需求如下：
According to the UML use case specification, how many use cases are there among the following requirements? "A buyer calls the company to place an order. The company collects the buyer's information, such as their name, address, and the details of the goods they wish to purchase. The company then provides the buyer with information on the goods, including pricing and expected delivery dates. If the company is out of stock on any of the requested items, the company will renegotiate the order. If the order is OK, the buyer pays for the order. If the buyer wants to pay with credit card, he thke payment by credit card. If the payment fail, the system will prompt the buyer to use a different payment method. After successful payment, the company creates the order, and ships to the buyer, and sends the invoice. If the buyer returns goods, The company will handle any returned goods.
Gpt回复：
Use Case 1 --- Place Order
- Primary actor: Buyer (telephone or system user)
- Preconditions: Buyer intends to purchase goods; system/agent able to take orders; product catalog accessible.
- Postconditions (success): Order details captured and recorded; buyer ready to pay or payment process started.
Basic flow (main success --- includes human-computer interactions):
- Buyer calls and requests to place an order.
- Agent or self-service system greets buyer and asks for buyer identity.
- Buyer provides name, contact details, and delivery address.
- System prompts for or agent enters buyer information into the Order Entry screen (
Capture Buyer Info). - System confirms stored buyer information; buyer verifies and confirms.
- System/agent asks which goods the buyer wants and requests quantity and any options.
- Buyer provides goods selection and quantities.
- Agent enters items into the Order Entry screen; system validates item codes and availability and displays item descriptions, unit prices, and estimated delivery dates (
Show Product Info). - System displays order summary (items, quantities, prices, totals, delivery estimate) and asks buyer to confirm or change the order.
- Buyer confirms the order (or requests renegotiation if unsatisfied).
- System records tentative order and transitions control to payment (invokes Make Payment use case) or marks order as awaiting payment method.
Alternative flows / extensions:
- A1 --- Buyer requests product information before choosing items: At step 6--8, buyer requests detailed product specs; system displays additional product details and returns to step 6.
- A2 --- Buyer requests to hold multiple items or split delivery: At step 8, agent records delivery preferences and system captures split-shipment instructions.
- A3 --- Out-of-stock renegotiation: If any requested item is unavailable, follow Alternative Flow A3 (see below).
- A4 --- Buyer requests a quote only (no immediate order): Agent/system generates a quote and ends use case with order not created.
Exception / alternate flows (numbered and referenced from basic flow steps):
- E1 --- Invalid or incomplete buyer information (step 4): System requests missing mandatory fields; if buyer cannot provide required delivery info, terminate with "Order Not Completed --- incomplete address".
- E2 --- Invalid product code or entry error (step 8): System prompts to re-enter; if repeated failures, escalate to supervisor or request buyer callback.
- E3 --- Out of stock (triggered at step 8):
- E3a --- System suggests available substitutes and displays price/delivery for substitutes; buyer can accept substitute (return to step 9) or decline.
- E3b --- System offers backorder with revised delivery date; buyer can accept (record backorder) or renegotiate quantities/items (return to step 6).
- E3c --- Buyer cancels order when items unavailable → use case ends with order cancelled.
- E4 --- System unavailable or network error during data entry: Agent notes info manually, informs buyer of need to call back, or schedules follow-up; system creates a temporary offline record when possible.
Use Case 2 --- Make Payment
- Primary actor: Buyer
- Secondary actors: Payment Gateway (for card), Accounting/Billing System
- Preconditions: Order has been placed or buyer has an order number; payment options available.
- Postconditions (success): Payment accepted and recorded; order marked as paid; system issues payment confirmation/receipt.
Basic flow (main success):
- System prompts buyer for payment method (e.g., credit card, bank transfer, cash-on-delivery, invoice).
- Buyer selects a payment method.
- System displays or prompts for the required payment details (e.g., card number, expiry, CVV; or bank transfer instructions).
- Buyer provides payment details verbally to agent or via secure input screen; agent/system enters details. (Human-computer interaction: data entry fields, masked input, validation messages.)
- System validates format of payment details locally (basic checks) and sends payment request to Payment Gateway if applicable.
- Payment Gateway processes payment and returns an authorization response.
- System displays payment success to buyer and issues receipt/invoice reference; payment status recorded in order.
- Control returns to Fulfill Order use case (order fulfillment begins).
Alternative flows / extensions:
- A1 --- Pay by credit card (sub-flow): Steps 3--6 follow credit-card-specific process (3D Secure, OTP). If 3D Secure required, system redirects buyer to authentication flow and waits for result. On success return to step 7.
- A2 --- Pay by invoice: System marks order for billing and sends invoice; payment may occur later (deferred payment path).
- A3 --- Cash on delivery selected: System records COD and schedules fulfillment with COD flag.
Exception / error flows:
- E1 --- Payment declined by gateway (step 6):
- E1a --- Gateway returns "insufficient funds" or "card declined": System notifies buyer, logs decline reason (if available), and offers alternative payment methods; buyer may re-enter different card or choose another method (return to step 1).
- E1b --- Authentication failed (3D Secure OTP not provided or failed): System prompts to retry authentication; if repeated failures > N times, cancel payment attempt and return to step 1 or request different method.
- E2 --- Network or gateway timeout (step 6): System displays "Payment service temporarily unavailable" and offers to retry or use another method; can queue a retry or abort.
- E3 --- Suspected fraud or security alert: System flags order, places a hold, notifies fraud review team; buyer informed that payment is on hold pending verification.
- E4 --- Invalid payment data format (step 4): System highlights erroneous fields and prompts correction.
Notes on human-computer interactions:
- All payment data entry must be secure (masked fields), show clear validation errors, and confirm success with a transaction reference. For phone payments the agent uses a secure payment terminal or PCI-compliant entry screen.
Use Case 3 --- Fulfill Order
- Primary actor: Company (fulfillment/shipping department), System
- Secondary actor: Shipping carrier, Accounting
- Preconditions: Order is created and paid (or has a fulfillment flag like COD/invoice). Warehouse stock levels available.
- Postconditions (success): Goods shipped, invoice sent, order status updated to Shipped/Completed.
Basic flow (main success):
- System receives confirmed and paid order (or order with fulfillment authorization).
- Warehouse system reserves/allocates inventory for the order (display pick list to warehouse staff). (Human-computer interactions: pick list, confirmation buttons.)
- Warehouse staff picks items and scans them into the system; system confirms picks and updates inventory.
- System creates shipping label and schedules carrier pickup or drop-off; system displays shipment details for packing.
- Packing staff packs items and attaches shipping label; system records shipment details (tracking number, carrier).
- System updates order status to "Shipped", triggers shipment notification to buyer (SMS/email) including tracking and expected delivery date.
- System generates and sends invoice to buyer (if not already issued), and updates accounting records.
- Process ends with order marked as Completed or In Transit as appropriate.
Alternative flows / extensions:
- A1 --- Partial shipment: If only some items are available, system creates a partial shipment for available items and leaves remaining items backordered. System notifies buyer of partial shipment and expected date for remaining items. (Follow steps 2--6 for partial items; create backorder record.)
- A2 --- Split fulfillment across warehouses: System splits pick lists per warehouse and schedules multi-shipment with corresponding tracking numbers.
- A3 --- Schedule delivery window: Buyer requested specific delivery window; system sends delivery instructions to carrier and confirms scheduling.
Exception / error flows:
- E1 --- Inventory shortage discovered during pick (step 2--3):
- E1a --- Item truly out of stock --- system marks backorder and notifies buyer with new ETA (possible renegotiation, refer back to Place Order).
- E1b --- Picking error (wrong item scanned): System flags mismatch, prompts staff to correct; if unresolved, hold order and notify supervisor.
- E2 --- Shipping label creation failure or carrier rejection (step 4): System retries label creation, if persists notify operations team and inform buyer of delay.
- E3 --- Address invalid / undeliverable (step 4--6): Carrier returns "undeliverable"; system notifies buyer to provide corrected address and schedules re-delivery or return-to-sender as per policy.
- E4 --- Invoice generation error: Accounting alerted; system retries invoice generation or allows manual invoice issuance.
Human-computer interactions to highlight:
- Pick/pack screens with item images, barcodes, and confirmation steps; shipment confirmation requiring scanning/entering tracking; notifications with one-click view of tracking.
Use Case 4 --- Handle Returned Goods (Handle Returns)
- Primary actor: Buyer (initiates return), Returns/Customer Service Staff
- Secondary actors: Warehouse (receiving), Refund/Accounting systems
- Preconditions: Buyer has received goods and requests return within allowable return window/policy.
- Postconditions (success): Return authorized, goods received and dispositioned, refund or replacement processed, inventory and accounting updated.
Basic flow (main success):
- Buyer requests a return by calling or using the returns portal and provides order number and reason for return.
- System/agent verifies order and return eligibility (warranty/return window, item condition policy).
- If eligible, system creates Return Merchandise Authorization (RMA) and provides return instructions (label, packaging, prepaid label if applicable). (Human-computer interactions: RMA form, generate return label, send email/SMS.)
- Buyer ships item back or schedules carrier pickup; buyer provides tracking number if required.
- Warehouse receives returned goods, scans RMA and items into returns receiving screen; system updates return status.
- Warehouse inspects returned goods and records disposition (resalable, refurbish, scrap).
- System triggers refund or replacement: Accounting issues refund to buyer (or system initiates replacement shipment).
- System updates inventory (if restocked) and closes RMA; buyer notified of completion.
Alternative flows / extensions:
- A1 --- Exchange instead of refund: Buyer requests replacement item; system processes exchange, reserves replacement stock, and schedules shipment once replacement is available.
- A2 --- Return denied: If item not eligible, system communicates reason and offers alternatives (repair, discounted replacement, or denial).
- A3 --- Return for repair under warranty: Instead of refund, system routes to repair workflow and notifies buyer of expected turnaround.
Exception / error flows:
- E1 --- Invalid RMA request (step 2): System denies return and explains reason (out of return window, non-returnable item).
- E2 --- Buyer fails to return item or returns wrong item (step 4--5): System notifies buyer; if wrong item, offers next steps for correct return; if none received within timeframe, RMA expires and refund denied.
- E3 --- Damage discovered on inspection inconsistent with claimed reason (step 6): System flags dispute, holds refund pending investigation; customer service contacts buyer to resolve.
- E4 --- Refund processing failure (step 7): Payment provider or accounting error prevents refund; system alerts finance team, notifies buyer of delay, and retries or issues manual refund.
Human-computer interactions emphasized:
- RMA creation form with eligibility checkboxes and automated label generation; receiving screen for scanning returns with disposition dropdowns and refund/replacement action buttons.
Summary of mapping and important notes:
- Each use case includes clear human-computer interactions at the points where data is entered, validated, or displayed (Order Entry screen, Payment screen/3D Secure flow, Pick/Pack/Shipping screens, RMA/Returns screen).
- Alternative flows cover common branching (substitutes/backorder, partial shipments, exchanges).
- Exception flows handle validation failures, external system failures (payment gateway, carrier), and business-rule denials (return window, fraud).