Domain-Driven Design Documentation

This section contains comprehensive Domain-Driven Design (DDD) documentation for the PakLog WMS/WES system. Each bounded context is thoroughly documented with aggregates, entities, value objects, and domain events.

Core Documentation

Bounded Contexts Overview NEW

Complete strategic design documentation for all 27 services:

Context map with relationships
Integration patterns between contexts
Shared kernel and partnerships
Anti-corruption layers
Ubiquitous language glossary

Aggregate Catalog NEW

Comprehensive catalog of all domain aggregates:

50+ aggregates across all services
Aggregate invariants and boundaries
State transitions and lifecycles
Domain events per aggregate
Value objects catalog

Bounded Contexts (Original 5 Services)

1. Inventory Context

Inventory management bounded context:

Aggregates: InventoryItem, StockLevel, Adjustment
Domain Events: StockReceived, StockAdjusted, StockMoved
Value Objects: SKU, Quantity, LocationId, BatchNumber
Domain Services: AllocationService, ReplenishmentService
Repository Patterns: InventoryRepository, StockLevelRepository

2. Order Management Context

Order processing and fulfillment domain:

Aggregates: Order, OrderLine, Allocation
Domain Events: OrderPlaced, OrderAllocated, OrderShipped
Value Objects: OrderNumber, CustomerId, ShippingAddress
Domain Services: OrderFulfillmentService, AllocationService
Saga Patterns: OrderFulfillmentSaga

3. Cartonization Context

Packing optimization bounded context:

Aggregates: PackingPlan, Container, PackedItem
Domain Events: ContainerSelected, ItemsPacked, PackingCompleted
Value Objects: Dimensions, Weight, ContainerType
Domain Services: PackingOptimizationService, ContainerSelectionService
Algorithms: 3D bin packing, weight distribution

4. Product Catalog Context

Product information management:

Aggregates: Product, ProductVariant, Category
Domain Events: ProductCreated, ProductUpdated, CategoryAssigned
Value Objects: SKU, Barcode, ProductAttributes
Domain Services: ProductClassificationService
Read Models: ProductSearchModel, ProductHierarchyModel

5. Shipment & Transportation Context

Outbound logistics domain:

Aggregates: Shipment, Carrier, TrackingInfo
Domain Events: ShipmentCreated, LabelGenerated, ShipmentDispatched
Value Objects: TrackingNumber, CarrierId, ShippingRate
Domain Services: RateShoppingService, LabelGenerationService
Integration: Carrier API adapters

Additional 16 Bounded Contexts

Phase 2: Execution Services

Wave Planning Service - Wave optimization strategies
Task Execution Service - Unified task management
Pick Execution Service - TSP path optimization
Pack & Ship Service - 3D bin packing
Physical Tracking Service - License plate tracking
Location Master Service - ABC slotting
Workload Planning Service - Labor forecasting

Phase 3: Advanced Operations

Returns Management - RMA and fraud detection
Robotics Fleet Management - A* pathfinding
WES Orchestration Engine - Saga pattern

Phase 4: Optimization

Predictive Analytics Platform - ML forecasting
Yard Management System - Dock scheduling
Cross-Docking Operations - Flow-through

Phase 5: Customer Services

Last-Mile Delivery - VRP optimization
Value-Added Services - Kitting workflows
Quality Compliance - SPC implementation

DDD Patterns Implemented

Strategic Patterns

Bounded Contexts

Clear boundaries between domains
Explicit context mapping
Shared kernel for common concepts
Published language for integration

Context Mapping

Customer-Supplier: Order Management → Task Execution
Conformist: Shipment → External Carrier APIs
Anti-Corruption Layer: Legacy system integration
Open Host Service: REST APIs for external consumers

Tactical Patterns

Aggregates

Consistency boundaries
Transactional boundaries
Invariant enforcement
Event sourcing where applicable

Entities

Unique identity
Lifecycle tracking
Mutable state with business logic

Value Objects

Immutability
No identity
Self-validation
Composable

Domain Events

Event storming outcomes
Event sourcing implementation
Event-driven choreography
Saga orchestration

Domain Services

Cross-aggregate operations
Complex business logic
External service coordination

Design Principles

1. Ubiquitous Language

Consistent terminology across code and documentation
Domain expert collaboration
Living documentation

2. Model-Driven Design

Rich domain models
Business logic in domain layer
Persistence ignorance

3. Layered Architecture

┌─────────────────────────────┐
│   Presentation Layer        │
├─────────────────────────────┤
│   Application Layer         │
├─────────────────────────────┤
│   Domain Layer              │
├─────────────────────────────┤
│   Infrastructure Layer      │
└─────────────────────────────┘

4. Event Sourcing & CQRS

Write model optimization
Read model projections
Event store implementation
Eventual consistency

Integration Patterns

Synchronous Integration

REST APIs with OpenAPI specs
GraphQL for flexible queries
gRPC for internal services

Asynchronous Integration

Domain events via Kafka
Event-driven choreography
Saga pattern for distributed transactions
Eventual consistency guarantees

Anti-Patterns Avoided

Anemic Domain Model: Rich behavior in domain objects
Smart UI: Business logic in domain layer
Generic Subdomains: Focused bounded contexts
Big Ball of Mud: Clear architectural boundaries

Implementation Guidelines

For Developers

Start with domain models, not database schemas
Use factory methods for complex object creation
Enforce invariants in aggregates
Emit domain events for state changes

For Architects

Define clear bounded contexts
Create context maps for integration
Choose appropriate consistency boundaries
Design for eventual consistency

For Domain Experts

Collaborate on ubiquitous language
Participate in event storming sessions
Validate domain models
Review business invariants

PakLog WMS/WES Documentation - Domain-Driven Design