Discover how SOLID principles improve both software development and DevOps practices. Read our case study and check video for key benefits and practical applications.
Programming is an art that requires not only technical skills but also an understanding of fundamental development principles. One set of principles that helps create reliable and scalable code is known as SOLID. These five principles of object-oriented design help developers write more understandable and maintainable code. In this case study, we will look at the application of SOLID principles in a company developing software for financial institutions. We will also discuss how these principles can be applied in DevOps practices, particularly with Terraform scripts. Additionally, we will highlight the importance of adhering to these principles in MVP (Minimum Viable Product) development and startups.
For startups and MVP development, following SOLID principles is crucial. Startups often operate under tight deadlines and limited resources, making it essential to build a strong foundation for their software from the beginning. Implementing SOLID principles helps ensure that the codebase remains flexible, maintainable, and scalable as the product evolves. This approach reduces the likelihood of costly refactoring down the line and allows the development team to respond quickly to changes in market demands or customer feedback.
Our client specializes in developing financial software for banks and other financial institutions. Their products include payment systems, account management systems, and analytical tools. The client base consists of large banks that require high reliability and security from the software.
The client faced the problem of maintaining and scaling their code. Over time, the programs became more complex, and any change in one module caused a ripple effect of changes in other parts of the system. This led to delays in developing new features and increased maintenance costs. The main problems were:
To address the challenges faced by the client, we decided to implement the SOLID principles throughout their software development and DevOps processes. These principles would provide a structured and systematic approach to refactoring the existing codebase and improving infrastructure automation. By doing so, we aimed to achieve a more modular, maintainable, and scalable system. Below, we discuss how each of the SOLID principles was applied and the specific benefits realized in both development and DevOps contexts.
The first step in improving the code was implementing the Single Responsibility Principle. The team divided the classes so that each one performed only one task. This reduced dependencies between components and simplified their testing. For example, a class responsible for processing transactions was divided into several smaller classes: one for validation, another for database logging, and another for logging.
To increase flexibility, the team applied the Open/Closed Principle. Existing classes were modified so that they could be extended without changing the original code. This was achieved through the use of abstract classes and interfaces. For example, to add new payment methods, an interface PaymentMethod was created, and each new payment method implemented this interface without affecting the core system code.
Adhering to the Liskov Substitution Principle, the team ensured that subclass objects could be used in place of base class objects without affecting the correctness of the program. This was achieved by clearly defining class contracts and testing subclasses for compliance with these contracts.
To reduce interface redundancy, the Interface Segregation Principle was implemented. Instead of one large interface that included many methods, several narrowly specialized interfaces were created. This allowed classes to implement only the methods they really needed, simplifying development and maintenance.
The final step was implementing the Dependency Inversion Principle. The team changed the application architecture so that higher-level modules did not depend on lower-level modules. Instead, both depended on abstractions. This was achieved by using interfaces and injecting dependencies through constructors. For example, a class processing payments no longer directly depended on a specific payment service implementation but received it through an interface.
Implementing the SOLID principles yielded significant results for our client:
Overall, the implementation of SOLID principles resulted in a robust, flexible, and maintainable codebase that not only met the current needs of the client but also positioned them well for future growth and adaptation. The principles provided a solid foundation for both software development and DevOps practices, ensuring long-term success and sustainability.
The SOLID principles are fundamental to creating robust, maintainable, and scalable software systems. By adhering to these principles in development, we can ensure that each part of the system is focused, modular, and easier to manage. This approach not only improves the overall quality of the codebase but also makes it more adaptable to change. In this section, we explore how each SOLID principle can be applied in software development, providing specific examples of their benefits and implementation.
In software development, the Single Responsibility Principle means that each class or module should have only one responsibility. For instance, in a financial application, you might have separate classes for validating transactions, processing payments, and logging activities. This separation makes the code easier to understand and maintain. If a change is needed in the validation process, it can be done without affecting the payment processing or logging functionality.
The Open/Closed Principle in development implies that software entities should be open for extension but closed for modification. For example, if a financial application needs to support new payment methods, this can be achieved by adding new classes that implement a common interface without modifying the existing payment processing code. This approach allows developers to introduce new features with minimal risk of introducing bugs into the existing system.
Adhering to the Liskov Substitution Principle ensures that objects of a superclass can be replaced with objects of a subclass without affecting the correctness of the application. For example, in a reporting system, if a base report class is designed to generate PDF reports, a subclass might be introduced to generate Excel reports. The application should be able to handle both types of reports interchangeably, ensuring that new types of reports can be integrated seamlessly.
The Interface Segregation Principle suggests that no client should be forced to depend on methods it does not use. For instance, in a user management system, separate interfaces can be created for user authentication, user profile management, and user notifications. This way, a class that handles user authentication does not need to implement methods related to profile management or notifications, making the code more modular and easier to manage.
The Dependency Inversion Principle means that high-level modules should not depend on low-level modules but both should depend on abstractions. For example, in a notification system, instead of the main application directly depending on specific implementations of email or SMS notification services, it can depend on an abstract notification interface. This allows for easy swapping of different notification methods without changing the core application logic.
Applying SOLID principles in DevOps practices enhances the modularity and scalability of infrastructure management. By structuring scripts and configurations according to these principles, DevOps teams can create more maintainable and flexible automation pipelines. This leads to improved efficiency, easier troubleshooting, and faster deployment cycles. In this section, we discuss how SOLID principles can be incorporated into DevOps workflows, with a focus on practical examples and their impact on infrastructure automation.
In DevOps, the Single Responsibility Principle means that each script or module should be responsible for only one part of the infrastructure. For example, you might have one script that handles network configuration, another script for setting up databases, and yet another for managing server instances. This modular approach makes it easier to test and maintain individual components and reduces the risk of errors during deployment.
The Open/Closed Principle in DevOps implies that existing configurations can be extended without changing the core code. For instance, if you need to add new types of instances or storage options in your infrastructure, you can do so by adding new configuration files or modules. This way, the core scripts remain unchanged, minimizing the risk of introducing errors into the deployment process.
Adhering to the Liskov Substitution Principle in DevOps ensures that one resource can be replaced with another without disrupting the system’s functionality. For example, if you need to switch from one type of database instance to another (e.g., from a general-purpose instance to a memory-optimized instance), the infrastructure should support this change without requiring modifications to the deployment scripts.
The Interface Segregation Principle in DevOps means that scripts should have narrow, specialized interfaces. For example, a module for setting up a virtual private cloud (VPC) should only include variables and methods relevant to VPC configuration. Separate modules can handle different aspects like security groups or subnet configurations. This specialization makes the modules easier to understand, use, and maintain.
The Dependency Inversion Principle in DevOps helps reduce the dependency of high-level modules on low-level ones. For example, in a continuous integration/continuous deployment (CI/CD) pipeline, instead of having the pipeline directly depend on specific deployment scripts, it can use abstract deployment interfaces. This way, different deployment strategies (e.g., blue-green deployment, canary releases) can be implemented and swapped without changing the core CI/CD pipeline logic.
Implementing SOLID principles significantly improved software quality, reduced maintenance costs, and increased the speed of developing new features. This, in turn, allowed us to provide clients with high-quality and reliable products that meet modern financial market requirements. The application of these principles in various fields, including DevOps, demonstrated their versatility and effectiveness in improving processes and systems. For startups and MVP development, adhering to these principles is especially crucial, as it sets a solid foundation for future growth and adaptability.
At Managed Code, we specialize in software development and DevOps solutions that leverage industry best practices like SOLID principles. Our experienced team is dedicated to helping businesses build robust, maintainable, and scalable systems that drive success. Whether you're developing a new product or optimizing your infrastructure, Managed Code has the expertise to guide you every step of the way.
Contact us to learn how we can help you implement SOLID principles and achieve your development goals.
