✅ 1. Microservices Architecture

• Breaks an application into small, independent services
  
  

• Each service:
  
  

  • Owns its own data
    
    

  • Has its own deployment lifecycle
    
    

  • Communicates over lightweight protocols (typically HTTP/REST or messaging)
    
    

Pros: Scalability, independent deployment
Cons: Complexity in distributed coordination

✅ 2. API Gateway Pattern

• A single entry point for all client requests
  
  

• Handles routing, authentication, rate limiting, caching, etc.
  
  

Benefits:

• Centralized access control
  
  

• Reduces client complexity
  
  

✅ 3. Service Discovery Pattern

• Helps microservices find and communicate with each other dynamically
  
  

• Client-side discovery: e.g., Netflix Eureka
  
  

• Server-side discovery: via API Gateway or service mesh
  
  

✅ 4. Database per Service Pattern

• Each microservice manages its own database schema
  
  

• Prevents tight coupling through shared databases
  
  

Challenge: Handling cross-service queries (often resolved with CQRS or event-driven approaches)

✅ 5. Event-Driven Architecture

• Services communicate asynchronously via events (e.g., Kafka, RabbitMQ)
  
  

• Promotes loose coupling and reactive design
  
  

✅ 6. Circuit Breaker Pattern

• Prevents cascading failures by breaking communication to a failing service temporarily
  
  

• Libraries: Netflix Hystrix, Resilience4j
  
  

✅ 7. Bulkhead Pattern

• Isolates failures in one part of the system from affecting others
  
  

• Example: Use separate thread pools for different services
  
  

✅ 8. Strangler Pattern

• Used for gradual migration from a monolith to microservices
  
  

• Incrementally replace parts of the monolith with new services
  
  

✅ 9. Saga Pattern

• Manages distributed transactions across microservices
  
  

• Types:
  
  

  • Choreography: each service knows what to do next
    
    

  • Orchestration: a central orchestrator coordinates the flow
    
    

✅ 10. Sidecar Pattern

• Deploy helper components (e.g., logging, monitoring, proxy) alongside services in containers
  
  

• Common in service meshes like Istio
  
  

🔧 Tooling & Technologies to Know:

• API Gateway: Kong, NGINX, Spring Cloud Gateway
  
  

• Service Discovery: Eureka, Consul, Kubernetes DNS
  
  

• Messaging: Kafka, RabbitMQ, AWS SNS/SQS
  
  

• Resilience: Resilience4j, Hystrix
  
  

• Observability: Prometheus, Grafana, ELK, OpenTelemetry
  
  

• Deployment: Docker, Kubernetes, Helm