Microservices Architecture Explained
What Is Microservices Architecture?
Microservices architecture is a design approach where a single application is built as a suite of small, independently deployable services, each running in its own process and communicating via lightweight protocols (typically HTTP/REST or gRPC). According to the 2025 CNCF Survey, 78% of organizations now use microservices in production, up from 58% in 2022.
In system design interviews, microservices questions test your ability to decompose a monolith, define service boundaries, and handle distributed system challenges like consistency, discovery, and fault tolerance.
Microservices vs Monolith: When to Use Each
| Factor | Monolith | Microservices |
|---|---|---|
| Team Size | 1-15 engineers | 15+ engineers |
| Deploy Speed | Slower (whole app) | Faster (per service) |
| Complexity | Low initially | Higher (networking, observability) |
| Scaling | Scale entire app | Scale individual services |
| Best For | MVPs, startups | Large-scale production systems |
Key Design Patterns for Microservices
- API Gateway — Single entry point routing to backend services. See API design best practices
- Service Discovery — Consul, Eureka, or Kubernetes DNS for locating service instances
- Circuit Breaker — Prevent cascade failures using Hystrix or Resilience4j pattern
- Saga Pattern — Distributed transactions via choreography or orchestration
- Event Sourcing — Store state changes as immutable events. Pairs with message queue architecture
- CQRS — Separate read and write models for different optimization strategies
How to Answer Microservices Interview Questions
When asked "How would you decompose this system into microservices?", follow this structure:
- Identify bounded contexts from domain-driven design (DDD)
- Define service APIs and data ownership (each service owns its database)
- Choose communication: synchronous (REST/gRPC) vs asynchronous (Kafka/RabbitMQ)
- Address cross-cutting concerns: auth, logging, tracing (OpenTelemetry)
- Discuss deployment: Kubernetes, Docker, CI/CD pipelines
Use AissenceAI's system design AI for real-time prompts during microservices architecture discussions.