# System Architecture Design of IoT-Based Smart Cities
## 5 Reference Architecture Design  
### Architecture Framework and Viewpoint Selection  
The selection of an architecture framework and viewpoints is a crucial step in the software development process as it forms the foundation for the design and implementation of a system. The choice of a framework and viewpoints should be based on the specific needs and concerns of the stakeholders involved in the project.  
When selecting an architecture framework, it is important to consider the overall goals and objectives of the system, as well as the constraints and limitations imposed by the development environment. In addition, the framework should provide a structure and methodology for modeling and analyzing the system. Finally, it should be supported by tools and resources to aid the design and implementation process.  
Once a framework has been chosen, selecting viewpoints is the next step. Viewpoints represent the stakeholders' different concerns and should be chosen based on their relevance to the system being developed. For example, the Views and Beyond (V and B) approach distinguishes three different viewpoints categories: the module view, component and connector view, and deployment view. These viewpoints document the system's principal units of implementation, its units of execution, and the relationships between the system's software and its development and execution environments.  
It is important to note that selecting a framework and viewpoints is not a one-time process but rather an ongoing process that may change over time as the system evolves. As the system is developed, new concerns may arise, and it may be necessary to modify or add new viewpoints to the architecture to address these concerns.  
Decomposition, layered, and deployment viewpoints have been selected for the smart city case study for a few reasons. First, the decomposition viewpoint is useful for breaking down a complex system into smaller, more manageable parts. It helps to identify the key components of a system and how they interact with one another. In the case of a smart city, decomposition can be used to identify the various subsystems that make up the city, such as transportation, energy, and communication systems. This can aid in understanding how different parts of the city interact and how to optimize their performance.  
The layered viewpoint, on the other hand, is useful for organizing the different components of a system into logical layers. This helps to separate concerns and make the system more modular. For example, in the case of a smart city, layering can be used to separate the different levels of control and management, such as the city-wide control system, the district control system, and the local control system. This can aid in understanding how control and management flow through the city and how to optimize performance.  
The deployment viewpoint, finally, is useful for understanding how a system is deployed in the real world. It helps to identify the physical components of a system and how they are connected. For example, in the case of a smart city, deployment can be used to identify the different physical infrastructure that makes up the city, such as roads, buildings, and communication networks. This can aid in understanding how the city is physically constructed and how to optimize its performance.  
In the following subsections, we describe the architectural views for each of these viewpoints.