Checkout — Place Order

Click a message, participant, or fragment chip to focus it · a • after a label means that message carries details · ← → move between messages · Ctrl + scroll or pinch to zoom · Esc clears focus · − on a card folds away the services only it uses

1. Customer to Storefront (sync): Clicks Place order
2. Storefront to Order API (sync): Place the order [HTTPS]
3. Order API to Order API (sync, self-message): Validates the cart
4. Order API to Payments (sync): Create charge [REST]
5. Payments to Order API (reply): charge.succeeded
6. Order API to Orders DB (sync): INSERT order [SQL]
7. Order API to Customer (async): Emails the receipt
8. Order API to Orders DB (async): Writes audit row
9. Order API to Storefront (reply): 201 Created
10. Order API to Storefront (reply): 402 Payment Required
11. Storefront to Customer (sync): Shows onboarding tips