> For the complete documentation index, see [llms.txt](https://docs.payments.thalescloud.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.payments.thalescloud.io/transit-digitization/implement-apple-transit/account-based-ticketing-abt/transaction-notification.md).

# Transaction Notification

Notifications are triggered by Transit Issuer so the travel events can be displayed within the wallet. In case, the transit card supports retail purchases, the purchases can also be notified.

This section provides an overview of the workflow, including detailed steps, sequence diagrams, and potential error scenarios.

### Workflow <a href="#workflow" id="workflow"></a>

Below are the high level steps of the message notification workflow:

1. **Notification initiation** : The Transit Issuer instructs D1 Transit to send transaction notification to a targeted digital card.
2. **Device notification**: D1 Transit uses APNS in order to send a push notification to the right device.
3. **Transaction Details retrieval**: Device connects to D1 Transit platform in order to retrieve the transaction details.

### Sequence Diagram <a href="#sequence-diagram" id="sequence-diagram"></a>

#### Notification initiation <a href="#notification-initiation" id="notification-initiation"></a>

The Transit issuer instructs D1 Transit to send transaction notification to the specified digital card using handleEvent API.

#### Device notification and Transaction Details retrieval <a href="#device-notification-and-transaction-details-retrieval" id="device-notification-and-transaction-details-retrieval"></a>

D1 Transit platform uses APNS to send a push notification to the device. The device connects to D1 Transit in order to retrieve the transaction details which D1 Transit pulls from Transit Issuer.

**Error Scenarios**

**Device is offline**

If the device is offline, the request to notify the transaction details is queued and will be sent to the device as soon as it reconnects.

<figure><img src="/files/up8meogaojFpP9OlHHn5" alt=""><figcaption></figcaption></figure>


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