Microservices Architecture: When to Use and When to Avoid

Microservices Architecture: When to Use and When to Avoid

Microservices are everywhere, but are they right for your project? Let's explore the architecture, patterns, and real-world considerations.

What Are Microservices?

Microservices architecture breaks down applications into small, independent services that:

• Run in their own process
• Communicate via APIs (HTTP, gRPC, message queues)
• Can be deployed independently
• Are organized around business capabilities

Monolith vs Microservices

Monolithic Architecture

┌─────────────────────────────┐
│      Single Application     │
│  ┌─────────────────────┐   │
│  │   User Management   │   │
│  ├─────────────────────┤   │
│  │   Order Processing  │   │
│  ├─────────────────────┤   │
│  │  Payment Processing │   │
│  ├─────────────────────┤   │
│  │   Inventory         │   │
│  └─────────────────────┘   │
│    Single Database          │
└─────────────────────────────┘

Pros:

• ✅ Simple to develop
• ✅ Easy to test
• ✅ Simple deployment
• ✅ No network overhead

Cons:

• ❌ Tight coupling
• ❌ Difficult to scale
• ❌ Technology lock-in
• ❌ Large codebase

Microservices Architecture

┌──────────────┐  ┌──────────────┐  ┌──────────────┐
│    User      │  │    Order     │  │   Payment    │
│   Service    │  │   Service    │  │   Service    │
│  ┌────────┐  │  │  ┌────────┐  │  │  ┌────────┐  │
│  │  DB    │  │  │  │  DB    │  │  │  │  DB    │  │
│  └────────┘  │  │  └────────┘  │  │  └────────┘  │
└──────────────┘  └──────────────┘  └──────────────┘
       │                 │                  │
       └─────────────────┴──────────────────┘
                    API Gateway

Pros:

• ✅ Independent deployment
• ✅ Technology flexibility
• ✅ Easy to scale
• ✅ Fault isolation

Cons:

• ❌ Complex infrastructure
• ❌ Network latency
• ❌ Data consistency challenges
• ❌ Testing complexity

Microservices Patterns

1. API Gateway Pattern

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2. Service Discovery Pattern

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3. Circuit Breaker Pattern

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4. Event-Driven Architecture

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5. Saga Pattern (Distributed Transactions)

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Database Strategies

Database per Service

┌──────────────┐     ┌──────────────┐
│User Service  │     │Order Service │
│  ┌────────┐  │     │  ┌────────┐  │
│  │ Users  │  │     │  │ Orders │  │
│  │   DB   │  │     │  │   DB   │  │
│  └────────┘  │     │  └────────┘  │
└──────────────┘     └──────────────┘

Pros:

• ✅ Loose coupling
• ✅ Independent scaling

Cons:

• ❌ No ACID transactions
• ❌ Data duplication

Shared Database (Anti-pattern)

┌──────────────┐     ┌──────────────┐
│User Service  │     │Order Service │
└──────┬───────┘     └──────┬───────┘
       │                    │
       └────────┬───────────┘
                │
         ┌──────▼──────┐
         │   Shared    │
         │  Database   │
         └─────────────┘

Why avoid?

• ❌ Tight coupling
• ❌ Schema changes affect all services
• ❌ Defeats microservices purpose

Communication Patterns

Synchronous (REST/gRPC)

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Asynchronous (Message Queue)

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Deployment Strategies

Docker Compose (Development)

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Kubernetes (Production)

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When to Use Microservices

✅ Use when:

• Large, complex application
• Multiple independent teams
• Different scaling requirements per feature
• Need for technology diversity
• High availability requirements

❌ Avoid when:

• Small application or startup
• Small team (< 5 developers)
• Tight deadlines
• Limited DevOps expertise
• Simple CRUD application

Migration Strategy

Strangler Fig Pattern

Phase 1: Monolith
┌─────────────────┐
│    Monolith     │
└─────────────────┘

Phase 2: Extract first service
┌─────────────┐   ┌──────────┐
│  Monolith   │   │  User    │
│  (minus     │   │  Service │
│   users)    │   └──────────┘
└─────────────┘

Phase 3: Extract more services
┌─────────┐ ┌────────┐ ┌─────────┐
│Monolith │ │  User  │ │  Order  │
│ (core)  │ │Service │ │ Service │
└─────────┘ └────────┘ └─────────┘

Conclusion

Microservices aren't a silver bullet:

• Start simple with monolith
• Extract services when needed
• Use proven patterns (API Gateway, Circuit Breaker, Saga)
• Invest in DevOps (CI/CD, monitoring, logging)
• Plan for failure (resilience, fallbacks)

Remember: Complexity is a feature, not a bug. Only add it when you need it! 🎯