NeuralBlitz What I do
- Design bounded contexts and their boundaries
- Create rich domain models
- Implement aggregates and aggregate roots
- Design value objects
- Define domain events
- Apply strategic and tactical DDD
When to use me
When building complex domain logic, modeling business domains, or structuring large applications.
Strategic Design
Bounded Contexts
- Clear boundaries around domain models
- Each context has its own ubiquitous language
- Context mapping relationships:
- Customer/Supplier: Upstream/downstream
- Conformist: Downstream follows upstream
- Anticorruption Layer: Translation layer
- Open Host Service: Published language
- Separate Ways: No relationship
Ubiquitous Language
- Shared language between developers and domain experts
- Embedded in code (class names, methods)
- Consistent terminology
Context Maps
- Visual representation of system boundaries
- Integration points
- Team responsibilities
Tactical Design
Entities
- Identity that persists over time
- Mutable state
- Unique identifier
class Order {
private OrderId id;
private Money total;
// Entity with unique ID
}
Value Objects
- Immutable
- No identity
- Compares by value
class Money {
private final BigDecimal amount;
private final Currency currency;
// Value object - immutable, compared by value
}
Aggregates
- Cluster of related objects
- Aggregate root controls access
- Invariants enforced within boundary
- One entity per aggregate typically
class OrderAggregate {
private OrderId id;
private List<OrderLine> lines; // Only aggregate root can modify
public void addLine(Product product, int quantity) {
// Invariants enforced here
}
}
Domain Events
- Something significant happened
- Immutable
- Named in past tense
class OrderPlacedEvent {
private OrderId orderId;
private Money total;
private Instant occurredAt;
}
Repositories
- Collection-like interface
- Persist aggregates
- Abstract storage details
Domain Services
- Operations that don't belong to entities
- Cross-aggregate operations
- Stateless
Factories
- Complex object creation
- Hide implementation details
DDD Patterns
- CQRS with DDD
- Event sourcing
- Specification pattern
- Side effects
- Policy
- Strategy