Merge pull request #15040 from nextcloud/feature/13980/push-for-deleted-notifications

Notifications overhaul

14 files changed, 355 insertions, 222 deletions

diff --git a/lib/composer/composer/autoload_classmap.php b/lib/composer/composer/autoload_classmap.php
index 1fa9f6243f9..d8d9227cb07 100644
--- a/lib/composer/composer/autoload_classmap.php
+++ b/lib/composer/composer/autoload_classmap.php
@@ -347,6 +347,7 @@ return array(
     'OCP\\Migration\\IOutput' => $baseDir . '/lib/public/Migration/IOutput.php',
     'OCP\\Migration\\IRepairStep' => $baseDir . '/lib/public/Migration/IRepairStep.php',
     'OCP\\Migration\\SimpleMigrationStep' => $baseDir . '/lib/public/Migration/SimpleMigrationStep.php',
+    'OCP\\Notification\\AlreadyProcessedException' => $baseDir . '/lib/public/Notification/AlreadyProcessedException.php',
     'OCP\\Notification\\IAction' => $baseDir . '/lib/public/Notification/IAction.php',
     'OCP\\Notification\\IApp' => $baseDir . '/lib/public/Notification/IApp.php',
     'OCP\\Notification\\IManager' => $baseDir . '/lib/public/Notification/IManager.php',
diff --git a/lib/composer/composer/autoload_static.php b/lib/composer/composer/autoload_static.php
index 58c1b031f90..043846e04df 100644
--- a/lib/composer/composer/autoload_static.php
+++ b/lib/composer/composer/autoload_static.php
@@ -381,6 +381,7 @@ class ComposerStaticInit53792487c5a8370acc0b06b1a864ff4c
         'OCP\\Migration\\IOutput' => __DIR__ . '/../../..' . '/lib/public/Migration/IOutput.php',
         'OCP\\Migration\\IRepairStep' => __DIR__ . '/../../..' . '/lib/public/Migration/IRepairStep.php',
         'OCP\\Migration\\SimpleMigrationStep' => __DIR__ . '/../../..' . '/lib/public/Migration/SimpleMigrationStep.php',
+        'OCP\\Notification\\AlreadyProcessedException' => __DIR__ . '/../../..' . '/lib/public/Notification/AlreadyProcessedException.php',
         'OCP\\Notification\\IAction' => __DIR__ . '/../../..' . '/lib/public/Notification/IAction.php',
         'OCP\\Notification\\IApp' => __DIR__ . '/../../..' . '/lib/public/Notification/IApp.php',
         'OCP\\Notification\\IManager' => __DIR__ . '/../../..' . '/lib/public/Notification/IManager.php',
diff --git a/lib/private/Authentication/Listeners/RemoteWipeNotificationsListener.php b/lib/private/Authentication/Listeners/RemoteWipeNotificationsListener.php
index ffddddff1d8..57213a8a191 100644
--- a/lib/private/Authentication/Listeners/RemoteWipeNotificationsListener.php
+++ b/lib/private/Authentication/Listeners/RemoteWipeNotificationsListener.php
@@ -61,7 +61,7 @@ class RemoteWipeNotificationsListener implements IEventListener {
 		$notification->setApp('auth')
 			->setUser($token->getUID())
 			->setDateTime($this->timeFactory->getDateTime())
-			->setObject('token', $token->getId())
+			->setObject('token', (string) $token->getId())
 			->setSubject($event, [
 				'name' => $token->getName(),
 			]);
diff --git a/lib/private/Authentication/Notifications/Notifier.php b/lib/private/Authentication/Notifications/Notifier.php
index 0aafc115b22..f76bb077a3c 100644
--- a/lib/private/Authentication/Notifications/Notifier.php
+++ b/lib/private/Authentication/Notifications/Notifier.php
@@ -42,7 +42,7 @@ class Notifier implements INotifier {
 	/**
 	 * @inheritDoc
 	 */
-	public function prepare(INotification $notification, $languageCode) {
+	public function prepare(INotification $notification, string $languageCode): INotification {
 		if ($notification->getApp() !== 'auth') {
 			// Not my app => throw
 			throw new InvalidArgumentException();
@@ -74,4 +74,23 @@ class Notifier implements INotifier {
 		}
 	}
 
+	/**
+	 * Identifier of the notifier, only use [a-z0-9_]
+	 *
+	 * @return string
+	 * @since 17.0.0
+	 */
+	public function getID(): string {
+		return 'auth';
+	}
+
+	/**
+	 * Human readable name describing the notifier
+	 *
+	 * @return string
+	 * @since 17.0.0
+	 */
+	public function getName(): string {
+		return $this->factory->get('lib')->t('Authentication');
+	}
 }
diff --git a/lib/private/Notification/Action.php b/lib/private/Notification/Action.php
index 8dfeecb98cb..f6d6a333583 100644
--- a/lib/private/Notification/Action.php
+++ b/lib/private/Notification/Action.php
@@ -1,4 +1,5 @@
 <?php
+declare(strict_types=1);
 /**
  * @copyright Copyright (c) 2016, ownCloud, Inc.
  *
@@ -45,9 +46,6 @@ class Action implements IAction {
 	/** @var bool */
 	protected $primary;
 
-	/**
-	 * Constructor
-	 */
 	public function __construct() {
 		$this->label = '';
 		$this->labelParsed = '';
@@ -62,8 +60,8 @@ class Action implements IAction {
 	 * @throws \InvalidArgumentException if the label is invalid
 	 * @since 8.2.0
 	 */
-	public function setLabel($label) {
-		if (!is_string($label) || $label === '' || isset($label[32])) {
+	public function setLabel(string $label): IAction {
+		if ($label === '' || isset($label[32])) {
 			throw new \InvalidArgumentException('The given label is invalid');
 		}
 		$this->label = $label;
@@ -74,7 +72,7 @@ class Action implements IAction {
 	 * @return string
 	 * @since 8.2.0
 	 */
-	public function getLabel() {
+	public function getLabel(): string {
 		return $this->label;
 	}
 
@@ -84,8 +82,8 @@ class Action implements IAction {
 	 * @throws \InvalidArgumentException if the label is invalid
 	 * @since 8.2.0
 	 */
-	public function setParsedLabel($label) {
-		if (!is_string($label) || $label === '') {
+	public function setParsedLabel(string $label): IAction {
+		if ($label === '') {
 			throw new \InvalidArgumentException('The given parsed label is invalid');
 		}
 		$this->labelParsed = $label;
@@ -96,21 +94,16 @@ class Action implements IAction {
 	 * @return string
 	 * @since 8.2.0
 	 */
-	public function getParsedLabel() {
+	public function getParsedLabel(): string {
 		return $this->labelParsed;
 	}
 
 	/**
 	 * @param $primary bool
 	 * @return $this
-	 * @throws \InvalidArgumentException if $primary is invalid
 	 * @since 9.0.0
 	 */
-	public function setPrimary($primary) {
-		if (!is_bool($primary)) {
-			throw new \InvalidArgumentException('The given primary option is invalid');
-		}
-
+	public function setPrimary(bool $primary): IAction {
 		$this->primary = $primary;
 		return $this;
 	}
@@ -119,7 +112,7 @@ class Action implements IAction {
 	 * @return bool
 	 * @since 9.0.0
 	 */
-	public function isPrimary() {
+	public function isPrimary(): bool {
 		return $this->primary;
 	}
 
@@ -130,11 +123,17 @@ class Action implements IAction {
 	 * @throws \InvalidArgumentException if the link is invalid
 	 * @since 8.2.0
 	 */
-	public function setLink($link, $requestType) {
-		if (!is_string($link) || $link === '' || isset($link[256])) {
+	public function setLink(string $link, string $requestType): IAction {
+		if ($link === '' || isset($link[256])) {
 			throw new \InvalidArgumentException('The given link is invalid');
 		}
-		if (!in_array($requestType, ['GET', 'POST', 'PUT', 'DELETE'], true)) {
+		if (!in_array($requestType, [
+			self::TYPE_GET,
+			self::TYPE_POST,
+			self::TYPE_PUT,
+			self::TYPE_DELETE,
+			self::TYPE_WEB,
+		], true)) {
 			throw new \InvalidArgumentException('The given request type is invalid');
 		}
 		$this->link = $link;
@@ -146,7 +145,7 @@ class Action implements IAction {
 	 * @return string
 	 * @since 8.2.0
 	 */
-	public function getLink() {
+	public function getLink(): string {
 		return $this->link;
 	}
 
@@ -154,21 +153,21 @@ class Action implements IAction {
 	 * @return string
 	 * @since 8.2.0
 	 */
-	public function getRequestType() {
+	public function getRequestType(): string {
 		return $this->requestType;
 	}
 
 	/**
 	 * @return bool
 	 */
-	public function isValid() {
+	public function isValid(): bool {
 		return $this->label !== '' && $this->link !== '';
 	}
 
 	/**
 	 * @return bool
 	 */
-	public function isValidParsed() {
+	public function isValidParsed(): bool {
 		return $this->labelParsed !== '' && $this->link !== '';
 	}
 }
diff --git a/lib/private/Notification/Manager.php b/lib/private/Notification/Manager.php
index 4c3f7a2453c..fae0a66491e 100644
--- a/lib/private/Notification/Manager.php
+++ b/lib/private/Notification/Manager.php
@@ -1,4 +1,5 @@
 <?php
+declare(strict_types=1);
 /**
  * @copyright Copyright (c) 2016, ownCloud, Inc.
  *
@@ -25,6 +26,9 @@
 namespace OC\Notification;
 
 
+use OCP\AppFramework\QueryException;
+use OCP\ILogger;
+use OCP\Notification\AlreadyProcessedException;
 use OCP\Notification\IApp;
 use OCP\Notification\IManager;
 use OCP\Notification\INotification;
@@ -34,52 +38,39 @@ use OCP\RichObjectStrings\IValidator;
 class Manager implements IManager {
 	/** @var IValidator */
 	protected $validator;
+	/** @var ILogger */
+	protected $logger;
 
 	/** @var IApp[] */
 	protected $apps;
+	/** @var string[] */
+	protected $appClasses;
 
 	/** @var INotifier[] */
 	protected $notifiers;
-
-	/** @var array[] */
-	protected $notifiersInfo;
-
-	/** @var \Closure[] */
-	protected $appsClosures;
-
-	/** @var \Closure[] */
-	protected $notifiersClosures;
-
-	/** @var \Closure[] */
-	protected $notifiersInfoClosures;
+	/** @var string[] */
+	protected $notifierClasses;
 
 	/** @var bool */
 	protected $preparingPushNotification;
 
-	/**
-	 * Manager constructor.
-	 *
-	 * @param IValidator $validator
-	 */
-	public function __construct(IValidator $validator) {
+	public function __construct(IValidator $validator,
+								ILogger $logger) {
 		$this->validator = $validator;
+		$this->logger = $logger;
 		$this->apps = [];
 		$this->notifiers = [];
-		$this->notifiersInfo = [];
-		$this->appsClosures = [];
-		$this->notifiersClosures = [];
-		$this->notifiersInfoClosures = [];
+		$this->appClasses = [];
+		$this->notifierClasses = [];
 		$this->preparingPushNotification = false;
 	}
-
 	/**
-	 * @param \Closure $service The service must implement IApp, otherwise a
+	 * @param string $appClass The service must implement IApp, otherwise a
 	 *                          \InvalidArgumentException is thrown later
-	 * @since 8.2.0
+	 * @since 17.0.0
 	 */
-	public function registerApp(\Closure $service) {
-		$this->appsClosures[] = $service;
-		$this->apps = [];
+	public function registerApp(string $appClass): void {
+		$this->appClasses[] = $appClass;
 	}
 
 	/**
@@ -87,76 +78,91 @@ class Manager implements IManager {
 	 *                          \InvalidArgumentException is thrown later
 	 * @param \Closure $info    An array with the keys 'id' and 'name' containing
 	 *                          the app id and the app name
+	 * @deprecated 17.0.0 use registerNotifierService instead.
 	 * @since 8.2.0 - Parameter $info was added in 9.0.0
 	 */
 	public function registerNotifier(\Closure $service, \Closure $info) {
-		$this->notifiersClosures[] = $service;
-		$this->notifiersInfoClosures[] = $info;
-		$this->notifiers = [];
-		$this->notifiersInfo = [];
+		$infoData = $info();
+		$this->logger->logException(new \InvalidArgumentException(
+			'Notifier ' . $infoData['name'] . ' (id: ' . $infoData['id'] . ') is not considered because it is using the old way to register.'
+		));
+	}
+
+	/**
+	 * @param string $notifierService The service must implement INotifier, otherwise a
+	 *                          \InvalidArgumentException is thrown later
+	 * @since 17.0.0
+	 */
+	public function registerNotifierService(string $notifierService): void {
+		$this->notifierClasses[] = $notifierService;
 	}
 
 	/**
 	 * @return IApp[]
 	 */
 	protected function getApps(): array {
-		if (!empty($this->apps)) {
+		if (empty($this->appClasses)) {
 			return $this->apps;
 		}
 
-		$this->apps = [];
-		foreach ($this->appsClosures as $closure) {
-			$app = $closure();
+		foreach ($this->appClasses as $appClass) {
+			try {
+				$app = \OC::$server->query($appClass);
+			} catch (QueryException $e) {
+				$this->logger->logException($e, [
+					'message' => 'Failed to load notification app class: ' . $appClass,
+					'app' => 'notifications',
+				]);
+				continue;
+			}
+
 			if (!($app instanceof IApp)) {
-				throw new \InvalidArgumentException('The given notification app does not implement the IApp interface');
+				$this->logger->error('Notification app class ' . $appClass . ' is not implementing ' . IApp::class, [
+					'app' => 'notifications',
+				]);
+				continue;
 			}
+
 			$this->apps[] = $app;
 		}
 
+		$this->appClasses = [];
+
 		return $this->apps;
 	}
 
 	/**
 	 * @return INotifier[]
 	 */
-	protected function getNotifiers(): array {
-		if (!empty($this->notifiers)) {
+	public function getNotifiers(): array {
+		if (empty($this->notifierClasses)) {
 			return $this->notifiers;
 		}
 
-		$this->notifiers = [];
-		foreach ($this->notifiersClosures as $closure) {
-			$notifier = $closure();
-			if (!($notifier instanceof INotifier)) {
-				throw new \InvalidArgumentException('The given notifier does not implement the INotifier interface');
+		foreach ($this->notifierClasses as $notifierClass) {
+			try {
+				$notifier = \OC::$server->query($notifierClass);
+			} catch (QueryException $e) {
+				$this->logger->logException($e, [
+					'message' => 'Failed to load notification notifier class: ' . $notifierClass,
+					'app' => 'notifications',
+				]);
+				continue;
 			}
-			$this->notifiers[] = $notifier;
-		}
 
-		return $this->notifiers;
-	}
+			if (!($notifier instanceof INotifier)) {
+				$this->logger->error('Notification notifier class ' . $notifierClass . ' is not implementing ' . INotifier::class, [
+					'app' => 'notifications',
+				]);
+				continue;
+			}
 
-	/**
-	 * @return array[]
-	 */
-	public function listNotifiers(): array {
-		if (!empty($this->notifiersInfo)) {
-			return $this->notifiersInfo;
+			$this->notifiers[] = $notifier;
 		}
 
-		$this->notifiersInfo = [];
-		foreach ($this->notifiersInfoClosures as $closure) {
-			$notifier = $closure();
-			if (!\is_array($notifier) || \count($notifier) !== 2 || !isset($notifier['id'], $notifier['name'])) {
-				throw new \InvalidArgumentException('The given notifier information is invalid');
-			}
-			if (isset($this->notifiersInfo[$notifier['id']])) {
-				throw new \InvalidArgumentException('The given notifier ID ' . $notifier['id'] . ' is already in use');
-			}
-			$this->notifiersInfo[$notifier['id']] = $notifier['name'];
-		}
+		$this->notifierClasses = [];
 
-		return $this->notifiersInfo;
+		return $this->notifiers;
 	}
 
 	/**
@@ -172,14 +178,14 @@ class Manager implements IManager {
 	 * @since 8.2.0
 	 */
 	public function hasNotifiers(): bool {
-		return !empty($this->notifiersClosures);
+		return !empty($this->notifiers) || !empty($this->notifierClasses);
 	}
 
 	/**
 	 * @param bool $preparingPushNotification
 	 * @since 14.0.0
 	 */
-	public function setPreparingPushNotification($preparingPushNotification) {
+	public function setPreparingPushNotification(bool $preparingPushNotification): void {
 		$this->preparingPushNotification = $preparingPushNotification;
 	}
 
@@ -196,7 +202,7 @@ class Manager implements IManager {
 	 * @throws \InvalidArgumentException When the notification is not valid
 	 * @since 8.2.0
 	 */
-	public function notify(INotification $notification) {
+	public function notify(INotification $notification): void {
 		if (!$notification->isValid()) {
 			throw new \InvalidArgumentException('The given notification is invalid');
 		}
@@ -212,13 +218,34 @@ class Manager implements IManager {
 	}
 
 	/**
+	 * Identifier of the notifier, only use [a-z0-9_]
+	 *
+	 * @return string
+	 * @since 17.0.0
+	 */
+	public function getID(): string {
+		return 'core';
+	}
+
+	/**
+	 * Human readable name describing the notifier
+	 *
+	 * @return string
+	 * @since 17.0.0
+	 */
+	public function getName(): string {
+		return 'core';
+	}
+
+	/**
 	 * @param INotification $notification
 	 * @param string $languageCode The code of the language that should be used to prepare the notification
 	 * @return INotification
 	 * @throws \InvalidArgumentException When the notification was not prepared by a notifier
+	 * @throws AlreadyProcessedException When the notification is not needed anymore and should be deleted
 	 * @since 8.2.0
 	 */
-	public function prepare(INotification $notification, $languageCode): INotification {
+	public function prepare(INotification $notification, string $languageCode): INotification {
 		$notifiers = $this->getNotifiers();
 
 		foreach ($notifiers as $notifier) {
@@ -226,6 +253,9 @@ class Manager implements IManager {
 				$notification = $notifier->prepare($notification, $languageCode);
 			} catch (\InvalidArgumentException $e) {
 				continue;
+			} catch (AlreadyProcessedException $e) {
+				$this->markProcessed($notification);
+				throw new \InvalidArgumentException('The given notification has been processed');
 			}
 
 			if (!($notification instanceof INotification) || !$notification->isValidParsed()) {
@@ -243,7 +273,7 @@ class Manager implements IManager {
 	/**
 	 * @param INotification $notification
 	 */
-	public function markProcessed(INotification $notification) {
+	public function markProcessed(INotification $notification): void {
 		$apps = $this->getApps();
 
 		foreach ($apps as $app) {
diff --git a/lib/private/Notification/Notification.php b/lib/private/Notification/Notification.php
index 47f415d15d3..e64c059db2a 100644
--- a/lib/private/Notification/Notification.php
+++ b/lib/private/Notification/Notification.php
@@ -1,5 +1,5 @@
 <?php
-declare (strict_types = 1);
+declare(strict_types=1);
 /**
  * @copyright Copyright (c) 2016, ownCloud, Inc.
  *
@@ -99,11 +99,6 @@ class Notification implements INotification {
 	/** @var bool */
 	protected $hasPrimaryParsedAction;
 
-	/**
-	 * Constructor
-	 *
-	 * @param IValidator $richValidator
-	 */
 	public function __construct(IValidator $richValidator) {
 		$this->richValidator = $richValidator;
 		$this->app = '';
@@ -134,8 +129,8 @@ class Notification implements INotification {
 	 * @throws \InvalidArgumentException if the app id is invalid
 	 * @since 8.2.0
 	 */
-	public function setApp(string $app) {
-		if (trim($app) === '' || isset($app[32])) {
+	public function setApp(string $app): INotification {
+		if ($app === '' || isset($app[32])) {
 			throw new \InvalidArgumentException('The given app name is invalid');
 		}
 		$this->app = $app;
@@ -146,7 +141,7 @@ class Notification implements INotification {
 	 * @return string
 	 * @since 8.2.0
 	 */
-	public function getApp() {
+	public function getApp(): string {
 		return $this->app;
 	}
 
@@ -156,8 +151,8 @@ class Notification implements INotification {
 	 * @throws \InvalidArgumentException if the user id is invalid
 	 * @since 8.2.0
 	 */
-	public function setUser(string $user) {
-		if (trim($user) === '' || isset($user[64])) {
+	public function setUser(string $user): INotification {
+		if ($user === '' || isset($user[64])) {
 			throw new \InvalidArgumentException('The given user id is invalid');
 		}
 		$this->user = $user;
@@ -168,7 +163,7 @@ class Notification implements INotification {
 	 * @return string
 	 * @since 8.2.0
 	 */
-	public function getUser() {
+	public function getUser(): string {
 		return $this->user;
 	}
 
@@ -178,7 +173,7 @@ class Notification implements INotification {
 	 * @throws \InvalidArgumentException if the $dateTime is invalid
 	 * @since 9.0.0
 	 */
-	public function setDateTime(\DateTime $dateTime) {
+	public function setDateTime(\DateTime $dateTime): INotification {
 		if ($dateTime->getTimestamp() === 0) {
 			throw new \InvalidArgumentException('The given date time is invalid');
 		}
@@ -190,7 +185,7 @@ class Notification implements INotification {
 	 * @return \DateTime
 	 * @since 9.0.0
 	 */
-	public function getDateTime() {
+	public function getDateTime(): \DateTime {
 		return $this->dateTime;
 	}
 
@@ -201,13 +196,13 @@ class Notification implements INotification {
 	 * @throws \InvalidArgumentException if the object type or id is invalid
 	 * @since 8.2.0 - 9.0.0: Type of $id changed to string
 	 */
-	public function setObject(string $type, $id) {
-		if (trim($type) === '' || isset($type[64])) {
+	public function setObject(string $type, string $id): INotification {
+		if ($type === '' || isset($type[64])) {
 			throw new \InvalidArgumentException('The given object type is invalid');
 		}
 		$this->objectType = $type;
 
-		if (!is_int($id) && (!is_string($id) || $id === '' || isset($id[64]))) {
+		if ($id === '' || isset($id[64])) {
 			throw new \InvalidArgumentException('The given object id is invalid');
 		}
 		$this->objectId = (string) $id;
@@ -218,7 +213,7 @@ class Notification implements INotification {
 	 * @return string
 	 * @since 8.2.0
 	 */
-	public function getObjectType() {
+	public function getObjectType(): string {
 		return $this->objectType;
 	}
 
@@ -226,7 +221,7 @@ class Notification implements INotification {
 	 * @return string
 	 * @since 8.2.0 - 9.0.0: Return type changed to string
 	 */
-	public function getObjectId() {
+	public function getObjectId(): string {
 		return $this->objectId;
 	}
 
@@ -237,8 +232,8 @@ class Notification implements INotification {
 	 * @throws \InvalidArgumentException if the subject or parameters are invalid
 	 * @since 8.2.0
 	 */
-	public function setSubject(string $subject, array $parameters = []) {
-		if (trim($subject) === '' || isset($subject[64])) {
+	public function setSubject(string $subject, array $parameters = []): INotification {
+		if ($subject === '' || isset($subject[64])) {
 			throw new \InvalidArgumentException('The given subject is invalid');
 		}
 
@@ -252,15 +247,15 @@ class Notification implements INotification {
 	 * @return string
 	 * @since 8.2.0
 	 */
-	public function getSubject() {
+	public function getSubject(): string {
 		return $this->subject;
 	}
 
 	/**
-	 * @return string[]
+	 * @return array
 	 * @since 8.2.0
 	 */
-	public function getSubjectParameters() {
+	public function getSubjectParameters(): array {
 		return $this->subjectParameters;
 	}
 
@@ -270,8 +265,8 @@ class Notification implements INotification {
 	 * @throws \InvalidArgumentException if the subject is invalid
 	 * @since 8.2.0
 	 */
-	public function setParsedSubject(string $subject) {
-		if (trim($subject) === '') {
+	public function setParsedSubject(string $subject): INotification {
+		if ($subject === '') {
 			throw new \InvalidArgumentException('The given parsed subject is invalid');
 		}
 		$this->subjectParsed = $subject;
@@ -282,7 +277,7 @@ class Notification implements INotification {
 	 * @return string
 	 * @since 8.2.0
 	 */
-	public function getParsedSubject() {
+	public function getParsedSubject(): string {
 		return $this->subjectParsed;
 	}
 
@@ -293,8 +288,8 @@ class Notification implements INotification {
 	 * @throws \InvalidArgumentException if the subject or parameters are invalid
 	 * @since 11.0.0
 	 */
-	public function setRichSubject(string $subject, array $parameters = []) {
-		if (trim($subject) === '') {
+	public function setRichSubject(string $subject, array $parameters = []): INotification {
+		if ($subject === '') {
 			throw new \InvalidArgumentException('The given parsed subject is invalid');
 		}
 
@@ -308,7 +303,7 @@ class Notification implements INotification {
 	 * @return string
 	 * @since 11.0.0
 	 */
-	public function getRichSubject() {
+	public function getRichSubject(): string {
 		return $this->subjectRich;
 	}
 
@@ -316,7 +311,7 @@ class Notification implements INotification {
 	 * @return array[]
 	 * @since 11.0.0
 	 */
-	public function getRichSubjectParameters() {
+	public function getRichSubjectParameters(): array {
 		return $this->subjectRichParameters;
 	}
 
@@ -327,8 +322,8 @@ class Notification implements INotification {
 	 * @throws \InvalidArgumentException if the message or parameters are invalid
 	 * @since 8.2.0
 	 */
-	public function setMessage(string $message, array $parameters = []) {
-		if (trim($message) === '' || isset($message[64])) {
+	public function setMessage(string $message, array $parameters = []): INotification {
+		if ($message === '' || isset($message[64])) {
 			throw new \InvalidArgumentException('The given message is invalid');
 		}
 
@@ -342,15 +337,15 @@ class Notification implements INotification {
 	 * @return string
 	 * @since 8.2.0
 	 */
-	public function getMessage() {
+	public function getMessage(): string {
 		return $this->message;
 	}
 
 	/**
-	 * @return string[]
+	 * @return array
 	 * @since 8.2.0
 	 */
-	public function getMessageParameters() {
+	public function getMessageParameters(): array {
 		return $this->messageParameters;
 	}
 
@@ -360,8 +355,8 @@ class Notification implements INotification {
 	 * @throws \InvalidArgumentException if the message is invalid
 	 * @since 8.2.0
 	 */
-	public function setParsedMessage(string $message) {
-		if (trim($message) === '') {
+	public function setParsedMessage(string $message): INotification {
+		if ($message === '') {
 			throw new \InvalidArgumentException('The given parsed message is invalid');
 		}
 		$this->messageParsed = $message;
@@ -372,7 +367,7 @@ class Notification implements INotification {
 	 * @return string
 	 * @since 8.2.0
 	 */
-	public function getParsedMessage() {
+	public function getParsedMessage(): string {
 		return $this->messageParsed;
 	}
 
@@ -383,8 +378,8 @@ class Notification implements INotification {
 	 * @throws \InvalidArgumentException if the message or parameters are invalid
 	 * @since 11.0.0
 	 */
-	public function setRichMessage(string $message, array $parameters = []) {
-		if (trim($message) === '') {
+	public function setRichMessage(string $message, array $parameters = []): INotification {
+		if ($message === '') {
 			throw new \InvalidArgumentException('The given parsed message is invalid');
 		}
 
@@ -398,7 +393,7 @@ class Notification implements INotification {
 	 * @return string
 	 * @since 11.0.0
 	 */
-	public function getRichMessage() {
+	public function getRichMessage(): string {
 		return $this->messageRich;
 	}
 
@@ -406,7 +401,7 @@ class Notification implements INotification {
 	 * @return array[]
 	 * @since 11.0.0
 	 */
-	public function getRichMessageParameters() {
+	public function getRichMessageParameters(): array {
 		return $this->messageRichParameters;
 	}
 
@@ -416,8 +411,8 @@ class Notification implements INotification {
 	 * @throws \InvalidArgumentException if the link is invalid
 	 * @since 8.2.0
 	 */
-	public function setLink(string $link) {
-		if (trim($link) === '' || isset($link[4000])) {
+	public function setLink(string $link): INotification {
+		if ($link === '' || isset($link[4000])) {
 			throw new \InvalidArgumentException('The given link is invalid');
 		}
 		$this->link = $link;
@@ -428,7 +423,7 @@ class Notification implements INotification {
 	 * @return string
 	 * @since 8.2.0
 	 */
-	public function getLink() {
+	public function getLink(): string {
 		return $this->link;
 	}
 
@@ -438,8 +433,8 @@ class Notification implements INotification {
 	 * @throws \InvalidArgumentException if the icon is invalid
 	 * @since 11.0.0
 	 */
-	public function setIcon(string $icon) {
-		if (trim($icon) === '' || isset($icon[4000])) {
+	public function setIcon(string $icon): INotification {
+		if ($icon === '' || isset($icon[4000])) {
 			throw new \InvalidArgumentException('The given icon is invalid');
 		}
 		$this->icon = $icon;
@@ -450,7 +445,7 @@ class Notification implements INotification {
 	 * @return string
 	 * @since 11.0.0
 	 */
-	public function getIcon() {
+	public function getIcon(): string {
 		return $this->icon;
 	}
 
@@ -458,7 +453,7 @@ class Notification implements INotification {
 	 * @return IAction
 	 * @since 8.2.0
 	 */
-	public function createAction() {
+	public function createAction(): IAction {
 		return new Action();
 	}
 
@@ -468,7 +463,7 @@ class Notification implements INotification {
 	 * @throws \InvalidArgumentException if the action is invalid
 	 * @since 8.2.0
 	 */
-	public function addAction(IAction $action) {
+	public function addAction(IAction $action): INotification {
 		if (!$action->isValid()) {
 			throw new \InvalidArgumentException('The given action is invalid');
 		}
@@ -489,7 +484,7 @@ class Notification implements INotification {
 	 * @return IAction[]
 	 * @since 8.2.0
 	 */
-	public function getActions() {
+	public function getActions(): array {
 		return $this->actions;
 	}
 
@@ -499,7 +494,7 @@ class Notification implements INotification {
 	 * @throws \InvalidArgumentException if the action is invalid
 	 * @since 8.2.0
 	 */
-	public function addParsedAction(IAction $action) {
+	public function addParsedAction(IAction $action): INotification {
 		if (!$action->isValidParsed()) {
 			throw new \InvalidArgumentException('The given parsed action is invalid');
 		}
@@ -524,7 +519,7 @@ class Notification implements INotification {
 	 * @return IAction[]
 	 * @since 8.2.0
 	 */
-	public function getParsedActions() {
+	public function getParsedActions(): array {
 		return $this->actionsParsed;
 	}
 
@@ -532,7 +527,7 @@ class Notification implements INotification {
 	 * @return bool
 	 * @since 8.2.0
 	 */
-	public function isValid() {
+	public function isValid(): bool {
 		return
 			$this->isValidCommon()
 			&&
@@ -544,7 +539,7 @@ class Notification implements INotification {
 	 * @return bool
 	 * @since 8.2.0
 	 */
-	public function isValidParsed() {
+	public function isValidParsed(): bool {
 		if ($this->getRichSubject() !== '' || !empty($this->getRichSubjectParameters())) {
 			try {
 				$this->richValidator->validate($this->getRichSubject(), $this->getRichSubjectParameters());
@@ -568,10 +563,7 @@ class Notification implements INotification {
 		;
 	}
 
-	/**
-	 * @return bool
-	 */
-	protected function isValidCommon() {
+	protected function isValidCommon(): bool {
 		return
 			$this->getApp() !== ''
 			&&
diff --git a/lib/private/Server.php b/lib/private/Server.php
index ccdb31c3e82..64180f1cd7c 100644
--- a/lib/private/Server.php
+++ b/lib/private/Server.php
@@ -900,7 +900,8 @@ class Server extends ServerContainer implements IServerContainer {
 		});
 		$this->registerService(\OCP\Notification\IManager::class, function (Server $c) {
 			return new Manager(
-				$c->query(IValidator::class)
+				$c->query(IValidator::class),
+				$c->getLogger()
 			);
 		});
 		$this->registerAlias('NotificationManager', \OCP\Notification\IManager::class);
diff --git a/lib/public/Notification/AlreadyProcessedException.php b/lib/public/Notification/AlreadyProcessedException.php
new file mode 100644
index 00000000000..0ccac25f0fb
--- /dev/null
+++ b/lib/public/Notification/AlreadyProcessedException.php
@@ -0,0 +1,38 @@
+<?php
+declare(strict_types=1);
+/**
+ * @copyright Copyright (c) 2019 Joas Schilling <coding@schilljs.com>
+ *
+ * @license GNU AGPL version 3 or any later version
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+namespace OCP\Notification;
+
+
+/**
+ * @since 17.0.0
+ */
+class AlreadyProcessedException extends \RuntimeException {
+
+	/**
+	 * @since 17.0.0
+	 */
+	public function __construct() {
+		parent::__construct('Notification is processed already');
+	}
+
+}
diff --git a/lib/public/Notification/IAction.php b/lib/public/Notification/IAction.php
index 6f2b78e3a8d..718a61b2f39 100644
--- a/lib/public/Notification/IAction.php
+++ b/lib/public/Notification/IAction.php
@@ -1,4 +1,5 @@
 <?php
+declare(strict_types=1);
 /**
  * @copyright Copyright (c) 2016, ownCloud, Inc.
  *
@@ -29,19 +30,41 @@ namespace OCP\Notification;
  * @since 9.0.0
  */
 interface IAction {
+
+	/**
+	 * @since 17.0.0
+	 */
+	public const TYPE_GET = 'GET';
+	/**
+	 * @since 17.0.0
+	 */
+	public const TYPE_POST = 'POST';
+	/**
+	 * @since 17.0.0
+	 */
+	public const TYPE_PUT = 'PUT';
+	/**
+	 * @since 17.0.0
+	 */
+	public const TYPE_DELETE = 'DELETE';
+	/**
+	 * @since 17.0.0
+	 */
+	public const TYPE_WEB = 'WEB';
+
 	/**
 	 * @param string $label
 	 * @return $this
 	 * @throws \InvalidArgumentException if the label is invalid
 	 * @since 9.0.0
 	 */
-	public function setLabel($label);
+	public function setLabel(string $label): IAction;
 
 	/**
 	 * @return string
 	 * @since 9.0.0
 	 */
-	public function getLabel();
+	public function getLabel(): string;
 
 	/**
 	 * @param string $label
@@ -49,27 +72,27 @@ interface IAction {
 	 * @throws \InvalidArgumentException if the label is invalid
 	 * @since 9.0.0
 	 */
-	public function setParsedLabel($label);
+	public function setParsedLabel(string $label): IAction;
 
 	/**
 	 * @return string
 	 * @since 9.0.0
 	 */
-	public function getParsedLabel();
+	public function getParsedLabel(): string;
 
 	/**
-	 * @param $primary bool
+	 * @param bool $primary
 	 * @return $this
 	 * @throws \InvalidArgumentException if $primary is invalid
 	 * @since 9.0.0
 	 */
-	public function setPrimary($primary);
+	public function setPrimary(bool $primary): IAction;
 
 	/**
 	 * @return bool
 	 * @since 9.0.0
 	 */
-	public function isPrimary();
+	public function isPrimary(): bool;
 
 	/**
 	 * @param string $link
@@ -78,29 +101,29 @@ interface IAction {
 	 * @throws \InvalidArgumentException if the link is invalid
 	 * @since 9.0.0
 	 */
-	public function setLink($link, $requestType);
+	public function setLink(string $link, string $requestType): IAction;
 
 	/**
 	 * @return string
 	 * @since 9.0.0
 	 */
-	public function getLink();
+	public function getLink(): string;
 
 	/**
 	 * @return string
 	 * @since 9.0.0
 	 */
-	public function getRequestType();
+	public function getRequestType(): string;
 
 	/**
 	 * @return bool
 	 * @since 9.0.0
 	 */
-	public function isValid();
+	public function isValid(): bool;
 
 	/**
 	 * @return bool
 	 * @since 9.0.0
 	 */
-	public function isValidParsed();
+	public function isValidParsed(): bool;
 }
diff --git a/lib/public/Notification/IApp.php b/lib/public/Notification/IApp.php
index 8f7b9b3d013..58d2a1fa5b8 100644
--- a/lib/public/Notification/IApp.php
+++ b/lib/public/Notification/IApp.php
@@ -1,4 +1,5 @@
 <?php
+declare(strict_types=1);
 /**
  * @copyright Copyright (c) 2016, ownCloud, Inc.
  *
@@ -34,18 +35,18 @@ interface IApp {
 	 * @throws \InvalidArgumentException When the notification is not valid
 	 * @since 9.0.0
 	 */
-	public function notify(INotification $notification);
+	public function notify(INotification $notification): void;
 
 	/**
 	 * @param INotification $notification
 	 * @since 9.0.0
 	 */
-	public function markProcessed(INotification $notification);
+	public function markProcessed(INotification $notification): void;
 
 	/**
 	 * @param INotification $notification
 	 * @return int
 	 * @since 9.0.0
 	 */
-	public function getCount(INotification $notification);
+	public function getCount(INotification $notification): int;
 }
diff --git a/lib/public/Notification/IManager.php b/lib/public/Notification/IManager.php
index 003e5f1bad1..af890594d4c 100644
--- a/lib/public/Notification/IManager.php
+++ b/lib/public/Notification/IManager.php
@@ -1,4 +1,5 @@
 <?php
+declare(strict_types=1);
 /**
  * @copyright Copyright (c) 2016, ownCloud, Inc.
  *
@@ -30,48 +31,56 @@ namespace OCP\Notification;
  */
 interface IManager extends IApp, INotifier {
 	/**
-	 * @param \Closure $service The service must implement IApp, otherwise a
+	 * @param string $appClass The service must implement IApp, otherwise a
 	 *                          \InvalidArgumentException is thrown later
-	 * @since 9.0.0
+	 * @since 17.0.0
 	 */
-	public function registerApp(\Closure $service);
+	public function registerApp(string $appClass): void;
 
 	/**
 	 * @param \Closure $service The service must implement INotifier, otherwise a
 	 *                          \InvalidArgumentException is thrown later
 	 * @param \Closure $info    An array with the keys 'id' and 'name' containing
 	 *                          the app id and the app name
-	 * @since 9.0.0
+	 * @deprecated 17.0.0 use registerNotifierService instead.
+	 * @since 8.2.0 - Parameter $info was added in 9.0.0
 	 */
 	public function registerNotifier(\Closure $service, \Closure $info);
 
 	/**
-	 * @return array App ID => App Name
+	 * @param string $notifierService The service must implement INotifier, otherwise a
+	 *                          \InvalidArgumentException is thrown later
+	 * @since 17.0.0
+	 */
+	public function registerNotifierService(string $notifierService): void;
+
+	/**
+	 * @return INotifier[]
 	 * @since 9.0.0
 	 */
-	public function listNotifiers();
+	public function getNotifiers(): array;
 
 	/**
 	 * @return INotification
 	 * @since 9.0.0
 	 */
-	public function createNotification();
+	public function createNotification(): INotification;
 
 	/**
 	 * @return bool
 	 * @since 9.0.0
 	 */
-	public function hasNotifiers();
+	public function hasNotifiers(): bool;
 
 	/**
 	 * @param bool $preparingPushNotification
 	 * @since 14.0.0
 	 */
-	public function setPreparingPushNotification($preparingPushNotification);
+	public function setPreparingPushNotification(bool $preparingPushNotification): void;
 
 	/**
 	 * @return bool
 	 * @since 14.0.0
 	 */
-	public function isPreparingPushNotification();
+	public function isPreparingPushNotification(): bool;
 }
diff --git a/lib/public/Notification/INotification.php b/lib/public/Notification/INotification.php
index f7400e4778b..7261409e355 100644
--- a/lib/public/Notification/INotification.php
+++ b/lib/public/Notification/INotification.php
@@ -1,5 +1,5 @@
 <?php
-declare (strict_types = 1);
+declare(strict_types=1);
 /**
  * @copyright Copyright (c) 2016, ownCloud, Inc.
  *
@@ -37,13 +37,13 @@ interface INotification {
 	 * @throws \InvalidArgumentException if the app id is invalid
 	 * @since 9.0.0
 	 */
-	public function setApp(string $app);
+	public function setApp(string $app): INotification;
 
 	/**
 	 * @return string
 	 * @since 9.0.0
 	 */
-	public function getApp();
+	public function getApp(): string;
 
 	/**
 	 * @param string $user
@@ -51,13 +51,13 @@ interface INotification {
 	 * @throws \InvalidArgumentException if the user id is invalid
 	 * @since 9.0.0
 	 */
-	public function setUser(string $user);
+	public function setUser(string $user): INotification;
 
 	/**
 	 * @return string
 	 * @since 9.0.0
 	 */
-	public function getUser();
+	public function getUser(): string;
 
 	/**
 	 * @param \DateTime $dateTime
@@ -65,13 +65,13 @@ interface INotification {
 	 * @throws \InvalidArgumentException if the $dateTime is invalid
 	 * @since 9.0.0
 	 */
-	public function setDateTime(\DateTime $dateTime);
+	public function setDateTime(\DateTime $dateTime): INotification;
 
 	/**
 	 * @return \DateTime
 	 * @since 9.0.0
 	 */
-	public function getDateTime();
+	public function getDateTime(): \DateTime;
 
 	/**
 	 * @param string $type
@@ -80,19 +80,19 @@ interface INotification {
 	 * @throws \InvalidArgumentException if the object type or id is invalid
 	 * @since 9.0.0
 	 */
-	public function setObject(string $type, $id);
+	public function setObject(string $type, string $id): INotification;
 
 	/**
 	 * @return string
 	 * @since 9.0.0
 	 */
-	public function getObjectType();
+	public function getObjectType(): string;
 
 	/**
 	 * @return string
 	 * @since 9.0.0
 	 */
-	public function getObjectId();
+	public function getObjectId(): string;
 
 	/**
 	 * @param string $subject
@@ -101,19 +101,19 @@ interface INotification {
 	 * @throws \InvalidArgumentException if the subject or parameters are invalid
 	 * @since 9.0.0
 	 */
-	public function setSubject(string $subject, array $parameters = []);
+	public function setSubject(string $subject, array $parameters = []): INotification;
 
 	/**
 	 * @return string
 	 * @since 9.0.0
 	 */
-	public function getSubject();
+	public function getSubject(): string;
 
 	/**
-	 * @return string[]
+	 * @return array
 	 * @since 9.0.0
 	 */
-	public function getSubjectParameters();
+	public function getSubjectParameters(): array;
 
 	/**
 	 * Set a parsed subject
@@ -132,13 +132,13 @@ interface INotification {
 	 * @throws \InvalidArgumentException if the subject is invalid
 	 * @since 9.0.0
 	 */
-	public function setParsedSubject(string $subject);
+	public function setParsedSubject(string $subject): INotification;
 
 	/**
 	 * @return string
 	 * @since 9.0.0
 	 */
-	public function getParsedSubject();
+	public function getParsedSubject(): string;
 
 	/**
 	 * Set a RichObjectString subject
@@ -157,19 +157,19 @@ interface INotification {
 	 * @throws \InvalidArgumentException if the subject or parameters are invalid
 	 * @since 11.0.0
 	 */
-	public function setRichSubject(string $subject, array $parameters = []);
+	public function setRichSubject(string $subject, array $parameters = []): INotification;
 
 	/**
 	 * @return string
 	 * @since 11.0.0
 	 */
-	public function getRichSubject();
+	public function getRichSubject(): string;
 
 	/**
 	 * @return array[]
 	 * @since 11.0.0
 	 */
-	public function getRichSubjectParameters();
+	public function getRichSubjectParameters(): array;
 
 	/**
 	 * @param string $message
@@ -178,19 +178,19 @@ interface INotification {
 	 * @throws \InvalidArgumentException if the message or parameters are invalid
 	 * @since 9.0.0
 	 */
-	public function setMessage(string $message, array $parameters = []);
+	public function setMessage(string $message, array $parameters = []): INotification;
 
 	/**
 	 * @return string
 	 * @since 9.0.0
 	 */
-	public function getMessage();
+	public function getMessage(): string;
 
 	/**
-	 * @return string[]
+	 * @return array
 	 * @since 9.0.0
 	 */
-	public function getMessageParameters();
+	public function getMessageParameters(): array;
 
 	/**
 	 * Set a parsed message
@@ -209,13 +209,13 @@ interface INotification {
 	 * @throws \InvalidArgumentException if the message is invalid
 	 * @since 9.0.0
 	 */
-	public function setParsedMessage(string $message);
+	public function setParsedMessage(string $message): INotification;
 
 	/**
 	 * @return string
 	 * @since 9.0.0
 	 */
-	public function getParsedMessage();
+	public function getParsedMessage(): string;
 
 	/**
 	 * Set a RichObjectString message
@@ -234,19 +234,19 @@ interface INotification {
 	 * @throws \InvalidArgumentException if the message or parameters are invalid
 	 * @since 11.0.0
 	 */
-	public function setRichMessage(string $message, array $parameters = []);
+	public function setRichMessage(string $message, array $parameters = []): INotification;
 
 	/**
 	 * @return string
 	 * @since 11.0.0
 	 */
-	public function getRichMessage();
+	public function getRichMessage(): string;
 
 	/**
 	 * @return array[]
 	 * @since 11.0.0
 	 */
-	public function getRichMessageParameters();
+	public function getRichMessageParameters(): array;
 
 	/**
 	 * @param string $link
@@ -254,13 +254,13 @@ interface INotification {
 	 * @throws \InvalidArgumentException if the link is invalid
 	 * @since 9.0.0
 	 */
-	public function setLink(string $link);
+	public function setLink(string $link): INotification;
 
 	/**
 	 * @return string
 	 * @since 9.0.0
 	 */
-	public function getLink();
+	public function getLink(): string;
 
 	/**
 	 * @param string $icon
@@ -268,19 +268,19 @@ interface INotification {
 	 * @throws \InvalidArgumentException if the icon is invalid
 	 * @since 11.0.0
 	 */
-	public function setIcon(string $icon);
+	public function setIcon(string $icon): INotification;
 
 	/**
 	 * @return string
 	 * @since 11.0.0
 	 */
-	public function getIcon();
+	public function getIcon(): string;
 
 	/**
 	 * @return IAction
 	 * @since 9.0.0
 	 */
-	public function createAction();
+	public function createAction(): IAction;
 
 	/**
 	 * @param IAction $action
@@ -288,13 +288,13 @@ interface INotification {
 	 * @throws \InvalidArgumentException if the action is invalid
 	 * @since 9.0.0
 	 */
-	public function addAction(IAction $action);
+	public function addAction(IAction $action): INotification;
 
 	/**
 	 * @return IAction[]
 	 * @since 9.0.0
 	 */
-	public function getActions();
+	public function getActions(): array;
 
 	/**
 	 * @param IAction $action
@@ -302,23 +302,23 @@ interface INotification {
 	 * @throws \InvalidArgumentException if the action is invalid
 	 * @since 9.0.0
 	 */
-	public function addParsedAction(IAction $action);
+	public function addParsedAction(IAction $action): INotification;
 
 	/**
 	 * @return IAction[]
 	 * @since 9.0.0
 	 */
-	public function getParsedActions();
+	public function getParsedActions(): array;
 
 	/**
 	 * @return bool
 	 * @since 9.0.0
 	 */
-	public function isValid();
+	public function isValid(): bool;
 
 	/**
 	 * @return bool
 	 * @since 9.0.0
 	 */
-	public function isValidParsed();
+	public function isValidParsed(): bool;
 }
diff --git a/lib/public/Notification/INotifier.php b/lib/public/Notification/INotifier.php
index 5e2a47266ad..b730b1d8015 100644
--- a/lib/public/Notification/INotifier.php
+++ b/lib/public/Notification/INotifier.php
@@ -1,4 +1,5 @@
 <?php
+declare(strict_types=1);
 /**
  * @copyright Copyright (c) 2016, ownCloud, Inc.
  *
@@ -29,12 +30,30 @@ namespace OCP\Notification;
  * @since 9.0.0
  */
 interface INotifier {
+
+	/**
+	 * Identifier of the notifier, only use [a-z0-9_]
+	 *
+	 * @return string
+	 * @since 17.0.0
+	 */
+	public function getID(): string;
+
+	/**
+	 * Human readable name describing the notifier
+	 *
+	 * @return string
+	 * @since 17.0.0
+	 */
+	public function getName(): string;
+
 	/**
 	 * @param INotification $notification
 	 * @param string $languageCode The code of the language that should be used to prepare the notification
 	 * @return INotification
 	 * @throws \InvalidArgumentException When the notification was not prepared by a notifier
+	 * @throws AlreadyProcessedException When the notification is not needed anymore and should be deleted
 	 * @since 9.0.0
 	 */
-	public function prepare(INotification $notification, $languageCode);
+	public function prepare(INotification $notification, string $languageCode): INotification;
 }