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Backend Development

NestJS, Database, API Design, Payment, Message Queue

0 articles

WebRTC Signaling Gateway: NestJS WebSocket Real-Time Call Signaling Design

In-depth analysis of NestJS's CallGateway based on Socket.IO WebRTC signaling gateway design, covering triple delivery guarantee for call invitations, Offer/Answer SDP exchange, ICE candidate relay, Redis offline caching, and FCM push wake-up

Backend Development

Prisma Optimistic Locking in Practice: Dual-Currency Wallet System with Audit Trail for Financial Tracking

An in-depth analysis of a production-grade NestJS wallet service, covering Prisma update where optimistic locking, dual-currency accounting (cash + coins), freeze/unfreeze mechanisms, and complete transaction flow tracking.

Backend Development

Order Payment Pipeline: Coupon + Flash Sale + Coins + Group Buy Four-Layer Price Calculation

An in-depth analysis of the `OrderService.checkOut` method in a NestJS project, demonstrating how to chain four layers of price calculation (flash sale, coupon, coins, group buy) and five subsystems within a Prisma transaction, covering optimistic lock debit, atomic inventory deduction, and a complete refund flow.

Backend Development

Gemini AI Production-Grade Integration: Four-Layer Circuit Breaker Degradation and Triple Quota Control

An in-depth analysis of the production-grade encapsulation of @google-cloud/vertexai (Gemini 2.5 Flash) in a NestJS project, covering core implementations such as a four-layer service level degradation system, triple quota control, circuit breaker pattern, and exponential backoff retry.

Backend Development

Financial Audit System: NestJS Xendit Payout + @DistributedLock + Cron Ghost Order Auto-Recovery

In-depth analysis of a production-grade financial audit system, covering distributed locks to prevent duplicate payouts, Xendit third-party payout integration, Cron auto-recovery mechanisms, and a complete state machine design.

Backend Development