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Architecture

System Overview​

Flows is a PostgreSQL-based billing and metering platform designed for energy communities. It provides a complete solution for customer management, meter reading, tariff calculation, and billing.

Architecture Diagram​

Components​

Database Layer​

The PostgreSQL database is the heart of Flows, containing:

  • Public Schema - Core business entities (customers, accounts, meters, payments)
  • Flows Schema - Operational data (meter shadows, registry, sync status)
  • Views - Materialized views for reporting and analytics
  • Functions - Stored procedures for complex operations

API Layer​

PostgREST provides automatic REST API generation from the database schema:

  • CRUD Operations - Automatic endpoints for all tables
  • RPC Functions - Custom business logic exposed as API endpoints
  • Row Level Security - Database-level access control
  • Real-time Subscriptions - WebSocket support for live updates

Background Jobs​

Scheduled and event-driven jobs handle:

  • Meter Synchronization - Regular sync of meter readings
  • Tariff Updates - Apply tariff changes to meters
  • Billing Runs - Monthly billing calculations
  • Payment Processing - Bank reconciliation
  • Notifications - Email and SMS alerts

Integration Points​

  • Meter Communication - EMOP protocol over TCP/IP
  • Payment Gateways - Bank API integration
  • Email Services - SMTP or API-based email
  • SMS Services - SMS gateway for notifications

Data Flow​

Meter Reading Flow​

Billing Flow​

Scalability​

Horizontal Scaling​

  • Read Replicas - Scale read operations
  • Connection Pooling - PgBouncer for connection management
  • Load Balancing - Multiple API instances

Vertical Scaling​

  • Database Optimization - Indexes, partitioning, vacuum
  • Query Optimization - Explain analyze, query planning
  • Resource Allocation - CPU, memory, storage tuning

Security​

Authentication & Authorization​

  • JWT Tokens - Stateless authentication
  • Row Level Security - Database-level access control
  • API Keys - Service-to-service authentication
  • Role-Based Access - Customer, admin, service roles

Data Protection​

  • Encryption at Rest - Database encryption
  • Encryption in Transit - TLS/SSL
  • Audit Logging - Complete audit trail
  • GDPR Compliance - Data privacy controls

Deployment​

Container Deployment​

version: '3.8'
services:
  postgres:
    image: postgres:14
    environment:
      POSTGRES_DB: flows
      
  postgrest:
    image: postgrest/postgrest
    environment:
      PGRST_DB_URI: postgres://user:pass@postgres/flows
      
  jobs:
    image: simtricity/flows-jobs
    environment:
      DATABASE_URL: postgres://user:pass@postgres/flows

Cloud Deployment​

  • Database - Supabase, AWS RDS, Google Cloud SQL
  • API - Vercel, AWS Lambda, Google Cloud Run
  • Jobs - Fly.io, AWS ECS, Kubernetes CronJobs

Monitoring​

Metrics​

  • API Metrics - Request rate, latency, errors
  • Database Metrics - Connections, query performance
  • Job Metrics - Execution time, success rate
  • Business Metrics - Billing accuracy, sync success

Logging​

  • Application Logs - Structured logging with context
  • Database Logs - Query logs, slow queries
  • Audit Logs - User actions, data changes
  • Error Tracking - Sentry, Rollbar integration