DDD: Bounded Contexts — Where Models Apply

A bounded context is the explicit boundary within which a domain model is consistent — the same word means different things across boundaries.

When to use

• Large domain with multiple teams or subdomains
• Preventing model pollution across services
• Defining microservice or module boundaries

Tradeoffs

• Context mapping adds coordination overhead at boundaries
• Misaligned context and team boundaries cause friction

Go

// package sales
type Customer struct {
    ID          string
    Name        string
    CreditLimit float64
    SalesRepID  string
}

// package shipping
type Customer struct {
    ID               string
    Name             string
    ShippingAddress  Address
    DeliveryPrefs    string
}

Python

# module: sales/models.py
from dataclasses import dataclass

@dataclass
class Customer:
    id: str
    name: str
    credit_limit: float
    sales_rep_id: str

# module: shipping/models.py
@dataclass
class Customer:
    id: str
    name: str
    shipping_address: str
    delivery_prefs: str

Gotcha: A microservice boundary should align with a bounded context boundary — not the other way around.