Real-Time WebSocket Architecture: Powering 30-Second Rider Matching

When a customer hits 'Confirm Order', a complex symphony of distributed events must execute in parallel within seconds:

• The customer's digital payment is captured and verified.
• An audio alert triggers on the merchant's POS tablet.
• Nearby active delivery riders within a 2km radius receive an interactive order notification with pickup coordinates and payout details.
• Live GPS telemetry maps the rider's approach in real-time on the customer's phone screen.

Event-Driven Architecture with Redis Pub/Sub

FirstMartt utilizes persistent bi-directional WebSocket connections managed across lightweight microservice instances:

• **Zero Polling Overhead:** Eliminates battery-draining HTTP polling by pushing order state changes instantly over lightweight WebSocket frames.
• **Idempotent State Machines:** Guarantees that even if cellular connection drops momentarily, order state transitions (Created → Accepted → Packed → Dispatched → Delivered) never duplicate or drop.
• **Automatic Reconnection & Queue Buffer:** Offline rider devices automatically replay unacknowledged event packets the millisecond network connection resumes.

This robust architecture ensures 99.99% dispatch reliability during heavy peak rush hours.