diff --git a/include/class-App.php b/include/class-App.php
index 72cfd12..f781c17 100644
--- a/include/class-App.php
+++ b/include/class-App.php
@@ -1,47 +1,66 @@
 <?php
 # WikiCAPTCHA Control Room
 # Copyright (C) 2019 Valerio Bozzolan and contributors
 #
 # This program is free software: you can redistribute it and/or modify
 # it under the terms of the GNU 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 General Public License for more details.
 #
 # You should have received a copy of the GNU General Public License
 # along with this program. If not, see <http://www.gnu.org/licenses/>.
 
 /**
  * Methods of an App class
  */
 trait AppTrait {
 
 	/**
 	 * Get the App ID
 	 *
 	 * @return int
 	 */
 	public function getAppID() {
 		return $this->get( 'app_ID' );
 	}
 
 	/**
 	 * Get the App name
 	 *
 	 * @return string
 	 */
 	public function getAppName() {
 		return $this->get( 'app_name' );
 	}
+
+	/**
+	 * Normalize an App after being retrieved from database
+	 */
+	protected function normalizeApp() {
+		$this->integers( 'app_ID' );
+	}
 }
 
 /**
  * Class that can wrap an App retrieved from the database
+ *
+ * An App rappresents an instance of a WikiCAPTCHA application
+ * assigned to a website.
  */
 class App {
 
+	use AppTrait;
+
+	/**
+	 * Constructor
+	 */
+	public function __construct() {
+		$this->normalizeApp();
+	}
+
 }