Monolith vs. Microservice Architecture
Architecture Comparison
Monolithic Architecture (with Spring Boot)
Single Application Approach
In Spring Boot, all business logic, data access layers, and web layers are packaged into a single JAR file.
Spring Boot Advantages
- Auto-configuration for rapid startup
- Embedded server (Tomcat/Jetty) for easy deployment
- Leverage all features of Spring Framework
Development Process
- Rapid configuration with Spring Boot starter dependencies
- Database operations with Spring Data JPA
- Security with Spring Security
- Integration testing with Spring Test
Limitations
- Startup time increases as application grows
- Technology stack changes are difficult
- Merge conflicts increase in large teams
Suitable Scenarios
- Small-medium scale projects
- Prototype development
- Teams with few developers
- Projects requiring rapid time-to-market
Microservice Architecture (Spring Boot + Spring Cloud)
Service-Oriented Approach
Each microservice is developed as a separate Spring Boot application with its own database.
Spring Cloud Ecosystem
- Service Discovery (Eureka)
- API Gateway (Spring Cloud Gateway)
- Circuit Breaker (Hystrix/Resilience4j)
- Distributed Configuration (Spring Cloud Config)
Communication Models
- REST APIs with Spring WebMVC/WebFlux
- Async messaging with Spring Cloud Stream + RabbitMQ/Kafka
- Inter-service communication with OpenFeign client
Data Management
- Each service has its own PostgreSQL/MongoDB instance
- Saga pattern for distributed transactions
- Event sourcing with Spring Cloud Stream
Deployment
- Each service in separate Docker container
- Kubernetes orchestration
- Health checks with Spring Boot actuator
- Git-based deployment pipeline
Organizational Advantages
- Conway's Law: Team structure reflects service architecture
- Different teams can use different technology stacks
- Independent release cycles
Operational Complexity
- Service mesh (Istio)
- Distributed tracing (Sleuth + Zipkin)
- Centralized logging (ELK stack)
- Monitoring (Micrometer + Prometheus)
Hybrid Architecture Approach
Strangler Fig Pattern
Strategy for gradually transforming monolithic applications to microservices
Modular Monolith
- Modular structure with domain-driven design
- Ease of transition to microservices in the future
Bounded Context
- Each module has its own data model and business logic
- Loose coupling
Shared Kernel
- Management of commonly used code
- Versioning strategy
Anti-Corruption Layer
Translation layer between old and new systems
Decision Criteria
| Criteria | Monolithic | Microservices |
|---|---|---|
| Team Size | < 10 people | > 10 people |
| Deployment Frequency | Weekly/Monthly | Daily/Hourly |
| System Complexity | Simple-Medium | Complex |
| Performance Requirements | Medium | High |
| Operational Experience | Limited | Advanced |
Best Practices
For Monolithic
- Use modular design
- Loose coupling with dependency injection
- Comprehensive testing strategy
- CI/CD pipeline setup
For Microservices
- Domain-driven design approach
- API-first development
- Robust monitoring and observability
- Failure isolation and resilience patterns