Supply Chain Context¶

The Supply Chain context manages vendor relationships and bulk ordering for the restaurant chain. It coordinates with the Inventory context to ensure adequate stock across locations.

Purpose¶

A 500-location restaurant chain can't have each location ordering independently — bulk purchasing saves money and ensures consistency. The Supply Chain context handles the procurement lifecycle from order creation through approval, shipping, receipt, and issue reporting.

Interview Connection¶

From the Head Chef's interview:

"I source local ingredients required to prepare our menu items."

The Head Chef works at the corporate level to standardize ingredients and manage supplier relationships. The Supply Chain context formalizes this process with tracked purchase orders.

Types¶

type PurchaseOrderId is Id(SupplyChain.PurchaseOrder) with {
  briefly "Purchase order identifier"
  described by "Unique identifier for a purchase order."
}

type VendorId is UUID with {
  briefly "Vendor identifier"
  described by "Unique identifier for a vendor."
}

type PurchaseOrderStatus is any of {
  PoDraft,
  PoSubmitted,
  PoApproved,
  PoShipped,
  PoReceived,
  PoDisputed
} with {
  briefly "Purchase order status"
  described by "Current status of a purchase order."
}

type OrderLineItem is {
  lineItemName is String(1, 200)
  lineItemQuantity is Decimal(10, 2)
  lineItemUnit is String(1, 20)
  lineItemUnitPrice is Decimal(10, 2)
} with {
  briefly "Order line item"
  described by "A single item in a purchase order."
}

Note the PoDisputed status — if a shipment has quality issues, the purchase order can be disputed rather than simply accepted.

Entity: PurchaseOrder¶

The PurchaseOrder entity has a 5-command lifecycle:

entity PurchaseOrder is {

  command CreateBulkOrder is {
    purchaseOrderId is PurchaseOrderId
    vendorId is VendorId
    vendorName is String(1, 200)
    orderLineItems is many OrderLineItem
    requestedDeliveryDate is Date
  }

  command ApproveOrder is {
    purchaseOrderId is PurchaseOrderId
    approvedAt is TimeStamp
  }

  command ShipOrder is {
    purchaseOrderId is PurchaseOrderId
    shippedAt is TimeStamp
    trackingNumber is optional String(1, 100)
  }

  command ReceiveShipment is {
    purchaseOrderId is PurchaseOrderId
    receivedAt is TimeStamp
    receivedCondition is String(1, 200)
  }

  command ReportIssue is {
    purchaseOrderId is PurchaseOrderId
    purchaseOrderIssueType is String(1, 50)
    purchaseOrderIssueDescription is String(1, 1000)
    issueReportedAt is TimeStamp
  }

  // Events: BulkOrderCreated, OrderApproved, OrderShipped,
  //         ShipmentReceived, IssueReported

  state ActivePurchaseOrder of PurchaseOrder.PurchaseOrderStateData

  handler PurchaseOrderHandler is {
    on command CreateBulkOrder {
      morph entity SupplyChain.PurchaseOrder to state
        SupplyChain.PurchaseOrder.ActivePurchaseOrder
        with command CreateBulkOrder
      tell event BulkOrderCreated to
        entity SupplyChain.PurchaseOrder
    }
    on command ApproveOrder {
      tell event OrderApproved to
        entity SupplyChain.PurchaseOrder
    }
    on command ShipOrder {
      tell event OrderShipped to
        entity SupplyChain.PurchaseOrder
    }
    on command ReceiveShipment {
      tell event ShipmentReceived to
        entity SupplyChain.PurchaseOrder
    }
    on command ReportIssue {
      tell event IssueReported to
        entity SupplyChain.PurchaseOrder
    }
  }
}

The lifecycle: Create → Approve → Ship → Receive → (optional) Report Issue.

The ReportIssue command can trigger a follow-up that changes the order status to PoDisputed, initiating a resolution process with the vendor.

Repository¶

repository PurchaseOrderRepository is {
  schema PurchaseOrderData is relational
    of purchaseOrders as PurchaseOrder
    index on field PurchaseOrder.purchaseOrderId
    index on field PurchaseOrder.vendorId
    index on field PurchaseOrder.purchaseOrderStatus
}

The index on vendorId supports vendor-centric views — how many orders are outstanding with a specific vendor, what's the order history, etc.

Design Decisions¶

Why no adaptor to Inventory? When a shipment is received at a restaurant location, the Inventory context's ReceiveStock command is called directly by the receiving clerk. The supply chain tracks the corporate-level purchase order, while inventory tracks the location-level stock. These are different levels of abstraction that don't need tight coupling.

Why many OrderLineItem? Bulk purchase orders typically contain multiple items — different cuts of meat, sauces, packaging, etc. The many keyword models a collection of line items within a single order.