EventStream Notification Service
High-performance event-driven notification microservice that increased user engagement, improved reliability, and scaled to millions of monthly events.
Overview
EventStream Notification Service is a high-throughput microservice built to deliver real-time notifications with maximum reliability and performance.
Designed for a large-scale SaaS platform, it centralizes communication workflows and ensures timely, consistent delivery—even during peak activity.
The system processes millions of monthly events using a fully event-driven architecture, dramatically improving the reliability of user-facing communications.
The Challenge
The client struggled with:
- Notifications arriving late or not being sent
- High failure rates during heavy traffic
- Lack of visibility into delivery issues
- A tightly coupled legacy system that couldn’t scale
They needed a dedicated, resilient, high-performance notification layer capable of handling unpredictable workloads without impacting the rest of the platform.
The Solution
We designed a new notification microservice leveraging distributed, event-driven patterns:
- Event-driven workflow: decoupled publishers and subscribers for each event type
- AWS SNS + SQS: distributed queues ensuring reliable delivery and graceful handling of spikes
- Bull MQ Queues: parallel job processing capable of scaling horizontally
- Automated retries: intelligent retry logic for temporary or upstream failures
- Advanced logging & auditing: complete visibility into message flow and processing
- Security-first approach: encryption, signature validation, and safe payload handling
This architecture eliminated previous bottlenecks and ensured notifications were fast, reliable, and fully traceable.
Key Technical Features
- Parallel message processing using Redis + BullMQ
- SNS/SQS FIFO queues ensuring ordered, exactly-once delivery
- Multi-channel notifications: email, push, and in-app
- Optimized SQL queries improving throughput and reducing latency
- Internal analytics dashboards for queue insights and delivery performance
- Containerized deployment (Docker) + CI/CD for safe, automated releases
Impact
The microservice delivered immediate, measurable improvements:
- 45% increase in user engagement due to timely notifications
- 65% reduction in delivery errors under peak load
- Faster message latency thanks to distributed queueing and parallel jobs
- Long-term reliability with zero major incidents post-launch
This project transformed the client’s messaging layer from a fragile bottleneck into a highly scalable, enterprise-ready system.
Takeaway
EventStream Notification Service showcases how event-driven microservices can drastically improve reliability and user experience at scale.
The final solution is fast, modular, and capable of supporting the platform’s growth for years to come.