# System Architecture Design of IoT-Based Smart Cities
## 6 Case Study Research
### Architecture Viewpoints  
We can now define the application views for the smart charging system based on the reference architecture. These views include the application decomposition view (Figure 8), the application layered view (Figure 9), and the application deployment view (Figure 10). For the Smart Charging System, the decomposition view would provide a clear understanding of the various selected components from the reference model and the following modules:  
* User Authentication Module: This module manages the authentication and authorization of users, ensuring that only authorized users have access to the charging system;
* User Management Module: This module is responsible for managing the users, including creating and updating user accounts and handling authentication and authorization for accessing the charging stations;  
Figure 7: Conceptual diagram of Smart Charging System (1 and * stands for one-to-many relation). * Charging Session Management Module: This module manages the charging sessions, including starting and stopping the charging process, monitoring the charging progress, and collecting charging data;
* Charging Station Locator Module: Allows users to find available charging stations nearby and reserve a charging slot;
* Payment Processing Module: This module manages the payment transactions for the charging services;
* Energy Management Module: This module monitors and manages the energy usage and distribution for the charging stations;
* Charging Scheduling Module: This module allows users to schedule their charging sessions in advance and receive reminders;
* Charging Station Management Module: This module is responsible for managing the charging stations, including monitoring their status and handling scheduling and billing for the charging sessions;
* Energy Grid Integration Module: This module connects the charging system to the energy grid, enabling the charging stations to access grid power as needed;
* Load Balancing Module: This module balances the load on the charging stations, ensuring that they operate at optimal levels;
* Maintenance Module: This module manages the maintenance tasks for the charging stations, ensuring that they are kept in good working condition;
* Data Analytics Module: This module gathers and analyzes data from the charging system, providing valuable insights into the system's performance and usage. This information could be used to improve the system and better meet users' needs. Each module is interconnected and interdependent, working together to form a comprehensive smart charging system. The decomposition view helps to clearly illustrate these relationships and the functional responsibilities of each module. The layered view is then defined based on the selected features and the related modules, as shown in Figure 9.  
Figure 8: Decomposition View for Smart Charging System. The deployment view of the smart charging system can be derived from the reference deployment view and is depicted as a network of various devices and components (Figure 10). In this deployment view, the following components can be included:  
* General Cloud Server: This component represents the central server that manages the charging system. It collects and processes data from the other components and provides centralized control and management functions;  
Figure 10: Deployment View for Smart Charging System (1 and * stands for one to many relation). Figure 9: Layering View for Smart Charging System. * Client Node: The client node represents the end-users or consumers who access the charging system.