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EMV Successful Commit

note

In this web sequence diagram, Payter details the core flow of an EMV payment which is successfully authorized, and later committed. In this case, the Committed amount is less than or equal to the Authorized amount, for simplicity.

Flow​

Payment Flow DiagramPayment Flow Diagram

Comments​

  1. When using Always Scanning there could hours or days between these two events.
  2. The controller needs to Decide to Authorize. If they are choosing to accept RFID cards then these follow a different flow, with the local controller either checking online itself, or comparing to a whitelist of card ID's. Even where no RFID cards are accepted, this decision is required.
  3. The controller needs to interpret the Authorization outcome - in this case it is Approved, but logic for handling Declines should be implemented.
  4. Different use cases will have different expectations here. Smart Vending for example may complete the Vend within a few seconds, whereas EV Charging could be several hours. Critically, the vend should be finalised, which leads to the final amount being known.
  5. Once the final amount is known, a "Commit" is sent to confirm this. Without this message, no funds will be settled to the merchant.
Minimum Commands

Integrators need to implement the following commands as an absolute minimum in this approach:

  • Start Session
  • Auth Session
  • Commit Session

Additionally, these commands are also needed depending on variable outcomes:

  • Void Session - used where Vend was unsuccessful.
  • Cancel Session - used where an RFID Card was read and no further action is needed from PSP to authorize this card. This flow is detailed in the next section.