Software Architecture Patterns

Understanding software architecture patterns and design principles is crucial for building scalable and maintainable applications. Let's explore some key patterns and principles.

Clean Architecture

Clean Architecture promotes separation of concerns and dependency rules:

// Domain Layer
interface User {
	id: string;
	name: string;
	email: string;
}

// Use Case Layer
class CreateUserUseCase {
	constructor(private userRepository: UserRepository) {}

	async execute(userData: User): Promise<User> {
		return this.userRepository.create(userData);
	}
}

// Repository Interface
interface UserRepository {
	create(user: User): Promise<User>;
	findById(id: string): Promise<User | null>;
}

SOLID Principles

Single Responsibility

A class should have only one reason to change:

// Bad
class UserService {
	saveUser() {
		/* ... */
	}
	sendEmail() {
		/* ... */
	}
	generateReport() {
		/* ... */
	}
}

// Good
class UserService {
	saveUser() {
		/* ... */
	}
}

class EmailService {
	sendEmail() {
		/* ... */
	}
}

class ReportService {
	generateReport() {
		/* ... */
	}
}

Microservices Architecture

Break down applications into small, independent services:

// User Service
class UserService {
	async createUser(user: User): Promise<User> {
		// Handle user creation
		return user;
	}
}

// Order Service
class OrderService {
	async createOrder(order: Order): Promise<Order> {
		// Handle order creation
		return order;
	}
}

Event-Driven Architecture

Use events for loose coupling between components:

interface EventBus {
	publish(event: Event): void;
	subscribe(eventType: string, handler: (event: Event) => void): void;
}

class OrderCreatedEvent implements Event {
	constructor(public readonly orderId: string) {}
}

class NotificationHandler {
	handle(event: OrderCreatedEvent) {
		// Send notification
	}
}

Repository Pattern

Abstract data access logic:

interface Repository<T> {
	findById(id: string): Promise<T | null>;
	findAll(): Promise<T[]>;
	create(entity: T): Promise<T>;
	update(entity: T): Promise<T>;
	delete(id: string): Promise<void>;
}

class UserRepository implements Repository<User> {
	// Implementation
}

Best Practices

1. Follow SOLID principles
2. Use dependency injection
3. Keep components loosely coupled
4. Write testable code
5. Document architecture decisions
6. Consider scalability from the start

Common Anti-patterns to Avoid

1. God Objects
2. Tight Coupling
3. Premature Optimization
4. Magic Strings/Numbers
5. Duplicate Code

Conclusion

Choosing the right architecture patterns and following solid design principles is crucial for building maintainable and scalable applications. These patterns and principles provide a foundation for writing clean, testable, and maintainable code.