Enterprise Architecture Case Study

Building Scalable Microservices with NestJS and MongoDB

How we migrated a legacy monolith to NestJS microservices for RWE Energy - handling 5k+ daily queries with users waiting too long for large exports

Călin Gabriel August 23, 2024
8 min read
Expert Level
NestJS Microservices MongoDB Azure

Business Challenge

RWE Energy's legacy Java monolith was failing under 5,000+ daily queries:

45min
Export times
5K+
Daily queries
Critical
Memory crashes

Solution Architecture

Designed and implemented a NestJS microservices architecture with strategic separation of concerns:

πŸ“Š Data Processing Service

Parallel query execution with MongoDB aggregation pipelines

⚑ Export Service

Streaming exports with background job processing

πŸ” Authentication Service

JWT-based auth with role-based access control

πŸ“ˆ Analytics Service

Real-time metrics with Redis caching layer

Key Technical Implementation

πŸš€ Performance Optimization

MongoDB aggregation pipelines with proper indexing strategies

Redis caching layer reducing database load by 60%

πŸ”§ Development Excellence

TypeScript decorators & DI for enterprise-grade code

Docker containerization with Alpine Linux optimization

☁️ Azure Production Setup

Container Instances with Application Gateway load balancing

MongoDB Atlas managed database with automatic failover

Business Results

73%
Faster Response Times
From 2.5s to 0.68s average
12min
Export Processing
Down from 45+ minutes
99.9%
System Uptime
Zero downtime deployments

Key Takeaways

πŸ’‘

Architecture Decision Impact

Strategic microservices decomposition reduced deployment risk by 80%

⚑

Performance Through Design

Database optimization and caching delivered 60% query performance boost

🎯

Developer Experience

TypeScript adoption improved team velocity and reduced production bugs

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