Introduce BackendService for managing external storage backends

Backends are registered to the BackendService through new data
structures:

Backends are concrete classes, deriving from
\OCA\Files_External\Lib\Backend\Backend. During construction, the
various configuration parameters of the Backend can be set, in a design
similar to Symfony Console.

DefinitionParameter stores a parameter configuration for an external
storage: name of parameter, human-readable name, type of parameter
(text, password, hidden, checkbox), flags (optional or not).

Storages in the StoragesController now get their parameters validated
server-side (fixes a TODO).

31 files changed, 1638 insertions, 558 deletions

diff --git a/apps/files_external/appinfo/app.php b/apps/files_external/appinfo/app.php
index 66897eba3d3..37a489535ea 100644
--- a/apps/files_external/appinfo/app.php
+++ b/apps/files_external/appinfo/app.php
@@ -30,9 +30,6 @@
  * along with this program.  If not, see <http://www.gnu.org/licenses/>
  *
  */
-$app = new \OCA\Files_external\Appinfo\Application();
-
-$l = \OC::$server->getL10N('files_external');
 
 OC::$CLASSPATH['OC\Files\Storage\StreamWrapper'] = 'files_external/lib/streamwrapper.php';
 OC::$CLASSPATH['OC\Files\Storage\FTP'] = 'files_external/lib/ftp.php';
@@ -50,6 +47,11 @@ OC::$CLASSPATH['OCA\Files\External\Api'] = 'files_external/lib/api.php';
 
 require_once __DIR__ . '/../3rdparty/autoload.php';
 
+$app = new \OCA\Files_external\Appinfo\Application();
+$appContainer = $app->getContainer();
+
+$l = \OC::$server->getL10N('files_external');
+
 OCP\App::registerAdmin('files_external', 'settings');
 if (OCP\Config::getAppValue('files_external', 'allow_user_mounting', 'yes') == 'yes') {
 	OCP\App::registerPersonal('files_external', 'personal');
@@ -63,6 +65,9 @@ if (OCP\Config::getAppValue('files_external', 'allow_user_mounting', 'yes') == '
 	"name" => $l->t('External storage')
 ]);
 
+// Teach OC_Mount_Config about the AppFramework
+\OC_Mount_Config::initApp($appContainer);
+
 // connecting hooks
 OCP\Util::connectHook('OC_Filesystem', 'post_initMountPoints', '\OC_Mount_Config', 'initMountPointsHook');
 OCP\Util::connectHook('OC_User', 'post_login', 'OC\Files\Storage\SMB_OC', 'login');
@@ -237,5 +242,5 @@ OC_Mount_Config::registerBackend('\OC\Files\Storage\SFTP_Key', [
 	'custom' => 'sftp_key',
 	]
 );
-$mountProvider = new \OCA\Files_External\Config\ConfigAdapter();
+$mountProvider = $appContainer->query('OCA\Files_External\Config\ConfigAdapter');
 \OC::$server->getMountProviderCollection()->registerProvider($mountProvider);
diff --git a/apps/files_external/appinfo/application.php b/apps/files_external/appinfo/application.php
index d77a302466c..b8b1fdaa27e 100644
--- a/apps/files_external/appinfo/application.php
+++ b/apps/files_external/appinfo/application.php
@@ -3,6 +3,7 @@
  * @author Morris Jobke <hey@morrisjobke.de>
  * @author Ross Nicoll <jrn@jrn.me.uk>
  * @author Vincent Petry <pvince81@owncloud.com>
+ * @author Robin McCorkell <rmccorkell@owncloud.com>
  *
  * @copyright Copyright (c) 2015, ownCloud, Inc.
  * @license AGPL-3.0
@@ -26,6 +27,9 @@ namespace OCA\Files_External\AppInfo;
 use \OCA\Files_External\Controller\AjaxController;
 use \OCP\AppFramework\App;
 use \OCP\IContainer;
+use \OCA\Files_External\Service\BackendService;
+use \OCA\Files_External\Lib\BackendConfig;
+use \OCA\Files_External\Lib\BackendParameter;
 
 /**
  * @package OCA\Files_External\Appinfo
@@ -45,5 +49,16 @@ class Application extends App {
 				$c->query('Request')
 			);
 		});
+
+		$this->loadBackends();
 	}
+
+	/**
+	 * Load storage backends provided by this app
+	 */
+	protected function loadBackends() {
+		$container = $this->getContainer();
+		$service = $container->query('OCA\\Files_External\\Service\\BackendService');
+	}
+
 }
diff --git a/apps/files_external/controller/globalstoragescontroller.php b/apps/files_external/controller/globalstoragescontroller.php
index 33f870d48e3..11f7fd6afa5 100644
--- a/apps/files_external/controller/globalstoragescontroller.php
+++ b/apps/files_external/controller/globalstoragescontroller.php
@@ -81,14 +81,18 @@ class GlobalStoragesController extends StoragesController {
 		$applicableGroups,
 		$priority
 	) {
-		$newStorage = new StorageConfig();
-		$newStorage->setMountPoint($mountPoint);
-		$newStorage->setBackendClass($backendClass);
-		$newStorage->setBackendOptions($backendOptions);
-		$newStorage->setMountOptions($mountOptions);
-		$newStorage->setApplicableUsers($applicableUsers);
-		$newStorage->setApplicableGroups($applicableGroups);
-		$newStorage->setPriority($priority);
+		$newStorage = $this->createStorage(
+			$mountPoint,
+			$backendClass,
+			$backendOptions,
+			$mountOptions,
+			$applicableUsers,
+			$applicableGroups,
+			$priority
+		);
+		if ($newStorage instanceof DataResponse) {
+			return $newStorage;
+		}
 
 		$response = $this->validate($newStorage);
 		if (!empty($response)) {
@@ -129,14 +133,19 @@ class GlobalStoragesController extends StoragesController {
 		$applicableGroups,
 		$priority
 	) {
-		$storage = new StorageConfig($id);
-		$storage->setMountPoint($mountPoint);
-		$storage->setBackendClass($backendClass);
-		$storage->setBackendOptions($backendOptions);
-		$storage->setMountOptions($mountOptions);
-		$storage->setApplicableUsers($applicableUsers);
-		$storage->setApplicableGroups($applicableGroups);
-		$storage->setPriority($priority);
+		$storage = $this->createStorage(
+			$mountPoint,
+			$backendClass,
+			$backendOptions,
+			$mountOptions,
+			$applicableUsers,
+			$applicableGroups,
+			$priority
+		);
+		if ($storage instanceof DataResponse) {
+			return $storage;
+		}
+		$storage->setId($id);
 
 		$response = $this->validate($storage);
 		if (!empty($response)) {
diff --git a/apps/files_external/controller/storagescontroller.php b/apps/files_external/controller/storagescontroller.php
index c09ceacc7d7..c653b51bf89 100644
--- a/apps/files_external/controller/storagescontroller.php
+++ b/apps/files_external/controller/storagescontroller.php
@@ -32,6 +32,7 @@ use \OCP\AppFramework\Http;
 use \OCA\Files_external\Service\StoragesService;
 use \OCA\Files_external\NotFoundException;
 use \OCA\Files_external\Lib\StorageConfig;
+use \OCA\Files_External\Lib\Backend\Backend;
 
 /**
  * Base class for storages controllers
@@ -72,6 +73,48 @@ abstract class StoragesController extends Controller {
 	}
 
 	/**
+	 * Create a storage from its parameters
+	 *
+	 * @param string $mountPoint storage mount point
+	 * @param string $backendClass backend class name
+	 * @param array $backendOptions backend-specific options
+	 * @param array|null $mountOptions mount-specific options
+	 * @param array|null $applicableUsers users for which to mount the storage
+	 * @param array|null $applicableGroups groups for which to mount the storage
+	 * @param int|null $priority priority
+	 *
+	 * @return StorageConfig|DataResponse
+	 */
+	protected function createStorage(
+		$mountPoint,
+		$backendClass,
+		$backendOptions,
+		$mountOptions = null,
+		$applicableUsers = null,
+		$applicableGroups = null,
+		$priority = null
+	) {
+		try {
+			return $this->service->createStorage(
+				$mountPoint,
+				$backendClass,
+				$backendOptions,
+				$mountOptions,
+				$applicableUsers,
+				$applicableGroups,
+				$priority
+			);
+		} catch (\InvalidArgumentException $e) {
+			return new DataResponse(
+				[
+					'message' => (string)$this->l10n->t('Invalid backend class "%s"', [$backendClass])
+				],
+				Http::STATUS_UNPROCESSABLE_ENTITY
+			);
+		}
+	}
+
+	/**
 	 * Validate storage config
 	 *
 	 * @param StorageConfig $storage storage config
@@ -89,14 +132,24 @@ abstract class StoragesController extends Controller {
 			);
 		}
 
-		// TODO: validate that other attrs are set
-
-		$backends = \OC_Mount_Config::getBackends();
-		if (!isset($backends[$storage->getBackendClass()])) {
+		/** @var Backend */
+		$backend = $storage->getBackend();
+		if (!$backend || $backend->checkDependencies()) {
 			// invalid backend
 			return new DataResponse(
 				array(
-					'message' => (string)$this->l10n->t('Invalid storage backend "%s"', array($storage->getBackendClass()))
+					'message' => (string)$this->l10n->t('Invalid storage backend "%s"', [
+						$storage->getBackend()->getClass()
+					])
+				),
+				Http::STATUS_UNPROCESSABLE_ENTITY
+			);
+		}
+		if (!$backend->validateStorage($storage)) {
+			// unsatisfied parameters
+			return new DataResponse(
+				array(
+					'message' => (string)$this->l10n->t('Unsatisfied backend parameters')
 				),
 				Http::STATUS_UNPROCESSABLE_ENTITY
 			);
@@ -114,10 +167,14 @@ abstract class StoragesController extends Controller {
 	 * @param StorageConfig $storage storage configuration
 	 */
 	protected function updateStorageStatus(StorageConfig &$storage) {
+		/** @var Backend */
+		$backend = $storage->getBackend();
+		$backend->manipulateStorageConfig($storage);
+
 		// update status (can be time-consuming)
 		$storage->setStatus(
 			\OC_Mount_Config::getBackendStatus(
-				$storage->getBackendClass(),
+				$storage->getBackend()->getStorageClass(),
 				$storage->getBackendOptions(),
 				false
 			)
diff --git a/apps/files_external/controller/userstoragescontroller.php b/apps/files_external/controller/userstoragescontroller.php
index f5d22e5caa6..5a5bff7ba70 100644
--- a/apps/files_external/controller/userstoragescontroller.php
+++ b/apps/files_external/controller/userstoragescontroller.php
@@ -30,8 +30,10 @@ use \OCP\AppFramework\Http\DataResponse;
 use \OCP\AppFramework\Controller;
 use \OCP\AppFramework\Http;
 use \OCA\Files_external\Service\UserStoragesService;
+use \OCA\Files_External\Service\BackendService;
 use \OCA\Files_external\NotFoundException;
 use \OCA\Files_external\Lib\StorageConfig;
+use \OCA\Files_External\Lib\Backend\Backend;
 
 /**
  * User storages controller
@@ -69,17 +71,20 @@ class UserStoragesController extends StoragesController {
 	protected function validate(StorageConfig $storage) {
 		$result = parent::validate($storage);
 
-		if ($result != null) {
+		if ($result !== null) {
 			return $result;
 		}
 
 		// Verify that the mount point applies for the current user
 		// Prevent non-admin users from mounting local storage and other disabled backends
-		$allowedBackends = \OC_Mount_Config::getPersonalBackends();
-		if (!isset($allowedBackends[$storage->getBackendClass()])) {
+		/** @var Backend */
+		$backend = $storage->getBackend();
+		if (!$backend->isVisibleFor(BackendService::VISIBILITY_PERSONAL)) {
 			return new DataResponse(
 				array(
-					'message' => (string)$this->l10n->t('Invalid storage backend "%s"', array($storage->getBackendClass()))
+					'message' => (string)$this->l10n->t('Admin-only storage backend "%s"', [
+						$storage->getBackend()->getClass()
+					])
 				),
 				Http::STATUS_UNPROCESSABLE_ENTITY
 			);
@@ -117,11 +122,15 @@ class UserStoragesController extends StoragesController {
 		$backendOptions,
 		$mountOptions
 	) {
-		$newStorage = new StorageConfig();
-		$newStorage->setMountPoint($mountPoint);
-		$newStorage->setBackendClass($backendClass);
-		$newStorage->setBackendOptions($backendOptions);
-		$newStorage->setMountOptions($mountOptions);
+		$newStorage = $this->createStorage(
+			$mountPoint,
+			$backendClass,
+			$backendOptions,
+			$mountOptions
+		);
+		if ($newStorage instanceOf DataResponse) {
+			return $newStorage;
+		}
 
 		$response = $this->validate($newStorage);
 		if (!empty($response)) {
@@ -157,11 +166,16 @@ class UserStoragesController extends StoragesController {
 		$backendOptions,
 		$mountOptions
 	) {
-		$storage = new StorageConfig($id);
-		$storage->setMountPoint($mountPoint);
-		$storage->setBackendClass($backendClass);
-		$storage->setBackendOptions($backendOptions);
-		$storage->setMountOptions($mountOptions);
+		$storage = $this->createStorage(
+			$mountPoint,
+			$backendClass,
+			$backendOptions,
+			$mountOptions
+		);
+		if ($storage instanceOf DataResponse) {
+			return $storage;
+		}
+		$storage->setId($id);
 
 		$response = $this->validate($storage);
 		if (!empty($response)) {
diff --git a/apps/files_external/lib/backend/backend.php b/apps/files_external/lib/backend/backend.php
new file mode 100644
index 00000000000..e7cd27a1d6c
--- /dev/null
+++ b/apps/files_external/lib/backend/backend.php
@@ -0,0 +1,94 @@
+<?php
+/**
+ * @author Robin McCorkell <rmccorkell@owncloud.com>
+ *
+ * @copyright Copyright (c) 2015, ownCloud, Inc.
+ * @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\Files_External\Lib\Backend;
+
+use \OCA\Files_External\Lib\StorageConfig;
+use \OCA\Files_External\Lib\VisibilityTrait;
+use \OCA\Files_External\Lib\FrontendDefinitionTrait;
+use \OCA\Files_External\Lib\PriorityTrait;
+use \OCA\Files_External\Lib\DependencyTrait;
+use \OCA\Files_External\Lib\StorageModifierTrait;
+
+/**
+ * Storage backend
+ */
+class Backend implements \JsonSerializable {
+
+	use VisibilityTrait;
+	use FrontendDefinitionTrait;
+	use PriorityTrait;
+	use DependencyTrait;
+	use StorageModifierTrait;
+
+	/** @var string storage class */
+	private $storageClass;
+
+	/**
+	 * @return string
+	 */
+	public function getClass() {
+		// return storage class for legacy compat
+		return $this->getStorageClass();
+	}
+
+	/**
+	 * @return string
+	 */
+	public function getStorageClass() {
+		return $this->storageClass;
+	}
+
+	/**
+	 * @param string $class
+	 * @return self
+	 */
+	public function setStorageClass($class) {
+		$this->storageClass = $class;
+		return $this;
+	}
+
+	/**
+	 * Serialize into JSON for client-side JS
+	 *
+	 * @return array
+	 */
+	public function jsonSerialize() {
+		$data = $this->jsonSerializeDefinition();
+
+		$data['backend'] = $data['name']; // legacy compat
+		$data['priority'] = $this->getPriority();
+
+		return $data;
+	}
+
+	/**
+	 * Check if parameters are satisfied in a StorageConfig
+	 *
+	 * @param StorageConfig $storage
+	 * @return bool
+	 */
+	public function validateStorage(StorageConfig $storage) {
+		return $this->validateStorageDefinition($storage);
+	}
+
+}
+
diff --git a/apps/files_external/lib/config.php b/apps/files_external/lib/config.php
index 8fcf39cc767..11dec94621a 100644
--- a/apps/files_external/lib/config.php
+++ b/apps/files_external/lib/config.php
@@ -32,6 +32,9 @@
  */
 
 use phpseclib\Crypt\AES;
+use \OCP\AppFramework\IAppContainer;
+use \OCA\Files_External\Lib\BackendConfig;
+use \OCA\Files_External\Service\BackendService;
 
 /**
  * Class to configure mount.json globally and for users
@@ -51,71 +54,19 @@ class OC_Mount_Config {
 	// whether to skip backend test (for unit tests, as this static class is not mockable)
 	public static $skipTest = false;
 
-	private static $backends = array();
+	/** @var IAppContainer */
+	private static $appContainer;
 
 	/**
-	 * @param string $class
-	 * @param array $definition
-	 * @return bool
-	 */
-	public static function registerBackend($class, $definition) {
-		if (!isset($definition['backend'])) {
-			return false;
-		}
-
-		OC_Mount_Config::$backends[$class] = $definition;
-		return true;
-	}
-
-	/**
-	 * Setup backends
+	 * Teach OC_Mount_Config about the AppFramework
 	 *
-	 * @return array of previously registered backends
+	 * @param IAppContainer $appContainer
 	 */
-	public static function setUp($backends = array()) {
-		$backup = self::$backends;
-		self::$backends = $backends;
-
-		return $backup;
-	}
-
-	/**
-	 * Get details on each of the external storage backends, used for the mount config UI
-	 * If a custom UI is needed, add the key 'custom' and a javascript file with that name will be loaded
-	 * If the configuration parameter should be secret, add a '*' to the beginning of the value
-	 * If the configuration parameter is a boolean, add a '!' to the beginning of the value
-	 * If the configuration parameter is optional, add a '&' to the beginning of the value
-	 * If the configuration parameter is hidden, add a '#' to the beginning of the value
-	 *
-	 * @return array
-	 */
-	public static function getBackends() {
-		$sortFunc = function ($a, $b) {
-			return strcasecmp($a['backend'], $b['backend']);
-		};
-
-		$backEnds = array();
-
-		foreach (OC_Mount_Config::$backends as $class => $backend) {
-			if (isset($backend['has_dependencies']) and $backend['has_dependencies'] === true) {
-				if (!method_exists($class, 'checkDependencies')) {
-					\OCP\Util::writeLog('files_external',
-						"Backend class $class has dependencies but doesn't provide method checkDependencies()",
-						\OCP\Util::DEBUG);
-					continue;
-				} elseif ($class::checkDependencies() !== true) {
-					continue;
-				}
-			}
-			$backEnds[$class] = $backend;
-		}
-
-		uasort($backEnds, $sortFunc);
-
-		return $backEnds;
+	public static function initApp(IAppContainer $appContainer) {
+		self::$appContainer = $appContainer;
 	}
 
-	/**
+	/*
 	 * Hook that mounts the given user's visible mount points
 	 *
 	 * @param array $data
@@ -151,14 +102,14 @@ class OC_Mount_Config {
 	/**
 	 * Returns the mount points for the given user.
 	 * The mount point is relative to the data directory.
+	 * TODO: Move me into StoragesService
 	 *
 	 * @param string $user user
 	 * @return array of mount point string as key, mountpoint config as value
 	 */
 	public static function getAbsoluteMountPoints($user) {
 		$mountPoints = array();
-
-		$backends = self::getBackends();
+		$backendService = self::$appContainer->query('OCA\Files_External\Service\BackendService');
 
 		// Load system mount points
 		$mountConfig = self::readData();
@@ -166,18 +117,20 @@ class OC_Mount_Config {
 		// Global mount points (is this redundant?)
 		if (isset($mountConfig[self::MOUNT_TYPE_GLOBAL])) {
 			foreach ($mountConfig[self::MOUNT_TYPE_GLOBAL] as $mountPoint => $options) {
+				$backend = $backendService->getBackend($options['class']);
 				$options['personal'] = false;
 				$options['options'] = self::decryptPasswords($options['options']);
 				if (!isset($options['priority'])) {
-					$options['priority'] = $backends[$options['class']]['priority'];
+					$options['priority'] = $backend->getPriority();
 				}
 
+
 				// Override if priority greater
 				if ((!isset($mountPoints[$mountPoint]))
 					|| ($options['priority'] >= $mountPoints[$mountPoint]['priority'])
 				) {
 					$options['priority_type'] = self::MOUNT_TYPE_GLOBAL;
-					$options['backend'] = $backends[$options['class']]['backend'];
+					$options['backend'] = $backend->getText();
 					$mountPoints[$mountPoint] = $options;
 				}
 			}
@@ -190,10 +143,11 @@ class OC_Mount_Config {
 				foreach ($options as &$option) {
 					$option = self::setUserVars($user, $option);
 				}
+				$backend = $backendService->getBackend($options['class']);
 				$options['personal'] = false;
 				$options['options'] = self::decryptPasswords($options['options']);
 				if (!isset($options['priority'])) {
-					$options['priority'] = $backends[$options['class']]['priority'];
+					$options['priority'] = $backend->getPriority();
 				}
 
 				// Override if priority greater
@@ -201,7 +155,7 @@ class OC_Mount_Config {
 					|| ($options['priority'] >= $mountPoints[$mountPoint]['priority'])
 				) {
 					$options['priority_type'] = self::MOUNT_TYPE_GLOBAL;
-					$options['backend'] = $backends[$options['class']]['backend'];
+					$options['backend'] = $backend->getText();
 					$mountPoints[$mountPoint] = $options;
 				}
 			}
@@ -215,10 +169,11 @@ class OC_Mount_Config {
 						foreach ($options as &$option) {
 							$option = self::setUserVars($user, $option);
 						}
+						$backend = $backendService->getBackend($options['class']);
 						$options['personal'] = false;
 						$options['options'] = self::decryptPasswords($options['options']);
 						if (!isset($options['priority'])) {
-							$options['priority'] = $backends[$options['class']]['priority'];
+							$options['priority'] = $backend->getPriority();
 						}
 
 						// Override if priority greater or if priority type different
@@ -227,7 +182,7 @@ class OC_Mount_Config {
 							|| ($mountPoints[$mountPoint]['priority_type'] !== self::MOUNT_TYPE_GROUP)
 						) {
 							$options['priority_type'] = self::MOUNT_TYPE_GROUP;
-							$options['backend'] = $backends[$options['class']]['backend'];
+							$options['backend'] = $backend->getText();
 							$mountPoints[$mountPoint] = $options;
 						}
 					}
@@ -243,10 +198,11 @@ class OC_Mount_Config {
 						foreach ($options as &$option) {
 							$option = self::setUserVars($user, $option);
 						}
+						$backend = $backendService->getBackend($options['class']);
 						$options['personal'] = false;
 						$options['options'] = self::decryptPasswords($options['options']);
 						if (!isset($options['priority'])) {
-							$options['priority'] = $backends[$options['class']]['priority'];
+							$options['priority'] = $backend->getPriority();
 						}
 
 						// Override if priority greater or if priority type different
@@ -255,7 +211,7 @@ class OC_Mount_Config {
 							|| ($mountPoints[$mountPoint]['priority_type'] !== self::MOUNT_TYPE_USER)
 						) {
 							$options['priority_type'] = self::MOUNT_TYPE_USER;
-							$options['backend'] = $backends[$options['class']]['backend'];
+							$options['backend'] = $backend->getText();
 							$mountPoints[$mountPoint] = $options;
 						}
 					}
@@ -263,19 +219,18 @@ class OC_Mount_Config {
 			}
 		}
 
-		$personalBackends = self::getPersonalBackends();
-
 		// Load personal mount points
 		$mountConfig = self::readData($user);
 		if (isset($mountConfig[self::MOUNT_TYPE_USER][$user])) {
 			foreach ($mountConfig[self::MOUNT_TYPE_USER][$user] as $mountPoint => $options) {
-				if (isset($personalBackends[$options['class']])) {
+				$backend = $backendService->getBackend($options['class']);
+				if ($backend->isVisibleFor(BackendService::VISIBILITY_PERSONAL)) {
 					$options['personal'] = true;
 					$options['options'] = self::decryptPasswords($options['options']);
 
 					// Always override previous config
 					$options['priority_type'] = self::MOUNT_TYPE_PERSONAL;
-					$options['backend'] = $backends[$options['class']]['backend'];
+					$options['backend'] = $backend->getText();
 					$mountPoints[$mountPoint] = $options;
 				}
 			}
@@ -304,43 +259,6 @@ class OC_Mount_Config {
 		return $input;
 	}
 
-
-	/**
-	 * Get details on each of the external storage backends, used for the mount config UI
-	 * Some backends are not available as a personal backend, f.e. Local and such that have
-	 * been disabled by the admin.
-	 *
-	 * If a custom UI is needed, add the key 'custom' and a javascript file with that name will be loaded
-	 * If the configuration parameter should be secret, add a '*' to the beginning of the value
-	 * If the configuration parameter is a boolean, add a '!' to the beginning of the value
-	 * If the configuration parameter is optional, add a '&' to the beginning of the value
-	 * If the configuration parameter is hidden, add a '#' to the beginning of the value
-	 *
-	 * @return array
-	 */
-	public static function getPersonalBackends() {
-
-		// Check whether the user has permissions to add personal storage backends
-		// return an empty array if this is not the case
-		if (OCP\Config::getAppValue('files_external', 'allow_user_mounting', 'yes') !== 'yes') {
-			return array();
-		}
-
-		$backEnds = self::getBackends();
-
-		// Remove local storage and other disabled storages
-		unset($backEnds['\OC\Files\Storage\Local']);
-
-		$allowedBackEnds = explode(',', OCP\Config::getAppValue('files_external', 'user_mounting_backends', ''));
-		foreach ($backEnds as $backend => $null) {
-			if (!in_array($backend, $allowedBackEnds)) {
-				unset($backEnds[$backend]);
-			}
-		}
-
-		return $backEnds;
-	}
-
 	/**
 	 * Get the system mount points
 	 * The returned array is not in the same format as getUserMountPoints()
@@ -349,7 +267,7 @@ class OC_Mount_Config {
 	 */
 	public static function getSystemMountPoints() {
 		$mountPoints = self::readData();
-		$backends = self::getBackends();
+		$backendService = self::$appContainer->query('\OCA\Files_External\Service\BackendService');
 		$system = array();
 		if (isset($mountPoints[self::MOUNT_TYPE_GROUP])) {
 			foreach ($mountPoints[self::MOUNT_TYPE_GROUP] as $group => $mounts) {
@@ -358,9 +276,10 @@ class OC_Mount_Config {
 					if (strpos($mount['class'], 'OC_Filestorage_') !== false) {
 						$mount['class'] = '\OC\Files\Storage\\' . substr($mount['class'], 15);
 					}
+					$backend = $backendService->getBackend($mount['class']);
 					$mount['options'] = self::decryptPasswords($mount['options']);
 					if (!isset($mount['priority'])) {
-						$mount['priority'] = $backends[$mount['class']]['priority'];
+						$mount['priority'] = $backend->getPriority();
 					}
 					// Remove '/$user/files/' from mount point
 					$mountPoint = substr($mountPoint, 13);
@@ -368,7 +287,7 @@ class OC_Mount_Config {
 					$config = array(
 						'class' => $mount['class'],
 						'mountpoint' => $mountPoint,
-						'backend' => $backends[$mount['class']]['backend'],
+						'backend' => $backend->getText(),
 						'priority' => $mount['priority'],
 						'options' => $mount['options'],
 						'applicable' => array('groups' => array($group), 'users' => array())
@@ -401,16 +320,17 @@ class OC_Mount_Config {
 					if (strpos($mount['class'], 'OC_Filestorage_') !== false) {
 						$mount['class'] = '\OC\Files\Storage\\' . substr($mount['class'], 15);
 					}
+					$backend = $backendService->getBackend($mount['class']);
 					$mount['options'] = self::decryptPasswords($mount['options']);
 					if (!isset($mount['priority'])) {
-						$mount['priority'] = $backends[$mount['class']]['priority'];
+						$mount['priority'] = $backend->getPriority();
 					}
 					// Remove '/$user/files/' from mount point
 					$mountPoint = substr($mountPoint, 13);
 					$config = array(
 						'class' => $mount['class'],
 						'mountpoint' => $mountPoint,
-						'backend' => $backends[$mount['class']]['backend'],
+						'backend' => $backend->getText(),
 						'priority' => $mount['priority'],
 						'options' => $mount['options'],
 						'applicable' => array('groups' => array(), 'users' => array($user))
@@ -447,7 +367,7 @@ class OC_Mount_Config {
 	 */
 	public static function getPersonalMountPoints() {
 		$mountPoints = self::readData(OCP\User::getUser());
-		$backEnds = self::getBackends();
+		$backendService = self::$appContainer->query('\OCA\Files_External\Service\BackendService');
 		$uid = OCP\User::getUser();
 		$personal = array();
 		if (isset($mountPoints[self::MOUNT_TYPE_USER][$uid])) {
@@ -456,12 +376,13 @@ class OC_Mount_Config {
 				if (strpos($mount['class'], 'OC_Filestorage_') !== false) {
 					$mount['class'] = '\OC\Files\Storage\\' . substr($mount['class'], 15);
 				}
+				$backend = $backendService->getBackend($mount['class']);
 				$mount['options'] = self::decryptPasswords($mount['options']);
 				$config = array(
 					'class' => $mount['class'],
 					// Remove '/uid/files/' from mount point
 					'mountpoint' => substr($mountPoint, strlen($uid) + 8),
-					'backend' => $backEnds[$mount['class']]['backend'],
+					'backend' => $backend->getText(),
 					'options' => $mount['options']
 				);
 				if (isset($mount['id'])) {
@@ -535,7 +456,7 @@ class OC_Mount_Config {
 										 $applicable,
 										 $isPersonal = false,
 										 $priority = null) {
-		$backends = self::getBackends();
+		$backendService = self::$appContainer->query('\OCA\Files_External\Service\BackendService');
 		$mountPoint = OC\Files\Filesystem::normalizePath($mountPoint);
 		$relMountPoint = $mountPoint;
 		if ($mountPoint === '' || $mountPoint === '/') {
@@ -543,15 +464,15 @@ class OC_Mount_Config {
 			return false;
 		}
 
-		if (!isset($backends[$class])) {
+		$backend = $backendService->getBackend($class);
+		if (!isset($backend)) {
 			// invalid backend
 			return false;
 		}
 		if ($isPersonal) {
 			// Verify that the mount point applies for the current user
 			// Prevent non-admin users from mounting local storage and other disabled backends
-			$allowed_backends = self::getPersonalBackends();
-			if ($applicable != OCP\User::getUser() || !isset($allowed_backends[$class])) {
+			if ($applicable != OCP\User::getUser() || !$backend->isVisibleFor(BackendConfig::VISIBILITY_PERSONAL)) {
 				return false;
 			}
 			$mountPoint = '/' . $applicable . '/files/' . ltrim($mountPoint, '/');
@@ -578,13 +499,8 @@ class OC_Mount_Config {
 
 		// Set default priority if none set
 		if (!isset($mountPoints[$mountType][$applicable][$mountPoint]['priority'])) {
-			if (isset($backends[$class]['priority'])) {
-				$mountPoints[$mountType][$applicable][$mountPoint]['priority']
-					= $backends[$class]['priority'];
-			} else {
-				$mountPoints[$mountType][$applicable][$mountPoint]['priority']
-					= 100;
-			}
+			$mountPoints[$mountType][$applicable][$mountPoint]['priority']
+				= $backend->getPriority();
 		}
 
 		self::writeData($isPersonal ? OCP\User::getUser() : null, $mountPoints);
@@ -721,74 +637,35 @@ class OC_Mount_Config {
 	}
 
 	/**
-	 * check dependencies
+	 * Get backend dependency message
+	 * TODO: move into AppFramework along with templates
+	 *
+	 * @param BackendConfig[] $backends
+	 * @return string
 	 */
-	public static function checkDependencies() {
-		$dependencies = array();
-		foreach (OC_Mount_Config::$backends as $class => $backend) {
-			if (isset($backend['has_dependencies']) and $backend['has_dependencies'] === true) {
-				$result = $class::checkDependencies();
-				if ($result !== true) {
-					if (!is_array($result)) {
-						$result = array($result);
-					}
-					foreach ($result as $key => $value) {
-						if (is_numeric($key)) {
-							OC_Mount_Config::addDependency($dependencies, $value, $backend['backend']);
-						} else {
-							OC_Mount_Config::addDependency($dependencies, $key, $backend['backend'], $value);
-						}
-					}
-				}
-			}
-		}
-
-		if (count($dependencies) > 0) {
-			return OC_Mount_Config::generateDependencyMessage($dependencies);
-		}
-		return '';
-	}
-
-	private static function addDependency(&$dependencies, $module, $backend, $message = null) {
-		if (!isset($dependencies[$module])) {
-			$dependencies[$module] = array();
-		}
-
-		if ($message === null) {
-			$dependencies[$module][] = $backend;
-		} else {
-			$dependencies[$module][] = array('backend' => $backend, 'message' => $message);
-		}
-	}
-
-	private static function generateDependencyMessage($dependencies) {
+	public static function dependencyMessage($backends) {
 		$l = new \OC_L10N('files_external');
-		$dependencyMessage = '';
-		foreach ($dependencies as $module => $backends) {
-			$dependencyGroup = array();
-			foreach ($backends as $backend) {
-				if (is_array($backend)) {
-					$dependencyMessage .= '<br />' . $l->t('<b>Note:</b> ') . $backend['message'];
+		$message = '';
+		$dependencyGroups = [];
+
+		foreach ($backends as $backend) {
+			foreach ($backend->checkDependencies() as $dependency) {
+				if ($message = $dependency->getMessage()) {
+					$message .= '<br />' . $l->t('<b>Note:</b> ') . $message;
 				} else {
-					$dependencyGroup[] = $backend;
+					$dependencyGroups[$dependency->getDependency()][] = $backend;
 				}
 			}
+		}
 
-			$dependencyGroupCount = count($dependencyGroup);
-			if ($dependencyGroupCount > 0) {
-				$backends = '';
-				for ($i = 0; $i < $dependencyGroupCount; $i++) {
-					if ($i > 0 && $i === $dependencyGroupCount - 1) {
-						$backends .= ' ' . $l->t('and') . ' ';
-					} elseif ($i > 0) {
-						$backends .= ', ';
-					}
-					$backends .= '<i>' . $dependencyGroup[$i] . '</i>';
-				}
-				$dependencyMessage .= '<br />' . OC_Mount_Config::getSingleDependencyMessage($l, $module, $backends);
-			}
+		foreach ($dependencyGroups as $module => $dependants) {
+			$backends = implode(', ', array_map(function($backend) {
+				return '<i>' . $backend->getText() . '</i>';
+			}, $dependants));
+			$message .= '<br />' . OC_Mount_Config::getSingleDependencyMessage($l, $module, $backends);
 		}
-		return $dependencyMessage;
+
+		return $message;
 	}
 
 	/**
diff --git a/apps/files_external/lib/config/configadapter.php b/apps/files_external/lib/config/configadapter.php
index b5c2ba4fc92..6956de1e748 100644
--- a/apps/files_external/lib/config/configadapter.php
+++ b/apps/files_external/lib/config/configadapter.php
@@ -24,14 +24,23 @@ namespace OCA\Files_External\Config;
 
 use OC\Files\Mount\MountPoint;
 use OCP\Files\Storage\IStorageFactory;
-use OCA\Files_External\PersonalMount;
+use OCA\Files_External\Lib\PersonalMount;
 use OCP\Files\Config\IMountProvider;
 use OCP\IUser;
+use OCA\Files_external\Service\UserStoragesService;
 
 /**
  * Make the old files_external config work with the new public mount config api
  */
 class ConfigAdapter implements IMountProvider {
+
+	/**
+	 * @param UserStoragesService $userStoragesService
+	 */
+	public function __construct(UserStoragesService $userStoragesService) {
+		$this->userStoragesService = $userStoragesService;
+	}
+
 	/**
 	 * Get all mountpoints applicable for the user
 	 *
@@ -49,7 +58,8 @@ class ConfigAdapter implements IMountProvider {
 			}
 			$mountOptions = isset($options['mountOptions']) ? $options['mountOptions'] : [];
 			if (isset($options['personal']) && $options['personal']) {
-				$mounts[] = new PersonalMount($options['class'], $mountPoint, $options['options'], $loader, $mountOptions);
+				$mount = new PersonalMount($this->userStoragesService, $options['id'], $options['class'], $mountPoint, $options['options'], $loader, $mountOptions);
+				$mounts[] = $mount;
 			} else {
 				$mounts[] = new MountPoint($options['class'], $mountPoint, $options['options'], $loader, $mountOptions);
 			}
diff --git a/apps/files_external/lib/definitionparameter.php b/apps/files_external/lib/definitionparameter.php
new file mode 100644
index 00000000000..4b560908b69
--- /dev/null
+++ b/apps/files_external/lib/definitionparameter.php
@@ -0,0 +1,179 @@
+<?php
+/**
+ * @author Robin McCorkell <rmccorkell@karoshi.org.uk>
+ *
+ * @copyright Copyright (c) 2015, ownCloud, Inc.
+ * @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\Files_External\Lib;
+
+/**
+ * Parameter for an external storage definition
+ */
+class DefinitionParameter implements \JsonSerializable {
+
+	/** Value constants */
+	const VALUE_TEXT = 0;
+	const VALUE_BOOLEAN = 1;
+	const VALUE_PASSWORD = 2;
+	const VALUE_HIDDEN = 3;
+
+	/** Flag constants */
+	const FLAG_NONE = 0;
+	const FLAG_OPTIONAL = 1;
+
+	/** @var string name of parameter */
+	private $name;
+
+	/** @var string human-readable parameter text */
+	private $text;
+
+	/** @var int value type, see self::VALUE_* constants */
+	private $type = self::VALUE_TEXT;
+
+	/** @var int flags, see self::FLAG_* constants */
+	private $flags = self::FLAG_NONE;
+
+	/**
+	 * @param string $name
+	 * @param string $text
+	 */
+	public function __construct($name, $text) {
+		$this->name = $name;
+		$this->text = $text;
+	}
+
+	/**
+	 * @return string
+	 */
+	public function getName() {
+		return $this->name;
+	}
+
+	/**
+	 * @return string
+	 */
+	public function getText() {
+		return $this->text;
+	}
+
+	/**
+	 * Get value type
+	 *
+	 * @return int
+	 */
+	public function getType() {
+		return $this->type;
+	}
+
+	/**
+	 * Set value type
+	 *
+	 * @param int $type
+	 * @return self
+	 */
+	public function setType($type) {
+		$this->type = $type;
+		return $this;
+	}
+
+	/**
+	 * @return int
+	 */
+	public function getFlags() {
+		return $this->flags;
+	}
+
+	/**
+	 * @param int $flags
+	 * @return self
+	 */
+	public function setFlags($flags) {
+		$this->flags = $flags;
+		return $this;
+	}
+
+	/**
+	 * @param int $flag
+	 * @return self
+	 */
+	public function setFlag($flag) {
+		$this->flags |= $flag;
+		return $this;
+	}
+
+	/**
+	 * @param int $flag
+	 * @return bool
+	 */
+	public function isFlagSet($flag) {
+		return (bool) $this->flags & $flag;
+	}
+
+	/**
+	 * Serialize into JSON for client-side JS
+	 *
+	 * @return string
+	 */
+	public function jsonSerialize() {
+		$prefix = '';
+		switch ($this->getType()) {
+			case self::VALUE_BOOLEAN:
+				$prefix = '!';
+				break;
+			case self::VALUE_PASSWORD:
+				$prefix = '*';
+				break;
+			case self::VALUE_HIDDEN:
+				$prefix = '#';
+				break;
+		}
+
+		switch ($this->getFlags()) {
+			case self::FLAG_OPTIONAL:
+				$prefix = '&' . $prefix;
+				break;
+		}
+
+		return $prefix . $this->getText();
+	}
+
+	/**
+	 * Validate a parameter value against this
+	 *
+	 * @param mixed $value Value to check
+	 * @return bool success
+	 */
+	public function validateValue($value) {
+		if ($this->getFlags() & self::FLAG_OPTIONAL) {
+			return true;
+		}
+		switch ($this->getType()) {
+		case self::VALUE_BOOLEAN:
+			if (!is_bool($value)) {
+				return false;
+			}
+			break;
+		default:
+			if (empty($value)) {
+				return false;
+			}
+			break;
+		}
+		return true;
+	}
+}
diff --git a/apps/files_external/lib/dependencytrait.php b/apps/files_external/lib/dependencytrait.php
new file mode 100644
index 00000000000..116421eab14
--- /dev/null
+++ b/apps/files_external/lib/dependencytrait.php
@@ -0,0 +1,86 @@
+<?php
+/**
+ * @author Robin McCorkell <rmccorkell@owncloud.com>
+ *
+ * @copyright Copyright (c) 2015, ownCloud, Inc.
+ * @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\Files_External\Lib;
+
+use \OCA\Files_External\Lib\MissingDependency;
+
+/**
+ * Trait for objects that have dependencies for use
+ */
+trait DependencyTrait {
+
+	/** @var callable|null dependency check */
+	private $dependencyCheck = null;
+
+	/**
+	 * @return bool
+	 */
+	public function hasDependencies() {
+		return !is_null($this->dependencyCheck);
+	}
+
+	/**
+	 * @param callable $dependencyCheck
+	 * @return self
+	 */
+	public function setDependencyCheck(callable $dependencyCheck) {
+		$this->dependencyCheck = $dependencyCheck;
+		return $this;
+	}
+
+	/**
+	 * Check if object is valid for use
+	 *
+	 * @return MissingDependency[] Unsatisfied dependencies
+	 */
+	public function checkDependencies() {
+		$ret = [];
+
+		if ($this->hasDependencies()) {
+			$result = call_user_func($this->dependencyCheck);
+			if ($result !== true) {
+				if (!is_array($result)) {
+					$result = [$result];
+				}
+				foreach ($result as $key => $value) {
+					if (!($value instanceof MissingDependency)) {
+						$module = null;
+						$message = null;
+						if (is_numeric($key)) {
+							$module = $value;
+						} else {
+							$module = $key;
+							$message = $value;
+						}
+						$value = new MissingDependency($module, $this);
+						$value->setMessage($message);
+					}
+					$ret[] = $value;
+				}
+			}
+		}
+
+		return $ret;
+	}
+
+}
+
diff --git a/apps/files_external/lib/frontenddefinitiontrait.php b/apps/files_external/lib/frontenddefinitiontrait.php
new file mode 100644
index 00000000000..4b826372d2f
--- /dev/null
+++ b/apps/files_external/lib/frontenddefinitiontrait.php
@@ -0,0 +1,147 @@
+<?php
+/**
+ * @author Robin McCorkell <rmccorkell@owncloud.com>
+ *
+ * @copyright Copyright (c) 2015, ownCloud, Inc.
+ * @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\Files_External\Lib;
+
+use \OCA\Files_External\Lib\DefinitionParameter;
+use \OCA\Files_External\Lib\StorageConfig;
+
+/**
+ * Trait for objects that have a frontend representation
+ */
+trait FrontendDefinitionTrait {
+
+	/** @var string human-readable mechanism name */
+	private $text;
+
+	/** @var DefinitionParameter[] parameters for mechanism */
+	private $parameters = [];
+
+	/** @var string|null custom JS */
+	private $customJs = null;
+
+	/**
+	 * @return string
+	 */
+	public function getText() {
+		return $this->text;
+	}
+
+	/**
+	 * @param string $text
+	 * @return self
+	 */
+	public function setText($text) {
+		$this->text = $text;
+		return $this;
+	}
+
+	/**
+	 * @param FrontendDefinitionTrait $a
+	 * @param FrontendDefinitionTrait $b
+	 * @return int
+	 */
+	public static function lexicalCompare(FrontendDefinitionTrait $a, FrontendDefinitionTrait $b) {
+		return strcmp($a->getText(), $b->getText());
+	}
+
+	/**
+	 * @return DefinitionParameter[]
+	 */
+	public function getParameters() {
+		return $this->parameters;
+	}
+
+	/**
+	 * @param DefinitionParameter[] $parameters
+	 * @return self
+	 */
+	public function addParameters(array $parameters) {
+		foreach ($parameters as $parameter) {
+			$this->addParameter($parameter);
+		}
+		return $this;
+	}
+
+	/**
+	 * @param DefinitionParameter $parameter
+	 * @return self
+	 */
+	public function addParameter(DefinitionParameter $parameter) {
+		$this->parameters[$parameter->getName()] = $parameter;
+		return $this;
+	}
+
+	/**
+	 * @return string|null
+	 */
+	public function getCustomJs() {
+		return $this->customJs;
+	}
+
+	/**
+	 * @param string $custom
+	 * @return self
+	 */
+	public function setCustomJs($custom) {
+		$this->customJs = $custom;
+		return $this;
+	}
+
+	/**
+	 * Serialize into JSON for client-side JS
+	 *
+	 * @return array
+	 */
+	public function jsonSerializeDefinition() {
+		$configuration = [];
+		foreach ($this->getParameters() as $parameter) {
+			$configuration[$parameter->getName()] = $parameter;
+		}
+
+		$data = [
+			'name' => $this->getText(),
+			'configuration' => $configuration,
+		];
+		if (isset($this->customJs)) {
+			$data['custom'] = $this->getCustomJs();
+		}
+		return $data;
+	}
+
+	/**
+	 * Check if parameters are satisfied in a StorageConfig
+	 *
+	 * @param StorageConfig $storage
+	 * @return bool
+	 */
+	public function validateStorageDefinition(StorageConfig $storage) {
+		$options = $storage->getBackendOptions();
+		foreach ($this->getParameters() as $name => $parameter) {
+			$value = isset($options[$name]) ? $options[$name] : null;
+			if (!$parameter->validateValue($value)) {
+				return false;
+			}
+		}
+		return true;
+	}
+
+}
diff --git a/apps/files_external/lib/missingdependency.php b/apps/files_external/lib/missingdependency.php
new file mode 100644
index 00000000000..9b25aeacc9b
--- /dev/null
+++ b/apps/files_external/lib/missingdependency.php
@@ -0,0 +1,64 @@
+<?php
+/**
+ * @author Robin McCorkell <rmccorkell@karoshi.org.uk>
+ *
+ * @copyright Copyright (c) 2015, ownCloud, Inc.
+ * @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\Files_External\Lib;
+
+/**
+ * External storage backend dependency
+ */
+class MissingDependency {
+
+	/** @var string */
+	private $dependency;
+
+	/** @var string|null Custom message */
+	private $message = null;
+
+	/**
+	 * @param string $dependency
+	 */
+	public function __construct($dependency) {
+		$this->dependency = $dependency;
+	}
+
+	/**
+	 * @return string
+	 */
+	public function getDependency() {
+		return $this->dependency;
+	}
+
+	/**
+	 * @return string|null
+	 */
+	public function getMessage() {
+		return $this->message;
+	}
+
+	/**
+	 * @param string $message
+	 * @return self
+	 */
+	public function setMessage($message) {
+		$this->message = $message;
+		return $this;
+	}
+}
diff --git a/apps/files_external/lib/personalmount.php b/apps/files_external/lib/personalmount.php
index bbffc958641..d177f1a1ad0 100644
--- a/apps/files_external/lib/personalmount.php
+++ b/apps/files_external/lib/personalmount.php
@@ -20,15 +20,45 @@
  *
  */
 
-namespace OCA\Files_External;
+namespace OCA\Files_External\Lib;
 
 use OC\Files\Mount\MountPoint;
 use OC\Files\Mount\MoveableMount;
+use OCA\Files_External\Service\UserStoragesService;
 
 /**
  * Person mount points can be moved by the user
  */
 class PersonalMount extends MountPoint implements MoveableMount {
+	/** @var UserStoragesService */
+	protected $storagesService;
+
+	/** @var int */
+	protected $storageId;
+
+	/**
+	 * @param UserStoragesService $storagesService
+	 * @param int $storageId
+	 * @param string|\OC\Files\Storage\Storage $storage
+	 * @param string $mountpoint
+	 * @param array $arguments (optional) configuration for the storage backend
+	 * @param \OCP\Files\Storage\IStorageFactory $loader
+	 * @param array $mountOptions mount specific options
+	 */
+	public function __construct(
+		UserStoragesService $storagesService,
+		$storageId,
+		$storage,
+		$mountpoint,
+		$arguments = null,
+		$loader = null,
+		$mountOptions = null
+	) {
+		parent::__construct($storage, $mountpoint, $arguments, $loader, $mountOptions);
+		$this->storagesService = $storagesService;
+		$this->storageId = $storageId;
+	}
+
 	/**
 	 * Move the mount point to $target
 	 *
@@ -36,9 +66,13 @@ class PersonalMount extends MountPoint implements MoveableMount {
 	 * @return bool
 	 */
 	public function moveMount($target) {
-		$result = \OC_Mount_Config::movePersonalMountPoint($this->getMountPoint(), $target, \OC_Mount_Config::MOUNT_TYPE_USER);
+		$storage = $this->storagesService->getStorage($this->storageId);
+		// remove "/$user/files" prefix
+		$targetParts = explode('/', trim($target, '/'), 3);
+		$storage->setMountPoint($targetParts[2]);
+		$this->storagesService->updateStorage($storage);
 		$this->setMountPoint($target);
-		return $result;
+		return true;
 	}
 
 	/**
@@ -47,8 +81,7 @@ class PersonalMount extends MountPoint implements MoveableMount {
 	 * @return bool
 	 */
 	public function removeMount() {
-		$user = \OCP\User::getUser();
-		$relativeMountPoint = substr($this->getMountPoint(), strlen('/' . $user . '/files/'));
-		return \OC_Mount_Config::removeMountPoint($relativeMountPoint, \OC_Mount_Config::MOUNT_TYPE_USER, $user , true);
+		$this->storagesService->removeStorage($this->storageId);
+		return true;
 	}
 }
diff --git a/apps/files_external/lib/prioritytrait.php b/apps/files_external/lib/prioritytrait.php
new file mode 100644
index 00000000000..22f9fe275d8
--- /dev/null
+++ b/apps/files_external/lib/prioritytrait.php
@@ -0,0 +1,60 @@
+<?php
+/**
+ * @author Robin McCorkell <rmccorkell@karoshi.org.uk>
+ *
+ * @copyright Copyright (c) 2015, ownCloud, Inc.
+ * @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\Files_External\Lib;
+
+use \OCA\Files_External\Service\BackendService;
+
+/**
+ * Trait to implement priority mechanics for a configuration class
+ */
+trait PriorityTrait {
+
+	/** @var int initial priority */
+	protected $priority = BackendService::PRIORITY_DEFAULT;
+
+	/**
+	 * @return int
+	 */
+	public function getPriority() {
+		return $this->priority;
+	}
+
+	/**
+	 * @param int $priority
+	 * @return self
+	 */
+	public function setPriority($priority) {
+		$this->priority = $priority;
+		return $this;
+	}
+
+	/**
+	 * @param PriorityTrait $a
+	 * @param PriorityTrait $b
+	 * @return int
+	 */
+	public static function priorityCompare(PriorityTrait $a, PriorityTrait $b) {
+		return ($a->getPriority() - $b->getPriority());
+	}
+
+}
+
diff --git a/apps/files_external/lib/storageconfig.php b/apps/files_external/lib/storageconfig.php
index 92c27701d80..cf8271ff4eb 100644
--- a/apps/files_external/lib/storageconfig.php
+++ b/apps/files_external/lib/storageconfig.php
@@ -21,6 +21,8 @@
 
 namespace OCA\Files_external\Lib;
 
+use \OCA\Files_External\Lib\Backend\Backend;
+
 /**
  * External storage configuration
  */
@@ -34,11 +36,11 @@ class StorageConfig implements \JsonSerializable {
 	private $id;
 
 	/**
-	 * Backend class name
+	 * Backend
 	 *
-	 * @var string
+	 * @var Backend
 	 */
-	private $backendClass;
+	private $backend;
 
 	/**
 	 * Backend options
@@ -138,21 +140,17 @@ class StorageConfig implements \JsonSerializable {
 	}
 
 	/**
-	 * Returns the external storage backend class name
-	 *
-	 * @return string external storage backend class name
+	 * @return Backend
 	 */
-	public function getBackendClass() {
-		return $this->backendClass;
+	public function getBackend() {
+		return $this->backend;
 	}
 
 	/**
-	 * Sets the external storage backend class name
-	 *
-	 * @param string external storage backend class name
+	 * @param Backend
 	 */
-	public function setBackendClass($backendClass) {
-		$this->backendClass = $backendClass;
+	public function setBackend(Backend $backend) {
+		$this->backend= $backend;
 	}
 
 	/**
@@ -174,6 +172,25 @@ class StorageConfig implements \JsonSerializable {
 	}
 
 	/**
+	 * @param string $key
+	 * @return mixed
+	 */
+	public function getBackendOption($key) {
+		if (isset($this->backendOptions[$key])) {
+			return $this->backendOptions[$key];
+		}
+		return null;
+	}
+
+	/**
+	 * @param string $key
+	 * @param mixed $value
+	 */
+	public function setBackendOption($key, $value) {
+		$this->backendOptions[$key] = $value;
+	}
+
+	/**
 	 * Returns the mount priority
 	 *
 	 * @return int priority
@@ -283,7 +300,7 @@ class StorageConfig implements \JsonSerializable {
 			$result['id'] = $this->id;
 		}
 		$result['mountPoint'] = $this->mountPoint;
-		$result['backendClass'] = $this->backendClass;
+		$result['backendClass'] = $this->backend->getClass();
 		$result['backendOptions'] = $this->backendOptions;
 		if (!is_null($this->priority)) {
 			$result['priority'] = $this->priority;
diff --git a/apps/files_external/lib/storagemodifiertrait.php b/apps/files_external/lib/storagemodifiertrait.php
new file mode 100644
index 00000000000..f78116103db
--- /dev/null
+++ b/apps/files_external/lib/storagemodifiertrait.php
@@ -0,0 +1,51 @@
+<?php
+/**
+ * @author Robin McCorkell <rmccorkell@owncloud.com>
+ *
+ * @copyright Copyright (c) 2015, ownCloud, Inc.
+ * @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\Files_External\Lib;
+
+use \OCP\Files\Storage;
+use \OCA\Files_External\Lib\StorageConfig;
+
+/**
+ * Trait for objects that can modify StorageConfigs and wrap Storages
+ */
+trait StorageModifierTrait {
+
+	/**
+	 * Modify a StorageConfig parameters
+	 *
+	 * @param StorageConfig $storage
+	 */
+	public function manipulateStorageConfig(StorageConfig &$storage) {
+	}
+
+	/**
+	 * Wrap a Storage if necessary
+	 *
+	 * @param Storage $storage
+	 * @return Storage
+	 */
+	public function wrapStorage(Storage $storage) {
+		return $storage;
+	}
+
+}
+
diff --git a/apps/files_external/lib/visibilitytrait.php b/apps/files_external/lib/visibilitytrait.php
new file mode 100644
index 00000000000..06c95dd70c9
--- /dev/null
+++ b/apps/files_external/lib/visibilitytrait.php
@@ -0,0 +1,129 @@
+<?php
+/**
+ * @author Robin McCorkell <rmccorkell@karoshi.org.uk>
+ *
+ * @copyright Copyright (c) 2015, ownCloud, Inc.
+ * @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\Files_External\Lib;
+
+use \OCA\Files_External\Service\BackendService;
+
+/**
+ * Trait to implement visibility mechanics for a configuration class
+ */
+trait VisibilityTrait {
+
+	/** @var int visibility */
+	protected $visibility = BackendService::VISIBILITY_DEFAULT;
+
+	/** @var int allowed visibilities */
+	protected $allowedVisibility = BackendService::VISIBILITY_DEFAULT;
+
+	/**
+	 * @return int
+	 */
+	public function getVisibility() {
+		return $this->visibility;
+	}
+
+	/**
+	 * Check if the backend is visible for a user type
+	 *
+	 * @param int $visibility
+	 * @return bool
+	 */
+	public function isVisibleFor($visibility) {
+		if ($this->visibility & $visibility) {
+			return true;
+		}
+		return false;
+	}
+
+	/**
+	 * @param int $visibility
+	 * @return self
+	 */
+	public function setVisibility($visibility) {
+		$this->visibility = $visibility;
+		$this->allowedVisibility |= $visibility;
+		return $this;
+	}
+
+	/**
+	 * @param int $visibility
+	 * @return self
+	 */
+	public function addVisibility($visibility) {
+		return $this->setVisibility($this->visibility | $visibility);
+	}
+
+	/**
+	 * @param int $visibility
+	 * @return self
+	 */
+	public function removeVisibility($visibility) {
+		return $this->setVisibility($this->visibility & ~$visibility);
+	}
+
+	/**
+	 * @return int
+	 */
+	public function getAllowedVisibility() {
+		return $this->allowedVisibility;
+	}
+
+	/**
+	 * Check if the backend is allowed to be visible for a user type
+	 *
+	 * @param int $allowedVisibility
+	 * @return bool
+	 */
+	public function isAllowedVisibleFor($allowedVisibility) {
+		if ($this->allowedVisibility & $allowedVisibility) {
+			return true;
+		}
+		return false;
+	}
+
+	/**
+	 * @param int $allowedVisibility
+	 * @return self
+	 */
+	public function setAllowedVisibility($allowedVisibility) {
+		$this->allowedVisibility = $allowedVisibility;
+		$this->visibility &= $allowedVisibility;
+		return $this;
+	}
+
+	/**
+	 * @param int $allowedVisibility
+	 * @return self
+	 */
+	public function addAllowedVisibility($allowedVisibility) {
+		return $this->setAllowedVisibility($this->allowedVisibility | $allowedVisibility);
+	}
+
+	/**
+	 * @param int $allowedVisibility
+	 * @return self
+	 */
+	public function removeAllowedVisibility($allowedVisibility) {
+		return $this->setAllowedVisibility($this->allowedVisibility & ~$allowedVisibility);
+	}
+
+}
diff --git a/apps/files_external/personal.php b/apps/files_external/personal.php
index 1ac0f65a1f0..e204cdbeb99 100644
--- a/apps/files_external/personal.php
+++ b/apps/files_external/personal.php
@@ -24,34 +24,20 @@
  *
  */
 
-OCP\Util::addScript('files_external', 'settings');
-OCP\Util::addStyle('files_external', 'settings');
-$backends = OC_Mount_Config::getPersonalBackends();
+use \OCA\Files_External\Service\BackendService;
 
-$mounts = OC_Mount_Config::getPersonalMountPoints();
-$hasId = true;
-foreach ($mounts as $mount) {
-	if (!isset($mount['id'])) {
-		// some mount points are missing ids
-		$hasId = false;
-		break;
-	}
-}
+$app = new \OCA\Files_external\Appinfo\Application();
+$appContainer = $app->getContainer();
+$backendService = $appContainer->query('OCA\Files_External\Service\BackendService');
+$userStoragesService = $appContainer->query('OCA\Files_external\Service\UserStoragesService');
 
-if (!$hasId) {
-	$service = new \OCA\Files_external\Service\UserStoragesService(\OC::$server->getUserSession());
-	// this will trigger the new storage code which will automatically
-	// generate storage config ids
-	$service->getAllStorages();
-	// re-read updated config
-	$mounts = OC_Mount_Config::getPersonalMountPoints();
-	// TODO: use the new storage config format in the template
-}
+OCP\Util::addScript('files_external', 'settings');
+OCP\Util::addStyle('files_external', 'settings');
 
 $tmpl = new OCP\Template('files_external', 'settings');
 $tmpl->assign('encryptionEnabled', \OC::$server->getEncryptionManager()->isEnabled());
 $tmpl->assign('isAdminPage', false);
-$tmpl->assign('mounts', $mounts);
-$tmpl->assign('dependencies', OC_Mount_Config::checkDependencies());
-$tmpl->assign('backends', $backends);
+$tmpl->assign('storages', $userStoragesService->getAllStorages());
+$tmpl->assign('dependencies', OC_Mount_Config::dependencyMessage($backendService->getBackends()));
+$tmpl->assign('backends', $backendService->getBackendsVisibleFor(BackendService::VISIBILITY_PERSONAL));
 return $tmpl->fetchPage();
diff --git a/apps/files_external/service/backendservice.php b/apps/files_external/service/backendservice.php
new file mode 100644
index 00000000000..f5859bc7272
--- /dev/null
+++ b/apps/files_external/service/backendservice.php
@@ -0,0 +1,170 @@
+<?php
+/**
+ * @author Robin McCorkell <rmccorkell@karoshi.org.uk>
+ *
+ * @copyright Copyright (c) 2015, ownCloud, Inc.
+ * @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\Files_External\Service;
+
+use \OCP\IConfig;
+
+use \OCA\Files_External\Lib\Backend\Backend;
+
+/**
+ * Service class to manage backend definitions
+ */
+class BackendService {
+
+	/** Visibility constants for VisibilityTrait */
+	const VISIBILITY_NONE = 0;
+	const VISIBILITY_PERSONAL = 1;
+	const VISIBILITY_ADMIN = 2;
+	//const VISIBILITY_ALIENS = 4;
+
+	const VISIBILITY_DEFAULT = 3; // PERSONAL | ADMIN
+
+	/** Priority constants for PriorityTrait */
+	const PRIORITY_DEFAULT = 100;
+
+	/** @var IConfig */
+	protected $config;
+
+	/** @var bool */
+	private $userMountingAllowed = true;
+
+	/** @var string[] */
+	private $userMountingBackends = [];
+
+	/** @var Backend[] */
+	private $backends = [];
+
+	/**
+	 * @param IConfig $config
+	 */
+	public function __construct(
+		IConfig $config
+	) {
+		$this->config = $config;
+
+		// Load config values
+		if ($this->config->getAppValue('files_external', 'allow_user_mounting', 'yes') !== 'yes') {
+			$this->userMountingAllowed = false;
+		}
+		$this->userMountingBackends = explode(',',
+			$this->config->getAppValue('files_external', 'user_mounting_backends', '')
+		);
+	}
+
+	/**
+	 * Register a backend
+	 *
+	 * @param Backend $backend
+	 */
+	public function registerBackend(Backend $backend) {
+		if (!$this->isAllowedUserBackend($backend)) {
+			$backend->removeVisibility(BackendService::VISIBILITY_PERSONAL);
+		}
+		$this->backends[$backend->getClass()] = $backend;
+	}
+
+	/**
+	 * @param Backend[] $backends
+	 */
+	public function registerBackends(array $backends) {
+		foreach ($backends as $backend) {
+			$this->registerBackend($backend);
+		}
+	}
+
+	/**
+	 * Get all backends
+	 *
+	 * @return Backend[]
+	 */
+	public function getBackends() {
+		return $this->backends;
+	}
+
+	/**
+	 * Get all available backends
+	 *
+	 * @return Backend[]
+	 */
+	public function getAvailableBackends() {
+		return array_filter($this->getBackends(), function($backend) {
+			return empty($backend->checkDependencies());
+		});
+	}
+
+	/**
+	 * Get backends visible for $visibleFor
+	 *
+	 * @param int $visibleFor
+	 * @return Backend[]
+	 */
+	public function getBackendsVisibleFor($visibleFor) {
+		return array_filter($this->getAvailableBackends(), function($backend) use ($visibleFor) {
+			return $backend->isVisibleFor($visibleFor);
+		});
+	}
+
+	/**
+	 * Get backends allowed to be visible for $visibleFor
+	 *
+	 * @param int $visibleFor
+	 * @return Backend[]
+	 */
+	public function getBackendsAllowedVisibleFor($visibleFor) {
+		return array_filter($this->getAvailableBackends(), function($backend) use ($visibleFor) {
+			return $backend->isAllowedVisibleFor($visibleFor);
+		});
+	}
+
+	/**
+	 * @param string $class Backend class name
+	 * @return Backend|null
+	 */
+	public function getBackend($class) {
+		if (isset($this->backends[$class])) {
+			return $this->backends[$class];
+		}
+		return null;
+	}
+
+	/**
+	 * @return bool
+	 */
+	public function isUserMountingAllowed() {
+		return $this->userMountingAllowed;
+	}
+
+	/**
+	 * Check a backend if a user is allowed to mount it
+	 *
+	 * @param Backend $backend
+	 * @return bool
+	 */
+	protected function isAllowedUserBackend(Backend $backend) {
+		if ($this->userMountingAllowed &&
+			in_array($backend->getClass(), $this->userMountingBackends)
+		) {
+			return true;
+		}
+		return false;
+	}
+}
diff --git a/apps/files_external/service/storagesservice.php b/apps/files_external/service/storagesservice.php
index 930f994455e..5f11d9ace68 100644
--- a/apps/files_external/service/storagesservice.php
+++ b/apps/files_external/service/storagesservice.php
@@ -28,12 +28,23 @@ use \OC\Files\Filesystem;
 
 use \OCA\Files_external\Lib\StorageConfig;
 use \OCA\Files_external\NotFoundException;
+use \OCA\Files_External\Service\BackendService;
 
 /**
  * Service class to manage external storages
  */
 abstract class StoragesService {
 
+	/** @var BackendService */
+	protected $backendService;
+
+	/**
+	 * @param BackendService $backendService
+	 */
+	public function __construct(BackendService $backendService) {
+		$this->backendService = $backendService;
+	}
+
 	/**
 	 * Read legacy config data
 	 *
@@ -60,14 +71,17 @@ abstract class StoragesService {
 		$applicable,
 		$storageOptions
 	) {
-		$storageConfig->setBackendClass($storageOptions['class']);
+		$backend = $this->backendService->getBackend($storageOptions['class']);
+		$storageConfig->setBackend($backend);
+
 		$storageConfig->setBackendOptions($storageOptions['options']);
 		if (isset($storageOptions['mountOptions'])) {
 			$storageConfig->setMountOptions($storageOptions['mountOptions']);
 		}
-		if (isset($storageOptions['priority'])) {
-			$storageConfig->setPriority($storageOptions['priority']);
+		if (!isset($storageOptions['priority'])) {
+			$storageOptions['priority'] = $backend->getPriority();
 		}
+		$storageConfig->setPriority($storageOptions['priority']);
 
 		if ($mountType === \OC_Mount_Config::MOUNT_TYPE_USER) {
 			$applicableUsers = $storageConfig->getApplicableUsers();
@@ -222,7 +236,7 @@ abstract class StoragesService {
 
 		$options = [
 			'id' => $storageConfig->getId(),
-			'class' => $storageConfig->getBackendClass(),
+			'class' => $storageConfig->getBackend()->getClass(),
 			'options' => $storageConfig->getBackendOptions(),
 		];
 
@@ -297,6 +311,52 @@ abstract class StoragesService {
 	}
 
 	/**
+	 * Create a storage from its parameters
+	 *
+	 * @param string $mountPoint storage mount point
+	 * @param string $backendClass backend class name
+	 * @param array $backendOptions backend-specific options
+	 * @param array|null $mountOptions mount-specific options
+	 * @param array|null $applicableUsers users for which to mount the storage
+	 * @param array|null $applicableGroups groups for which to mount the storage
+	 * @param int|null $priority priority
+	 *
+	 * @return StorageConfig
+	 */
+	public function createStorage(
+		$mountPoint,
+		$backendClass,
+		$backendOptions,
+		$mountOptions = null,
+		$applicableUsers = null,
+		$applicableGroups = null,
+		$priority = null
+	) {
+		$backend = $this->backendService->getBackend($backendClass);
+		if (!$backend) {
+			throw new \InvalidArgumentException('Unable to get backend for backend class '.$backendClass);
+		}
+		$newStorage = new StorageConfig();
+		$newStorage->setMountPoint($mountPoint);
+		$newStorage->setBackend($backend);
+		$newStorage->setBackendOptions($backendOptions);
+		if (isset($mountOptions)) {
+			$newStorage->setMountOptions($mountOptions);
+		}
+		if (isset($applicableUsers)) {
+			$newStorage->setApplicableUsers($applicableUsers);
+		}
+		if (isset($applicableGroups)) {
+			$newStorage->setApplicableGroups($applicableGroups);
+		}
+		if (isset($priority)) {
+			$newStorage->setPriority($priority);
+		}
+
+		return $newStorage;
+	}
+
+	/**
 	 * Triggers the given hook signal for all the applicables given
 	 *
 	 * @param string $signal signal
diff --git a/apps/files_external/service/userstoragesservice.php b/apps/files_external/service/userstoragesservice.php
index 2f2556043fe..7ca911d45fb 100644
--- a/apps/files_external/service/userstoragesservice.php
+++ b/apps/files_external/service/userstoragesservice.php
@@ -26,6 +26,7 @@ use \OC\Files\Filesystem;
 
 use \OCA\Files_external\Lib\StorageConfig;
 use \OCA\Files_external\NotFoundException;
+use \OCA\Files_External\Service\BackendService;
 
 /**
  * Service class to manage user external storages
@@ -43,12 +44,15 @@ class UserStoragesService extends StoragesService {
 	/**
 	 * Create a user storages service
 	 *
+	 * @param BackendService $backendService
 	 * @param IUserSession $userSession user session
 	 */
 	public function __construct(
+		BackendService $backendService,
 		IUserSession $userSession
 	) {
 		$this->userSession = $userSession;
+		parent::__construct($backendService);
 	}
 
 	/**
diff --git a/apps/files_external/settings.php b/apps/files_external/settings.php
index 6db68713d98..7c53db4c0dd 100644
--- a/apps/files_external/settings.php
+++ b/apps/files_external/settings.php
@@ -26,54 +26,27 @@
  *
  */
 
+use \OCA\Files_External\Service\BackendService;
+
 OC_Util::checkAdminUser();
 
+$app = new \OCA\Files_external\Appinfo\Application();
+$appContainer = $app->getContainer();
+$backendService = $appContainer->query('OCA\Files_External\Service\BackendService');
+$globalStoragesService = $appContainer->query('OCA\Files_external\Service\GlobalStoragesService');
+
 OCP\Util::addScript('files_external', 'settings');
 OCP\Util::addStyle('files_external', 'settings');
 
 \OC_Util::addVendorScript('select2/select2');
 \OC_Util::addVendorStyle('select2/select2');
 
-$backends = OC_Mount_Config::getBackends();
-$personal_backends = array();
-$enabled_backends = explode(',', OCP\Config::getAppValue('files_external', 'user_mounting_backends', ''));
-foreach ($backends as $class => $backend)
-{
-	if ($class != '\OC\Files\Storage\Local')
-	{
-		$personal_backends[$class] = array(
-			'backend'	=> $backend['backend'],
-			'enabled'	=> in_array($class, $enabled_backends),
-		);
-	}
-}
-
-$mounts = OC_Mount_Config::getSystemMountPoints();
-$hasId = true;
-foreach ($mounts as $mount) {
-	if (!isset($mount['id'])) {
-		// some mount points are missing ids
-		$hasId = false;
-		break;
-	}
-}
-
-if (!$hasId) {
-	$service = new \OCA\Files_external\Service\GlobalStoragesService();
-	// this will trigger the new storage code which will automatically
-	// generate storage config ids
-	$service->getAllStorages();
-	// re-read updated config
-	$mounts = OC_Mount_Config::getSystemMountPoints();
-	// TODO: use the new storage config format in the template
-}
-
 $tmpl = new OCP\Template('files_external', 'settings');
 $tmpl->assign('encryptionEnabled', \OC::$server->getEncryptionManager()->isEnabled());
 $tmpl->assign('isAdminPage', true);
-$tmpl->assign('mounts', $mounts);
-$tmpl->assign('backends', $backends);
-$tmpl->assign('personal_backends', $personal_backends);
-$tmpl->assign('dependencies', OC_Mount_Config::checkDependencies());
-$tmpl->assign('allowUserMounting', OCP\Config::getAppValue('files_external', 'allow_user_mounting', 'yes'));
+$tmpl->assign('storages', $globalStoragesService->getAllStorages());
+$tmpl->assign('backends', $backendService->getBackendsVisibleFor(BackendService::VISIBILITY_ADMIN));
+$tmpl->assign('userBackends', $backendService->getBackendsAllowedVisibleFor(BackendService::VISIBILITY_PERSONAL));
+$tmpl->assign('dependencies', OC_Mount_Config::dependencyMessage($backendService->getBackends()));
+$tmpl->assign('allowUserMounting', $backendService->isUserMountingAllowed());
 return $tmpl->fetchPage();
diff --git a/apps/files_external/templates/settings.php b/apps/files_external/templates/settings.php
index b886c2e1b1b..f931c62eecd 100644
--- a/apps/files_external/templates/settings.php
+++ b/apps/files_external/templates/settings.php
@@ -1,3 +1,8 @@
+<?php
+	use \OCA\Files_External\Lib\Backend\Backend;
+	use \OCA\Files_External\Lib\DefinitionParameter;
+	use \OCA\Files_External\Service\BackendService;
+?>
 <form id="files_external" class="section" data-encryption-enabled="<?php echo $_['encryptionEnabled']?'true': 'false'; ?>">
 	<h2><?php p($l->t('External Storage')); ?></h2>
 	<?php if (isset($_['dependencies']) and ($_['dependencies']<>'')) print_unescaped(''.$_['dependencies'].''); ?>
@@ -14,103 +19,149 @@
 			</tr>
 		</thead>
 		<tbody>
-		<?php $_['mounts'] = array_merge($_['mounts'], array('' => array('id' => ''))); ?>
-		<?php foreach ($_['mounts'] as $mount): ?>
-			<tr <?php print_unescaped(isset($mount['mountpoint']) ? 'class="'.OC_Util::sanitizeHTML($mount['class']).'"' : 'id="addMountPoint"'); ?> data-id="<?php p($mount['id']) ?>">
+		<?php foreach ($_['storages'] as $storage): ?>
+			<tr class="<?php p($storage->getBackend()->getClass()); ?>" data-id="<?php p($storage->getId()); ?>">
 				<td class="status">
 					<span></span>
 				</td>
 				<td class="mountPoint"><input type="text" name="mountPoint"
-											  value="<?php p(isset($mount['mountpoint']) ? $mount['mountpoint'] : ''); ?>"
-											  data-mountpoint="<?php p(isset($mount['mountpoint']) ? $mount['mountpoint'] : ''); ?>"
+											  value="<?php p(ltrim($storage->getMountPoint(), '/')); ?>"
+											  data-mountpoint="<?php p(ltrim($storage->getMountPoint(), '/')); ?>"
 											  placeholder="<?php p($l->t('Folder name')); ?>" />
 				</td>
-				<?php if (!isset($mount['mountpoint'])): ?>
-					<td class="backend">
-						<select id="selectBackend" class="selectBackend" data-configurations='<?php p(json_encode($_['backends'])); ?>'>
-							<option value="" disabled selected
-									style="display:none;"><?php p($l->t('Add storage')); ?></option>
-							<?php foreach ($_['backends'] as $class => $backend): ?>
-								<option value="<?php p($class); ?>"><?php p($backend['backend']); ?></option>
-							<?php endforeach; ?>
-						</select>
-					</td>
-				<?php else: ?>
-					<td class="backend" data-class="<?php p($mount['class']); ?>"><?php p($mount['backend']); ?>
-					</td>
-				<?php endif; ?>
-				<td class ="configuration">
-					<?php if (isset($mount['options'])): ?>
-						<?php foreach ($mount['options'] as $parameter => $value): ?>
-							<?php if (isset($_['backends'][$mount['class']]['configuration'][$parameter])): ?>
+				<td class="backend" data-class="<?php p($storage->getBackend()->getClass()); ?>"><?php p($storage->getBackend()->getText()); ?>
+				</td>
+				<td class="configuration">
+					<?php $options = $storage->getBackendOptions(); ?>
+					<?php foreach ($storage->getBackend()->getParameters() as $parameter): ?>
+						<?php
+							$value = '';
+							if (isset($options[$parameter->getName()])) {
+								$value = $options[$parameter->getName()];
+							}
+							$placeholder = $parameter->getText();
+							$is_optional = $parameter->isFlagSet(DefinitionParameter::FLAG_OPTIONAL);
+
+							switch ($parameter->getType()) {
+							case DefinitionParameter::VALUE_PASSWORD: ?>
+								<input type="password"
+								   <?php if ($is_optional): ?> class="optional"<?php endif; ?>
+								   data-parameter="<?php p($parameter->getName()); ?>"
+								   value="<?php p($value); ?>"
+								   placeholder="<?php p($placeholder); ?>"
+								/>
 								<?php
-									$placeholder = $_['backends'][$mount['class']]['configuration'][$parameter];
-									$is_optional = FALSE;
-									if (strpos($placeholder, '&') === 0) {
-										$is_optional = TRUE;
-										$placeholder = substr($placeholder, 1);
-									}
-								?>
-								<?php if (strpos($placeholder, '*') === 0): ?>
-									<input type="password"
-										   <?php if ($is_optional): ?> class="optional"<?php endif; ?>
-										   data-parameter="<?php p($parameter); ?>"
-										   value="<?php p($value); ?>"
-										   placeholder="<?php p(substr($placeholder, 1)); ?>" />
-								<?php elseif (strpos($placeholder, '!') === 0): ?>
-									<label><input type="checkbox"
-												  data-parameter="<?php p($parameter); ?>"
-												  <?php if ($value == 'true'): ?> checked="checked"<?php endif; ?>
-												  /><?php p(substr($placeholder, 1)); ?></label>
-								<?php elseif (strpos($placeholder, '#') === 0): ?>
-									<input type="hidden"
-										   data-parameter="<?php p($parameter); ?>"
-										   value="<?php p($value); ?>" />
-								<?php else: ?>
-									<input type="text"
-										   <?php if ($is_optional): ?> class="optional"<?php endif; ?>
-										   data-parameter="<?php p($parameter); ?>"
-										   value="<?php p($value); ?>"
-										   placeholder="<?php p($placeholder); ?>" />
-								<?php endif; ?>
-							<?php endif; ?>
-						<?php endforeach; ?>
-						<?php if (isset($_['backends'][$mount['class']]['custom'])): ?>
-							<?php OCP\Util::addScript('files_external', $_['backends'][$mount['class']]['custom']); ?>
-						<?php endif; ?>
-					<?php endif; ?>
+								break;
+							case DefinitionParameter::VALUE_BOOLEAN: ?>
+								<label>
+									<input type="checkbox"
+										data-parameter="<?php p($parameter->getName()); ?>"
+									 	<?php if ($value == 'true'): ?> checked="checked"<?php endif; ?>
+									/>
+									<?php p($placeholder); ?>
+								</label>
+								<?php
+								break;
+							case DefinitionParameter::VALUE_HIDDEN: ?>
+								<input type="hidden"
+									data-parameter="<?php p($parameter->getName()); ?>"
+									value="<?php p($value); ?>"
+								/>
+								<?php
+								break;
+							default: ?>
+								<input type="text"
+									<?php if ($is_optional): ?> class="optional"<?php endif; ?>
+									data-parameter="<?php p($parameter->getName()); ?>"
+									value="<?php p($value); ?>"
+									placeholder="<?php p($placeholder); ?>"
+								/>
+								<?php
+							}
+						?>
+					<?php endforeach; ?>
+					<?php
+						$customJs = $storage->getBackend()->getCustomJs();
+						if (isset($customJs)) {
+							\OCP\Util::addScript('files_external', $customJs);
+						}
+					?>
 				</td>
 				<?php if ($_['isAdminPage']): ?>
-				<td class="applicable"
-					align="right"
-					data-applicable-groups='<?php if (isset($mount['applicable']['groups']))
-													print_unescaped(json_encode($mount['applicable']['groups'])); ?>'
-					data-applicable-users='<?php if (isset($mount['applicable']['users']))
-													print_unescaped(json_encode($mount['applicable']['users'])); ?>'>
-					<input type="hidden" class="applicableUsers" style="width:20em;" value=""/>
-				</td>
+					<td class="applicable"
+						align="right"
+						data-applicable-groups='<?php print_unescaped(json_encode($storage->getApplicableGroups())); ?>'
+						data-applicable-users='<?php print_unescaped(json_encode($storage->getApplicableUsers())); ?>'>
+						<input type="hidden" class="applicableUsers" style="width:20em;" value=""/>
+					</td>
 				<?php endif; ?>
-				<td class="mountOptionsToggle <?php if (!isset($mount['mountpoint'])) { p('hidden'); } ?>"
-					><img
+				<td class="mountOptionsToggle">
+					<img
 						class="svg action"
 						title="<?php p($l->t('Advanced settings')); ?>"
 						alt="<?php p($l->t('Advanced settings')); ?>"
-						src="<?php print_unescaped(image_path('core', 'actions/settings.svg')); ?>" />
-					<input type="hidden" class="mountOptions" value="<?php isset($mount['mountOptions']) ? p(json_encode($mount['mountOptions'])) : '' ?>" />
+						src="<?php print_unescaped(image_path('core', 'actions/settings.svg')); ?>"
+					/>
+					<input type="hidden" class="mountOptions" value="<?php p(json_encode($storage->getMountOptions())); ?>" />
 					<?php if ($_['isAdminPage']): ?>
-					<?php if (isset($mount['priority'])): ?>
-					<input type="hidden" class="priority" value="<?php p($mount['priority']) ?>" />
-					<?php endif; ?>
+						<input type="hidden" class="priority" value="<?php p($storage->getPriority()); ?>" />
 					<?php endif; ?>
 				</td>
-				<td <?php if (isset($mount['mountpoint'])): ?>class="remove"
-					<?php else: ?>class="hidden"
-					<?php endif ?>><img alt="<?php p($l->t('Delete')); ?>"
-										title="<?php p($l->t('Delete')); ?>"
-										class="svg action"
-										src="<?php print_unescaped(image_path('core', 'actions/delete.svg')); ?>" /></td>
+				<td class="remove">
+					<img alt="<?php p($l->t('Delete')); ?>"
+						title="<?php p($l->t('Delete')); ?>"
+						class="svg action"
+						src="<?php print_unescaped(image_path('core', 'actions/delete.svg')); ?>"
+					/>
+				</td>
 			</tr>
 		<?php endforeach; ?>
+			<tr id="addMountPoint">
+				<td class="status">
+					<span></span>
+				</td>
+				<td class="mountPoint"><input type="text" name="mountPoint" value=""
+					placeholder="<?php p($l->t('Folder name')); ?>">
+				</td>
+				<td class="backend">
+					<select id="selectBackend" class="selectBackend" data-configurations='<?php p(json_encode($_['backends'])); ?>'>
+						<option value="" disabled selected
+							style="display:none;">
+							<?php p($l->t('Add storage')); ?>
+						</option>
+						<?php
+							$sortedBackends = $_['backends'];
+							uasort($sortedBackends, function($a, $b) {
+								return strcasecmp($a->getText(), $b->getText());
+							});
+						?>
+						<?php foreach ($sortedBackends as $backend): ?>
+							<option value="<?php p($backend->getClass()); ?>"><?php p($backend->getText()); ?></option>
+						<?php endforeach; ?>
+					</select>
+				</td>
+				<td class="configuration"</td>
+				<?php if ($_['isAdminPage']): ?>
+					<td class="applicable" align="right">
+						<input type="hidden" class="applicableUsers" style="width:20em;" value="" />
+					</td>
+				<?php endif; ?>
+				<td class="mountOptionsToggle hidden">
+					<img class="svg action"
+						title="<?php p($l->t('Advanced settings')); ?>"
+						alt="<?php p($l->t('Advanced settings')); ?>"
+						src="<?php print_unescaped(image_path('core', 'actions/settings.svg')); ?>"
+					/>
+					<input type="hidden" class="mountOptions" value="" />
+				</td>
+				<td class="hidden">
+					<img class="svg action"
+						alt="<?php p($l->t('Delete')); ?>"
+						title="<?php p($l->t('Delete')); ?>"
+						src="<?php print_unescaped(image_path('core', 'actions/delete.svg')); ?>"
+					/>
+				</td>
+			</tr>
 		</tbody>
 	</table>
 	<br />
@@ -123,9 +174,9 @@
 
 		<p id="userMountingBackends"<?php if ($_['allowUserMounting'] != 'yes'): ?> class="hidden"<?php endif; ?>>
 			<?php p($l->t('Allow users to mount the following external storage')); ?><br />
-			<?php $i = 0; foreach ($_['personal_backends'] as $class => $backend): ?>
-				<input type="checkbox" id="allowUserMountingBackends<?php p($i); ?>" name="allowUserMountingBackends[]" value="<?php p($class); ?>" <?php if ($backend['enabled']) print_unescaped(' checked="checked"'); ?> />
-				<label for="allowUserMountingBackends<?php p($i); ?>"><?php p($backend['backend']); ?></label> <br />
+			<?php $i = 0; foreach ($_['userBackends'] as $backend): ?>
+				<input type="checkbox" id="allowUserMountingBackends<?php p($i); ?>" name="allowUserMountingBackends[]" value="<?php p($backend->getClass()); ?>" <?php if ($backend->isVisibleFor(BackendService::VISIBILITY_PERSONAL)) print_unescaped(' checked="checked"'); ?> />
+				<label for="allowUserMountingBackends<?php p($i); ?>"><?php p($backend->getText()); ?></label> <br />
 				<?php $i++; ?>
 			<?php endforeach; ?>
 		</p>
diff --git a/apps/files_external/tests/controller/globalstoragescontrollertest.php b/apps/files_external/tests/controller/globalstoragescontrollertest.php
index fc58743454a..e1bfad8caf6 100644
--- a/apps/files_external/tests/controller/globalstoragescontrollertest.php
+++ b/apps/files_external/tests/controller/globalstoragescontrollertest.php
@@ -28,7 +28,9 @@ use \OCA\Files_external\NotFoundException;
 class GlobalStoragesControllerTest extends StoragesControllerTest {
 	public function setUp() {
 		parent::setUp();
-		$this->service = $this->getMock('\OCA\Files_external\Service\GlobalStoragesService');
+		$this->service = $this->getMockBuilder('\OCA\Files_external\Service\GlobalStoragesService')
+			->disableOriginalConstructor()
+			->getMock();
 
 		$this->controller = new GlobalStoragesController(
 			'files_external',
diff --git a/apps/files_external/tests/controller/storagescontrollertest.php b/apps/files_external/tests/controller/storagescontrollertest.php
index 86874ef9786..f3e8c9afbac 100644
--- a/apps/files_external/tests/controller/storagescontrollertest.php
+++ b/apps/files_external/tests/controller/storagescontrollertest.php
@@ -47,11 +47,33 @@ abstract class StoragesControllerTest extends \Test\TestCase {
 		\OC_Mount_Config::$skipTest = false;
 	}
 
+	protected function getBackendMock($class = '\OCA\Files_External\Lib\Backend\SMB', $storageClass = '\OC\Files\Storage\SMB') {
+		$backend = $this->getMockBuilder('\OCA\Files_External\Lib\Backend\Backend')
+			->disableOriginalConstructor()
+			->getMock();
+		$backend->method('getStorageClass')
+			->willReturn($storageClass);
+		$backend->method('getClass')
+			->willReturn($storageClass);
+		return $backend;
+	}
+
 	public function testAddStorage() {
+		$backend = $this->getBackendMock();
+		$backend->method('validateStorage')
+			->willReturn(true);
+		$backend->method('isVisibleFor')
+			->willReturn(true);
+
 		$storageConfig = new StorageConfig(1);
 		$storageConfig->setMountPoint('mount');
+		$storageConfig->setBackend($backend);
+		$storageConfig->setBackendOptions([]);
 
 		$this->service->expects($this->once())
+			->method('createStorage')
+			->will($this->returnValue($storageConfig));
+		$this->service->expects($this->once())
 			->method('addStorage')
 			->will($this->returnValue($storageConfig));
 
@@ -71,10 +93,21 @@ abstract class StoragesControllerTest extends \Test\TestCase {
 	}
 
 	public function testUpdateStorage() {
+		$backend = $this->getBackendMock();
+		$backend->method('validateStorage')
+			->willReturn(true);
+		$backend->method('isVisibleFor')
+			->willReturn(true);
+
 		$storageConfig = new StorageConfig(1);
 		$storageConfig->setMountPoint('mount');
+		$storageConfig->setBackend($backend);
+		$storageConfig->setBackendOptions([]);
 
 		$this->service->expects($this->once())
+			->method('createStorage')
+			->will($this->returnValue($storageConfig));
+		$this->service->expects($this->once())
 			->method('updateStorage')
 			->will($this->returnValue($storageConfig));
 
@@ -106,6 +139,14 @@ abstract class StoragesControllerTest extends \Test\TestCase {
 	 * @dataProvider mountPointNamesProvider
 	 */
 	public function testAddOrUpdateStorageInvalidMountPoint($mountPoint) {
+		$storageConfig = new StorageConfig(1);
+		$storageConfig->setMountPoint($mountPoint);
+		$storageConfig->setBackend($this->getBackendMock());
+		$storageConfig->setBackendOptions([]);
+
+		$this->service->expects($this->exactly(2))
+			->method('createStorage')
+			->will($this->returnValue($storageConfig));
 		$this->service->expects($this->never())
 			->method('addStorage');
 		$this->service->expects($this->never())
@@ -138,6 +179,9 @@ abstract class StoragesControllerTest extends \Test\TestCase {
 	}
 
 	public function testAddOrUpdateStorageInvalidBackend() {
+		$this->service->expects($this->exactly(2))
+			->method('createStorage')
+			->will($this->throwException(new \InvalidArgumentException()));
 		$this->service->expects($this->never())
 			->method('addStorage');
 		$this->service->expects($this->never())
@@ -170,6 +214,20 @@ abstract class StoragesControllerTest extends \Test\TestCase {
 	}
 
 	public function testUpdateStorageNonExisting() {
+		$backend = $this->getBackendMock();
+		$backend->method('validateStorage')
+			->willReturn(true);
+		$backend->method('isVisibleFor')
+			->willReturn(true);
+
+		$storageConfig = new StorageConfig(255);
+		$storageConfig->setMountPoint('mount');
+		$storageConfig->setBackend($backend);
+		$storageConfig->setBackendOptions([]);
+
+		$this->service->expects($this->once())
+			->method('createStorage')
+			->will($this->returnValue($storageConfig));
 		$this->service->expects($this->once())
 			->method('updateStorage')
 			->will($this->throwException(new NotFoundException()));
@@ -206,9 +264,10 @@ abstract class StoragesControllerTest extends \Test\TestCase {
 	}
 
 	public function testGetStorage() {
+		$backend = $this->getBackendMock();
 		$storageConfig = new StorageConfig(1);
 		$storageConfig->setMountPoint('test');
-		$storageConfig->setBackendClass('\OC\Files\Storage\SMB');
+		$storageConfig->setBackend($backend);
 		$storageConfig->setBackendOptions(['user' => 'test', 'password', 'password123']);
 		$storageConfig->setMountOptions(['priority' => false]);
 
diff --git a/apps/files_external/tests/controller/userstoragescontrollertest.php b/apps/files_external/tests/controller/userstoragescontrollertest.php
index f9b4c5b2681..99825f26394 100644
--- a/apps/files_external/tests/controller/userstoragescontrollertest.php
+++ b/apps/files_external/tests/controller/userstoragescontrollertest.php
@@ -24,6 +24,8 @@ use \OCA\Files_external\Controller\UserStoragesController;
 use \OCA\Files_external\Service\UserStoragesService;
 use \OCP\AppFramework\Http;
 use \OCA\Files_external\NotFoundException;
+use \OCA\Files_External\Lib\StorageConfig;
+use \OCA\Files_External\Service\BackendService;
 
 class UserStoragesControllerTest extends StoragesControllerTest {
 
@@ -44,41 +46,22 @@ class UserStoragesControllerTest extends StoragesControllerTest {
 			$this->getMock('\OCP\IL10N'),
 			$this->service
 		);
-
-		$config = \OC::$server->getConfig();
-
-		$this->oldAllowedBackends = $config->getAppValue(
-			'files_external',
-			'user_mounting_backends',
-			''
-		);
-		$config->setAppValue(
-			'files_external',
-			'user_mounting_backends',
-			'\OC\Files\Storage\SMB'
-		);
 	}
 
-	public function tearDown() {
-		$config = \OC::$server->getConfig();
-		$config->setAppValue(
-			'files_external',
-			'user_mounting_backends',
-			$this->oldAllowedBackends
-		);
-		parent::tearDown();
-	}
+	public function testAddOrUpdateStorageDisallowedBackend() {
+		$backend = $this->getBackendMock();
+		$backend->method('isVisibleFor')
+			->with(BackendService::VISIBILITY_PERSONAL)
+			->willReturn(false);
 
-	function disallowedBackendClassProvider() {
-		return array(
-			array('\OC\Files\Storage\Local'),
-			array('\OC\Files\Storage\FTP'),
-		);
-	}
-	/**
-	 * @dataProvider disallowedBackendClassProvider
-	 */
-	public function testAddOrUpdateStorageDisallowedBackend($backendClass) {
+		$storageConfig = new StorageConfig(1);
+		$storageConfig->setMountPoint('mount');
+		$storageConfig->setBackend($backend);
+		$storageConfig->setBackendOptions([]);
+
+		$this->service->expects($this->exactly(2))
+			->method('createStorage')
+			->will($this->returnValue($storageConfig));
 		$this->service->expects($this->never())
 			->method('addStorage');
 		$this->service->expects($this->never())
@@ -86,7 +69,7 @@ class UserStoragesControllerTest extends StoragesControllerTest {
 
 		$response = $this->controller->create(
 			'mount',
-			$backendClass,
+			'\OC\Files\Storage\SMB',
 			array(),
 			[],
 			[],
@@ -99,7 +82,7 @@ class UserStoragesControllerTest extends StoragesControllerTest {
 		$response = $this->controller->update(
 			1,
 			'mount',
-			$backendClass,
+			'\OC\Files\Storage\SMB',
 			array(),
 			[],
 			[],
diff --git a/apps/files_external/tests/dynamicmountconfig.php b/apps/files_external/tests/dynamicmountconfig.php
deleted file mode 100644
index 48791ca89a5..00000000000
--- a/apps/files_external/tests/dynamicmountconfig.php
+++ /dev/null
@@ -1,104 +0,0 @@
-<?php
-/**
- * @author Joas Schilling <nickvergessen@owncloud.com>
- * @author Morris Jobke <hey@morrisjobke.de>
- * @author Thomas Müller <thomas.mueller@tmit.eu>
- *
- * @copyright Copyright (c) 2015, ownCloud, Inc.
- * @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/>
- *
- */
-
-require_once __DIR__ . '/../../../lib/base.php';
-
-/**
- * Class Test_Mount_Config_Dummy_Backend
- */
-class Test_Mount_Config_Dummy_Backend {
-	public static $checkDependencies = true;
-
-	public static function checkDependencies() {
-		return self::$checkDependencies;
-	}
-}
-
-/**
- * Class Test_Dynamic_Mount_Config
- */
-class Test_Dynamic_Mount_Config extends \Test\TestCase {
-
-	private $backup;
-
-	public function testRegistration() {
-
-		// second registration shall return false
-		$result = OC_Mount_Config::registerBackend('Test_Mount_Config_Dummy_Backend', array(
-			'backend' => 'Test Dummy',
-			'configuration' => array(),
-			'has_dependencies' => true));
-
-		$this->assertTrue($result);
-	}
-
-	public function testDependencyGetBackend() {
-
-		// is the backend listed?
-		Test_Mount_Config_Dummy_Backend::$checkDependencies = true;
-		$backEnds = OC_Mount_Config::getBackends();
-		$this->assertArrayHasKey('Test_Mount_Config_Dummy_Backend', $backEnds);
-
-		// backend shall not be listed
-		Test_Mount_Config_Dummy_Backend::$checkDependencies = false;
-
-		$backEnds = OC_Mount_Config::getBackends();
-		$this->assertArrayNotHasKey('Test_Mount_Config_Dummy_Backend', $backEnds);
-
-	}
-
-	public function testCheckDependencies() {
-
-		Test_Mount_Config_Dummy_Backend::$checkDependencies = true;
-		$message = OC_Mount_Config::checkDependencies();
-		$this->assertEmpty($message);
-
-		// backend shall not be listed
-		Test_Mount_Config_Dummy_Backend::$checkDependencies = array('dummy');
-
-		$message = OC_Mount_Config::checkDependencies();
-		$this->assertEquals('<br /><b>Note:</b> "dummy" is not installed. Mounting of <i>Test Dummy</i> is not possible. Please ask your system administrator to install it.',
-			$message);
-
-	}
-
-	protected function setUp() {
-		parent::setUp();
-
-		$this->backup = OC_Mount_Config::setUp();
-
-		// register dummy backend
-		$result = OC_Mount_Config::registerBackend('Test_Mount_Config_Dummy_Backend', array(
-			'backend' => 'Test Dummy',
-			'configuration' => array(),
-			'has_dependencies' => true));
-
-		$this->assertTrue($result);
-	}
-
-	protected function tearDown()
-	{
-		OC_Mount_Config::setUp($this->backup);
-		parent::tearDown();
-	}
-}
diff --git a/apps/files_external/tests/service/globalstoragesservicetest.php b/apps/files_external/tests/service/globalstoragesservicetest.php
index ac25f58b1d1..422f3543f35 100644
--- a/apps/files_external/tests/service/globalstoragesservicetest.php
+++ b/apps/files_external/tests/service/globalstoragesservicetest.php
@@ -29,7 +29,7 @@ use \OCA\Files_external\Lib\StorageConfig;
 class GlobalStoragesServiceTest extends StoragesServiceTest {
 	public function setUp() {
 		parent::setUp();
-		$this->service = new GlobalStoragesService();
+		$this->service = new GlobalStoragesService($this->backendService);
 	}
 
 	public function tearDown() {
@@ -59,7 +59,7 @@ class GlobalStoragesServiceTest extends StoragesServiceTest {
 		return [
 			// all users
 			[
-				$this->makeStorageConfig([
+				[
 					'mountPoint' => 'mountpoint',
 					'backendClass' => '\OC\Files\Storage\SMB',
 					'backendOptions' => [
@@ -70,11 +70,11 @@ class GlobalStoragesServiceTest extends StoragesServiceTest {
 					'applicableUsers' => [],
 					'applicableGroups' => [],
 					'priority' => 15,
-				]),
+				],
 			],
 			// some users
 			[
-				$this->makeStorageConfig([
+				[
 					'mountPoint' => 'mountpoint',
 					'backendClass' => '\OC\Files\Storage\SMB',
 					'backendOptions' => [
@@ -85,11 +85,11 @@ class GlobalStoragesServiceTest extends StoragesServiceTest {
 					'applicableUsers' => ['user1', 'user2'],
 					'applicableGroups' => [],
 					'priority' => 15,
-				]),
+				],
 			],
 			// some groups
 			[
-				$this->makeStorageConfig([
+				[
 					'mountPoint' => 'mountpoint',
 					'backendClass' => '\OC\Files\Storage\SMB',
 					'backendOptions' => [
@@ -100,11 +100,11 @@ class GlobalStoragesServiceTest extends StoragesServiceTest {
 					'applicableUsers' => [],
 					'applicableGroups' => ['group1', 'group2'],
 					'priority' => 15,
-				]),
+				],
 			],
 			// both users and groups
 			[
-				$this->makeStorageConfig([
+				[
 					'mountPoint' => 'mountpoint',
 					'backendClass' => '\OC\Files\Storage\SMB',
 					'backendOptions' => [
@@ -115,7 +115,7 @@ class GlobalStoragesServiceTest extends StoragesServiceTest {
 					'applicableUsers' => ['user1', 'user2'],
 					'applicableGroups' => ['group1', 'group2'],
 					'priority' => 15,
-				]),
+				],
 			],
 		];
 	}
@@ -123,7 +123,8 @@ class GlobalStoragesServiceTest extends StoragesServiceTest {
 	/**
 	 * @dataProvider storageDataProvider
 	 */
-	public function testAddStorage($storage) {
+	public function testAddStorage($storageParams) {
+		$storage = $this->makeStorageConfig($storageParams);
 		$newStorage = $this->service->addStorage($storage);
 
 		$this->assertEquals(1, $newStorage->getId());
@@ -132,7 +133,7 @@ class GlobalStoragesServiceTest extends StoragesServiceTest {
 		$newStorage = $this->service->getStorage(1);
 
 		$this->assertEquals($storage->getMountPoint(), $newStorage->getMountPoint());
-		$this->assertEquals($storage->getBackendClass(), $newStorage->getBackendClass());
+		$this->assertEquals($storage->getBackend(), $newStorage->getBackend());
 		$this->assertEquals($storage->getBackendOptions(), $newStorage->getBackendOptions());
 		$this->assertEquals($storage->getApplicableUsers(), $newStorage->getApplicableUsers());
 		$this->assertEquals($storage->getApplicableGroups(), $newStorage->getApplicableGroups());
@@ -148,7 +149,8 @@ class GlobalStoragesServiceTest extends StoragesServiceTest {
 	/**
 	 * @dataProvider storageDataProvider
 	 */
-	public function testUpdateStorage($updatedStorage) {
+	public function testUpdateStorage($updatedStorageParams) {
+		$updatedStorage = $this->makeStorageConfig($updatedStorageParams);
 		$storage = $this->makeStorageConfig([
 			'mountPoint' => 'mountpoint',
 			'backendClass' => '\OC\Files\Storage\SMB',
diff --git a/apps/files_external/tests/service/storagesservicetest.php b/apps/files_external/tests/service/storagesservicetest.php
index 36f68a83b11..99e179cc93a 100644
--- a/apps/files_external/tests/service/storagesservicetest.php
+++ b/apps/files_external/tests/service/storagesservicetest.php
@@ -24,6 +24,7 @@ use \OC\Files\Filesystem;
 
 use \OCA\Files_external\NotFoundException;
 use \OCA\Files_external\Lib\StorageConfig;
+use \OCA\Files_External\Lib\BackendService;
 
 abstract class StoragesServiceTest extends \Test\TestCase {
 
@@ -32,6 +33,9 @@ abstract class StoragesServiceTest extends \Test\TestCase {
 	 */
 	protected $service;
 
+	/** @var BackendService */
+	protected $backendService;
+
 	/**
 	 * Data directory
 	 *
@@ -55,6 +59,25 @@ abstract class StoragesServiceTest extends \Test\TestCase {
 		);
 		\OC_Mount_Config::$skipTest = true;
 
+		$this->backendService =
+			$this->getMockBuilder('\OCA\Files_External\Service\BackendService')
+			->disableOriginalConstructor()
+			->getMock();
+
+		$backends = [
+			'\OC\Files\Storage\SMB' => $this->getBackendMock('\OCA\Files_External\Lib\Backend\SMB', '\OC\Files\Storage\SMB'),
+			'\OC\Files\Storage\SFTP' => $this->getBackendMock('\OCA\Files_External\Lib\Backend\SFTP', '\OC\Files\Storage\SFTP'),
+		];
+		$this->backendService->method('getBackend')
+			->will($this->returnCallback(function($backendClass) use ($backends) {
+				if (isset($backends[$backendClass])) {
+					return $backends[$backendClass];
+				}
+				return null;
+			}));
+		$this->backendService->method('getBackends')
+			->will($this->returnValue($backends));
+
 		\OCP\Util::connectHook(
 			Filesystem::CLASSNAME,
 			Filesystem::signal_create_mount,
@@ -71,6 +94,17 @@ abstract class StoragesServiceTest extends \Test\TestCase {
 		self::$hookCalls = array();
 	}
 
+	protected function getBackendMock($class = '\OCA\Files_External\Lib\Backend\SMB', $storageClass = '\OC\Files\Storage\SMB') {
+		$backend = $this->getMockBuilder('\OCA\Files_External\Lib\Backend\Backend')
+			->disableOriginalConstructor()
+			->getMock();
+		$backend->method('getStorageClass')
+			->willReturn($storageClass);
+		$backend->method('getClass')
+			->willReturn($storageClass);
+		return $backend;
+	}
+
 	/**
 	 * Creates a StorageConfig instance based on array data
 	 *
@@ -84,7 +118,12 @@ abstract class StoragesServiceTest extends \Test\TestCase {
 			$storage->setId($data['id']);
 		}
 		$storage->setMountPoint($data['mountPoint']);
-		$storage->setBackendClass($data['backendClass']);
+		if (!isset($data['backend'])) {
+			// data providers are run before $this->backendService is initialised
+			// so $data['backend'] can be specified directly
+			$data['backend'] = $this->backendService->getBackend($data['backendClass']);
+		}
+		$storage->setBackend($data['backend']);
 		$storage->setBackendOptions($data['backendOptions']);
 		if (isset($data['applicableUsers'])) {
 			$storage->setApplicableUsers($data['applicableUsers']);
@@ -106,16 +145,18 @@ abstract class StoragesServiceTest extends \Test\TestCase {
 	 * @expectedException \OCA\Files_external\NotFoundException
 	 */
 	public function testNonExistingStorage() {
+		$backend = $this->backendService->getBackend('\OC\Files\Storage\SMB');
 		$storage = new StorageConfig(255);
 		$storage->setMountPoint('mountpoint');
-		$storage->setBackendClass('\OC\Files\Storage\SMB');
+		$storage->setBackend($backend);
 		$this->service->updateStorage($storage);
 	}
 
 	public function testDeleteStorage() {
+		$backend = $this->backendService->getBackend('\OC\Files\Storage\SMB');
 		$storage = new StorageConfig(255);
 		$storage->setMountPoint('mountpoint');
-		$storage->setBackendClass('\OC\Files\Storage\SMB');
+		$storage->setBackend($backend);
 		$storage->setBackendOptions(['password' => 'testPassword']);
 
 		$newStorage = $this->service->addStorage($storage);
diff --git a/apps/files_external/tests/service/userstoragesservicetest.php b/apps/files_external/tests/service/userstoragesservicetest.php
index ab102741ee2..98a9993918a 100644
--- a/apps/files_external/tests/service/userstoragesservicetest.php
+++ b/apps/files_external/tests/service/userstoragesservicetest.php
@@ -40,7 +40,7 @@ class UserStoragesServiceTest extends StoragesServiceTest {
 			->method('getUser')
 			->will($this->returnValue($this->user));
 
-		$this->service = new UserStoragesService($userSession);
+		$this->service = new UserStoragesService($this->backendService, $userSession);
 
 		// create home folder
 		mkdir($this->dataDir . '/' . $this->userId . '/');
@@ -76,7 +76,7 @@ class UserStoragesServiceTest extends StoragesServiceTest {
 		$newStorage = $this->service->getStorage(1);
 
 		$this->assertEquals($storage->getMountPoint(), $newStorage->getMountPoint());
-		$this->assertEquals($storage->getBackendClass(), $newStorage->getBackendClass());
+		$this->assertEquals($storage->getBackend(), $newStorage->getBackend());
 		$this->assertEquals($storage->getBackendOptions(), $newStorage->getBackendOptions());
 		$this->assertEquals(1, $newStorage->getId());
 		$this->assertEquals(0, $newStorage->getStatus());
diff --git a/apps/files_external/tests/storageconfigtest.php b/apps/files_external/tests/storageconfigtest.php
index c30a4935ce1..69edb36e707 100644
--- a/apps/files_external/tests/storageconfigtest.php
+++ b/apps/files_external/tests/storageconfigtest.php
@@ -26,9 +26,15 @@ use \OCA\Files_external\Lib\StorageConfig;
 class StorageConfigTest extends \Test\TestCase {
 
 	public function testJsonSerialization() {
+		$backend = $this->getMockBuilder('\OCA\Files_External\Lib\Backend\Backend')
+			->disableOriginalConstructor()
+			->getMock();
+		$backend->method('getClass')
+			->willReturn('\OC\Files\Storage\SMB');
+
 		$storageConfig = new StorageConfig(1);
 		$storageConfig->setMountPoint('test');
-		$storageConfig->setBackendClass('\OC\Files\Storage\SMB');
+		$storageConfig->setBackend($backend);
 		$storageConfig->setBackendOptions(['user' => 'test', 'password' => 'password123']);
 		$storageConfig->setPriority(128);
 		$storageConfig->setApplicableUsers(['user1', 'user2']);