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Refundable One Time Payment Code

Overview

Google Standard Payments supports cash-based FOPs (forms of payment) like convenience store purchases (such as a 7-Eleven). At a high level, a user who wants to pay for goods generates a reference number through the Payment integrator. The user then takes this reference number to a convenience store, kiosk, or bank and pays the reference number.

Note: The Cash FOP is also called the Reference Number FOP.

1) The user adds a payment method

2) Then they choose where to pay

3) Finally, they are given payment instructions

Concepts and terminology

{setvar <顏色> 付款結果。付款詳情

符號和會議

針對這些文件中「必須」、「不得」、「必要」、「應」、「不應」、「應該」、「建議」、「可能」和「選用」等重要字詞，均以 RFC 2119 的說明表示。

時間戳記

所有時間戳記都以毫秒表示，自世界標準時間 Unix 紀元 (1970 年 1 月 1 日) 起。

例如：

• 2019 年 4 月 23 日下午 8:23:25 (GMT = 1556051005000 毫秒)
• 2018 年 8 月 16 日下午 12:28:35 (GMT = 1534422515000 毫秒)

金額

這個 API 中的金額值會採用「微量」的格式，也就是 Google 的標準。微量是以整數為準的固定精確度格式。如要以微量單位表示金額，請將標準貨幣值乘以 1,000,000。

例如：

• $1.23 美元 = 12,30000 微秒
• $0.01 美元 = 10,000 微秒

冪等

這個 API 中的所有方法呼叫都必須具有冪等行為。Google 會定期重試要求，確保兩方的交易狀態相同。整合商不得嘗試重新處理任何已順利處理完畢的要求。請改為回報成功處理的回應。所有方法都有共用的 RequestHeader，其中包含 requestId。requestId 是所有呼叫的冪等鍵。

任何非終端機回應 (HTTP 200 失敗) 都不得以冪等方式處理。因此，如果先前收到 400 (廣告請求錯誤/失敗的先決條件) 一次，第二次呼叫時，就不能以冪等方式傳回 400，就必須重新評估。重新評估時，系統可能會傳回 400 錯誤，或已成功處理。

如要進一步瞭解冪等性，請參閱這份詳細指南。

整合商

使用 Google 付款平台為自家業務的公司。客戶可以是 YouTube 或 AdWords 等內部 (第一方)，也可以是想將服務整合到 Google 生態系統的外部 (第三方) 商家。

付款方式

付款方式。這比樂器一般。Visa、MasterCard 和 PayPal 都是 FOP。

方式

特定客戶適用的付款方式。例如使用者的信用卡或 PayPal 帳戶。針對特定客戶，代碼化 FOP 也是其中一種方式，因為其是一種客戶的付款方式，可以安全地儲存在我們的系統中。

權杖

代表特定使用者付款方式的 Google 系統代表。因為其中包含購買所需的所有資訊，而憑證也是付款方式。這可能包括使用者在整合商中所擁有的帳號。

Key flows

Google uses two key flows to create and pay these reference numbers:

1. Generate Reference Number Flow.
2. Pay Reference Number Flow.

Later, reconciliation and settlement from resulting purchases are handled by the remittance flow.

The diagram below illustrates each of these flows.

Cash FOP overview

The first two flows are described in more detail in the following sections. See the Remittance flow page if you want to know more about that flow.

Generate reference number

The purpose of the generate reference number flow is to create and exchange an identifier (reference number) that both Google and the integrator can use to identify a purchase. The user can then use this reference number at a convenience store, kiosk, or bank to complete the purchase. This identifier is generated by the integrator at Google's request by calling the generateReferenceNumber method. The request for generation of the reference number includes an amount and a transaction description.

The following diagram illustrates how a reference number is generated and sent to the customer with instructions.

Generate reference number flow

Here is a list of the objects and what they represent:

• User: This is the person who wants to pay for something using this form of payment.
• Google UI: This is the interface where the User makes their purchase. It could be through the web or through an app.
• Google Server: The backend server at Google that requests the generation of the reference number and creates payment instructions for the user.
• Payment Integrator Server: The backend server of the Payment Integrator that keeps track of the payment details and generates the reference number.

This flow begins with the user who wants to use this cash form of payment.

1. The User accesses the Google UI which sends sends a request for a reference number.
2. The Google UI sends a message to the Google Server that it needs a reference number (getReferenceNumber).
3. The Google Server asks the Payment Integrator Server to generate a reference number (generateReferenceNumber).
4. The Payment Integrator Server generates and sends the reference number to the Google Server.
5. The Google Server creates payment instructions to go along with the reference number. Then it sends this information to the Google UI.
6. The Google UI sends these instructions and reference number to the User.

Notes on reference numbers

Reference numbers can only be paid once, and they can be cancelled through the cancel reference number flow. Also, reference numbers must be alphanumeric, and it must support multiple display formats.

In addition to displaying the reference number, Google's UIs can optionally represent the reference number in the Code 128 format (a barcode format). Other barcode formats can be supported by request.

Pay Reference Number

The user will use this reference number at a convenience store, kiosk, or bank to identify the purchase the user wants to pay for. The integrator should have the user confirm the purchase being paid by displaying the purchase amount, date, and transaction description prior to paying.

Once the user chooses to pay, they must pay in full, and only pay once. This API does not support over or under payments on a single reference number. Multiple payments to a single reference number is also not supported.

Once the user pays, the integrator must immediately notify Google that this reference number has been paid via the referenceNumberPaidNotification method. By calling this method within seconds of the user physically paying, the integrator allows the user to quickly receive their goods. (This call can be added to a queue if the network is down.)

Once paid, the reference number and amount will be included in the remittance statement sent on T+2 days.

Note: If Google returns an error on referenceNumberPaidNotification, your server should retry the request indefinitely with exponential backoff and you should reach out to your Google point of contact to notify them of the issue.

Here is a sequence diagram that illustrates the payment of a reference number.

Pay reference number flow

The objects in the diagram represent the following:

• User: This is the person who wants to pay for something using this form of payment.
• Convenience Store: The location where the user makes their payment using the reference number and instructions given, such as a convenience store.
• Payment Integrator Server: The backend server of the Payment Integrator that keeps track of the payment details.
• Google Server: The backend server at Google that requests the generation of the reference number and creates payment instructions for the user.

This flow begins with the user who goes to a convenience store in order to make a payment according to the instructions given to them.

1. The User goes to a Convenience Store to make a payment.
2. After the transaction is complete, the convenience store notifies the payment integrator of payment.
3. The Payment Integrator Server sends a success message to the Convenience Store.
4. The Convenience Store conveys that the transaction was a success to the User, and the goods will be delivered to the User soon.
5. The Payment Integrator Server sends a message to Google’s Server that the reference number has been paid (referenceNumberPaidNotification). This step must not block step 4.
6. The Google Server responds with a message of success to the Payment Integrator Server.

Cancel reference number

Reference numbers can be cancelled by Google. If Google cancels a reference number, the cancelReferenceNumber method will be called. Upon successful return of this call, it is invalid to pay that reference number, and the integrator must refuse payment for this number. Upon success of this call, all future calls to the referenceNumberPaidNotification will fail.

If the payment process has already started, for example if the user has entered their reference number into a kiosk but has not yet paid, the integrator should return a HTTP 423 response code with ErrorResponse containing [USER_ACTION_IN_PROGRESS][google.standardpayments.v1.ErrorResponse].

Refund

Paid reference numbers can be refunded by Google using the request ID of the original generateReferenceNumber call (note that refunds will NOT use the reference number). If Google refunds a reference number, the refund method will be called. This method can be called multiple times with amounts totalling less than or equal to the original paid amount.

Next: Remittance flow