($queryBuilder));
+		$queryBuilder->expects($this->at(8))
+			->method('execute')
+			->with()
+			->will($this->returnValue($stmt));
+
+		$stmt->expects($this->at(0))
+			->method('fetch')
+			->with(\PDO::FETCH_ASSOC)
+			->will($this->returnValue(false));
+
+		$actual = $this->principalBackend->getPrincipalByPath($this->principalPrefix . '/db-123');
+		$this->assertEquals(null, $actual);
+	}
+
+	public function testGetPrincipalByPathWrongPrefix() {
+		$this->dbConnection->expects($this->never())
+			->method('getQueryBuilder');
+
+		$actual = $this->principalBackend->getPrincipalByPath('principals/users/foo-bar');
+		$this->assertEquals(null, $actual);
+	}
+
+	public function testGetGroupMemberSet() {
+		$actual = $this->principalBackend->getGroupMemberSet($this->principalPrefix . '/foo-bar');
+		$this->assertEquals([], $actual);
+	}
+
+	public function testGetGroupMembership() {
+		$actual = $this->principalBackend->getGroupMembership($this->principalPrefix . '/foo-bar');
+		$this->assertEquals([], $actual);
+	}
+
+	/**
+	 * @expectedException        \Sabre\DAV\Exception
+	 * @expectedExceptionMessage Setting members of the group is not supported yet
+	 */
+	public function testSetGroupMemberSet() {
+		$this->principalBackend->setGroupMemberSet($this->principalPrefix . '/foo-bar', ['foo', 'bar']);
+	}
+
+	public function testUpdatePrincipal() {
+		$propPatch = $this->createMock(PropPatch::class);
+		$actual = $this->principalBackend->updatePrincipal($this->principalPrefix . '/foo-bar', $propPatch);
+
+		$this->assertEquals(0, $actual);
+	}
+
+	/**
+	 * @dataProvider dataSearchPrincipals
+	 */
+	public function testSearchPrincipals($expected, $test) {
+		$user = $this->createMock(IUser::class);
+		$this->userSession->expects($this->once())
+			->method('getUser')
+			->with()
+			->will($this->returnValue($user));
+		$this->groupManager->expects($this->once())
+			->method('getUserGroupIds')
+			->with($user)
+			->will($this->returnValue(['group1', 'group2']));
+
+		$queryBuilder1 = $this->createMock(IQueryBuilder::class);
+		$queryBuilder2 = $this->createMock(IQueryBuilder::class);
+		$stmt1 = $this->createMock(\Doctrine\DBAL\Driver\Statement::class);
+		$stmt2 = $this->createMock(\Doctrine\DBAL\Driver\Statement::class);
+		$expr1 = $this->createMock(\OCP\DB\QueryBuilder\IExpressionBuilder::class);
+		$expr2 = $this->createMock(\OCP\DB\QueryBuilder\IExpressionBuilder::class);
+
+		$this->dbConnection->expects($this->at(0))
+			->method('getQueryBuilder')
+			->with()
+			->will($this->returnValue($queryBuilder1));
+		$this->dbConnection->expects($this->at(1))
+			->method('escapeLikeParameter')
+			->with('foo')
+			->will($this->returnValue('escapedFoo'));
+		$this->dbConnection->expects($this->at(2))
+			->method('getQueryBuilder')
+			->with()
+			->will($this->returnValue($queryBuilder2));
+		$this->dbConnection->expects($this->at(3))
+			->method('escapeLikeParameter')
+			->with('bar')
+			->will($this->returnValue('escapedBar'));
+
+		$queryBuilder1->method('expr')
+			->will($this->returnValue($expr1));
+		$queryBuilder2->method('expr')
+			->will($this->returnValue($expr2));
+
+		$expr1->method('iLike')
+			->will($this->returnValueMap([
+				['email', 'createNamedParameter-1', null, 'ILIKE_CLAUSE_1'],
+			]));
+		$expr2->method('iLike')
+			->will($this->returnValueMap([
+				['displayname', 'createNamedParameter-2', null, 'ILIKE_CLAUSE_2'],
+			]));
+
+		$queryBuilder1->method('expr')
+			->will($this->returnValue($expr1));
+		$queryBuilder2->method('expr')
+			->will($this->returnValue($expr2));
+
+		$queryBuilder1->method('createNamedParameter')
+			->will($this->returnValueMap([
+				['%escapedFoo%', \PDO::PARAM_STR, null, 'createNamedParameter-1'],
+			]));
+		$queryBuilder2->method('createNamedParameter')
+			->will($this->returnValueMap([
+				['%escapedBar%', \PDO::PARAM_STR, null, 'createNamedParameter-2'],
+			]));
+
+		$queryBuilder1->expects($this->at(0))
+			->method('select')
+			->with(['id', 'backend_id', 'resource_id', 'email', 'displayname', 'group_restrictions'])
+			->will($this->returnValue($queryBuilder1));
+		$queryBuilder1->expects($this->at(1))
+			->method('from')
+			->with($this->expectedDbTable)
+			->will($this->returnValue($queryBuilder1));
+		$queryBuilder1->expects($this->at(4))
+			->method('where')
+			->with('ILIKE_CLAUSE_1')
+			->will($this->returnValue($queryBuilder1));
+		$queryBuilder1->expects($this->at(5))
+			->method('execute')
+			->with()
+			->will($this->returnValue($stmt1));
+
+		$queryBuilder2->expects($this->at(0))
+			->method('select')
+			->with(['id', 'backend_id', 'resource_id', 'email', 'displayname', 'group_restrictions'])
+			->will($this->returnValue($queryBuilder2));
+		$queryBuilder2->expects($this->at(1))
+			->method('from')
+			->with($this->expectedDbTable)
+			->will($this->returnValue($queryBuilder2));
+		$queryBuilder2->expects($this->at(4))
+			->method('where')
+			->with('ILIKE_CLAUSE_2')
+			->will($this->returnValue($queryBuilder2));
+		$queryBuilder2->expects($this->at(5))
+			->method('execute')
+			->with()
+			->will($this->returnValue($stmt2));
+
+		$stmt1->expects($this->at(0))
+			->method('fetch')
+			->with(\PDO::FETCH_ASSOC)
+			->will($this->returnValue([
+				'id' => 0,
+				'backend_id' => 'db',
+				'resource_id' => '1',
+				'email' => '1',
+				'displayname' => 'Resource 1',
+				'group_restrictions' => null,
+			]));
+		$stmt1->expects($this->at(1))
+			->method('fetch')
+			->with(\PDO::FETCH_ASSOC)
+			->will($this->returnValue([
+				'id' => 1,
+				'backend_id' => 'db',
+				'resource_id' => '2',
+				'email' => '2',
+				'displayname' => 'Resource 2',
+				'group_restrictions' => '',
+			]));
+		$stmt1->expects($this->at(2))
+			->method('fetch')
+			->with(\PDO::FETCH_ASSOC)
+			->will($this->returnValue([
+				'id' => 2,
+				'backend_id' => 'db',
+				'resource_id' => '3',
+				'email' => '3',
+				'displayname' => 'Resource 3',
+				'group_restrictions' => '["group3"]',
+			]));
+		$stmt1->expects($this->at(3))
+			->method('fetch')
+			->with(\PDO::FETCH_ASSOC)
+			->will($this->returnValue([
+				'id' => 99,
+				'backend_id' => 'db',
+				'resource_id' => '99',
+				'email' => '99',
+				'displayname' => 'Resource 99',
+				'group_restrictions' => '["group1", "group2"]',
+			]));
+		$stmt1->expects($this->at(4))
+			->method('fetch')
+			->with(\PDO::FETCH_ASSOC)
+			->will($this->returnValue(null));
+
+		$stmt2->expects($this->at(0))
+			->method('fetch')
+			->with(\PDO::FETCH_ASSOC)
+			->will($this->returnValue([
+				'id' => 0,
+				'backend_id' => 'db',
+				'resource_id' => '4',
+				'email' => '4',
+				'displayname' => 'Resource 4',
+				'group_restrictions' => '[]'
+			]));
+		$stmt2->expects($this->at(1))
+			->method('fetch')
+			->with(\PDO::FETCH_ASSOC)
+			->will($this->returnValue([
+				'id' => 1,
+				'backend_id' => 'db',
+				'resource_id' => '5',
+				'email' => '5',
+				'displayname' => 'Resource 5',
+				'group_restrictions' => '["group1", "group5"]'
+			]));
+		$stmt2->expects($this->at(2))
+			->method('fetch')
+			->with(\PDO::FETCH_ASSOC)
+			->will($this->returnValue([
+				'id' => 99,
+				'backend_id' => 'db',
+				'resource_id' => '99',
+				'email' => '99',
+				'displayname' => 'Resource 99',
+				'group_restrictions' => '["group1", "group2"]',
+			]));
+		$stmt2->expects($this->at(3))
+			->method('fetch')
+			->with(\PDO::FETCH_ASSOC)
+			->will($this->returnValue(null));
+
+		$actual = $this->principalBackend->searchPrincipals($this->principalPrefix, [
+			'{http://sabredav.org/ns}email-address' => 'foo',
+			'{DAV:}displayname' => 'bar',
+		], $test);
+
+		$this->assertEquals(
+			str_replace('%prefix%', $this->principalPrefix, $expected),
+			$actual);
+	}
+
+	public function dataSearchPrincipals() {
+		// data providers are called before we subclass
+		// this class, $this->principalPrefix is null
+		// at that point, so we need this hack
+		return [
+			[[
+				'%prefix%/db-99'
+			], 'allof'],
+			[[
+				'%prefix%/db-1',
+				'%prefix%/db-2',
+				'%prefix%/db-99',
+				'%prefix%/db-4',
+				'%prefix%/db-5',
+			], 'anyof'],
+		];
+	}
+
+	public function testSearchPrincipalsEmptySearchProperties() {
+		$this->userSession->expects($this->never())
+			->method('getUser');
+		$this->groupManager->expects($this->never())
+			->method('getUserGroupIds');
+		$this->dbConnection->expects($this->never())
+			->method('getQueryBuilder');
+
+		$this->principalBackend->searchPrincipals($this->principalPrefix, []);
+	}
+
+	public function testSearchPrincipalsWrongPrincipalPrefix() {
+		$this->userSession->expects($this->never())
+			->method('getUser');
+		$this->groupManager->expects($this->never())
+			->method('getUserGroupIds');
+		$this->dbConnection->expects($this->never())
+			->method('getQueryBuilder');
+
+		$this->principalBackend->searchPrincipals('principals/users', [
+			'{http://sabredav.org/ns}email-address' => 'foo'
+		]);
+	}
+
+	public function testFindByUriByEmail() {
+		$user = $this->createMock(IUser::class);
+		$this->userSession->expects($this->once())
+			->method('getUser')
+			->with()
+			->will($this->returnValue($user));
+		$this->groupManager->expects($this->once())
+			->method('getUserGroupIds')
+			->with($user)
+			->will($this->returnValue(['group1', 'group2']));
+
+		$queryBuilder = $this->createMock(IQueryBuilder::class);
+		$stmt = $this->createMock(\Doctrine\DBAL\Driver\Statement::class);
+		$expr = $this->createMock(\OCP\DB\QueryBuilder\IExpressionBuilder::class);
+
+		$this->dbConnection->expects($this->at(0))
+			->method('getQueryBuilder')
+			->with()
+			->will($this->returnValue($queryBuilder));
+		$queryBuilder->method('expr')
+			->will($this->returnValue($expr));
+		$expr->method('eq')
+			->will($this->returnValueMap([
+				['email', 'createNamedParameter-1', null, 'WHERE_CLAUSE_1'],
+			]));
+		$queryBuilder->method('createNamedParameter')
+			->will($this->returnValueMap([
+				['foo@bar.com', \PDO::PARAM_STR, null, 'createNamedParameter-1'],
+			]));
+
+		$queryBuilder->expects($this->at(0))
+			->method('select')
+			->with(['id', 'backend_id', 'resource_id', 'email', 'displayname', 'group_restrictions'])
+			->will($this->returnValue($queryBuilder));
+		$queryBuilder->expects($this->at(1))
+			->method('from')
+			->with($this->expectedDbTable)
+			->will($this->returnValue($queryBuilder));
+		$queryBuilder->expects($this->at(4))
+			->method('where')
+			->with('WHERE_CLAUSE_1')
+			->will($this->returnValue($queryBuilder));
+		$queryBuilder->expects($this->at(5))
+			->method('execute')
+			->with()
+			->will($this->returnValue($stmt));
+
+		$stmt->expects($this->at(0))
+			->method('fetch')
+			->with(\PDO::FETCH_ASSOC)
+			->will($this->returnValue([
+				'id' => 0,
+				'backend_id' => 'db',
+				'resource_id' => '123',
+				'email' => 'foo@bar.com',
+				'displayname' => 'Resource 123',
+				'group_restrictions' => '["group1"]',
+			]));
+
+		$actual = $this->principalBackend->findByUri('mailto:foo@bar.com', $this->principalPrefix);
+		$this->assertEquals($this->principalPrefix . '/db-123', $actual);
+	}
+
+	public function testFindByUriByEmailForbiddenResource() {
+		$user = $this->createMock(IUser::class);
+		$this->userSession->expects($this->once())
+			->method('getUser')
+			->with()
+			->will($this->returnValue($user));
+		$this->groupManager->expects($this->once())
+			->method('getUserGroupIds')
+			->with($user)
+			->will($this->returnValue(['group1', 'group2']));
+
+		$queryBuilder = $this->createMock(IQueryBuilder::class);
+		$stmt = $this->createMock(\Doctrine\DBAL\Driver\Statement::class);
+		$expr = $this->createMock(\OCP\DB\QueryBuilder\IExpressionBuilder::class);
+
+		$this->dbConnection->expects($this->at(0))
+			->method('getQueryBuilder')
+			->with()
+			->will($this->returnValue($queryBuilder));
+		$queryBuilder->method('expr')
+			->will($this->returnValue($expr));
+		$expr->method('eq')
+			->will($this->returnValueMap([
+				['email', 'createNamedParameter-1', null, 'WHERE_CLAUSE_1'],
+			]));
+		$queryBuilder->method('createNamedParameter')
+			->will($this->returnValueMap([
+				['foo@bar.com', \PDO::PARAM_STR, null, 'createNamedParameter-1'],
+			]));
+
+		$queryBuilder->expects($this->at(0))
+			->method('select')
+			->with(['id', 'backend_id', 'resource_id', 'email', 'displayname', 'group_restrictions'])
+			->will($this->returnValue($queryBuilder));
+		$queryBuilder->expects($this->at(1))
+			->method('from')
+			->with($this->expectedDbTable)
+			->will($this->returnValue($queryBuilder));
+		$queryBuilder->expects($this->at(4))
+			->method('where')
+			->with('WHERE_CLAUSE_1')
+			->will($this->returnValue($queryBuilder));
+		$queryBuilder->expects($this->at(5))
+			->method('execute')
+			->with()
+			->will($this->returnValue($stmt));
+
+		$stmt->expects($this->at(0))
+			->method('fetch')
+			->with(\PDO::FETCH_ASSOC)
+			->will($this->returnValue([
+				'id' => 0,
+				'backend_id' => 'db',
+				'resource_id' => '123',
+				'email' => 'foo@bar.com',
+				'displayname' => 'Resource 123',
+				'group_restrictions' => '["group3"]',
+			]));
+
+		$actual = $this->principalBackend->findByUri('mailto:foo@bar.com', $this->principalPrefix);
+		$this->assertEquals(null, $actual);
+	}
+
+	public function testFindByUriByEmailNotFound() {
+		$user = $this->createMock(IUser::class);
+		$this->userSession->expects($this->once())
+			->method('getUser')
+			->with()
+			->will($this->returnValue($user));
+		$this->groupManager->expects($this->once())
+			->method('getUserGroupIds')
+			->with($user)
+			->will($this->returnValue(['group1', 'group2']));
+
+		$queryBuilder = $this->createMock(IQueryBuilder::class);
+		$stmt = $this->createMock(\Doctrine\DBAL\Driver\Statement::class);
+		$expr = $this->createMock(\OCP\DB\QueryBuilder\IExpressionBuilder::class);
+
+		$this->dbConnection->expects($this->at(0))
+			->method('getQueryBuilder')
+			->with()
+			->will($this->returnValue($queryBuilder));
+		$queryBuilder->method('expr')
+			->will($this->returnValue($expr));
+		$expr->method('eq')
+			->will($this->returnValueMap([
+				['email', 'createNamedParameter-1', null, 'WHERE_CLAUSE_1'],
+			]));
+		$queryBuilder->method('createNamedParameter')
+			->will($this->returnValueMap([
+				['foo@bar.com', \PDO::PARAM_STR, null, 'createNamedParameter-1'],
+			]));
+
+		$queryBuilder->expects($this->at(0))
+			->method('select')
+			->with(['id', 'backend_id', 'resource_id', 'email', 'displayname', 'group_restrictions'])
+			->will($this->returnValue($queryBuilder));
+		$queryBuilder->expects($this->at(1))
+			->method('from')
+			->with($this->expectedDbTable)
+			->will($this->returnValue($queryBuilder));
+		$queryBuilder->expects($this->at(4))
+			->method('where')
+			->with('WHERE_CLAUSE_1')
+			->will($this->returnValue($queryBuilder));
+		$queryBuilder->expects($this->at(5))
+			->method('execute')
+			->with()
+			->will($this->returnValue($stmt));
+
+		$stmt->expects($this->at(0))
+			->method('fetch')
+			->with(\PDO::FETCH_ASSOC)
+			->will($this->returnValue(null));
+
+		$actual = $this->principalBackend->findByUri('mailto:foo@bar.com', $this->principalPrefix);
+		$this->assertEquals(null, $actual);
+	}
+
+	public function testFindByUriByPrincipal() {
+		$user = $this->createMock(IUser::class);
+		$this->userSession->expects($this->once())
+			->method('getUser')
+			->with()
+			->will($this->returnValue($user));
+		$this->groupManager->expects($this->once())
+			->method('getUserGroupIds')
+			->with($user)
+			->will($this->returnValue(['group1', 'group2']));
+
+		$queryBuilder = $this->createMock(IQueryBuilder::class);
+		$stmt = $this->createMock(\Doctrine\DBAL\Driver\Statement::class);
+		$expr = $this->createMock(\OCP\DB\QueryBuilder\IExpressionBuilder::class);
+
+		$this->dbConnection->expects($this->at(0))
+			->method('getQueryBuilder')
+			->with()
+			->will($this->returnValue($queryBuilder));
+		$queryBuilder->method('expr')
+			->will($this->returnValue($expr));
+		$expr->method('eq')
+			->will($this->returnValueMap([
+				['email', 'createNamedParameter-1', null, 'WHERE_CLAUSE_1'],
+			]));
+		$queryBuilder->method('createNamedParameter')
+			->will($this->returnValueMap([
+				['foo@bar.com', \PDO::PARAM_STR, null, 'createNamedParameter-1'],
+			]));
+
+		$queryBuilder->expects($this->at(0))
+			->method('select')
+			->with(['id', 'backend_id', 'resource_id', 'email', 'displayname', 'group_restrictions'])
+			->will($this->returnValue($queryBuilder));
+		$queryBuilder->expects($this->at(1))
+			->method('from')
+			->with($this->expectedDbTable)
+			->will($this->returnValue($queryBuilder));
+		$queryBuilder->expects($this->at(4))
+			->method('where')
+			->with('WHERE_CLAUSE_1')
+			->will($this->returnValue($queryBuilder));
+		$queryBuilder->expects($this->at(5))
+			->method('execute')
+			->with()
+			->will($this->returnValue($stmt));
+
+		$stmt->expects($this->at(0))
+			->method('fetch')
+			->with(\PDO::FETCH_ASSOC)
+			->will($this->returnValue([
+				'id' => 0,
+				'backend_id' => 'db',
+				'resource_id' => '123',
+				'email' => 'foo@bar.com',
+				'displayname' => 'Resource 123',
+				'group_restrictions' => '["group1"]',
+			]));
+
+		$actual = $this->principalBackend->findByUri('mailto:foo@bar.com', $this->principalPrefix);
+		$this->assertEquals($this->principalPrefix . '/db-123', $actual);
+	}
+
+	public function testFindByUriByPrincipalForbiddenResource() {
+		$user = $this->createMock(IUser::class);
+		$this->userSession->expects($this->once())
+			->method('getUser')
+			->with()
+			->will($this->returnValue($user));
+		$this->groupManager->expects($this->once())
+			->method('getUserGroupIds')
+			->with($user)
+			->will($this->returnValue(['group1', 'group2']));
+
+		$queryBuilder = $this->createMock(IQueryBuilder::class);
+		$stmt = $this->createMock(\Doctrine\DBAL\Driver\Statement::class);
+		$expr = $this->createMock(\OCP\DB\QueryBuilder\IExpressionBuilder::class);
+
+		$this->dbConnection->expects($this->at(0))
+			->method('getQueryBuilder')
+			->with()
+			->will($this->returnValue($queryBuilder));
+		$queryBuilder->method('expr')
+			->will($this->returnValue($expr));
+		$expr->method('eq')
+			->will($this->returnValueMap([
+				['backend_id', 'createNamedParameter-1', null, 'WHERE_CLAUSE_1'],
+				['resource_id', 'createNamedParameter-2', null, 'WHERE_CLAUSE_2'],
+			]));
+		$queryBuilder->method('createNamedParameter')
+			->will($this->returnValueMap([
+				['db', \PDO::PARAM_STR, null, 'createNamedParameter-1'],
+				['123', \PDO::PARAM_STR, null, 'createNamedParameter-2'],
+			]));
+
+		$queryBuilder->expects($this->at(0))
+			->method('select')
+			->with(['id', 'backend_id', 'resource_id', 'email', 'displayname', 'group_restrictions'])
+			->will($this->returnValue($queryBuilder));
+		$queryBuilder->expects($this->at(1))
+			->method('from')
+			->with($this->expectedDbTable)
+			->will($this->returnValue($queryBuilder));
+		$queryBuilder->expects($this->at(4))
+			->method('where')
+			->with('WHERE_CLAUSE_1')
+			->will($this->returnValue($queryBuilder));
+		$queryBuilder->expects($this->at(7))
+			->method('andWhere')
+			->with('WHERE_CLAUSE_2')
+			->will($this->returnValue($queryBuilder));
+		$queryBuilder->expects($this->at(8))
+			->method('execute')
+			->with()
+			->will($this->returnValue($stmt));
+
+		$stmt->expects($this->at(0))
+			->method('fetch')
+			->with(\PDO::FETCH_ASSOC)
+			->will($this->returnValue([
+				'id' => 0,
+				'backend_id' => 'db',
+				'resource_id' => '123',
+				'email' => 'foo@bar.com',
+				'displayname' => 'Resource 123',
+				'group_restrictions' => '["group3"]',
+			]));
+
+		$actual = $this->principalBackend->findByUri('principal:' . $this->principalPrefix . '/db-123', $this->principalPrefix);
+		$this->assertEquals(null, $actual);
+	}
+
+	public function testFindByUriByPrincipalNotFound() {
+		$user = $this->createMock(IUser::class);
+		$this->userSession->expects($this->once())
+			->method('getUser')
+			->with()
+			->will($this->returnValue($user));
+		$this->groupManager->expects($this->once())
+			->method('getUserGroupIds')
+			->with($user)
+			->will($this->returnValue(['group1', 'group2']));
+
+		$queryBuilder = $this->createMock(IQueryBuilder::class);
+		$stmt = $this->createMock(\Doctrine\DBAL\Driver\Statement::class);
+		$expr = $this->createMock(\OCP\DB\QueryBuilder\IExpressionBuilder::class);
+
+		$this->dbConnection->expects($this->at(0))
+			->method('getQueryBuilder')
+			->with()
+			->will($this->returnValue($queryBuilder));
+		$queryBuilder->method('expr')
+			->will($this->returnValue($expr));
+		$expr->method('eq')
+			->will($this->returnValueMap([
+				['backend_id', 'createNamedParameter-1', null, 'WHERE_CLAUSE_1'],
+				['resource_id', 'createNamedParameter-2', null, 'WHERE_CLAUSE_2'],
+			]));
+		$queryBuilder->method('createNamedParameter')
+			->will($this->returnValueMap([
+				['db', \PDO::PARAM_STR, null, 'createNamedParameter-1'],
+				['123', \PDO::PARAM_STR, null, 'createNamedParameter-2'],
+			]));
+
+		$queryBuilder->expects($this->at(0))
+			->method('select')
+			->with(['id', 'backend_id', 'resource_id', 'email', 'displayname', 'group_restrictions'])
+			->will($this->returnValue($queryBuilder));
+		$queryBuilder->expects($this->at(1))
+			->method('from')
+			->with($this->expectedDbTable)
+			->will($this->returnValue($queryBuilder));
+		$queryBuilder->expects($this->at(4))
+			->method('where')
+			->with('WHERE_CLAUSE_1')
+			->will($this->returnValue($queryBuilder));
+		$queryBuilder->expects($this->at(7))
+			->method('andWhere')
+			->with('WHERE_CLAUSE_2')
+			->will($this->returnValue($queryBuilder));
+		$queryBuilder->expects($this->at(8))
+			->method('execute')
+			->with()
+			->will($this->returnValue($stmt));
+
+		$stmt->expects($this->at(0))
+			->method('fetch')
+			->with(\PDO::FETCH_ASSOC)
+			->will($this->returnValue(null));
+
+		$actual = $this->principalBackend->findByUri('principal:' . $this->principalPrefix . '/db-123', $this->principalPrefix);
+		$this->assertEquals(null, $actual);
+	}
+
+	public function testFindByUriByUnknownUri() {
+		$user = $this->createMock(IUser::class);
+		$this->userSession->expects($this->once())
+			->method('getUser')
+			->with()
+			->will($this->returnValue($user));
+		$this->groupManager->expects($this->once())
+			->method('getUserGroupIds')
+			->with($user)
+			->will($this->returnValue(['group1', 'group2']));
+
+		$actual = $this->principalBackend->findByUri('foobar:blub', $this->principalPrefix);
+		$this->assertEquals(null, $actual);
+	}
+
+}
diff --git a/apps/dav/tests/unit/CalDAV/ResourceBooking/ResourcePrincipalBackendTest.php b/apps/dav/tests/unit/CalDAV/ResourceBooking/ResourcePrincipalBackendTest.php
new file mode 100644
index 0000000000000..f2c6b6f5f5e32
--- /dev/null
+++ b/apps/dav/tests/unit/CalDAV/ResourceBooking/ResourcePrincipalBackendTest.php
@@ -0,0 +1,35 @@
+<?php
+/**
+ * @copyright Copyright (c) 2018, Georg Ehrke
+ *
+ * @author Georg Ehrke <oc.list@georgehrke.com>
+ *
+ * @license AGPL-3.0
+ *
+ * This code is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License, version 3,
+ * as published by the Free Software Foundation.
+ *
+ * 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, version 3,
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>
+ *
+ */
+namespace OCA\DAV\Tests\unit\CalDAV\ResourceBooking;
+
+use OCA\DAV\CalDAV\ResourceBooking\ResourcePrincipalBackend;
+
+Class ResourcePrincipalBackendTest extends AbstractPrincipalBackendTest {
+	public function setUp() {
+		parent::setUp();
+
+		$this->principalBackend = new ResourcePrincipalBackend($this->dbConnection,
+			$this->userSession, $this->groupManager, $this->logger);
+		$this->expectedDbTable = 'calendar_resources_cache';
+		$this->principalPrefix = 'principals/calendar-resources';
+	}
+}
diff --git a/apps/dav/tests/unit/CalDAV/ResourceBooking/RoomPrincipalBackendTest.php b/apps/dav/tests/unit/CalDAV/ResourceBooking/RoomPrincipalBackendTest.php
new file mode 100644
index 0000000000000..f45121f454826
--- /dev/null
+++ b/apps/dav/tests/unit/CalDAV/ResourceBooking/RoomPrincipalBackendTest.php
@@ -0,0 +1,35 @@
+<?php
+/**
+ * @copyright Copyright (c) 2018, Georg Ehrke
+ *
+ * @author Georg Ehrke <oc.list@georgehrke.com>
+ *
+ * @license AGPL-3.0
+ *
+ * This code is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License, version 3,
+ * as published by the Free Software Foundation.
+ *
+ * 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, version 3,
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>
+ *
+ */
+namespace OCA\DAV\Tests\unit\CalDAV\ResourceBooking;
+
+use OCA\DAV\CalDAV\ResourceBooking\RoomPrincipalBackend;
+
+Class RoomPrincipalBackendTest extends AbstractPrincipalBackendTest {
+	public function setUp() {
+		parent::setUp();
+
+		$this->principalBackend = new RoomPrincipalBackend($this->dbConnection,
+			$this->userSession, $this->groupManager, $this->logger);
+		$this->expectedDbTable = 'calendar_rooms_cache';
+		$this->principalPrefix = 'principals/calendar-rooms';
+	}
+}
diff --git a/lib/composer/composer/autoload_classmap.php b/lib/composer/composer/autoload_classmap.php
index 2426272886b4a..54617de7798b7 100644
--- a/lib/composer/composer/autoload_classmap.php
+++ b/lib/composer/composer/autoload_classmap.php
@@ -76,8 +76,15 @@
     'OCP\\BackgroundJob' => $baseDir . '/lib/public/BackgroundJob.php',
     'OCP\\BackgroundJob\\IJob' => $baseDir . '/lib/public/BackgroundJob/IJob.php',
     'OCP\\BackgroundJob\\IJobList' => $baseDir . '/lib/public/BackgroundJob/IJobList.php',
+    'OCP\\Calendar\\BackendTemporarilyUnavailableException' => $baseDir . '/lib/public/Calendar/BackendTemporarilyUnavailableException.php',
     'OCP\\Calendar\\ICalendar' => $baseDir . '/lib/public/Calendar/ICalendar.php',
     'OCP\\Calendar\\IManager' => $baseDir . '/lib/public/Calendar/IManager.php',
+    'OCP\\Calendar\\Resource\\IBackend' => $baseDir . '/lib/public/Calendar/Resource/IBackend.php',
+    'OCP\\Calendar\\Resource\\IManager' => $baseDir . '/lib/public/Calendar/Resource/IManager.php',
+    'OCP\\Calendar\\Resource\\IResource' => $baseDir . '/lib/public/Calendar/Resource/IResource.php',
+    'OCP\\Calendar\\Room\\IBackend' => $baseDir . '/lib/public/Calendar/Room/IBackend.php',
+    'OCP\\Calendar\\Room\\IManager' => $baseDir . '/lib/public/Calendar/Room/IManager.php',
+    'OCP\\Calendar\\Room\\IRoom' => $baseDir . '/lib/public/Calendar/Room/IRoom.php',
     'OCP\\Capabilities\\ICapability' => $baseDir . '/lib/public/Capabilities/ICapability.php',
     'OCP\\Capabilities\\IPublicCapability' => $baseDir . '/lib/public/Capabilities/IPublicCapability.php',
     'OCP\\Collaboration\\AutoComplete\\IManager' => $baseDir . '/lib/public/Collaboration/AutoComplete/IManager.php',
@@ -441,6 +448,8 @@
     'OC\\Cache\\CappedMemoryCache' => $baseDir . '/lib/private/Cache/CappedMemoryCache.php',
     'OC\\Cache\\File' => $baseDir . '/lib/private/Cache/File.php',
     'OC\\Calendar\\Manager' => $baseDir . '/lib/private/Calendar/Manager.php',
+    'OC\\Calendar\\Resource\\Manager' => $baseDir . '/lib/private/Calendar/Resource/Manager.php',
+    'OC\\Calendar\\Room\\Manager' => $baseDir . '/lib/private/Calendar/Room/Manager.php',
     'OC\\CapabilitiesManager' => $baseDir . '/lib/private/CapabilitiesManager.php',
     'OC\\Collaboration\\AutoComplete\\Manager' => $baseDir . '/lib/private/Collaboration/AutoComplete/Manager.php',
     'OC\\Collaboration\\Collaborators\\GroupPlugin' => $baseDir . '/lib/private/Collaboration/Collaborators/GroupPlugin.php',
diff --git a/lib/composer/composer/autoload_static.php b/lib/composer/composer/autoload_static.php
index 26a38a29984fd..fc5a37388ec56 100644
--- a/lib/composer/composer/autoload_static.php
+++ b/lib/composer/composer/autoload_static.php
@@ -106,8 +106,15 @@ class ComposerStaticInit53792487c5a8370acc0b06b1a864ff4c
         'OCP\\BackgroundJob' => __DIR__ . '/../../..' . '/lib/public/BackgroundJob.php',
         'OCP\\BackgroundJob\\IJob' => __DIR__ . '/../../..' . '/lib/public/BackgroundJob/IJob.php',
         'OCP\\BackgroundJob\\IJobList' => __DIR__ . '/../../..' . '/lib/public/BackgroundJob/IJobList.php',
+        'OCP\\Calendar\\BackendTemporarilyUnavailableException' => __DIR__ . '/../../..' . '/lib/public/Calendar/BackendTemporarilyUnavailableException.php',
         'OCP\\Calendar\\ICalendar' => __DIR__ . '/../../..' . '/lib/public/Calendar/ICalendar.php',
         'OCP\\Calendar\\IManager' => __DIR__ . '/../../..' . '/lib/public/Calendar/IManager.php',
+        'OCP\\Calendar\\Resource\\IBackend' => __DIR__ . '/../../..' . '/lib/public/Calendar/Resource/IBackend.php',
+        'OCP\\Calendar\\Resource\\IManager' => __DIR__ . '/../../..' . '/lib/public/Calendar/Resource/IManager.php',
+        'OCP\\Calendar\\Resource\\IResource' => __DIR__ . '/../../..' . '/lib/public/Calendar/Resource/IResource.php',
+        'OCP\\Calendar\\Room\\IBackend' => __DIR__ . '/../../..' . '/lib/public/Calendar/Room/IBackend.php',
+        'OCP\\Calendar\\Room\\IManager' => __DIR__ . '/../../..' . '/lib/public/Calendar/Room/IManager.php',
+        'OCP\\Calendar\\Room\\IRoom' => __DIR__ . '/../../..' . '/lib/public/Calendar/Room/IRoom.php',
         'OCP\\Capabilities\\ICapability' => __DIR__ . '/../../..' . '/lib/public/Capabilities/ICapability.php',
         'OCP\\Capabilities\\IPublicCapability' => __DIR__ . '/../../..' . '/lib/public/Capabilities/IPublicCapability.php',
         'OCP\\Collaboration\\AutoComplete\\IManager' => __DIR__ . '/../../..' . '/lib/public/Collaboration/AutoComplete/IManager.php',
@@ -471,6 +478,8 @@ class ComposerStaticInit53792487c5a8370acc0b06b1a864ff4c
         'OC\\Cache\\CappedMemoryCache' => __DIR__ . '/../../..' . '/lib/private/Cache/CappedMemoryCache.php',
         'OC\\Cache\\File' => __DIR__ . '/../../..' . '/lib/private/Cache/File.php',
         'OC\\Calendar\\Manager' => __DIR__ . '/../../..' . '/lib/private/Calendar/Manager.php',
+        'OC\\Calendar\\Resource\\Manager' => __DIR__ . '/../../..' . '/lib/private/Calendar/Resource/Manager.php',
+        'OC\\Calendar\\Room\\Manager' => __DIR__ . '/../../..' . '/lib/private/Calendar/Room/Manager.php',
         'OC\\CapabilitiesManager' => __DIR__ . '/../../..' . '/lib/private/CapabilitiesManager.php',
         'OC\\Collaboration\\AutoComplete\\Manager' => __DIR__ . '/../../..' . '/lib/private/Collaboration/AutoComplete/Manager.php',
         'OC\\Collaboration\\Collaborators\\GroupPlugin' => __DIR__ . '/../../..' . '/lib/private/Collaboration/Collaborators/GroupPlugin.php',
diff --git a/lib/private/Calendar/Resource/Manager.php b/lib/private/Calendar/Resource/Manager.php
new file mode 100644
index 0000000000000..2d1746cb98901
--- /dev/null
+++ b/lib/private/Calendar/Resource/Manager.php
@@ -0,0 +1,83 @@
+<?php
+/**
+ * @copyright 2018, Georg Ehrke <oc.list@georgehrke.com>
+ *
+ * @author Georg Ehrke <oc.list@georgehrke.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 OC\Calendar\Resource;
+
+use OCP\Calendar\Resource\IBackend;
+
+class Manager implements \OCP\Calendar\Resource\IManager {
+
+	/** @var IBackend[] holds all registered resource backends */
+	private $backends;
+
+	/**
+	 * Registers a resource backend
+	 *
+	 * @param IBackend $backend
+	 * @return void
+	 * @since 14.0.0
+	 */
+	public function registerBackend(IBackend $backend) {
+		$this->backends[$backend->getBackendIdentifier()] = $backend;
+	}
+
+	/**
+	 * Unregisters a resource backend
+	 *
+	 * @param IBackend $backend
+	 * @return void
+	 * @since 14.0.0
+	 */
+	public function unregisterBackend(IBackend $backend) {
+		unset($this->backends[$backend->getBackendIdentifier()]);
+	}
+
+	/**
+	 * @return IBackend[]
+	 * @since 14.0.0
+	 */
+	public function getBackends():array {
+		return array_values($this->backends);
+	}
+
+	/**
+	 * @param string $backendId
+	 * @return IBackend|null
+	 */
+	public function getBackend($backendId):IBackend {
+		if (!isset($this->backends[$backendId])) {
+			return null;
+		}
+
+		return $this->backends[$backendId];
+	}
+
+	/**
+	 * removes all registered backend instances
+	 * @return void
+	 * @since 14.0.0
+	 */
+	public function clear() {
+		$this->backends = [];
+	}
+}
diff --git a/lib/private/Calendar/Room/Manager.php b/lib/private/Calendar/Room/Manager.php
new file mode 100644
index 0000000000000..9ddf1f1d7b7d0
--- /dev/null
+++ b/lib/private/Calendar/Room/Manager.php
@@ -0,0 +1,83 @@
+<?php
+/**
+ * @copyright 2018, Georg Ehrke <oc.list@georgehrke.com>
+ *
+ * @author Georg Ehrke <oc.list@georgehrke.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 OC\Calendar\Room;
+
+use OCP\Calendar\Room\IBackend;
+
+class Manager implements \OCP\Calendar\Room\IManager {
+
+	/** @var IBackend[] holds all registered resource backends */
+	private $backends;
+
+	/**
+	 * Registers a resource backend
+	 *
+	 * @param IBackend $backend
+	 * @return void
+	 * @since 14.0.0
+	 */
+	public function registerBackend(IBackend $backend) {
+		$this->backends[$backend->getBackendIdentifier()] = $backend;
+	}
+
+	/**
+	 * Unregisters a resource backend
+	 *
+	 * @param IBackend $backend
+	 * @return void
+	 * @since 14.0.0
+	 */
+	public function unregisterBackend(IBackend $backend) {
+		unset($this->backends[$backend->getBackendIdentifier()]);
+	}
+
+	/**
+	 * @return IBackend[]
+	 * @since 14.0.0
+	 */
+	public function getBackends():array {
+		return array_values($this->backends);
+	}
+
+	/**
+	 * @param string $backendId
+	 * @return IBackend|null
+	 */
+	public function getBackend($backendId):IBackend {
+		if (!isset($this->backends[$backendId])) {
+			return null;
+		}
+
+		return $this->backends[$backendId];
+	}
+
+	/**
+	 * removes all registered backend instances
+	 * @return void
+	 * @since 14.0.0
+	 */
+	public function clear() {
+		$this->backends = [];
+	}
+}
diff --git a/lib/private/Server.php b/lib/private/Server.php
index 31f088ea7186c..1603c50e26e4b 100644
--- a/lib/private/Server.php
+++ b/lib/private/Server.php
@@ -174,6 +174,12 @@ public function __construct($webRoot, \OC\Config $config) {
 		$this->registerAlias(\OCP\Calendar\IManager::class, \OC\Calendar\Manager::class);
 		$this->registerAlias('CalendarManager', \OC\Calendar\Manager::class);
 
+		$this->registerAlias(\OCP\Calendar\Resource\IManager::class, \OC\Calendar\Resource\Manager::class);
+		$this->registerAlias('CalendarResourceBackendManager', \OC\Calendar\Resource\Manager::class);
+
+		$this->registerAlias(\OCP\Calendar\Room\IManager::class, \OC\Calendar\Room\Manager::class);
+		$this->registerAlias('CalendarRoomBackendManager', \OC\Calendar\Room\Manager::class);
+
 		$this->registerAlias(\OCP\Contacts\IManager::class, \OC\ContactsManager::class);
 		$this->registerAlias('ContactsManager', \OCP\Contacts\IManager::class);
 
@@ -1174,6 +1180,20 @@ public function getCalendarManager() {
 		return $this->query('CalendarManager');
 	}
 
+	/**
+	 * @return \OCP\Calendar\Resource\IManager
+	 */
+	public function getCalendarResourceBackendManager() {
+		return $this->query('CalendarResourceBackendManager');
+	}
+
+	/**
+	 * @return \OCP\Calendar\Room\IManager
+	 */
+	public function getCalendarRoomBackendManager() {
+		return $this->query('CalendarRoomBackendManager');
+	}
+
 	private function connectDispatcher() {
 		$dispatcher = $this->getEventDispatcher();
 
diff --git a/lib/public/Calendar/BackendTemporarilyUnavailableException.php b/lib/public/Calendar/BackendTemporarilyUnavailableException.php
new file mode 100644
index 0000000000000..632a802359c0a
--- /dev/null
+++ b/lib/public/Calendar/BackendTemporarilyUnavailableException.php
@@ -0,0 +1,32 @@
+<?php
+/**
+ * @copyright 2018, Georg Ehrke <oc.list@georgehrke.com>
+ *
+ * @author Georg Ehrke <oc.list@georgehrke.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 OCP\Calendar;
+
+/**
+ * Class BackendTemporarilyUnavailableException
+ *
+ * @package OCP\Calendar
+ * @since 14.0.0
+ */
+class BackendTemporarilyUnavailableException extends \Exception {}
diff --git a/lib/public/Calendar/Resource/IBackend.php b/lib/public/Calendar/Resource/IBackend.php
new file mode 100644
index 0000000000000..24635219fe060
--- /dev/null
+++ b/lib/public/Calendar/Resource/IBackend.php
@@ -0,0 +1,70 @@
+<?php
+/**
+ * @copyright 2018, Georg Ehrke <oc.list@georgehrke.com>
+ *
+ * @author Georg Ehrke <oc.list@georgehrke.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 OCP\Calendar\Resource;
+use OCP\Calendar\BackendTemporarilyUnavailableException;
+
+/**
+ * Interface IBackend
+ *
+ * @package OCP\Calendar\Resource
+ * @since 14.0.0
+ */
+interface IBackend {
+
+	/**
+	 * get a list of all resources in this backend
+	 *
+	 * @throws BackendTemporarilyUnavailableException
+	 * @return IResource[]
+	 * @since 14.0.0
+	 */
+	public function getAllResources():array;
+
+	/**
+	 * get a list of all resource identifiers in this backend
+	 *
+	 * @throws BackendTemporarilyUnavailableException
+	 * @return string[]
+	 * @since 14.0.0
+	 */
+	public function listAllResources():array;
+
+	/**
+	 * get a resource by it's id
+	 *
+	 * @param string $id
+	 * @throws BackendTemporarilyUnavailableException
+	 * @return IResource|null
+	 * @since 14.0.0
+	 */
+	public function getResource($id);
+
+	/**
+	 * Get unique identifier of the backend
+	 *
+	 * @return string
+	 * @since 14.0.0
+	 */
+	public function getBackendIdentifier():string;
+}
diff --git a/lib/public/Calendar/Resource/IManager.php b/lib/public/Calendar/Resource/IManager.php
new file mode 100644
index 0000000000000..8542e13eba707
--- /dev/null
+++ b/lib/public/Calendar/Resource/IManager.php
@@ -0,0 +1,71 @@
+<?php
+/**
+ * @copyright 2018, Georg Ehrke <oc.list@georgehrke.com>
+ *
+ * @author Georg Ehrke <oc.list@georgehrke.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 OCP\Calendar\Resource;
+
+/**
+ * Interface IManager
+ *
+ * @package OCP\Calendar\Resource
+ * @since 14.0.0
+ */
+interface IManager {
+
+	/**
+	 * Registers a resource backend
+	 *
+	 * @param IBackend $backend
+	 * @return void
+	 * @since 14.0.0
+	 */
+	public function registerBackend(IBackend $backend);
+
+	/**
+	 * Unregisters a resource backend
+	 *
+	 * @param IBackend $backend
+	 * @return void
+	 * @since 14.0.0
+	 */
+	public function unregisterBackend(IBackend $backend);
+
+	/**
+	 * @return IBackend[]
+	 * @since 14.0.0
+	 */
+	public function getBackends():array;
+
+	/**
+	 * @param string $backendId
+	 * @return IBackend
+	 * @since 14.0.0
+	 */
+	public function getBackend($backendId):IBackend;
+
+	/**
+	 * removes all registered backend instances
+	 * @return void
+	 * @since 14.0.0
+	 */
+	public function clear();
+}
diff --git a/lib/public/Calendar/Resource/IResource.php b/lib/public/Calendar/Resource/IResource.php
new file mode 100644
index 0000000000000..1f588ccb48dba
--- /dev/null
+++ b/lib/public/Calendar/Resource/IResource.php
@@ -0,0 +1,80 @@
+<?php
+/**
+ * @copyright 2018, Georg Ehrke <oc.list@georgehrke.com>
+ *
+ * @author Georg Ehrke <oc.list@georgehrke.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 OCP\Calendar\Resource;
+
+/**
+ * Interface IResource
+ *
+ * @package OCP\Calendar\Resource
+ * @since 14.0.0
+ */
+interface IResource {
+
+	/**
+	 * get the resource id
+	 *
+	 * This id has to be unique within the backend
+	 *
+	 * @return string
+	 * @since 14.0.0
+	 */
+	public function getId():string;
+
+	/**
+	 * get the display name for a resource
+	 *
+	 * @return string
+	 * @since 14.0.0
+	 */
+	public function getDisplayName():string;
+
+	/**
+	 * Get a list of groupIds that are allowed to access this resource
+	 *
+	 * If an empty array is returned, no group restrictions are
+	 * applied.
+	 *
+	 * @return string[]
+	 * @since 14.0.0
+	 */
+	public function getGroupRestrictions():array;
+
+	/**
+	 * get email-address for resource
+	 *
+	 * The email address has to be globally unique
+	 *
+	 * @return string
+	 * @since 14.0.0
+	 */
+	public function getEMail():string;
+
+	/**
+	 * Get corresponding backend object
+	 *
+	 * @return IBackend
+	 * @since 14.0.0
+	 */
+	public function getBackend():IBackend;
+}
diff --git a/lib/public/Calendar/Room/IBackend.php b/lib/public/Calendar/Room/IBackend.php
new file mode 100644
index 0000000000000..f675012ab3948
--- /dev/null
+++ b/lib/public/Calendar/Room/IBackend.php
@@ -0,0 +1,70 @@
+<?php
+/**
+ * @copyright 2018, Georg Ehrke <oc.list@georgehrke.com>
+ *
+ * @author Georg Ehrke <oc.list@georgehrke.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 OCP\Calendar\Room;
+use OCP\Calendar\BackendTemporarilyUnavailableException;
+
+/**
+ * Interface IBackend
+ *
+ * @package OCP\Calendar\Room
+ * @since 14.0.0
+ */
+interface IBackend {
+
+	/**
+	 * get a list of all rooms in this backend
+	 *
+	 * @throws BackendTemporarilyUnavailableException
+	 * @return IRoom[]
+	 * @since 14.0.0
+	 */
+	public function getAllRooms():array;
+
+	/**
+	 * get a list of all room identifiers in this backend
+	 *
+	 * @throws BackendTemporarilyUnavailableException
+	 * @return string[]
+	 * @since 14.0.0
+	 */
+	public function listAllRooms():array;
+
+	/**
+	 * get a room by it's id
+	 *
+	 * @param string $id
+	 * @throws BackendTemporarilyUnavailableException
+	 * @return IRoom|null
+	 * @since 14.0.0
+	 */
+	public function getRoom($id);
+
+	/**
+	 * Get unique identifier of the backend
+	 *
+	 * @return string
+	 * @since 14.0.0
+	 */
+	public function getBackendIdentifier():string;
+}
diff --git a/lib/public/Calendar/Room/IManager.php b/lib/public/Calendar/Room/IManager.php
new file mode 100644
index 0000000000000..39e85c43e456a
--- /dev/null
+++ b/lib/public/Calendar/Room/IManager.php
@@ -0,0 +1,71 @@
+<?php
+/**
+ * @copyright 2018, Georg Ehrke <oc.list@georgehrke.com>
+ *
+ * @author Georg Ehrke <oc.list@georgehrke.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 OCP\Calendar\Room;
+
+/**
+ * Interface IManager
+ *
+ * @package OCP\Calendar\Room
+ * @since 14.0.0
+ */
+interface IManager {
+
+	/**
+	 * Registers a room backend
+	 *
+	 * @param IBackend $backend
+	 * @return void
+	 * @since 14.0.0
+	 */
+	public function registerBackend(IBackend $backend);
+
+	/**
+	 * Unregisters a room backend
+	 *
+	 * @param IBackend $backend
+	 * @return void
+	 * @since 14.0.0
+	 */
+	public function unregisterBackend(IBackend $backend);
+
+	/**
+	 * @return IBackend[]
+	 * @since 14.0.0
+	 */
+	public function getBackends():array;
+
+	/**
+	 * @param string $backendId
+	 * @return IBackend
+	 * @since 14.0.0
+	 */
+	public function getBackend($backendId):IBackend;
+
+	/**
+	 * removes all registered backend instances
+	 * @return void
+	 * @since 14.0.0
+	 */
+	public function clear();
+}
diff --git a/lib/public/Calendar/Room/IRoom.php b/lib/public/Calendar/Room/IRoom.php
new file mode 100644
index 0000000000000..d860bb6fc5708
--- /dev/null
+++ b/lib/public/Calendar/Room/IRoom.php
@@ -0,0 +1,80 @@
+<?php
+/**
+ * @copyright 2018, Georg Ehrke <oc.list@georgehrke.com>
+ *
+ * @author Georg Ehrke <oc.list@georgehrke.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 OCP\Calendar\Room;
+
+/**
+ * Interface IRoom
+ *
+ * @package OCP\Calendar\Room
+ * @since 14.0.0
+ */
+interface IRoom {
+
+	/**
+	 * get the room id
+	 *
+	 * This id has to be unique within the backend
+	 *
+	 * @return string
+	 * @since 14.0.0
+	 */
+	public function getId():string;
+
+	/**
+	 * get the display name for a room
+	 *
+	 * @return string
+	 * @since 14.0.0
+	 */
+	public function getDisplayName():string;
+
+	/**
+	 * Get a list of groupIds that are allowed to access this room
+	 *
+	 * If an empty array is returned, no group restrictions are
+	 * applied.
+	 *
+	 * @return string[]
+	 * @since 14.0.0
+	 */
+	public function getGroupRestrictions():array;
+
+	/**
+	 * get email-address for room
+	 *
+	 * The email address has to be globally unique
+	 *
+	 * @return string
+	 * @since 14.0.0
+	 */
+	public function getEMail():string;
+
+	/**
+	 * Get corresponding backend object
+	 *
+	 * @return IBackend
+	 * @since 14.0.0
+	 */
+	public function getBackend():IBackend;
+}
diff --git a/lib/public/IServerContainer.php b/lib/public/IServerContainer.php
index c38aaf9f2cb27..96015d3f8a8a3 100644
--- a/lib/public/IServerContainer.php
+++ b/lib/public/IServerContainer.php
@@ -67,6 +67,24 @@ interface IServerContainer extends IContainer {
 	 */
 	public function getCalendarManager();
 
+	/**
+	 * The calendar resource backend manager will act as a broker between consumers
+	 * for calendar resource information an providers which actual deliver the room information.
+	 *
+	 * @return \OCP\Calendar\Resource\IBackend
+	 * @since 14.0.0
+	 */
+	public function getCalendarResourceBackendManager();
+
+	/**
+	 * The calendar room backend manager will act as a broker between consumers
+	 * for calendar room information an providers which actual deliver the room information.
+	 *
+	 * @return \OCP\Calendar\Room\IBackend
+	 * @since 14.0.0
+	 */
+	public function getCalendarRoomBackendManager();
+
 	/**
 	 * The contacts manager will act as a broker between consumers for contacts information and
 	 * providers which actual deliver the contact information.
diff --git a/tests/lib/Calendar/Resource/ManagerTest.php b/tests/lib/Calendar/Resource/ManagerTest.php
new file mode 100644
index 0000000000000..ccc6bbf182b86
--- /dev/null
+++ b/tests/lib/Calendar/Resource/ManagerTest.php
@@ -0,0 +1,94 @@
+<?php
+/**
+ * @copyright 2018, Georg Ehrke <oc.list@georgehrke.com>
+ *
+ * @author Georg Ehrke <oc.list@georgehrke.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 Test\Calendar\Resource;
+
+use \OC\Calendar\Resource\Manager;
+use \OCP\Calendar\Resource\IBackend;
+use \Test\TestCase;
+
+class ManagerTest extends TestCase {
+
+	/** @var Manager */
+	private $manager;
+
+	protected function setUp() {
+		parent::setUp();
+
+		$this->manager = new Manager();
+	}
+
+	public function testRegisterUnregisterBackend() {
+		$backend1 = $this->createMock(IBackend::class);
+		$backend1->method('getBackendIdentifier')->will($this->returnValue('backend_1'));
+
+		$backend2 = $this->createMock(IBackend::class);
+		$backend2->method('getBackendIdentifier')->will($this->returnValue('backend_2'));
+
+		$this->manager->registerBackend($backend1);
+		$this->manager->registerBackend($backend2);
+
+		$this->assertEquals([
+			$backend1, $backend2
+		], $this->manager->getBackends());
+
+		$this->manager->unregisterBackend($backend1);
+
+		$this->assertEquals([
+			$backend2
+		], $this->manager->getBackends());
+	}
+
+	public function testGetBackend() {
+		$backend1 = $this->createMock(IBackend::class);
+		$backend1->method('getBackendIdentifier')->will($this->returnValue('backend_1'));
+
+		$backend2 = $this->createMock(IBackend::class);
+		$backend2->method('getBackendIdentifier')->will($this->returnValue('backend_2'));
+
+		$this->manager->registerBackend($backend1);
+		$this->manager->registerBackend($backend2);
+
+		$this->assertEquals($backend1, $this->manager->getBackend('backend_1'));
+		$this->assertEquals($backend2, $this->manager->getBackend('backend_2'));
+	}
+
+	public function testClear() {
+		$backend1 = $this->createMock(IBackend::class);
+		$backend1->method('getBackendIdentifier')->will($this->returnValue('backend_1'));
+
+		$backend2 = $this->createMock(IBackend::class);
+		$backend2->method('getBackendIdentifier')->will($this->returnValue('backend_2'));
+
+		$this->manager->registerBackend($backend1);
+		$this->manager->registerBackend($backend2);
+
+		$this->assertEquals([
+			$backend1, $backend2
+		], $this->manager->getBackends());
+
+		$this->manager->clear();
+
+		$this->assertEquals([], $this->manager->getBackends());
+	}
+}
diff --git a/tests/lib/Calendar/Room/ManagerTest.php b/tests/lib/Calendar/Room/ManagerTest.php
new file mode 100644
index 0000000000000..34d69d127e2eb
--- /dev/null
+++ b/tests/lib/Calendar/Room/ManagerTest.php
@@ -0,0 +1,94 @@
+<?php
+/**
+ * @copyright 2018, Georg Ehrke <oc.list@georgehrke.com>
+ *
+ * @author Georg Ehrke <oc.list@georgehrke.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 Test\Calendar\Room;
+
+use \OC\Calendar\Room\Manager;
+use \OCP\Calendar\Room\IBackend;
+use \Test\TestCase;
+
+class ManagerTest extends TestCase {
+
+	/** @var Manager */
+	private $manager;
+
+	protected function setUp() {
+		parent::setUp();
+
+		$this->manager = new Manager();
+	}
+
+	public function testRegisterUnregisterBackend() {
+		$backend1 = $this->createMock(IBackend::class);
+		$backend1->method('getBackendIdentifier')->will($this->returnValue('backend_1'));
+
+		$backend2 = $this->createMock(IBackend::class);
+		$backend2->method('getBackendIdentifier')->will($this->returnValue('backend_2'));
+
+		$this->manager->registerBackend($backend1);
+		$this->manager->registerBackend($backend2);
+
+		$this->assertEquals([
+			$backend1, $backend2
+		], $this->manager->getBackends());
+
+		$this->manager->unregisterBackend($backend1);
+
+		$this->assertEquals([
+			$backend2
+		], $this->manager->getBackends());
+	}
+
+	public function testGetBackend() {
+		$backend1 = $this->createMock(IBackend::class);
+		$backend1->method('getBackendIdentifier')->will($this->returnValue('backend_1'));
+
+		$backend2 = $this->createMock(IBackend::class);
+		$backend2->method('getBackendIdentifier')->will($this->returnValue('backend_2'));
+
+		$this->manager->registerBackend($backend1);
+		$this->manager->registerBackend($backend2);
+
+		$this->assertEquals($backend1, $this->manager->getBackend('backend_1'));
+		$this->assertEquals($backend2, $this->manager->getBackend('backend_2'));
+	}
+
+	public function testClear() {
+		$backend1 = $this->createMock(IBackend::class);
+		$backend1->method('getBackendIdentifier')->will($this->returnValue('backend_1'));
+
+		$backend2 = $this->createMock(IBackend::class);
+		$backend2->method('getBackendIdentifier')->will($this->returnValue('backend_2'));
+
+		$this->manager->registerBackend($backend1);
+		$this->manager->registerBackend($backend2);
+
+		$this->assertEquals([
+			$backend1, $backend2
+		], $this->manager->getBackends());
+
+		$this->manager->clear();
+
+		$this->assertEquals([], $this->manager->getBackends());
+	}
+}