Handling Millions of Operations - Building a Fault-Tolerant Payment System

Oct 5, 2024

When you’re processing payments and printing fiscal receipts, reliability isn’t optional—it’s mandatory. We built a system that handles millions of operations while maintaining fault tolerance and near-instant response times.

The Challenge

Restaurant systems need fiscal printing integration that:

  • Works reliably even during network issues
  • Handles high transaction volumes
  • Provides instant feedback
  • Never loses transactions

Our Architecture

Microservices with Message Queuing

Using NestJS microservices architecture with RabbitMQ, we built a system that decoupled payment processing from fiscal printing. This meant:

  • Individual service failures wouldn’t cascade
  • High throughput with message queuing
  • Easy horizontal scaling

Real-Time Communication

Socket.io provided real-time bidirectional communication between the frontend and backend, ensuring instant feedback on payment status and printing operations.

Fault Tolerance

The system was designed to handle:

  • Network disconnections
  • Printer offline scenarios
  • High concurrent load
  • Service failures

By implementing comprehensive retry logic, circuit breakers, and message persistence, we ensured that transactions were never lost, even during infrastructure issues.

Observability

We implemented:

  • OpenTelemetry for distributed tracing
  • Prometheus for metrics collection
  • Grafana for visualization

This gave us complete visibility into system behavior, allowing proactive issue detection.

The Results

After deployment, the system:

  • Processes 4+ million print operations
  • Active in 100+ restaurants
  • Near-instant operation times
  • Zero data loss even during network issues

Key Takeaways

Building systems that handle millions of operations requires thinking about fault tolerance from the start. Message queuing, circuit breakers, and comprehensive observability aren’t optional—they’re essential.

The system’s success came from designing for failure: assuming things will break and building resilience into every layer.

Building a system that needs to handle scale? TechTrail designs fault-tolerant architectures that never lose data, even under pressure. Get in touch to discuss your requirements.