Microservices Architecture
Comprehensive guide to microservices architecture patterns, principles, and best practices.
Overview
Microservices is an architectural style that structures an application as a collection of small, autonomous services modeled around a business domain.
Core Characteristics
- Small, focused services - Each service does one thing well
- Independent deployment - Deploy services without affecting others
- Decentralized data - Each service owns its data
- Technology diversity - Choose best tech for each service
- Organizational alignment - Services align with team boundaries
When to Use Microservices
✅ Good Fit:
- Large, complex domains
- Multiple teams need autonomy
- Different scaling requirements
- Need for technology diversity
- Frequent, independent deployments
❌ Probably Not:
- Small applications
- Single small team
- Simple CRUD operations
- Limited operational maturity
- Startup/MVP phase
Key Patterns
See Microservices Patterns for detailed implementations.
Decomposition Patterns
- Decompose by business capability
- Decompose by subdomain (DDD)
- Strangler Fig pattern (gradual migration)
Communication Patterns
- API Gateway
- Service Mesh
- Event-driven messaging
- Request/response (sync)
- Publish/subscribe (async)
Data Patterns
- Database per service
- Saga pattern (distributed transactions)
- Event sourcing
- CQRS
Deployment Patterns
- Service per container
- Serverless deployment
- Service per VM
###Cross-Cutting Concerns
- Service discovery
- Circuit breaker
- Distributed tracing
- Centralized logging
- Configuration management
Architecture Decisions
Document these in ADRs:
- Service Boundaries - How to decompose?
- Communication - Sync vs async?
- Data Consistency - Eventual vs strong?
- Discovery - Client-side vs server-side?
- API Gateway - Single vs multiple?
- Deployment - Containers, serverless, or VMs?
Best Practices
Design
- Model Around Business Domain - Use DDD
- Decentralize - Data, decisions, and governance
- Automate - CI/CD, testing, deployment
- Design for Failure - Circuit breakers, retries, fallbacks
- Monitor Everything - Logs, metrics, traces
Development
- Contract-First - Define APIs before implementation
- Independent Deployability - Avoid shared libraries
- Backward Compatibility - Version APIs carefully
- Test at Boundaries - Contract tests between services
- Isolate Failures - Bulkheads, timeouts
Operations
- Observability - Distributed tracing, centralized logs
- Automation - Infrastructure as code
- Service Mesh - For complex communication
- Chaos Engineering - Test resilience
- Gradual Rollouts - Canary, blue-green deployments
Reference Implementation
See our Microservices Reference Architecture
Resources
Last Updated: November 2025
Related: DDD | Event-Driven | API Design
Content to be expanded with specific implementation examples and case studies.