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Backend Architecture

Overview

This document describes the backend architecture for the Carepath Manager application, including Firebase integration, GraphQL API layer, and data flow patterns.

Architecture Layers

1. Frontend Layer (Angular)

  • Components: UI components for different views
  • Services: Angular services that communicate with backend
  • State Management: Local state management using RxJS

2. API Layer (GraphQL)

  • GraphQL Schema: Type definitions for all entities
  • Resolvers: Business logic for queries and mutations
  • Subscriptions: Real-time data updates
  • Authentication: JWT-based authentication middleware

3. Data Layer (Firebase)

  • Firestore: NoSQL document database for structured data
  • Authentication: Firebase Authentication for user management
  • Storage: Firebase Storage for file uploads
  • Real-time Database: For real-time messaging features

Technology Stack

Backend Technologies

  • Firebase Firestore: Primary database
  • Firebase Authentication: User authentication and authorization
  • Firebase Storage: File and document storage
  • Apollo GraphQL: API gateway and query language
  • TypeScript: Type-safe backend code

Frontend Integration

  • Apollo Client: GraphQL client for Angular
  • AngularFire: Official Angular library for Firebase
  • RxJS: Reactive programming for data streams

Data Flow

User Action → Angular Component → Angular Service → GraphQL Query/Mutation 
→ Apollo Client → GraphQL Resolver → Firebase Service → Firestore Database

Read Flow

  1. User triggers action in UI
  2. Component calls Angular service method
  3. Service executes GraphQL query via Apollo Client
  4. GraphQL resolver fetches data from Firebase
  5. Data flows back through the chain to UI

Write Flow

  1. User submits form/makes change
  2. Component validates and calls service
  3. Service executes GraphQL mutation
  4. Resolver updates Firebase Firestore
  5. Real-time listeners notify subscribed components

Security Model

Authentication

  • Firebase Authentication handles user login/signup
  • JWT tokens issued upon successful authentication
  • Tokens included in all GraphQL requests

Authorization

  • Firestore security rules enforce data access policies
  • GraphQL resolvers validate user permissions
  • Role-based access control (RBAC) for different user types

Data Protection

  • All data encrypted in transit (HTTPS)
  • Firestore encryption at rest
  • Sensitive data fields hashed/encrypted
  • HIPAA-compliant data handling

Scalability Considerations

Database Design

  • Denormalized data structure for read optimization
  • Composite indexes for complex queries
  • Pagination for large datasets
  • Caching layer for frequently accessed data

Performance Optimization

  • GraphQL query batching and deduplication
  • Firestore compound indexes
  • Client-side caching with Apollo
  • Lazy loading for large collections

Monitoring & Logging

Application Monitoring

  • Firebase Performance Monitoring
  • Error tracking and reporting
  • User analytics and usage patterns
  • API response time monitoring

Audit Logging

  • All data modifications logged
  • User action tracking
  • Compliance audit trails
  • Security event logging

Disaster Recovery

Backup Strategy

  • Automated daily Firestore backups
  • Point-in-time recovery capability
  • Geographic redundancy
  • Backup retention policy (30 days)

Recovery Procedures

  1. Identify incident and scope
  2. Restore from most recent backup
  3. Validate data integrity
  4. Resume normal operations
  5. Post-incident review

API Versioning

Version Strategy

  • URL-based versioning for breaking changes
  • Backward compatibility maintained for 2 versions
  • Deprecation warnings in responses
  • Migration guides for version upgrades

Future Enhancements

Planned Features

  • GraphQL subscriptions for real-time updates
  • Offline-first capabilities with service workers
  • Advanced caching strategies
  • Multi-region deployment
  • Microservices architecture for specific domains