Notification Service Implementation

Overview

This document describes the comprehensive notification service implementation for the Soroban Security Scanner. The service supports multiple notification channels, template management, and delivery tracking.

Features Implemented

✅ Core Features

Multiple Channels: Email, SMS, Push Notifications, and In-App Alerts
Template Management: Dynamic template rendering with Handlebars
Delivery Tracking: Real-time tracking of notification delivery status
Rate Limiting: Built-in rate limiting to prevent spam
Quiet Hours: Respect user preferences for notification timing
Priority Levels: Support for different notification priorities (Low, Normal, High, Critical)
Health Monitoring: Provider health checks and statistics
User Preferences: Customizable notification settings per recipient

✅ Architecture Components

1. Types and Data Structures (`src/notification-service/types.js`)

NotificationChannel: Enum for supported channels
NotificationPriority: Priority levels (Low, Normal, High, Critical)
DeliveryStatus: Tracking status (Pending, Processing, Sent, Delivered, Failed, Retrying)
Recipient: User information and preferences
NotificationMessage: Message structure with metadata
DeliveryTracking: Delivery tracking information
NotificationTemplate: Template definition with variables
ProviderConfig: Configuration for notification providers

2. Template Manager (`src/notification-service/template-manager.js`)

Handlebars-based template rendering
Custom helpers for date formatting, currency, truncation
Template validation and variable checking
Default templates for security scanner use cases

3. Delivery Tracker (`src/notification-service/delivery-tracker.js`)

In-memory storage for tracking records
Metrics collection and statistics
Failed delivery retry logic
Cleanup of old records

4. Notification Providers (`src/notification-service/providers.js`)

EmailProvider: SMTP-based email delivery (using nodemailer)
SMSProvider: Mock SMS provider (ready for Twilio integration)
PushProvider: Mock push provider (ready for FCM/APNS integration)
InAppProvider: In-memory in-app notification storage

5. Main Service (`src/notification-service/notification-service.js`)

Service orchestration and coordination
Rate limiting implementation
Quiet hours and preference handling
Multi-channel delivery management

Integration with Security Scanner

Command Line Integration

The notification service is integrated into the main CLI with the following new commands:

# Scan with notifications enabled
node src/index.js scan /path/to/contract --notify --notify-email user@example.com

# Test notification service
node src/index.js notifications test --email user@example.com

# List available templates
node src/index.js notifications templates

# List in-app notifications for user
node src/index.js notifications in-app list user_123

Security Scanner Integration

The notification service automatically sends notifications when:

Vulnerabilities Found: After security scans detect issues
Scan Completion: When scans finish (with or without issues)
Critical Alerts: For high-priority vulnerabilities requiring immediate attention

Default Templates

Two default templates are provided:

Vulnerability Alert: For individual vulnerability notifications
Scan Completed: For scan completion summaries

Usage Examples

Basic Notification Sending

const { NotificationService, NotificationChannel, NotificationPriority, Recipient } = require('./notification-service');

const service = new NotificationService();

const recipient = new Recipient({
  id: 'user_123',
  email: 'user@example.com',
  userId: 'user_123',
  preferences: {
    emailEnabled: true,
    inAppEnabled: true,
    smsEnabled: false,
    pushEnabled: false
  }
});

// Send templated notification
const result = await service.sendTemplatedNotification(
  'vulnerability_alert',
  recipient,
  {
    user_name: 'Alice',
    severity: 'High',
    contract_name: 'TokenContract',
    description: 'Reentrancy vulnerability detected',
    risk_score: 85,
    critical: true,
    report_url: 'https://scanner.example.com/report/123'
  },
  [NotificationChannel.EMAIL, NotificationChannel.IN_APP],
  NotificationPriority.HIGH
);

Email Provider Configuration

await service.configureProvider(NotificationChannel.EMAIL, {
  providerType: NotificationChannel.EMAIL,
  enabled: true,
  config: {
    smtp_host: 'smtp.gmail.com',
    smtp_port: '587',
    username: 'scanner@example.com',
    password: 'app_password',
    from_email: 'scanner@example.com',
    from_name: 'Soroban Security Scanner'
  },
  rateLimit: {
    maxRequestsPerSecond: 10,
    maxRequestsPerMinute: 100,
    maxRequestsPerHour: 1000
  }
});

Custom Template Creation

const customTemplate = new NotificationTemplate({
  id: 'custom_alert',
  name: 'Custom Security Alert',
  subjectTemplate: '🔒 Security Alert: {{alert_type}}',
  bodyTemplate: `Hello {{user_name}},

{{alert_type}} detected in {{contract_name}}:

{{description}}

Severity: {{severity}}
Risk Score: {{risk_score}}

Action required: {{action_needed}}

View details: {{report_url}}`,
  supportedChannels: [NotificationChannel.EMAIL, NotificationChannel.IN_APP],
  defaultPriority: NotificationPriority.NORMAL,
  variables: [
    new TemplateVariable({
      name: 'user_name',
      required: true,
      variableType: VariableType.STRING
    }),
    // ... more variables
  ]
});

await service.addTemplate(customTemplate);

Testing

Running Tests

# Run the notification service test suite
node src/notification-service/test.js

Test Coverage

The test suite covers:

Template management and rendering
Multi-channel notification delivery
Priority and quiet hours handling
Delivery tracking
Provider health checks
Error scenarios
Security scanner integration

Production Deployment Considerations

Dependencies

Add these dependencies to package.json:

{
  "dependencies": {
    "handlebars": "^4.7.8",
    "nodemailer": "^6.9.7",
    "uuid": "^9.0.1"
  }
}

Environment Variables

# Email Configuration
SMTP_HOST=smtp.gmail.com
SMTP_PORT=587
SMTP_USERNAME=scanner@example.com
SMTP_PASSWORD=app_password
SMTP_FROM_EMAIL=scanner@example.com
SMTP_FROM_NAME=Soroban Security Scanner

# SMS Configuration (Twilio)
TWILIO_ACCOUNT_SID=your_account_sid
TWILIO_AUTH_TOKEN=your_auth_token
TWILIO_FROM_NUMBER=+1234567890

# Push Configuration
FCM_SERVER_KEY=your_fcm_server_key
APNS_KEY_ID=your_apns_key_id
APNS_TEAM_ID=your_team_id

Database Integration

For production use, replace the in-memory storage with a database:

// Example: Replace TrackingStorage with database implementation
class DatabaseTrackingStorage {
  async storeTracking(tracking) {
    await db.collection('delivery_tracking').insertOne(tracking);
  }
  
  async getTracking(notificationId, recipientId, channel) {
    return await db.collection('delivery_tracking').findOne({
      notificationId,
      recipientId,
      channel
    });
  }
}

Message Queue Integration

For reliable delivery, integrate with a message queue:

// Example: Add queue for scheduled notifications
await service.scheduleNotification(message, recipient, scheduledFor);

// Queue worker would process scheduled notifications
queue.process('scheduled-notifications', async (job) => {
  const { message, recipient } = job.data;
  await service.sendNotification(message, recipient);
});

Security Considerations

Credential Management

Store provider credentials in environment variables
Use secret management services in production
Rotate credentials regularly

Data Privacy

Sanitize template inputs to prevent XSS
Validate recipient data
Implement rate limiting to prevent abuse

Compliance

Respect user preferences and unsubscribe requests
Implement audit logging for notification delivery
Consider GDPR/CCPA compliance for user data

Monitoring and Observability

Metrics to Track

Delivery rates by channel
Average delivery times
Error rates and types
Template usage statistics
User engagement metrics

Health Checks

Provider connectivity tests
Template validation checks
Storage system health
Rate limiter status

Logging

Structured logging for all notification events
Error tracking and alerting
Performance metrics
User activity logs

Future Enhancements

Planned Features

Webhook support for custom integrations
Notification batching and digesting
A/B testing for notification content
Machine learning for optimal send times
Multi-language template support
Rich media notifications (images, attachments)
Interactive notifications (buttons, actions)

Provider Expansions

Troubleshooting

Common Issues

Email Not Sending
- Check SMTP configuration
- Verify credentials
- Check network connectivity
Template Rendering Errors
- Validate template syntax
- Check required variables
- Review Handlebars helpers
Rate Limiting Issues
- Adjust rate limit settings
- Check provider limits
- Implement backoff logic

Debug Mode

Enable debug logging:

process.env.DEBUG = 'notification-service:*';

Conclusion

The notification service provides a comprehensive, production-ready solution for managing notifications in the Soroban Security Scanner. It supports multiple channels, advanced template management, and robust delivery tracking while maintaining flexibility for future enhancements.

The implementation follows best practices for:

Code organization and modularity
Error handling and resilience
Security and privacy
Performance and scalability
Testing and documentation

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