pos-system/services/order-service-net/docs/en/ARCHITECTURE.md

Order Service Architecture

Architecture documentation for Order Service - the orchestration brain.

Architecture Overview

graph TB
    subgraph "API Layer"
        C[Controllers]
        CMD[Commands]
        Q[Queries]
    end
    
    subgraph "Application Layer"
        SF[Strategy Factory]
        RS[RetailStrategy]
        SS[ServiceStrategy]
        FS[FnbStrategy]
    end
    
    subgraph "Domain Layer"
        O[Order Aggregate]
        OI[OrderItem]
        OS[OrderStatus]
    end
    
    subgraph "External Services"
        INV[Inventory Service]
        BOOK[Booking Service]
        FNB[F&B Engine]
    end
    
    C --> CMD
    CMD --> SF
    SF --> RS --> INV
    SF --> SS --> BOOK
    SF --> FS --> FNB
    CMD --> O
    
    style O fill:#50c878,stroke:#2d8659,color:#fff
    style SF fill:#9b59b6,stroke:#7d3c98,color:#fff

Strategy Pattern Implementation

classDiagram
    class ILineItemStrategy {
        <<interface>>
        +SupportedType ProductType
        +ValidateAsync(OrderItem, Guid) Task
        +ExecuteAsync(OrderItem, Guid) Task
    }
    
    class RetailStrategy {
        +SupportedType = Physical
        +ValidateAsync() CheckStock
        +ExecuteAsync() DeductStock
    }
    
    class ServiceStrategy {
        +SupportedType = Service
        +ValidateAsync() CheckSlot
        +ExecuteAsync() CreateAppointment
    }
    
    class FnbStrategy {
        +SupportedType = PreparedFood
        +ValidateAsync() Always OK
        +ExecuteAsync() CreateKitchenTicket
    }
    
    ILineItemStrategy <|.. RetailStrategy
    ILineItemStrategy <|.. ServiceStrategy
    ILineItemStrategy <|.. FnbStrategy

Order State Machine

stateDiagram-v2
    [*] --> Draft: Create Order
    Draft --> Validated: All Items Valid
    Validated --> Paid: Payment Success
    Paid --> Processing: Execute Items
    Processing --> Completed: All Items Done
    
    Draft --> Cancelled: Cancel
    Validated --> Cancelled: Cancel
    Paid --> Cancelled: Refund

Database Schema

erDiagram
    orders {
        uuid id PK
        uuid shop_id FK
        uuid customer_id FK
        varchar status
        decimal total_amount
        timestamp created_at
    }
    
    order_items {
        uuid id PK
        uuid order_id FK
        uuid product_id FK
        varchar product_type
        int quantity
        decimal unit_price
        varchar status
        jsonb metadata
    }
    
    orders ||--o{ order_items : contains

Order Processing Workflow

sequenceDiagram
    participant Handler as CreateOrderHandler
    participant Factory as StrategyFactory
    participant Strategies as ILineItemStrategy[]
    participant Payment as WalletService
    
    Handler->>Factory: GetStrategies()
    
    rect rgb(200, 230, 200)
        Note over Handler,Strategies: Phase 1: Validation
        loop Each Item
            Handler->>Factory: GetStrategy(item.Type)
            Factory-->>Handler: ILineItemStrategy
            Handler->>Strategies: ValidateAsync(item)
        end
    end
    
    Handler->>Payment: ProcessPayment(order)
    Payment-->>Handler: Success
    
    rect rgb(200, 200, 230)
        Note over Handler,Strategies: Phase 2: Execution
        loop Each Item
            Handler->>Strategies: ExecuteAsync(item)
        end
    end

Integration Points

Service	Protocol	Purpose
Catalog Service	HTTP	Get product details
Merchant Service	HTTP	Get shop features
Wallet Service	HTTP	Process payment
Inventory Service	HTTP	Stock operations
Booking Service	HTTP	Appointments
F&B Engine	Event Bus	Kitchen tickets

References

• Multi-vertical Architecture
• Strategy Pattern