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This guide walks through the Pre-Selection vending flow. You’ll understand the sequence of events that separate product selection from payment authorization within a single transaction, ensuring a smooth and secure vending session.

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Payment Flow

Visualize the Pre-Selection process with the diagram below, which illustrates each step of the single vending session flow, from product selection to payment authorization and dispensing.
Below is a breakdown of the diagram:
  1. The Nayax Device sends a message to the consumer: “Please Select a Product.”
  2. The consumer selects a product from the vending machine.
  3. The peripheral’s SDK sends a vending request to the Nayax Device. 
    vmc_vend_vend_request(vend_session_t *session)
  4. The Nayax Device sends a message to the consumer: “Please Present Card.”
  5. The consumer presents their payment card.
  6. The Nayax Device sends an authorization request to the Nayax Server.
  7. The Nayax Server forwards the authorization request to the Billing Provider.
  8. The Billing Provider sends an authorization response (approved) to the Nayax Server.
  9. The Nayax Server sends the authorization response (approved) back to the Nayax Device.
  10. The peripheral’s SDK handles transaction data received from the Nayax Device via the Transfer Data command (said data includes information about the Nayax transaction ID and the consumer’s card details): 
    vmc_vend_event_handler_cb(vm_vend_event_on_transaction_info)
  11. The SDK triggers “Vend Approved” events: 
    vmc_vend_event_handler_cb(vm_vend_event_on_vend_approved)
  12. The peripheral dispenses the product/ provides the service to the consumer.
  13. The SDK reports “vend success”: 
    vmc_vend_vend_status(&session, __true)
    And completes the vend session: 
    vmc_vend_vend_session_complete_lowlevel()
  14. Message to the consumer: “Please Take Product.”
  15. The Nayax Device sends a settlement request to the Nayax Server.
  16. The Nayax Server forwards the settlement request to the Billing Provider.
  17. The Billing Provider sends a settlement response (OK) to the Nayax Server.
  18. The Nayax Server returns the settlement response (OK) to the Nayax Device.
  19. The vending session ends.
  20. Message to Card Holder: “Thank you & Goodbye.”

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See Also

Payment Flows

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Methods & Functions