Event-Driven Architecture Example

This example demonstrates how to build an Event-Driven Architecture (EDA) system using LegibleSync with a plugin-based modular architecture.

Architecture Overview

The system is composed of independent plugins that communicate through events:

• Users Plugin: User management and authentication
• Products Plugin: Product catalog management
• Orders Plugin: Order processing and lifecycle
• Inventory Plugin: Stock management and alerts
• Notifications Plugin: Multi-channel notifications
• Analytics Plugin: Event tracking and reporting

Event Flow

User Registration → Welcome Email → Analytics Track
    ↓
Product Added → Inventory Update → Low Stock Alert
    ↓
Order Created → Inventory Deduct → Payment Process → Order Confirmed
    ↓
Notification Sent → Analytics Update

Plugin Structure

Each plugin follows the same structure:

plugin-name/
├── concepts/     # Business logic components
├── syncs/        # Event-driven rules
└── index.ts      # Plugin registration

Key EDA Patterns Demonstrated

1. Event Sourcing

• All business events are captured as ActionRecords
• Complete audit trail of system activity

2. CQRS (Command Query Responsibility Segregation)

• Commands: Write operations (create, update, delete)
• Queries: Read operations with filtering

3. Event-Driven Orchestration

• Declarative sync rules define event flows
• Automatic execution of business processes

4. Plugin Isolation

• Each plugin is independently deployable
• Loose coupling through event contracts

Running the Example

cd packages/example-eda
npm run dev

This will start the EDA system and demonstrate various event flows.

Testing

The example includes comprehensive test suites:

Unit Tests

# Run all unit tests
npm test

# Run specific test file
npm test -- EventBus.test.ts

# Run with coverage
npm run test:coverage

# Run tests in watch mode
npm run test:watch

Test Structure

• Unit Tests (__tests__/unit/): Test individual components

  • PluginManager.test.ts: Plugin loading and management
  • EventBus.test.ts: Event publishing and subscription
  • concepts/User.test.ts: User concept business logic

• Integration Tests (__tests__/integration/): Test complete workflows

  • ecommerce-flow.test.ts: End-to-end e-commerce scenarios

Test Coverage

The test suite covers:

• ✅ Plugin loading and initialization
• ✅ Event publishing and subscription
• ✅ Business logic validation
• ✅ Cross-plugin communication
• ✅ Error handling
• ✅ Async operation handling