Design a Stateful Banking System with Scheduled Payments and Account Merges

Question

Design a stateful banking system that supports scheduled payments and the ability to merge accounts.

Codemia · Accepted Answer

To design a stateful banking system, we need to establish clear requirements. Key functionalities include:
- User authentication to ensure secure access.
- Ability to create and manage bank accounts.
- Support for scheduled payments, allowing users to set up future transactions.
- Functionality for merging accounts, which involves transferring balances and transaction history.
- Transaction history tracking for auditing and user reference.

The system can be structured into several components:
1. **User Service**: Manages user accounts and authentication.
2. **Account Service**: Handles operations related to bank accounts, including creation, merging, and balance inquiries.
3. **Payment Service**: Responsible for processing scheduled payments and ensuring they are executed at the correct times.
4. **Database**: A relational database (like PostgreSQL) to store user and transaction data, ensuring ACID properties for data integrity.

For implementing scheduled payments, we can use a job scheduler that checks for pending payments at regular intervals. When a payment is due:
- The Payment Service retrieves the payment details from the database.
- It verifies that the account has sufficient funds.
- If successful, the payment is processed and recorded in the transaction history.
- Notifications can be sent to users confirming the payment execution.

Merging accounts requires careful handling of data:
1. **Transfer Balances**: The balance of the account being merged should be added to the primary account.
2. **Transaction History**: All transactions from the merged account should be transferred to the primary account, ensuring continuity.
3. **Data Integrity**: Implement checks to prevent merging if it would result in inconsistencies, such as overlapping transactions.

Some trade-offs and challenges include:
- **Scalability**: As the number of users grows, the system must efficiently handle increased load, particularly for scheduled payments.
- **Data Integrity**: Ensuring that account merges do not lead to data loss or corruption is critical. Implementing robust transaction management is essential.
- **Security**: Protecting sensitive user data and transaction information is paramount. Using encryption and secure access protocols can mitigate risks.

Design a Stateful Banking System with Scheduled Payments and Account Merges

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