/examples/multi-service/README.md

Multi-Service Example

Run multiple services in a single binary — the modular monolith pattern.

What It Shows

• Two independent services (users and orders) in one process
• Each service gets isolated server, client, store, and cache
• Shared registry and broker for inter-service communication
• Coordinated lifecycle with micro.NewGroup()

Run It

go run .

This starts both services:

• Users on :9001 — provides Users.Lookup
• Orders on :9002 — provides Orders.Create

Call the Services

From another terminal:

# Look up a user
micro call users Users.Lookup '{"id": "1"}'

# Create an order
micro call orders Orders.Create '{"user_id": "1"}'

How It Works

// Create isolated services
users := micro.New("users", micro.Address(":9001"))
orders := micro.New("orders", micro.Address(":9002"))

// Register handlers
users.Handle(new(Users))
orders.Handle(new(Orders))

// Run together — stops all when one exits
g := micro.NewGroup(users, orders)
g.Run()

Each service gets its own server and client, so they can be split into separate binaries later without code changes. The group handles coordinated startup and graceful shutdown.

When to Use This Pattern

• Early development — run everything locally in one process
• Testing — integration tests without Docker or networking
• Small teams — fewer moving parts until you need to scale independently
• Gradual migration — start monolith, split services one at a time

Splitting Later

When you're ready to run services independently, just move each into its own main.go:

func main() {
    svc := micro.New("users", micro.Address(":9001"))
    svc.Handle(new(Users))
    svc.Run()
}

No handler code changes needed — the registry handles discovery automatically.