Technical Whitepaper

Multi-Tenant Architecture

Multi-tenant applications allow multiple organizations to use a single application instance while maintaining data isolation. Key considerations:

• Data Isolation: Implement row-level security using organization identifiers
• Query Filtering: Automatically filter queries by tenant context
• Shared Infrastructure: Balance cost efficiency with security requirements
• Tenant Context: Maintain tenant context throughout the request lifecycle

Layered Architecture

A well-structured layered architecture improves maintainability and testability:

• Presentation Layer: UI components, API controllers
• Business Logic Layer: Domain services, business rules
• Data Access Layer: Repository pattern, ORM abstractions
• Infrastructure Layer: External services, utilities

Microservices vs Monolith

Choose the right architecture pattern based on your requirements:

• Start with Monolith: Easier to develop, test, and deploy initially
• Identify Boundaries: Use domain-driven design to identify service boundaries
• Evolve to Microservices: Extract services when benefits outweigh complexity
• Communication: Use REST APIs, message queues, or event-driven architecture

Authentication

• Token-Based Authentication: Use JWT or similar tokens for stateless authentication
• Token Refresh: Implement automatic token refresh before expiration
• Password Security: Hash passwords using bcrypt or Argon2, enforce strong password policies
• Multi-Factor Authentication: Support 2FA/MFA for enhanced security
• Session Management: Implement proper session timeout and invalidation

Authorization

• Role-Based Access Control (RBAC): Define roles and assign permissions
• Attribute-Based Access Control (ABAC): Fine-grained permissions based on attributes
• Permission Structure: Use hierarchical permission models (module:resource:action)
• Principle of Least Privilege: Grant minimum required permissions
• Permission Caching: Cache permissions for performance while ensuring consistency

Data Protection

• Encryption in Transit: Always use HTTPS/TLS for data transmission
• Encryption at Rest: Encrypt sensitive data in the database
• Input Validation: Validate and sanitize all user inputs
• SQL Injection Prevention: Use parameterized queries, ORM frameworks
• XSS Prevention: Sanitize outputs, use Content Security Policy (CSP)
• CSRF Protection: Implement CSRF tokens for state-changing operations

Database Optimization

• Indexing: Create appropriate indexes for frequently queried columns
• Query Optimization: Avoid N+1 queries, use eager loading where appropriate
• Connection Pooling: Implement connection pooling for database connections
• Pagination: Always paginate large result sets
• Caching: Cache frequently accessed data (Redis, Memcached)
• Read Replicas: Use read replicas for read-heavy workloads

Application Scaling

• Horizontal Scaling: Design stateless applications for horizontal scaling
• Load Balancing: Use load balancers to distribute traffic
• CDN: Serve static assets through CDN
• Async Processing: Offload heavy tasks to background jobs
• Rate Limiting: Implement rate limiting to prevent abuse

Performance Monitoring

• Application Performance Monitoring (APM): Track response times, error rates
• Logging: Structured logging with appropriate log levels
• Metrics: Track key performance indicators (KPIs)
• Alerting: Set up alerts for critical issues

Database Design Principles

• Normalization: Normalize to reduce redundancy, but denormalize for performance when needed
• Relationships: Define clear relationships with appropriate foreign keys
• Audit Fields: Include CreatedAt, UpdatedAt, CreatedBy for audit trails
• Soft Deletes: Use soft deletes for data recovery and audit purposes
• Versioning: Consider versioning for critical entities

Multi-Tenant Data Models

• Tenant Identifier: Include tenant/organization ID in all tenant-specific tables
• Composite Keys: Use composite keys with tenant ID for uniqueness
• Automatic Filtering: Implement middleware/filters to automatically filter by tenant
• Cross-Tenant Queries: Prevent accidental cross-tenant data access

JWT Implementation

• Token Structure: Include user ID, roles, permissions, organization context
• Token Expiration: Use short-lived access tokens and longer-lived refresh tokens
• Token Refresh: Implement automatic token refresh mechanism
• Token Storage: Store tokens securely (httpOnly cookies or secure storage)
• Token Revocation: Implement token blacklisting for logout/revocation

Permission Models

• Granular Permissions: Use hierarchical permission strings (module:resource:action)
• Wildcard Support: Support wildcards for flexible permission assignment
• Permission Inheritance: Combine role-based and direct user permissions
• Permission Caching: Cache effective permissions for performance
• Permission Validation: Validate permissions at API endpoints and UI components

RESTful Principles

• Resource-Based URLs: Use nouns for resources, not verbs
• HTTP Methods: Use appropriate HTTP methods (GET, POST, PUT, PATCH, DELETE)
• Status Codes: Return appropriate HTTP status codes
• Consistent Response Format: Use consistent response structure across all endpoints
• Versioning: Version your APIs (URL versioning or header versioning)

API Best Practices

• Pagination: Always paginate list endpoints
• Filtering & Sorting: Support filtering and sorting parameters
• Error Handling: Return descriptive error messages with error codes
• Documentation: Maintain up-to-date API documentation (OpenAPI/Swagger)
• Rate Limiting: Implement rate limiting to prevent abuse
• Validation: Validate all inputs and return clear validation errors

Component Architecture

• Component-Based: Build reusable, composable components
• Separation of Concerns: Separate presentation, business logic, and data access
• State Management: Use appropriate state management (Redux, MobX, or Context API)
• Routing: Implement client-side routing with lazy loading

Performance Optimization

• Code Splitting: Split code into chunks for lazy loading
• Tree Shaking: Remove unused code in production builds
• Image Optimization: Optimize images, use appropriate formats (WebP)
• Caching: Implement client-side caching strategies
• Bundle Size: Monitor and optimize bundle sizes

Test Pyramid

• Unit Tests: Test individual functions and components in isolation
• Integration Tests: Test interactions between components
• End-to-End Tests: Test complete user workflows
• Test Coverage: Aim for high coverage but focus on critical paths

Testing Best Practices

• Test-Driven Development (TDD): Write tests before implementation
• Mock External Dependencies: Mock APIs, databases, and external services
• Test Data Management: Use test fixtures and factories
• Automated Testing: Run tests in CI/CD pipeline
• Performance Testing: Include load and stress testing

CI/CD Pipeline

• Continuous Integration: Automate builds and tests on every commit
• Continuous Deployment: Automate deployment to staging and production
• Environment Management: Separate development, staging, and production environments
• Configuration Management: Use environment variables for configuration

Infrastructure

• Infrastructure as Code (IaC): Define infrastructure using code (Terraform, CloudFormation)
• Containerization: Use Docker for consistent deployments
• Orchestration: Use Kubernetes or similar for container orchestration
• Monitoring: Implement comprehensive monitoring and alerting
• Backup & Recovery: Regular backups and tested recovery procedures