Concepts
As professionals aiming to qualify as Certified Scrum Professionals for Developers (CSP-D), understanding the integration of vital design principles and patterns to enable emerging architectures is critical. This knowledge forms the pillar upon which the scale and sustainability of applications built using Agile and Scrum methodologies rest. This article will delve into three key design principles or patterns, their role in emerging architectures, and how they contribute to robust, scalable, and maintainable systems.
1. Single Responsibility Principle (SRP)
The Single Responsibility Principle, one of the five SALID principles, posits that a class should have only one reason to change. In essence, a class should only have one job or responsibility. The primary goal is to achieve high cohesion and low coupling, leading to significant maintenance advantages. In the context of emerging architectures like Microservices, the SRP plays a cardinal role.
Each microservice can be seen as a class with a single responsibility. Entities, services, and controllers within the microservice should follow the same principle. This strategy organizes code better, making it more readable and maintainable.
Consider an E-commerce application with different services such as user management, inventory management, and bill generation. Implementing SRP, each of these services would be independent microservices with a single responsibility.
2. Open Closed Principle (OCP)
The Open Closed Principle, another SOLID principle, states that software entities (classes, modules, functions, etc.) should be open for extension but closed for modification. This principle aims to make systems easy to extend without necessitating major changes to the existing system, hence minimizing the risk of breaking existing functionality.
Emerging architectures like plug-in architecture leverage OCP effectively. In this style, the core system is closed for modification but open for extension through plug-ins. For an example, a web browser is a core system that allows plug-in extensions for different functionality, like ad blocking, SEO analysis, and language translation. The core system does not require modification each time a new plug-in is added or an existing one is updated.
3. Model-View-Controller (MVC) Pattern
The MVC pattern separates an application into three interconnected components: the model, the view, and the controller. This pattern enhances scalability by promoting organized and modular coding and creating rich and interactive UIs.
For instance, in web applications, the model represents the data and the business logic. The view displays the data to the user, and the controller handles the user’s interactions. The separation of responsibilities in this pattern allows developers to work on individual components without impacting others. The MVC pattern has been integral to the evolution of architectures like Serverless and RESTful APIs.
Summary
As a summation, the table below underlines the discussed principles/patterns and their key implications for emerging architectures:
| Design Principle/Pattern | Key Implication |
|---|---|
| Single Responsibility Principle | High cohesion, low coupling, enhancing readability and maintainability |
| Open Closed Principle | Easy extension of the system with minimum modifications |
| Model-View-Controller | Separation of responsibilities, improving scalability and interactive UIs |
Understanding and integrating these design principles into your Scrum Developer skill set can be transformative. They can guide the design and architecture for durable, maintainable systems, maximizing business value throughout the software development lifecycle. To successfully apply these principles and patterns, always consider the context and the specific needs of the system and the project.
Answer the Questions in Comment Section
True or False: The Layering is one of the design principles that enable emerging architectures.
Answer: True.
Explanation: Layering is a principle used to separate functionality into distinct, isolated stages that communicate over well-defined interfaces.
Which of the following is a benefit of using design patterns in software development?
- a) They provide proven solutions to common problems.
- b) They lead to more efficient code.
- c) They introduce unnecessary complexity.
- d) They promote tightly coupled, monolithic architecture.
Answer: a) They provide proven solutions to common problems. And b) They lead to more efficient code.
Explanation: Design patterns are tested, proven solutions that can make the code more efficient and sustainable. They help to avoid complexities.
Which design principle emphasizes making software entities reusable?
- a) Single Responsibility Principle.
- b) Open-Closed Principle
- c) Interface Segregation Principle
- d) Dependency Inversion Principle
Answer: b) Open-Closed Principle.
Explanation: The Open-Closed Principle states that components should be open for extension, but closed for modification, thereby encouraging reusability.
True or False: Model View Controller (MVC) is an example of a design pattern.
Answer: True.
Explanation: MVC is a type of structural design pattern that separates application functionality into three interconnected components.
Which principle refers to the high level modules should not depend on low level modules?
- a) Single Responsibility Principle.
- b) Open-Closed Principle
- c) Interface Segregation Principle
- d) Dependency Inversion Principle
Answer: d) Dependency Inversion Principle
Explanation: Dependency Inversion Principle advises high-level modules to depend on abstractions, not on the low-level modules, hence promoting loose coupling.
True or False: encapsulation, inheritance and polymorphism are the pillar for object-oriented design patterns.
Answer: True
Explanation: These three principles are indeed the foundation for object-oriented design patterns, promoting abstraction, generalized code, and hiding of internal details.
Which principle states that many specific clients should not be forced to depend on interfaces they do not use?
- a) Single Responsibility Principle.
- b) Open-Closed Principle
- c) Interface Segregation Principle
- d) Dependency Inversion Principle
Answer: c) Interface Segregation Principle
Explanation: The Interface Segregation Principle stresses on avoiding fat interfaces and hence reducing the dependencies of one class to others.
Select the design principle that promotes individuals to work on a single task?
- a) Single Responsibility Principle.
- b) Open-Closed Principle
- c) Interface Segregation Principle
- d) Dependency Inversion Principle
Answer: a) Single Responsibility Principle.
Explanation: The Single Responsibility Principle indicates that a person should not be distracted with more than one work responsibility.
True or False: Excepting Adapter Pattern and Composite Pattern, all rest are the behavioral patterns.
Answer: False
Explanation: Adapter and Composite are structural patterns, but not all remaining are behavioral. For example, Singleton and Factory patterns are creational patterns.
Is SOLID a principle that enables emerging architectures?
Answer: True.
Explanation: SOLID is an acronym representing a collection of design principles intended to make software designs more understandable, flexible, and maintainable. It is pivotal for modern and emerging software architectures.
I think the Single Responsibility Principle is a key design principle for emerging architectures. It keeps modules focused and manageable.
The Dependency Injection pattern is crucial for decoupling dependencies and enabling more flexible architectures.
Implementing the Observer pattern can be very useful in event-driven architectures.
Thanks for the informative post!
I think the Interface Segregation Principle cannot be ignored. It ensures that clients don’t depend on methods they don’t use.
Appreciate the insights shared in this blog!
I think the Factory Method pattern is great for creating objects without exposing the instantiation logic.
Honestly, I think the blog missed out on discussing the Strategy pattern which is very useful in defining a family of algorithms.