Introduction to Software Architecture - Part 1: Paradigms, Architecture, and Patterns
Published: 2023-09-11 14:17:37

### What is Software Architecture?

Software architecture is the fundamental structure of a software system. It defines how the system's components are organized and interact with each other, as well as the general guidelines for software design and construction. In essence, software architecture is the skeleton or framework upon which the entire system is built.

Software architecture plays a critical role in software development, as it affects the quality, scalability, maintainability, and performance of the system.

## What are the Objectives of Software Architecture?

1. **Facilitate Understanding:** A good architecture makes it easier for developers and other project stakeholders to understand the structure and operation of the system.

2. **Promote Maintainability:** Well-designed architecture facilitates system maintenance over time, allowing changes to be made with minimal impact on other parts of the system.

3. **Enable Scalability:** Proper architecture allows the system to be scalable, capable of handling increased workloads or the addition of new features.

4. **Enhance Quality:** A solid architecture contributes to the overall quality of the system, including reliability, performance, security, and usability.

5. **Support Reusability:** A good architecture allows parts of the system to be reused in different contexts, saving time and development effort.

## What are the Fundamental Parts of Software Architecture?

### Programming Paradigms

Each programming language may have one or more paradigms. In the past, Java was primarily focused on Object-Oriented Programming (OOP), C was more focused on procedural programming, and JavaScript had a stronger focus on functional programming. While some languages support multiple paradigms, this is just one example. When building software, you can choose a programming paradigm that aligns with your needs. Here are some examples:

- **Procedural:** Focused more directly on imperative programming. In imperative code, each step and detail is explicitly dictated. Functions are still used but as helpers.

```typescript
function main() {
    const numbers: number[] = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
    
    const evenNumbers: number[] = [];

    for (let i = 0; i < numbers.length; i++) {
        if (numbers[i] % 2 === 0) {
            evenNumbers.push(numbers[i]);
        }
    }
    return evenNumbers;;

    console.log("Even numbers: " + evenNumbers.join(", "));
}

main();
```

- **Functional:** Unlike the procedural paradigm, functional programming is more declarative. Instead of giving step-by-step commands, you simply declare what you want and pass the necessary data. This paradigm focuses more on functions and declarations.

```typescript
function isEven(number: number): boolean {
    return number % 2 === 0;
}

function filterList(list: number[], predicate: (number: number) => boolean): number[] {
    return list.filter(predicate);
}

function main() {
    const numbers: number[] = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
    
    const evenNumbers: number[] = filterList(numbers, isEven);

    console.log("Even numbers: " + evenNumbers.join(", "));
}

main();
```

- **Object-Oriented:** Based on objects that contain data and methods. For example, an object representation of a `Person` that has a name and age. I won't delve into the pillars of OOP here as this is just an introduction.

```typescript
class Person {
    name: string;
    age: number;

    constructor(name: string, age: number) {
        this.name = name;
        this.age = age;
    }

    displayInfo(): void {
        console.log(`Name: ${this.name}, Age: ${this.age} years old`);
    }
}

const person1 = new Person("John", 30);
const person2 = new Person("Maria", 25);

person1.displayInfo();
person2.displayInfo();
```

### Components

Components are like libraries, frameworks, classes, functional modules (e.g., an inventory manager), and even microservices. An example would be the MVC architecture, which is a web architecture.

- **Controller:** After a request, the first place the request goes through is the controller. Based on the received information, it is processed, and a response is returned.
- **Model:** It's the representation part, which can be a database entity.
- **View:** It doesn't necessarily have to be HTML or something specific, just a way to represent the final response after the entire process of the components.

### Connections

An example of the MVC architecture is how each component communicates, which can be a function or class. I won't go into much detail as this is intuitive and depends on each architecture.

### Patterns and Guidelines

Code creation standards and rules are essential for maintaining cleaner and simpler code.

- **Guidelines:** If the programming paradigm is used, S.O.L.I.D will be used, which is a set of rules for best practices.
- **Code Patterns:** We can mention design patterns, security patterns, behavioral and structural patterns. For example, if S.O.L.I.D is used, you can use class creational and structural patterns to improve code scalability. You can also use security patterns like roles, JWT, and others, behavioral patterns to standardize behaviors in some situations, as well as clean code and various other practices.
- **Design Patterns:**

 We can mention MVC, documentation like Swagger or diagrams, version management with Git, and many others.

- **Testing Patterns:** They can be functional tests, non-functional tests, end-to-end tests, and others.

Basically, when creating software, various patterns can be used from the beginning of the project to code creation and testing.

### Layers

In software architecture, "layers" refer to the hierarchical and structured organization of system components and functionalities into distinct levels or layers. These can include presentation layers (user interface), business logic layers (application business rules), and data layers (database, storage system, and others).

### Hexagonal Architecture

Hexagonal Architecture, also known as Ports and Adapters Architecture, is an approach that places the application's domain at the center and isolates it from any technical or external details. It is called "hexagonal" because of its graphical representation with multiple concentric layers.

![Hexagonal Architecture](https://miro.medium.com/v2/resize:fit:2800/0*5GppEPBRzXgwvhuX.png)

1. **Domain (core):** The application's domain, which contains entities and business rules.
2. **Ports (ports):** Interfaces that define how the domain will be accessed and interacted with. These can be input ports, such as commands and API routes, and output ports for communication with databases and other systems.
3. **Adapters (adapters):** Adapters implement the ports defined in the domain. They serve as intermediaries for external elements, such as database (output port adapter) and input data (input port adapter).

### Clean Architecture

Clean Architecture is an approach proposed by Robert C. Martin (also known as Uncle Bob) that emphasizes independence from frameworks, libraries, implementation details, and code organization. It is represented by concentric layers, with the innermost layers being the most abstract and the outer

most layers being the most concrete.

![Clean Architecture](https://cdn-media-1.freecodecamp.org/images/YIABVRTHRz58ZiT6W-emBkfNIQUHBelp8t6U)

1. **Entities (Entities):** This layer contains business entities and pure data. They are the core of the application and should not depend on technical details.

2. **Use Cases (Use Cases):** This layer represents the logic that orchestrates entities and services to perform tasks.

3. **Interfaces (Input and Output Interfaces):** This layer defines interfaces that allow use cases to interact with the outside world, including user interfaces, database interfaces, and external service interfaces. The idea is to define these interfaces at the domain level, maintaining the core's independence.

4. **Frameworks and Drivers (Frameworks and Controllers):** This is the outermost layer that deals with technical details, such as frameworks, libraries, user interfaces, and drivers.

### Data Models

In software development, "data models" refer to the structured representation of data that an application uses, stores, or manipulates. These models are designed to represent information in an organized way and are essential for understanding and operating software systems.

### Architecture Decisions

Software architecture decisions are strategic choices made by architects or development teams during the design and development process of a software system. These decisions shape the software's structure, behavior, and performance, impacting its maintainability, scalability, and effectiveness. Here are some common and important architecture decisions to consider:

1. **Software Architecture:** Choosing the right software architecture is one of the most crucial decisions. This includes choosing between monolithic architectures, microservices, serverless, event-driven architectures, and more, depending on the project's needs.

2. **Technologies and Platforms:** Selecting the right technologies and platforms for development, such as programming language, framework, database management system, web server, operating system, and others.

3. **Scalability:** Deciding how the system will scale to handle increasing workloads. This involves choosing between vertical scalability (adding more resources to an existing server) or horizontal scalability (adding more servers).

4. **Security:** Defining security strategies, including authentication, authorization, data encryption, protection against attacks, identity and access management, and more.

5. **Data Management:** Planning how data will be stored, retrieved, and manipulated. This includes choosing databases, database schemas, caching and indexing strategies, and more.

6. **Communication and Integration:** Deciding how different components of the system will communicate and integrate. This may involve using APIs, asynchronous messaging, communication protocols, integration patterns, and more.

7. **User Interface Architecture:** Designing the structure of the user interface, including the choice of front-end technologies, interface design patterns, user experience (UX), and usability.

8. **State Management:** Determining how application state will be managed, especially in web and mobile applications. This includes choosing between local state management, global state management, and data flow patterns.

9. **Data Persistence:** Planning how data will be persisted, considering storage strategy, backups, disaster recovery, and data retention policies.

10. **Layered Architecture:** Deciding on the organization of components into layers, such as separating business logic, presentation logic, and data layer. This may involve architectures like MVC (Model-View-Controller) or MVVM (Model-View-ViewModel).

11. **Testability:** Designing the system so that it's easy to create and run automated tests, such as unit tests, integration tests, and acceptance tests.

12. **Monitoring and Logging:** Defining how the system will be monitored in production to track performance, identify issues, and collect data for analysis.

13. **Coding Standards:** Establishing coding standards, naming conventions, and code style guidelines to maintain source code consistency and quality.

14. **Version Control:** Deciding on the version control and collaboration strategy, such as using version control systems (e.g., Git) and collaborative development workflows.

15. **Software Development Lifecycle:** Choosing a development methodology, such as Agile, Scrum, Kanban, Waterfall, etc., and defining development, testing, and deployment processes.

16. **Distributed Architecture:** For distributed systems, deciding how components will be distributed across multiple machines and how communication between them will be handled.

17. **Availability and Fault Tolerance:** Designing strategies to ensure continuous system availability, including implementing redundancy and fault recovery mechanisms.

18. **Data Retention Policies:** Establishing policies for managing old and obsolete data, as well as compliance with privacy regulations and data retention requirements.

19. **Budget and Resources:** Taking into account budget and resource constraints when making architecture decisions.

20. **Scalability:** Scalability capacity is a key decision to handle increases in workload. Choosing between vertical scalability (adding more resources to an existing server) and horizontal scalability (adding more servers) will affect how the system responds to increased demand.

21. **Cache Architecture:** The use of caching, such as in-memory data caching, can significantly improve performance by reducing the need to query databases or perform repetitive calculations. Decisions about where and how to apply caching are important.

22. **Efficient Data Modeling:** Choosing an appropriate data model, optimizing queries, and creating database indexes can speed up data read and write operations.

23. **Parallelism and Concurrency:** Designing the system to take advantage of parallelism and concurrency can speed up task processing. This may include the use of threads, processes, concurrent programming, or even distributed systems.

24. **Efficient Memory Usage:** Ensuring that the system uses memory efficiently by minimizing memory leaks and unnecessary allocations can improve overall efficiency.

25. **Efficient Algorithms and Data Structures:** Choosing the right algorithms and using appropriate data structures can make a big difference in data processing performance.

26. **Resource Management:** Carefully managing resources like database connections, threads, memory, and network connections is important to avoid bottlenecks and performance issues.

The choice of a data model depends on the application's needs, storage requirements, query operations, and the characteristics of the data to be represented. Many systems commonly use a combination of different data models to meet various needs within the application.

- LinkedIn: [JeanVictor1](https://www.linkedin.com/in/jeanvictor1/)
- Dev.to: [@mrjeandev](https://dev.to/mrjeandev)