Revux Real Estate Platform

Project Overview

Revux is a comprehensive real estate marketplace platform that connects real estate agents with contractors for property services like photography, staging, maintenance, and more. This ambitious project showcases advanced software architecture patterns and full-stack development capabilities across mobile and web platforms.

As the sole developer and system architect, I designed and implemented both the backend API and mobile application, demonstrating expertise in enterprise-level patterns, scalable architecture design, and modern development practices.

The Challenge

Business Problem

Real estate agents often struggle to find reliable contractors for property services, while contractors lack a centralized platform to showcase their services to agents. The existing solutions were fragmented, with poor user experience and limited functionality.

Technical Requirements

• Multi-role authentication (Agents, Contractors, Admins)
• Real-time messaging between users
• Location-based services with mapping integration
• Payment processing for service transactions
• Media management for photos and documents
• Scalable architecture to handle growth
• Cross-platform deployment (mobile and web)

Architecture Challenges

• Complex business domain with multiple bounded contexts
• Need for high scalability and maintainability
• Integration with multiple external services (Firebase, Stripe, Google Maps)
• Real-time features and event-driven communication
• Multi-platform code sharing and consistency

The Solution

Dual Architecture Strategy

I implemented a sophisticated dual architecture pattern to demonstrate both traditional and modern approaches:

Legacy MVC Architecture (v1)

• Traditional Model-View-Controller pattern
• Feature-based organization in src/modules/*/
• Direct Firebase Firestore access
• RESTful endpoints at /agencies, /contractors, /orders

Modern DDD/CQRS Architecture (v2)

• Domain-Driven Design with Command Query Responsibility Segregation
• Located in src/modules/*/domain/, */application/, */infrastructure/
• Event-sourcing ready with EventBus and EventStore
• Versioned endpoints at /v2/agencies, /v2/contractors

Backend Implementation

Core Technologies

• Node.js 22 with TypeScript 5.7.3
• Express.js 4.21.2 for REST API
• Firebase Firestore for NoSQL database
• Firebase Authentication for user management
• AWS S3 for media storage
• Docker for containerization

Key Architectural Patterns

Domain-Driven Design:

export class Order extends AggregateRoot<OrderId> {
  private validateOrder(): void {
    if (this._total < 0) throw new Error("Order total cannot be negative");
    if (this._packageIds.length === 0 && this._serviceIds.length === 0) {
      throw new Error("Order must have at least one package or service");
    }
  }
}

CQRS Implementation:

• Commands for write operations (CreateOrder, ConfirmOrder)
• Queries for read operations (GetOrder, SearchOrders)
• Separate command and query handlers
• Event-driven communication between aggregates

Repository Pattern:

abstract class IServiceRepository {
  Future<Result<List<Service>>> fetchServices();
}

class ServiceRepositoryImpl implements IServiceRepository {
  final ServiceRemoteDatasource datasource;
  // Clean abstraction over data access
}

Advanced Features

Flexible Search Architecture:

• Enterprise-grade search with multiple filter support
• Array field filtering (e.g., serviceIds[])
• Dynamic Firestore query building
• Pagination and sorting capabilities

Conditional Entity Inclusion:

// GET /contractors/123?includeUser=true&includePortfolio=true
const includeUser = shouldInclude(req.query, "User");
const includePortfolio = shouldInclude(req.query, "Portfolio");

Comprehensive Error Handling:

• Custom exception hierarchy
• Consistent error responses
• HTTP status code mapping
• Structured logging with sensitive data redaction

Frontend Implementation

Flutter Architecture

I implemented Clean Architecture with feature-first organization:

lib/features/<feature>/
├── domain/          # Business logic & entities
├── data/            # Data layer with repositories
├── presentation/    # UI layer with BLoC
└── service_injection.dart  # Dependency injection

State Management

• BLoC Pattern with flutter_bloc for predictable state management
• Result Monad for type-safe error handling
• Event-driven architecture for cross-feature communication

Error Handling with Result Pattern:

abstract class AppError {
  String get backendMessage;  // User-facing message
  String get frontendLog;     // Developer debugging
  String get errorCode;       // Programmatic handling
}

// Usage
final result = await repository.fetchServices();
if (result.isSuccess) {
  emit(ServiceLoaded(result.data!));
} else {
  emit(ServiceError(result.error!.backendMessage));
}

Key Features Implemented

Multi-Role Authentication:

• Firebase Authentication integration
• JWT token management with auto-refresh
• Role-based access control
• Session persistence across app restarts

Widget-Driven Development:

• Widgetbook integration for component catalog
• Isolated widget development and testing
• Living component documentation
• Design-dev collaboration workflow

Comprehensive Logging:

class LoggerService {
  static void trace(String message, [dynamic error, StackTrace?]) { ... }
  static void info(String message, [dynamic error, StackTrace?]) { ... }
  static void error(String message, [dynamic error, StackTrace?]) { ... }
}

Technical Implementation Details

Database Design

Firebase Firestore Structure:

• Users Collection - Multi-role user management
• Services Collection - Service catalog with categories
• Orders Collection - Transaction management
• Messages Collection - Real-time communication
• Reviews Collection - Rating and feedback system

Security Rules:

// Firestore Security Rules
rules_version = '2';
service cloud.firestore {
  match /databases/{database}/documents {
    match /users/{userId} {
      allow read, write: if request.auth != null && request.auth.uid == userId;
    }
    match /orders/{orderId} {
      allow read, write: if request.auth != null &&
        (resource.data.agentId == request.auth.uid ||
         resource.data.contractorId == request.auth.uid);
    }
  }
}

API Design

RESTful Endpoints:

• /v2/agencies - Real estate agency management
• /v2/contractors - Contractor profiles and services
• /v2/orders - Order processing and tracking
• /v2/services - Service catalog management
• /v2/messages - Real-time messaging system

Response Format:

// Consistent API responses
interface ApiResponse<T> {
  success: boolean;
  data?: T;
  error?: {
    message: string;
    code: string;
    details?: any;
  };
  pagination?: {
    limit: number;
    offset: number;
    total: number;
  };
}

Security Implementation

Authentication & Authorization:

• Firebase ID token validation
• Role-based access control (RBAC)
• JWT token refresh mechanism
• Secure token storage with flutter_secure_storage

Data Protection:

• Sensitive data redaction in logs
• Input validation with class-validator
• SQL injection prevention (NoSQL)
• CORS configuration and security headers

Performance Optimizations

Backend:

• Connection pooling for database access
• Request/response caching strategy
• Pagination on all list endpoints
• Conditional data loading (includes)

Frontend:

• Lazy loading for images and components
• BLoC state management for efficient rebuilds
• Optimized Firebase queries
• Memory management and disposal patterns

Current Status & Progress

Development Progress (75% Complete)

Completed Features:

• ✅ Core authentication system with multi-role support
• ✅ Service catalog and contractor management
• ✅ Order processing and tracking system
• ✅ Real-time messaging infrastructure
• ✅ Payment integration with Stripe
• ✅ Media upload and management
• ✅ Location services with Google Maps
• ✅ Review and rating system

In Progress:

• 🔄 Backend API optimization and performance tuning
• 🔄 Mobile app UI/UX refinements and testing
• 🔄 Payment integration testing and security audit
• 🔄 Production deployment and monitoring setup

Planned:

• 📋 Advanced analytics and reporting
• 📋 Push notification system
• 📋 Advanced search and filtering
• 📋 Multi-language support
• 📋 Admin dashboard enhancements

Production Deployment

Infrastructure:

• Production API: https://api.revux.io/
• Docker containerization for consistent deployment
• Firebase hosting for web components
• AWS S3 for media storage
• CI/CD pipeline with GitHub Actions

Monitoring & Logging:

• Winston logger with file persistence
• Health check endpoints
• Error tracking and alerting
• Performance monitoring setup

Key Achievements

Architecture Excellence

• Sophisticated dual architecture - Gradual migration from MVC to DDD/CQRS
• Clean Architecture implementation - Clear separation of concerns
• Event-driven design - Loose coupling and extensibility
• Repository pattern - Clean abstraction over data access

Technical Innovation

• Result monad error handling - Type-safe error management
• Widget-driven development - Component-first approach with Widgetbook
• Centralized dependency injection - Feature registry pattern
• Flexible JSON parsing - Handles backend inconsistencies gracefully

Scalability & Maintainability

• 30+ feature modules - Proven scalability in complexity
• Feature-first organization - Independent development capability
• Consistent patterns - Every feature follows same structure
• Comprehensive documentation - 25+ documentation files

Lessons Learned

Technical Insights

DDD/CQRS Benefits:

• Excellent for complex domains with clear business logic
• Independent read/write optimization capabilities
• Microservices-ready architecture
• Improved testability and maintainability

Challenges:

• Significant complexity overhead for simple operations
• Steeper learning curve for team members
• More code required for basic CRUD operations
• May be over-engineering for MVP stages

Firebase Trade-offs:

• ✅ Managed service with automatic scaling
• ✅ Real-time capabilities and global CDN
• ❌ NoSQL limitations for complex queries
• ❌ Vendor lock-in and cost scaling concerns

Development Process

Widget-Driven Development:

• Rapid UI prototyping and iteration
• Better design-dev collaboration
• Living component documentation
• Easier visual regression testing

Feature-First Organization:

• Scales well to large teams
• Clear ownership boundaries
• Independent deployment capability
• Easier onboarding for new developers

Architecture Decisions

Dual Architecture Strategy:

• Allows gradual migration without breaking changes
• Demonstrates both traditional and modern patterns
• Provides fallback options during transition
• Creates complexity that needs careful management

Future Enhancements

Short-term (Next 3 months)

• Complete backend optimization and performance tuning
• Implement comprehensive test coverage
• Add production monitoring and alerting
• Security audit and hardening

Medium-term (3-6 months)

• Advanced analytics and reporting dashboard
• Push notification system implementation
• Multi-language support (i18n)
• Advanced search with AI-powered recommendations

Long-term (6+ months)

• Microservices extraction planning
• Machine learning integration for matching
• Multi-region deployment
• Advanced business intelligence features

Technology Stack Summary

Backend Technologies

• Runtime: Node.js 22 (Alpine)
• Language: TypeScript 5.7.3
• Framework: Express.js 4.21.2
• Database: Firebase Firestore
• Authentication: Firebase Auth + JWT
• Storage: AWS S3 SDK
• Containerization: Docker
• Logging: Winston 3.17.0

Frontend Technologies

• Framework: Flutter SDK ^3.7.2
• State Management: flutter_bloc ^9.1.0
• Dependency Injection: get_it ^8.0.3
• Networking: dio ^5.4.0
• Routing: go_router ^14.6.2
• Firebase: firebase_auth, firebase_core, firebase_storage
• Payments: flutter_stripe ^11.4.0
• Maps: google_maps_flutter ^2.12.1

Development Tools

• Testing: Vitest 3.2.3, mocktail ^1.0.4
• Documentation: TypeDoc 0.28.5, Widgetbook ^3.9.0
• CI/CD: GitHub Actions
• Code Quality: ESLint, Prettier
• Version Control: Git with conventional commits

Conclusion

Revux represents a comprehensive demonstration of modern full-stack development practices, showcasing advanced architectural patterns, enterprise-level code organization, and production-ready implementation strategies. The project successfully handles complex business domains while maintaining clean separation of concerns and scalable design principles.

The dual architecture approach demonstrates both traditional MVC patterns and modern DDD/CQRS implementation, providing valuable insights into architectural evolution and migration strategies. The Flutter frontend showcases Clean Architecture principles with sophisticated state management and error handling patterns.

This project serves as an excellent example of how to build scalable, maintainable applications that can grow from MVP to enterprise-scale while maintaining code quality and developer productivity. The comprehensive documentation, consistent patterns, and production deployment demonstrate professional development practices and architectural maturity.

Note: This project is currently in active development with 75% completion. The case study will be updated as additional features are implemented and deployed to production.