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Market Maker Monitoring

MIBGAS operates the organized natural gas market in Spain and is subject to official regulation requiring continuous monitoring of Market Makers operating on its platform. MMM (Market Maker Monitoring) is the internal system that automates this oversight — from market data ingestion to regulatory compliance report generation.

As Tech Lead / Software Architect, I designed the microservices architecture, implemented the backend service (BFF), defined gRPC inter-service communication and REST backend-to-frontend communication, and made the key technology decisions for the project. Team of 2–3 engineers over approximately one year.

Architecture

Turborepo monorepo with 6 applications deployed on Google Cloud Platform:

  • Frontend (Next.js 15 / React 19): operator interface for market data visualization, manual collection triggers, and report downloads.
  • Backend BFF (NestJS / PostgreSQL): REST API with JWT. Single entry point for the frontend — microservices are never exposed directly.
  • Collection Service (NestJS / gRPC / SOAP): daily ingestion of order books, offers, and trades from MIBGAS’s external SOAP API. Triggered by Cloud Scheduler or manually from the frontend.
  • Compliance Service (NestJS / gRPC / stateless): compliance algorithm built from scratch, implementing the official Spanish regulatory standard.
  • Reporting Service (NestJS / gRPC / stateless): PDF generation (Puppeteer + Handlebars), Excel (ExcelJS), GCS storage, and email delivery (SendGrid).
  • Backtesting (React / Vite / standalone): internal tool to validate compliance algorithm changes by comparing CSV datasets using statistical metrics (MAE, RMSE, MAPE).

Key technical decisions

  • gRPC unary for all inter-service communication.
  • BFF pattern: the frontend never calls microservices directly. Next.js API routes act as a secure proxy, centralizing authentication and authorization.
  • Stateless Compliance and Reporting services: no database in these services; all persistence delegated to the Backend BFF’s single shared PostgreSQL instance, simplifying deployment and scaling.
  • Static mutexes to prevent duplicate concurrent compliance calculations for the same period (single Cloud SQL instance by design).
  • Standard PostgreSQL (TimescaleDB evaluated and discarded).

Outcome

System in production monitoring ~10 Market Makers, with automated generation of regulatory compliance reports per Spanish regulation.