Payments, Tax, and Shipping Integrations

Integrate external payment, tax, and shipping services without blocking the commerce platform unnecessarily.

55 min

3 sections

payments

tax

shipping

01. Keep external calls out of fragile paths when possible

Section 1 of 3

Payment, tax, and shipping systems are often external dependencies with their own latency and failure modes. Use synchronous API Extensions only when the platform must reject or mutate the resource before persistence. Use asynchronous Subscriptions when the business can react after the resource changes.

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Boundary choice:

Synchronous:
- Validate purchase order number format before Cart update
- Reject cart if regulated shipping restriction fails
- Add derived custom field required before persistence

Asynchronous:
- Send order to OMS
- Start invoice generation
- Notify data lake
- Trigger loyalty accrual
- Publish fulfillment events

Cart and Checkout State Machine

Orders, States, and OMS Handoff

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