Monolith vs Microservices

Monolith

┌────────────────────────┐
│       Monolith App     │
│  ┌──────┐ ┌──────┐    │
│  │ Auth │ │ Order│    │
│  └──────┘ └──────┘    │
│  ┌──────┐ ┌──────┐    │
│  │ User │ │Payment│   │
│  └──────┘ └──────┘    │
│       One Database     │
└────────────────────────┘
+ Simple, mudah develop & deploy
- Sulit scale satu bagian saja

Microservices

┌──────┐  ┌───────┐  ┌─────────┐
│ Auth │  │ Order │  │ Payment │
│ Svc  │  │  Svc  │  │   Svc   │
│  DB  │  │  DB   │  │   DB    │
└──┬───┘  └───┬───┘  └────┬────┘
   │          │            │
   └──── API Gateway ──────┘
              │
           Client
+ Scale independen per service
- Lebih complex (network, consistency)

Komunikasi antar Service

• Synchronous (HTTP/gRPC) — Service langsung call service lain. Simple tapi tight coupling.
• Asynchronous (Message Queue) — Kirim pesan via RabbitMQ/Kafka. Loose coupling tapi lebih complex.

// Synchronous: Order Service call Payment Service
const payment = await fetch("http://payment-service/charge", {
  method: "POST",
  body: JSON.stringify({ orderId: 123, amount: 99 }),
});

// Asynchronous: Order Service publish event
await messageQueue.publish("order.created", {
  orderId: 123, userId: 456, amount: 99
});
// Payment Service subscribe dan proses

Kapan Pakai Microservices?

• Mulai dengan monolith — Hampir selalu. Premature microservices = premature complexity
• Pisahkan saat — Tim sudah besar (>20 dev), perlu scale independen, domain sudah jelas