@sailboat-computer/event-bus/examples/schema-validation-example.ts

Standardized event bus for sailboat computer v3 with resilience features and offline capabilities

/**
 * Schema validation example
 * 
 * This example demonstrates how to use schema validation with the event bus.
 */

import { createEventBus, EventPriority, EventCategory } from '../src';

// Define a schema for a user created event
const userCreatedSchema = {
  type: 'object',
  properties: {
    id: { type: 'string' },
    username: { type: 'string' },
    email: { type: 'string', format: 'email' },
    createdAt: { type: 'string', format: 'date-time' }
  },
  required: ['id', 'username', 'email'],
  additionalProperties: false
};

// Define the event type
interface UserCreatedEvent {
  id: string;
  username: string;
  email: string;
  createdAt: string;
}

async function runExample() {
  console.log('Starting schema validation example...');
  
  // Create event bus
  const eventBus = createEventBus({
    adapter: {
      type: 'memory',
      config: {
        serviceName: 'schema-validation-example'
      }
    },
    offlineBuffer: {
      maxSize: 100,
      priorityRetention: true
    },
    metrics: {
      enabled: true,
      detailedTimings: true
    }
  });
  
  // Initialize event bus
  await eventBus.initialize({
    adapter: {
      type: 'memory',
      config: {
        serviceName: 'schema-validation-example'
      }
    },
    offlineBuffer: {
      maxSize: 100,
      priorityRetention: true
    },
    metrics: {
      enabled: true,
      detailedTimings: true
    }
  });
  
  // Register schema for user.created.v1 event
  eventBus.registerSchema<UserCreatedEvent>('user.created.v1', userCreatedSchema);
  
  console.log('Registered schema for user.created.v1 event');
  
  // Subscribe to user created events
  await eventBus.subscribe<UserCreatedEvent>('user.created.v1', (event) => {
    console.log(`User created: ${event.data.username} (${event.data.email})`);
  });
  
  console.log('Subscribed to user.created.v1 events');
  
  // Publish a valid event
  try {
    const validEvent: UserCreatedEvent = {
      id: '123',
      username: 'sailor',
      email: 'sailor@example.com',
      createdAt: new Date().toISOString()
    };
    
    console.log('Publishing valid event:', validEvent);
    
    await eventBus.publish<UserCreatedEvent>(
      'user.created.v1',
      validEvent,
      {
        priority: EventPriority.NORMAL,
        category: EventCategory.USER_ACTION
      }
    );
    
    console.log('Valid event published successfully');
  } catch (error) {
    console.error('Failed to publish valid event:', error);
  }
  
  // Publish an invalid event (missing required field)
  try {
    const invalidEvent = {
      id: '456',
      username: 'captain',
      // Missing email field
      createdAt: new Date().toISOString()
    };
    
    console.log('Publishing invalid event (missing email):', invalidEvent);
    
    await eventBus.publish<UserCreatedEvent>(
      'user.created.v1',
      invalidEvent as any,
      {
        priority: EventPriority.NORMAL,
        category: EventCategory.USER_ACTION
      }
    );
    
    console.log('Invalid event published successfully (this should not happen)');
  } catch (error) {
    console.error('Failed to publish invalid event (expected):', error.message);
  }
  
  // Publish an invalid event (additional property)
  try {
    const invalidEvent = {
      id: '789',
      username: 'admiral',
      email: 'admiral@example.com',
      createdAt: new Date().toISOString(),
      role: 'admin' // Additional property not in schema
    };
    
    console.log('Publishing invalid event (additional property):', invalidEvent);
    
    await eventBus.publish<UserCreatedEvent>(
      'user.created.v1',
      invalidEvent as any,
      {
        priority: EventPriority.NORMAL,
        category: EventCategory.USER_ACTION
      }
    );
    
    console.log('Invalid event published successfully (this should not happen)');
  } catch (error) {
    console.error('Failed to publish invalid event (expected):', error.message);
  }
  
  // Close event bus
  await eventBus.close();
  
  console.log('Schema validation example completed');
}

// Run the example
runExample().catch(error => {
  console.error('Example failed:', error);
  process.exit(1);
});