Software architects define software architecture as the high-level structure, or roadmap for developing a system, or a blueprint of the software system. However, these explanations can be confusing because they don’t clearly say what details the plan should include or what parts of the system it should focus on. They often leave out the specifics of what needs to be studied and how these ideas should actually help people create the software step by step.

How Do We Understand What Makes Up Software Architecture?

1. Architecture Characteristics
2. Structure
3. Architecture Decisions
4. Design Principles

Architecture Characteristics

Software architecture must satisfy key qualities or non-functional requirements to ensure the system meets business and technical needs.

• Scalability: The ability to handle increasing loads or data efficiently.
• Performance: Ensuring low latency and high throughput.
• Maintainability: The ease of modifying the system to fix issues or add features.
• Reliability: The system’s ability to function under expected and unexpected conditions.
• Security: Protecting data and processes from unauthorized access.
• Flexibility: Adapting to changing requirements or external conditions.
• Modularity: Structuring the system into independent, replaceable components.

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Structure

The structure of software architecture defines how components are organized and interact. This includes architectural patterns, frameworks, and modularity.

• Architectural Patterns: Well-known models like MVC (Model-View-Controller), Layered Architecture, Microservices, Event-Driven Architecture, etc.
• Software Architecture Frameworks: Models like 4+1 View Model and C4 Model, which provide systematic ways to visualize and define software structures.
• Modular Design: Dividing the system into independently deployable modules or layers.

If an architect is asked to describe an architecture and simply responds, “It’s a microservices architecture,” they are only describing the structure of the system, not its overall architecture.

Architecture Decisions

Architecture decisions shape how the software system will be structured and function. These include:

• Technology Stack: Choosing programming languages, frameworks, and tools.
• Architectural Patterns: Whether to use monolithic, microservices, event-driven, or other styles.
• Deployment Model: Cloud-based, on-premises, or hybrid infrastructure.
• Scalability, Performance, and Security Considerations: Addressing non-functional requirements in the design phase.
• Trade-offs: Balancing flexibility, complexity, cost, and time-to-market.

Organizations typically have an Architecture Review Board (ARB) or a Chief Architect responsible for evaluating and approving architectural decisions based on trade-offs.

Design Principles

Design principles guide architecture decisions to create well-organized, efficient systems.

• Separation of Concerns (SoC): Each component should focus on a specific responsibility, minimizing overlap and dependencies.
• Loose Coupling: Components should have minimal dependencies, often achieved through APIs or event-driven communication.
• High Cohesion: Related functions and data should be grouped together within modules for clarity and maintainability.
• Encapsulation: Internal details of components should be hidden from others to reduce complexity and increase reusability.
• Reusability: Designing components or services that can be reused in different contexts to save time and resources.
• Consistency: Ensuring uniformity in coding standards, naming conventions, and UI/UX practices across the system.

Design principles serve as guidelines rather than strict rules, allowing for flexibility in implementation while maintaining software quality.