An evolutionary design is the first principle that enables the architecture to adapt to changes. As customer demands and technologies evolve, the design should also develop and accommodate such changes, ensuring that the product remains relevant and valuable. Agile supports an incremental and iterative development approach that works well with an evolutionary design.
For instance, consider developing an app where new features like sign-up, news feed, and notification systems are requested. Initially, you might not design the architecture to handle notification systems. But as the product grows, this feature becomes essential, and the architecture should evolve to add on this feature seamlessly.
Principle 2: High Quality for Everyone
This principle suggests that everyone on an Agile team is responsible for maintaining high quality in all stages of product development. Traditional staged gate processes storing quality assurance until after development are not conducive in Agile environments. All stakeholders, from designers and developers to business analysts and QA professionals, are part of creating high-quality software.
Consider Scrum, one of the most popular Agile methodologies. Scrum calls for the Development team, Product Owner and Scrum Master to share the responsibility of maintaining high-quality development. For instance, if a QA professional identifies an architectural flaw during testing, the entire team takes responsibility for its correction, rather than blaming the person who created the design.
Principle 3: Simplicity
Agile favors simple designs that serve the present needs, rather than future predictions. This is characterized by the Agile Manifesto’s principle of “Maximize Work Not Done.” It means the architecture should be as simple as possible, agile enough for any changes, and efficient enough to avoid unnecessary complexity.
Consider the principle of YAGNI (You Aren’t Gonna Need It). YAGNI encourages developers to add functionality when the need arises, rather than assuming future requirements. It stresses the elimination of unnecessary complexity in design, which can add to the cost and time of development without proving value at the present.
| Principle | Meaning | Example |
|---|---|---|
| Evolutionary Design | Architecture should adapt over time | Adding a Notifications system to an app architecture that initially did not have one |
| High Quality for Everyone | Everyone is responsible for maintaining high quality | Entire Scrum team taking responsibility for architectural flaws discovered during testing |
| Simplicity | Design should be simple and serve present needs | Following YAGNI principle; adding functionalities only when needed |
In conclusion, following these principles can enhance architectural success in Agile environments. They encompass Agile values of adaptability, quality, simplicity, and responsiveness to change. Proper understanding and execution of these principles is instrumental in passing the Certified Scrum Developers (CSD) exam and, more importantly, succeeding in creating superior software products in Agile environments.
Practice Test
True or False: Flexibility is one of the key principles of architecture in an agile environment.
- True
- False
Answer: True
Explanation: Flexibility is a critical principle in agile architecture as it involves building an architecture which is able to adapt to changes swiftly.
Which of the following is not a principle of architecture in an Agile environment?
- A. Simplicity
- B. Elaboration
- C. Consistency
- D. Resilience
Answer: B. Elaboration
Explanation: Elaboration is not one of the major principles of architecture in an agile environment. The key principles are simplicity, consistency, flexibility, and resilience.
True or False: In an agile environment, consistency in architecture is not important.
- True
- False
Answer: False
Explanation: Consistency is a critical factor in the architecture of an agile environment. It ensures that the system performs functions in a uniform manner and simplifies the process.
Simplicity is a core principle in Agile Architecture, what does it mean?
- A. It means the architecture should have many features
- B. It means the architecture should be complex
- C. It means the architecture should be pared down to essential elements
- D. It means the architecture should be elaborate
Answer: C. It means the architecture should be pared down to essential elements
Explanation: The principle of simplicity in Agile refers to making the system as simple as possible by eliminating unnecessary complexity.
True or False: In an agile environment, the architecture needs to be resilient in order to handle changes in requirements or technology?
- True
- False
Answer: True
Explanation: Resilience is a key aspect of agile architecture, making it able to handle changes or disruptions without major modifications.
Which of the following are principles of architecture in an Agile environment? (Multiple Choices)
- A. Flexibility
- B. Simplicity
- C. Redundancy
- D. Resilience
Answer: A. Flexibility, B. Simplicity, D. Resilience
Explanation: In an agile environment, the architecture is mainly based on the principles of simplicity, flexibility, and resilience. Redundancy is not considered a major principle in Agile.
True or False: Freedom to add features without impacting existing functionality is a principle of agile environment architecture.
- True
- False
Answer: True
Explanation: This is true because agile environment architecture requires flexibility to allow adding or changing features without disrupting the system’s existing functionality.
In Agile, what does ‘resilience’ mean?
- A. The system’s ability to resist changes
- B. The system’s complexity
- C. The system’s ability to adapt and recover quickly from changes
- D. The system’s overall capacity
Answer: C. The system’s ability to adapt and recover quickly from changes.
Explanation: Resilience in Agile Architecture refers to the system’s capability to absorb changes or disruptions and recover quickly.
True or False: One of the principles of an agile environment is to have a complex architecture to ensure all potential scenarios are covered.
- True
- False
Answer: False
Explanation: In Agile, a key principle is simplicity. The architecture should be as simple as possible and complex scenarios should be broken down into simpler, manageable parts.
Which of the following is an element of an agile architecture?
- A. Rigidity
- B. Inconsistency
- C. Redundancy
- D. Consistency
Answer: D. Consistency
Explanation: Consistency is an element of agile architecture. It ensures same elements are treated in the same way across the system, making it simple and predictable.
Interview Questions
Q1: What is the principle of clean code in an agile environment?
A1: The clean code principle in agile architecture is about delivering pragmatic functionality in a straightforward, efficient manner with the end objective of reducing complexity. It emphasizes maintainability and comprehensibility of the code.
Q2: What does the principle of emergent design entail in the context of agile architecture?
A2: The emergent design is a principle of agile architecture that promotes the evolution of design and architecture over time. It allows the system design to gradually develop with increments according to the project’s changing requirements, enhancing flexibility and adaptability.
Q3: What is the purpose of the simplicity principle in agile architecture?
A3: The simplicity principle encourages developers to create the simplest possible design that meets the current user stories. It promotes efficiency, ease of understanding, and reduces the chance of making mistakes.
Q4: Can you explain the principle of continuous integration in agile architecture?
A4: Continuous integration is a principle in agile architecture that emphasizes on integrating work frequently, usually multiple times in a day. Each integration is verified by an automated build and automated tests to detect integration errors as quickly as possible.
Q5: What is refactoring and how does it contribute to the principles of agile architecture?
A5: Refactoring is the process of improving the design of existing code without changing its external behavior. In agile architecture, regular refactoring helps to improve the system’s structure, reduce complexity, and improve maintainability and extensibility.
Q6: How does YAGNI (You Ain’t Gonna Need It) contribute to the principles of agile architecture?
A6: YAGNI is an agile programming principle that states you should not add functionality until it is necessary. It’s a core practice in agile environments that helps to prevent over-engineering and encourages the delivery of necessary functionality in a timely manner.
Q7: What are the key agile architecture principles to support scalable systems?
A7: Key agile architecture principles to support scalable systems include using clean code, adopting emergent design, maintaining simplicity, continually integrating, refactoring regularly, and adhering to the YAGNI principle.
Q8: What is meant by the term ‘technical debt’ in agile architecture and how is it managed?
A8: Technical debt refers to the potential consequence of poor system design or architecture. It represents the future cost of additional work caused by choosing an easy or limited solution now instead of using a better approach. Technical debt is managed by regular refactoring, continuous integration, and maintaining clean code.
Q9: How does the principle of Test-Driven Development (TDD) fit into agile architecture?
A9: Test-Driven Development (TDD) is a software development practice in which unit tests are written before the code itself. It improves the quality and maintainability of the code, making it an integral part of agile architecture.
Q10: Why is the principle of continuous learning important in agile architecture?
A10: The principle of continuous learning emphasizes on constant development and refinement of architectural knowledge and technical skills. This principle supports the iterative, improvement-oriented nature of agile processes.
Q11: What is the role of the iterative development principle in agile architecture?
A11: Iterative development is a principle of agile architecture that encourages repetitive cycles of development that improves the system’s design and functionality based on feedback from each cycle. It helps to quickly detect problems and adjust the architectural design accordingly.
Q12: How does the principle of incremental design complement other agile architecture principles?
A12: The principle of incremental design complements other agile architecture principles by allowing additions to system features in small, manageable increments. This permits validation of system requirements step-by-step without the necessity of a full system design.
Q13: Could you explain the concept of “Fail Fast” in an Agile Environment and how it’s a principle of agile architecture?
A13: The “Fail Fast” principle encourages quick iterations where mistakes are recognized, and corrective action is taken immediately. In agile architecture, this principle helps eliminate unnecessary features and identify potential design flaws in the early stages.
Q14: What is code smells and how does it represent a principle in Agile Architecture?
A14: Code smells indicate deeper problems in the system’s code. They are usually not bugs— they do not prevent the program from functioning. Instead, they indicate weaknesses in design that may slow down development or increase the risk of bugs or failures in the future. Identifying and removing code smells is an agile architectural principle aimed at developing a maintainable and efficient system.
Q15: What role does the “Once and Only Once” principle play in Agile Architecture?
A15: The “Once and Only Once” principle dictates that information should exist in a system in one place only. By eliminating repetition, it makes the code simpler, cleaner, and more efficient, and helps maintain consistency, a crucial aspect of Agile Architecture.
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