Abdullah Hakim Mousa

Role: .NET Backend Developer & System Architect | Team Project 
Technologies: C#, .NET, ASP.NET Core Web API, Entity Framework Core, SQL Server, JWT Authentication, Clean Architecture, Repository Pattern 

System Architecture: Designed complete system architecture including Use Case Diagrams, Class Diagrams, Sequence Diagrams, ER Diagrams, Data Flow Diagrams (DFD), and System Architecture diagrams 

Authentication Service: Architected and built a complete Auth Service implementing JWT-based authentication, role-based authorization (RBAC), secure password hashing, and token refresh mechanisms 

Exam Service: Developed core Examination Service handling exam creation, scheduling, student enrollment, automated grading logic, result generation, and grade reporting 

Admin Service: Implemented Administration Service for user management, role assignments, permission management, system configuration, and comprehensive audit logging 

Database Design: Designed normalized relational database schemas with proper indexing, foreign key constraints, relationships, and performance optimization 

API Design: Built RESTful APIs following REST conventions with proper HTTP status codes, pagination, filtering, searching, and versioning 

Role: .NET Developer
Technologies: .NET 8, ASP.NET Core Web API, Clean Architecture, DDD, ConcurrentDictionary, ConcurrentQueue, IHttpClientFactory, xUnit, Moq, FluentAssertions, Swashbuckle, Rate Limiting 

Built a high-performance, stateless API for managing country-based IP blocking using thread-safe in-memory storage (no database dependency per requirements) 

Implemented Clean Architecture with strict separation: Domain → Infrastructure → API layers 

Designed strongly-typed Value Objects (e.g., CountryCode with ISO Alpha-2 validation) to eliminate primitive obsession and enforce domain rules at compile time 

Integrated IPGeolocation.io API for real-time IP-to-country lookups using resilient HTTP client patterns, connection pooling via IHttpClientFactory, and circuit breaker concepts 

Implemented the Result Pattern across all layers to eliminate exception-throwing for control flow, producing consistent, typed HTTP responses 

Built thread-safe repositories using ConcurrentDictionary and ConcurrentQueue enabling concurrent read/write operations without manual locking mechanisms 

Implemented rate limiting (100 requests/minute) to protect third-party API quotas (1,000 requests/day free tier) 

Developed comprehensive unit test suite with xUnit, Moq, and FluentAssertions covering core business logic, thread-safe dictionary behavior, domain value object validation, and edge cases 

Role: Backend Developer | Self-Directed Learning Project 
Technologies: .NET 10, ASP.NET Core Web API, EF Core, SQL Server, Clean Architecture, DDD, FluentValidation, AutoMapper, xUnit, Moq 

Built a production-grade e-commerce Web API demonstrating enterprise-level patterns and advanced EF Core features for high-performance data access 

Implemented Domain-Driven Design (DDD) with Aggregate Roots (Order), Value Objects (Address), Entities with encapsulated behavior, and domain events 

Designed strict layered architecture: Domain → Application → Infrastructure → API with dependency inversion and interface-based contracts 

Implemented automated auditing via custom EF Core SaveChangesInterceptor for automatic CreatedAt/UpdatedAt timestamps across all entities 

Built soft deletion mechanism using Global Query Filters and optimistic concurrency control using RowVersion tokens to prevent lost updates 

Optimized data access performance using .AsNoTracking(), explicit Select() projections (reducing payload by ~65%), and AsSplitQuery() for complex multi-collection loads 

Mastered advanced EF Core patterns: Compiled Queries (EF.CompileAsyncQuery), Bulk Operations (ExecuteUpdateAsync / ExecuteDeleteAsync), Explicit Transactions with Savepoints (CreateSavepointAsync, RollbackToSavepointAsync) 

Added FluentValidation for automatic request validation pipeline and Global Exception Handling Middleware for consistent, structured error responses 

Applied Result<T> to replace exceptions with structured success/failure states, enabling clean controller logic (reduced from ~150 lines to ~15 lines) 

Completed 10 structured learning tasks with score progression from 3.7 → 10.0, mastering query optimization, transaction management, and architectural patterns

Developed a full-stack personal blog platform with a production-ready backend using clean architecture and CQRS patterns. Engineered scalable microservices infrastructure with JWT authentication, database migrations, caching, and background job processing.

Backend Architecture & Development

• Designed and implemented clean architecture solution with CQRS pattern using MediatR for command/query separation

• Built ASP.NET Core RESTful API with Entity Framework Core (EF Core) and PostgreSQL, including automated database migrations

• Implemented JWT-based authentication and role-based authorization with admin policies and secure bearer token validation

• Developed comprehensive validation pipeline using FluentValidation with MediatR behavior pipeline

• Created service layers with dependency injection for storage (Azure Blob/local disk abstraction), email (MailKit), caching (Redis), and custom business logic

• Built background services for asynchronous operations: analytics data processing and email reply tracking

• Implemented multi-language support with CultureMiddleware for dynamic Arabic/English localization per request

• Configured Swagger/OpenAPI documentation for all API endpoints with development environment support

Infrastructure & DevOps

• Containerized backend with optimized multi-stage Dockerfile for production deployments

• Orchestrated development and production environments using docker-compose with PostgreSQL and Redis services

• Implemented distributed caching strategy using Redis for performance optimization

• Developed deployment automation scripts (PowerShell/Bash) for cross-platform CI/CD workflows

• Configured Nginx reverse proxy and rate limiting for production traffic management

• Managed database versioning through EF Core migrations with proper schema seeding