daily-notification-plugin/docs/CALLBACK_ANALYSIS.md

Callback & Dual Scheduling Analysis

Document Created: 2025-08-26 11:17:26 UTC
Author: Matthew Raymer
Status: 🔄 RESEARCH & ANALYSIS
Priority: 🔴 HIGH - Core functionality enhancement required

🎯 REQUIREMENTS ANALYSIS

User Feedback Summary

"BTW, I still think it's worth starting a branch where we use the notification plugin, but a note on the plugin itself: seems like it'll need a couple things. One is to accept some callbacks (eg. for API calls out to a reporting service and then saving in the DB). The other is that I believe we need two 'schedule' methods, one that does the call-API-store-in-DB function and the other that does the retrieve-from-DB-and-notify-user function."

Core Requirements Identified

1. Callback System: Accept callbacks for external service integration
2. Dual Scheduling: Separate content fetch from user notification
3. API Integration: Support for external reporting services
4. Database Operations: Callback-based storage and retrieval

---

🔍 CURRENT IMPLEMENTATION ANALYSIS

Existing Scheduling Method

// Current single method approach
async scheduleDailyNotification(options: NotificationOptions): Promise<void>

Current Behavior:

• Single method handles both content fetching and notification scheduling
• Limited to basic URL fetching without callback support
• No separation of concerns between data operations and user notification
• Basic error handling without external service integration

Current API Call Handling

// Basic URL fetching in Android implementation
String url = call.getString("url", "");
// No callback support for API responses
// No database storage integration
// No external service reporting

Gap Analysis

• ❌ No callback mechanism for external service integration
• ❌ No dual scheduling - single method handles everything
• ❌ Limited API integration - basic HTTP requests only
• ❌ No database callback support for storage operations
• ❌ No reporting service integration for analytics

---

🏗️ PROPOSED ARCHITECTURE

Dual Scheduling Methods

Method 1: Content Fetch & Storage

async scheduleContentFetch(options: ContentFetchOptions): Promise<void>

Purpose: Handle API calls and database storage Responsibilities:

• Make API calls to external services
• Execute database storage callbacks
• Handle retry logic and fallbacks
• Report to analytics/reporting services
• Cache content for later use

Method 2: User Notification

async scheduleUserNotification(options: UserNotificationOptions): Promise<void>

Purpose: Retrieve stored content and notify users Responsibilities:

• Retrieve content from database/cache
• Execute user notification callbacks
• Handle notification display logic
• Manage user interaction callbacks
• Track notification engagement

Callback System Architecture

Callback Types

interface CallbackSystem {
  // API callbacks
  apiCallbacks: {
    onSuccess: (response: any) => Promise<void>;
    onError: (error: Error) => Promise<void>;
    onRetry: (attempt: number) => Promise<boolean>;
  };
  
  // Database callbacks
  databaseCallbacks: {
    onStore: (data: any) => Promise<void>;
    onRetrieve: (id: string) => Promise<any>;
    onError: (error: Error) => Promise<void>;
  };
  
  // Reporting callbacks
  reportingCallbacks: {
    onMetrics: (metrics: NotificationMetrics) => Promise<void>;
    onAnalytics: (event: string, data: any) => Promise<void>;
  };
}

Callback Registration

interface CallbackRegistry {
  registerCallback(type: CallbackType, callback: Function): void;
  unregisterCallback(type: CallbackType, id: string): void;
  executeCallback(type: CallbackType, data: any): Promise<void>;
  validateCallback(callback: Function): boolean;
}

---

🔧 IMPLEMENTATION APPROACH

Phase 1: Interface Updates

Estimated Effort: 4-6 hours

1. Extend existing interfaces

   interface NotificationOptions {
     // Existing properties...
   
     // New callback properties
     apiCallbacks?: APICallbacks;
     databaseCallbacks?: DatabaseCallbacks;
     reportingCallbacks?: ReportingCallbacks;
   }
   

2. Create new scheduling interfaces

   interface ContentFetchOptions {
     url: string;
     apiCallbacks: APICallbacks;
     databaseCallbacks: DatabaseCallbacks;
     retryConfig: RetryConfig;
   }
   
   interface UserNotificationOptions {
     contentId: string;
     notificationCallbacks: NotificationCallbacks;
     userInteractionCallbacks: UserInteractionCallbacks;
   }
   

Phase 2: Core Implementation

Estimated Effort: 12-16 hours

1. Implement callback registry system

   • Callback registration and validation
   • Execution engine with error handling
   • Lifecycle management

2. Create dual scheduling methods

   • scheduleContentFetch() implementation
   • scheduleUserNotification() implementation
   • Backward compatibility layer

3. Add callback execution logic

   • API call handling with callbacks
   • Database operation callbacks
   • Reporting service integration

Phase 3: Platform Integration

Estimated Effort: 8-12 hours

1. Android implementation

   • WorkManager integration for background tasks
   • Callback execution in native code
   • Database callback support

2. iOS implementation

   • BGTaskScheduler integration
   • Callback handling in Swift
   • Core Data callback support

3. Web implementation

   • Service Worker integration
   • Browser notification callbacks
   • IndexedDB callback support

---

📊 COMPLEXITY ASSESSMENT

Technical Complexity: 🔴 HIGH

• Architecture Changes: Significant interface redesign required
• Platform Integration: Need to implement across Android/iOS/Web
• Callback Management: Complex lifecycle and error handling
• Backward Compatibility: Must maintain existing API functionality

Business Complexity: 🟡 MEDIUM

• User Impact: Existing users need migration path
• Testing Requirements: Comprehensive callback testing needed
• Documentation: Significant API documentation updates required
• Training: Team needs to understand new callback patterns

Risk Factors: 🔴 HIGH

• Interface Changes: Breaking changes to existing API
• Performance Impact: Callback overhead on notification delivery
• Platform Differences: Ensuring consistent behavior across platforms
• Error Handling: Complex callback failure scenarios

---

🚀 RECOMMENDED IMPLEMENTATION STRATEGY

1. Research & Design Phase (Days 1-2)

• Complete callback system design
• Create interface mockups
• Design migration strategy
• Plan testing approach

2. Core Implementation Phase (Days 2-4)

• Implement callback registry system
• Create dual scheduling methods
• Add callback execution logic
• Implement error handling

3. Platform Integration Phase (Days 4-5)

• Android callback integration
• iOS callback integration
• Web callback integration
• Cross-platform testing

4. Testing & Documentation Phase (Day 5)

• Comprehensive callback testing
• Performance validation
• API documentation updates
• Migration guide creation

---

🔒 SECURITY CONSIDERATIONS

Callback Security

• Input Validation: Validate all callback parameters
• Sandboxing: Execute callbacks in controlled environment
• Rate Limiting: Prevent callback abuse
• Authentication: Validate callback sources

Data Security

• Encryption: Encrypt sensitive data in callbacks
• Access Control: Limit callback access to necessary data
• Audit Logging: Log all callback executions
• Error Handling: Prevent information leakage in errors

---

📈 PERFORMANCE IMPACT

Callback Overhead

• Execution Time: Additional 10-50ms per callback
• Memory Usage: Callback registry storage
• Battery Impact: Minimal on modern devices
• Network Impact: Depends on callback implementation

Optimization Strategies

• Callback Batching: Execute multiple callbacks together
• Async Execution: Non-blocking callback execution
• Caching: Cache callback results where appropriate
• Lazy Loading: Load callbacks only when needed

---

🧪 TESTING STRATEGY

Unit Testing

• Callback Registration: Test callback registration/unregistration
• Callback Execution: Test successful and failed executions
• Error Handling: Test various error scenarios
• Performance: Test callback execution performance

Integration Testing

• API Integration: Test with real external services
• Database Integration: Test database callback scenarios
• Cross-Platform: Test consistency across platforms
• End-to-End: Test complete notification flow

Performance Testing

• Callback Latency: Measure callback execution time
• Memory Usage: Monitor memory impact of callbacks
• Battery Impact: Test battery usage with callbacks
• Scalability: Test with multiple concurrent callbacks

---

📚 REFERENCES & RESOURCES

Design Patterns

• Observer Pattern: For callback registration and execution
• Strategy Pattern: For different callback execution strategies
• Factory Pattern: For creating different callback types
• Chain of Responsibility: For callback execution flow

Platform-Specific Resources

• Android: WorkManager, AlarmManager, Room database
• iOS: BGTaskScheduler, UNCalendarNotificationTrigger, Core Data
• Web: Service Workers, IndexedDB, Browser Notifications API

Best Practices

• Error Handling: Comprehensive error handling for callbacks
• Performance: Optimize callback execution for mobile devices
• Security: Secure callback execution and data handling
• Testing: Thorough testing of callback scenarios

---

Next Steps: Complete callback system design and create implementation plan
Estimated Timeline: 3-5 days for full implementation
Success Criteria: Dual scheduling methods working with full callback support
Risk Level: 🔴 HIGH - Requires careful planning and implementation