# Handle a notification

> Alipay+ provides some notification interfaces to asynchronously notify the Acquiring Service Provider of the processing result.

Alipay+ provides some notification interfaces to asynchronously notify the Acquiring Service Provider of the processing result. The Acquiring Service Provider needs to handle the notifications properly and returns a response to Alipay+.

## Notification interfaces

The following table lists the notification interfaces that are provided for Auto Debit and how Alipay+ use them.

| Notification interfaces | Usage scenarios |
| --- | --- |
| [**authNotify**](../api_acq_tile/auth_notify) | Used by Alipay+ to notify the Acquiring Service Provider of the authorization processing result, for example: - Creation result of the auth code after handling the **prepare** interface. - Creation result of the access token after handling the **applyToken** interface. - Cancelation result of the access token after handling the **cancelToken** interface. |
| [**notifyPayment**](../api_acq_tile/notify_payment) | Used by Alipay+ to notify the Acquiring Service Provider of the payment processing result after handling the **pay** API request. |
| [**notifyRegistrationStatus**](../api_acq_tile/notify_registration_status) | Used by Alipay+ to notify the Acquiring Service Provider of the merchant registration result after handling the **registration** API request. |

## How to handle a notification

The following sections describe the common things that the Acquiring Service Provider needs to take into consideration when handling the notification.

### Accept a notification

For a scenario that a notification is required, an HTTP POST is fired. The HTTP request is sent in the raw JSON, of which the _Content-Type_ request header is specified as `application/json`. Ensure that the Acquiring Service Provider can access the HTTP body accordingly.

### Verify the signature

The notification request that Alipay+ sends to the Acquiring Service Provider is signed. The merchant needs to verify the signature to confirm whether the notification is sent from Alipay+. For how to validate a signature, see [Validate a signature](../api_acq_tile/signature#zjv0B).

After the notification is delivered successfully, verify and process the information from the notification body.

### Acknowledge the notification with a response

After receiving the notification, no matter what the content in the notification request body is, the Acquiring Service Provider must return a receipt acknowledgment message to Alipay+. Meanwhile, the response must also be signed.

> **Note**: The result in the notification response is only used for acknowledgment that whether the Acquiring Service Provider has received the notification or not.
>
> For example, for a **notifyPayment** request, no matter what the payment result is specified in the request, as long as the Acquiring Service Provider receives the notification, the Acquiring Service Provider needs to return a response where the value of _result.resultStatus_ must be set to `S`.

### Retry mechanism

After receiving the notification, respond with an HTTP status code of `200` and send an acknowledgement with result.resultStatus of `S` to indicate that your server received and processed the call. If you respond with another status code or acknowledge with other values, Alipay+ takes the notification delivery as unsuccessful. Therefore, Alipay+ will retry to send the notification.

> **Notes**:
>
> -   The interval between two adjacent times is: 2m, 10m, 10m, 1h, 2h, 6h, 15h
> -   The notifications will be sent at most 7 times during a period of up to 24 hours and 22 minutes. After that, no notifications will be sent anymore.
> -   The retry mechanism is not supported when you test Alipay+ APIs in the sandbox environment.

## More information

For more information about the notification interfaces, see:

-   [**authNotify**](../api_acq_tile/auth_notify)

-   [**notifyPayment**](../api_acq_tile/notify_payment)
-   [**notifyRegistrationStatus**](../api_acq_tile/notify_registration_status)