Bulk Transfer API

An example API for processing bank transfers in bulk.

Key Features

• Atomicity: All operations are executed within a database transaction to ensure all-or-nothing execution - either all transfers succeed or none are applied.
• Idempotency: Built-in idempotency key support enables safe retries without the risk of creating duplicate transfers.
• Isolation: Row-level locking on bank accounts prevents race conditions and ensures consistency under concurrent access.
• Precision: All monetary calculations use BigDecimal to maintain exact cent-level precision and avoid rounding errors.

Future Improvements

• Asynchronous Processing with Kafka: Integrate Kafka to enable event-driven processing of bulk transfers, improving throughput and system decoupling.
• Authentication & Authorization: Implement security mechanisms to authenticate API clients and restrict access based on roles or permissions.

How to Run

Using Docker

docker build . -t bulk_transfer_api
docker run -p 3000:3000 bulk_transfer_api

Locally

1. Install ruby 3.4.2
2. Prepare the database:

rails db:prepare

3. Start the Rails server:

rails s

API Endpoints

• POST /transfers/bulk_create - Create multiple transfers in a single request.
• GET /api-docs - Swagger API docs.