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System Architecture Overview

This document provides an overview of the MBC CQRS Serverless framework architecture.

AWS Infrastructure​

Component Description​

API Layer​

The entry point for receiving client requests.

  • API Gateway: REST API endpoints for CRUD operations
  • AppSync: GraphQL API for flexible queries and subscriptions
  • WebSocket API: Real-time bidirectional communication

Authentication​

  • Amazon Cognito: User authentication, JWT tokens, and user pools

Compute​

  • AWS Lambda: Serverless execution of NestJS applications

Data Storage​

  • DynamoDB: Primary event store for CQRS data persistence
  • RDS Aurora: Optional relational data for complex queries
  • S3: File and document storage

Messaging​

  • SNS: Event fan-out and topic-based publishing
  • SQS: Reliable message queuing and async processing

Orchestration​

  • Step Functions: Long-running workflows and saga patterns

Notifications​

  • SES: Transactional email delivery

Data Flow​

How requests flow through the system.

  1. Client Request: Client sends request via API Gateway, AppSync, or WebSocket
  2. Authentication: Cognito validates JWT tokens
  3. Command Execution: Lambda processes command and persists to DynamoDB
  4. Event Publishing: Events are published to SNS
  5. Event Processing: SQS queues trigger Lambda handlers for async processing
  6. Read Model Update: Projections update RDS for complex queries

Multi-Tenant Architecture​

Tenant isolation is achieved through:

  • Partition Key Prefix: Each tenant's data is prefixed with the tenant code
  • Request Context: Tenant information is extracted from JWT tokens
  • Query Filtering: All queries are automatically scoped to the tenant