The general architecture used in the proposed application model is known as client–server (see Figure 1). Its different elements are the following:Client: Mobile device used for the system.Server: Hosted in the cloud, and divided into two parts. The first part is the Google Cloud Messaging (GCM) server that handles all of the notifications and is responsible for sending the notification when the receiving clients are alive. The second part is the DataBase (DB) dedicated server, which stores all data related to users and the system in a database. It also serves as a gateway for sending notifications between the client and the GCM server.