Payment System Redesign

Tasks

• •Migrated the legacy PHP payment system to Java/Spring and redesigned payment verification, lesson-pass issuance, and failure recovery
• •Handled payment verification, storage, and lesson-pass issuance on the server after PortOne payment-completion webhooks, while the app queried an API for processing results
• •Controlled concurrent payment processing with Redis locks and checked whether a payment had already been processed, achieving 0 duplicate payments
• •Designed defensive logic for edge cases such as automatic refunds, coupon recovery, and compensation-ticket recovery, reducing payment-related CS issues by 90%
• •Unified payment flows around enum-based type handling, reducing the effort for adding new payment methods by more than 50%
• •Implemented and unit-tested a subscription expiration-date calculation algorithm
  • •Removed manual end-of-month correction work