Real-time systems are the backbone of modern applications. From collaborative tools to live dashboards, users expect instant feedback. At Astheron, we've spent years perfecting our approach to building systems that handle massive concurrent loads without breaking a sweat.
The Challenge
Our client, NexaFlow Systems, needed a logistics platform that could track thousands of shipments in real-time. The requirements were demanding: 50,000 concurrent WebSocket connections, sub-100ms message delivery, and zero tolerance for data loss.
Our Architecture
We chose a multi-layered approach:
1. Connection Management We used a horizontally-scalable WebSocket gateway built on Node.js. Each gateway instance handles up to 10,000 connections, with Redis pub/sub for cross-instance message routing.
2. Message Queue Behind the gateway, we implemented a durable message queue using Apache Kafka. This ensures no message is ever lost, even during gateway restarts or network partitions.
3. State Synchronization We built a custom CRDT (Conflict-free Replicated Data Type) layer that handles concurrent updates without coordination. This eliminated the need for distributed locks and dramatically reduced latency.
Results
The system has been running in production for over a year with:
- 99.99% uptime — only 4 minutes of downtime in 12 months
- 47ms average latency — well under our 100ms target
- 60,000 peak connections — 20% above our design target
Key Takeaways
- Design for failure — Every component should gracefully handle downstream failures
- Measure everything — We instrumented every layer with detailed metrics from day one
- Start simple — Our initial prototype used a single Node.js process. We scaled horizontally only when the data justified it
Real-time doesn't have to mean real complex. With the right architecture decisions upfront, you can build systems that scale elegantly.