SkyConnect Airline Booking Platform

Overview

SkyConnect is a modern airline booking platform built to handle high-concurrency seat reservations with real-time availability updates.

The Challenge

Traditional booking systems suffer from race conditions when multiple users try to reserve the same seat. We needed a system that could:

• Show real-time seat availability across concurrent sessions
• Handle payment processing without double-booking
• Scale to thousands of simultaneous users during flash sales

Architecture

The system uses a microservice-inspired architecture within a monorepo:

• Frontend: Next.js App Router with Server Components for fast initial loads
• API Layer: Next.js Route Handlers with middleware for auth & rate limiting
• Database: PostgreSQL with row-level locking for seat reservations
• Cache: Redis for session management and real-time seat availability
• Payments: Stripe integration with webhook handlers for async confirmation

Key Technical Decisions

Optimistic Locking for Seat Selection

We used PostgreSQL's SELECT FOR UPDATE SKIP LOCKED to handle concurrent seat selections without blocking other users:

BEGIN;
SELECT * FROM seats
WHERE flight_id = $1 AND seat_number = $2 AND status = 'available'
FOR UPDATE SKIP LOCKED;
-- If row returned, proceed with reservation
UPDATE seats SET status = 'held', held_by = $3, held_until = NOW() + INTERVAL '10 minutes'
WHERE id = $4;
COMMIT;

Real-Time Updates with Server-Sent Events

Instead of WebSockets (which are harder to scale), we used SSE for pushing seat availability changes to connected clients.

Results

• 99.97% uptime during peak booking periods
• Zero double-bookings across 50K+ reservations
• < 200ms average API response time
• 40% reduction in booking abandonment compared to the legacy system

Lessons Learned

1. Optimistic UI updates dramatically improve perceived performance
2. Redis pub/sub is excellent for lightweight real-time features
3. Always design for failure — every external service will go down eventually