Software Architecture

Software architecture defines the high-level structure of software systems and the discipline of creating such structures.

Architectural Patterns

Layered Architecture

Presentation Layer
    ↓
Business Logic Layer
    ↓
Data Access Layer
    ↓
Database

Microservices

• Independent, deployable services
• Single responsibility
• Decentralized data management
• Service communication via APIs

Event-Driven Architecture

• Asynchronous communication
• Loose coupling
• Event producers and consumers
• Message queues/brokers

Hexagonal Architecture (Ports & Adapters)

• Core business logic isolated
• External dependencies as adapters
• Testable and flexible

Design Principles

SOLID Principles

• Single Responsibility Principle
• Open/Closed Principle
• Liskov Substitution Principle
• Interface Segregation Principle
• Dependency Inversion Principle

DRY (Don't Repeat Yourself)

Avoid code duplication through abstraction and reusability.

KISS (Keep It Simple, Stupid)

Favor simplicity over complexity.

YAGNI (You Aren't Gonna Need It)

Don't add functionality until it's necessary.

Architecture Decision Records (ADRs)

Document important architectural decisions:

• Context: What is the issue?
• Decision: What did we decide?
• Consequences: What are the impacts?

Common Patterns

Repository Pattern

Abstracts data access logic.

Factory Pattern

Creates objects without specifying exact class.

Observer Pattern

Defines subscription mechanism for events.

Strategy Pattern

Defines family of algorithms, makes them interchangeable.

Trade-offs

Every architectural decision involves trade-offs:

• Performance vs Scalability
• Consistency vs Availability (CAP theorem)
• Complexity vs Flexibility
• Cost vs Quality

Documentation

• Architecture diagrams (C4 model)
• Component relationships
• Data flow diagrams
• Deployment architecture