SaFi Bank Space : Overdraft Technical documentation

Created by Jan Görig, last modified by User 13e07 on Nov 30, 2022

1. Key features

General business description: Product: Overdraft (=FundTawid)
The overdraft is modeled using the Temporal.io workflow.
Money is transferred from an internal overdraft bank account to the overdraft address of the customer’s main account when opening or top-upping overdraft and moved from the customer’s main account default address to an internal account when closing.
All the overdraft changes are stored in the database using the repository layer.
Workflows are paired to the accounts using the table in the database.
All the overdraft changes are sent as messages using Kafka.
The notifications are sent to the customer using Ably using the output manager.

2. Overdraft architecture

3. API documentation

The description is updated online using OpenAPI.

https://loan-manager.apps.brave.safibank.online/swagger-ui/

The overdraft uses the following endpoints:

POST /loan/overdraft/{accountId} - Request a new overdraft or top-up the existing one.
POST /loan/overdraft/{accountId}/repay - Request an overdraft repayment.
GET /loan/overdraft/{accountId}/summary - Get info about overdraft for the account.
GET /loan/overdraft/{accountId}/summary - Get info about overdraft history for the account.
POST /loan/overdraft/{accountId}/penalty/rebalance - Increase the overdraft penalty amount
POST /loan/overdraft/{accountId}/penalty/repay - Repay the penalty from the bank internal account

4. Kafka messages

The overdraft activity updates for refreshing of the user UI.

Topic: loans.overdraft-activity-updated.event.v4
Schema: https://github.com/SafiBank/SaFiMono/blob/main/common/schema/schemas/loans/OverdraftActivityUpdatedEventV4.avsc

The overdraft data snapshot:

Topic: loans.overdraft.snapshot.v4
Schema: https://github.com/SafiBank/SaFiMono/blob/main/common/schema/schemas/loans/OverdraftSnapshotV4.avsc

The overdraft update event:

Topic: loans.overdraft-updated.event.v3
Schema: https://github.com/SafiBank/SaFiMono/blob/main/common/schema/schemas/loans/OverdraftUpdatedEventV3.avsc

5. Database schema

6. Overdraft workflows

7. Overdraft technical workflows

8. Overdraft allowed transactions

When applying overdraft, only limited set of specified transaction types is allowed to be paid with overdraft. Type of transaction is given in instruction_details of a posting as following:

instruction_details: {
  transaction_type: TRANSACTION_TYPE,
  ...
}

The transaction types that are currently allowed for overdraft are defined in template-level parameter of main account product (smart contract) overdraft_allowed_transaction_types :

INTERNAL_TRANSACTION
BILL_PAYMENT
CARD_PAYMENT
OVERDRAFT_FEE
CARD_INQUIRY

For more information on transactions allowed for overdraft please see this overdraft documentation.

Attachments:

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