RKB
Md Abdur Razzak
MarketplaceLive Demo / App

Ooh Ahh

On-Demand Beauty Service Platform

A location-based service marketplace connecting users with nearby beauty professionals, similar to an Uber-style booking system for salon and home services.

Key Impact: Handled real-time booking workflows with low-latency updates

System Architecture & Design Patterns

Architecture Pattern

Modular Monolith with Event-Driven Socket Cluster & Redis Pub/Sub

Strategic Rationale

Chosen to maintain high development velocity while allowing real-time websocket connections to scale horizontally across multiple instances without state locking or session stickiness issues.

Technical Highlights
  • MongoDB 2DSphere indexing for sub-10ms geospatial provider discovery queries
  • Redis Pub/Sub adapter syncing real-time job bidding & live provider coordinates across Socket nodes
  • Stripe Webhook processing engine with idempotent event verification

Engineering Challenges & Solutions

Challenge 1

High-frequency provider GPS updates created excessive backend CPU utilization and MongoDB write contention.

Engineered Solution

Implemented client-side distance thresholding combined with Redis in-memory location caching, reducing database write operations by 70%+ while preserving live map accuracy.

Challenge 2

Payment webhook race conditions causing duplicate job booking confirmations.

Engineered Solution

Architected an idempotent transaction pipeline using Redis distributed locks (Redlock) and DB transaction state checks, guaranteeing single-execution semantics for payment events.

Tech Stack

Node.jsExpress.jsMongoDBRedisSocket.ioStripeFirebaseDocker

Core Capabilities

  • Location-based service discovery
  • Real-time booking & provider matching
  • In-app chat between user and provider
  • Job bidding / acceptance system
  • Live job status tracking
  • Notification system (SMS/Push)