Net Workshop — Advanced C# Patterns and Best Practices

Net Workshop: Mastering Modern .NET DevelopmentModern software development demands tools and frameworks that are productive, performant, and adaptable. .NET has evolved into a versatile, cross-platform ecosystem that meets those needs—from cloud services and microservices to desktop apps, mobile, and web. This article is a comprehensive workshop-style guide to mastering modern .NET development: its core principles, tooling, architecture patterns, practical workflows, and a series of hands-on exercises to build real-world apps.

Why .NET today?

.NET is cross-platform, high-performance, and production-proven. It runs on Windows, Linux, and macOS, supports languages such as C#, F#, and VB.NET, and powers applications ranging from Azure cloud services to Unity games. Key reasons to choose .NET:

Productivity: expressive language features (e.g., async/await, pattern matching), powerful IDEs (Visual Studio, Visual Studio Code).
Performance: .NET ⁄₈+ runtime improvements, ahead-of-time compilation, and Tiered Compilation.
Ecosystem: extensive libraries, NuGet packages, and first-class Azure integration.
Versatility: support for web (ASP.NET Core), desktop (WinForms/WPF/.NET MAUI), mobile (MAUI), cloud, gaming (Unity), and ML (.NET ML).

Core Concepts and Architecture

The runtime and framework

The .NET runtime (CLR/CoreCLR/Mono) executes managed code, provides GC, JIT/AOT compilation, and runtime services.
The Base Class Library (BCL) includes core primitives, collections, I/O, networking, and more.
.NET versions: .NET Core → .NET 5 → .NET 6 (LTS) → .NET 7 → .NET 8 (LTS). Prefer LTS for production stability.

Language choices

C# — the primary language for most .NET development; modern, object-oriented, with functional features.
F# — functional-first language, excellent for data processing and domain modeling.
VB.NET — legacy but still supported for certain enterprise scenarios.

Project types

ASP.NET Core — high-performance web apps and APIs.
.NET MAUI — cross-platform UI for mobile/desktop.
Console apps — for scripts, tools, and background services.
Class libraries — reusable components distributed via NuGet.
Blazor — C# in the browser via WebAssembly or server-rendered components.

Tooling and Developer Experience

IDEs and editors

Visual Studio (Windows/macOS) — full-featured IDE with designers, debugging, profiling, and Azure tools.
Visual Studio Code — lightweight, cross-platform, ideal with C# extension (OmniSharp) and debugger.
JetBrains Rider — powerful cross-platform IDE with deep refactoring and performance.

Build & package tools

dotnet CLI: new, build, run, test, pack, publish — the central command-line interface.
MSBuild: project build engine used under the hood.
NuGet: package manager for libraries and SDKs.

Debugging & profiling

Visual Studio remote debugging, memory and performance profilers.
dotnet-trace, dotnet-counters, dotnet-dump for cross-platform diagnostics.

Modern ASP.NET Core: Building Web APIs and Web Apps

Minimal APIs vs MVC vs Razor Pages vs Blazor

Minimal APIs: lightweight, fast, great for microservices and simple endpoints.
MVC: full-featured pattern for complex web apps with controllers and views.
Razor Pages: page-focused, simpler than MVC for page-based web apps.
Blazor: component-based UI using C# for client-side (WebAssembly) or server-side interactivity.

Designing APIs

Use RESTful principles or gRPC for high-performance binary RPC.
Version your APIs and use OpenAPI/Swagger for documentation.
Secure endpoints with JWTs, OAuth2, or cookie-based auth. Consider ASP.NET Core Identity for built-in identity management.

Performance best practices

Use response caching, compressed payloads, and optimized JSON (System.Text.Json).
Keep endpoints minimal and leverage asynchronous I/O.
Use connection pooling for databases, and connection resiliency (retries, backoff).

Dependency Injection, Testing, and Maintainability

Dependency Injection (DI)

Built-in DI container in ASP.NET Core. Register services with scoped, singleton, transient lifetimes.
Prefer constructor injection and program against interfaces.

Testing

Unit tests: xUnit, NUnit, or MSTest for isolated logic tests.
Integration tests: TestServer for end-to-end API testing without network.
Contract tests and consumer-driven testing for services that interact with external APIs.

SOLID & Clean Architecture

Separate concerns: UI, application logic, domain, and infrastructure.
Use ports-and-adapters (hexagonal) or Onion architecture for testability and adaptability.

Data Access and Persistence

Entity Framework Core (EF Core)

Lightweight, cross-platform ORM with LINQ support.
Use migrations for schema evolution and DbContext pooling for performance.
For complex queries or maximum performance, use raw SQL or Dapper.

NoSQL and distributed storage

Use Redis for caching and Pub/Sub patterns.
Cosmos DB, MongoDB for document-style storage when relational schema isn’t a fit.

Transactions and concurrency

Use database transactions for atomic operations; optimistic concurrency via rowversion/timestamps.
Implement idempotency for APIs that may be retried.

Cloud, CI/CD, and Deployment

Cloud-native patterns

Containerize with Docker; use Dockerfiles and multi-stage builds.
Use Kubernetes for orchestration or platform services like Azure App Services, Azure Functions for serverless.

CI/CD pipelines

GitHub Actions, Azure DevOps, or GitLab CI for automated builds, tests, and deployments.
Include static analysis, security scanning, and automated tests in pipelines.

Observability

Structured logging with Serilog, Seq, or ELK stack.
Distributed tracing with OpenTelemetry and correlate traces across services.
Metrics via Prometheus and dashboards in Grafana.

Security and Compliance

Use secure defaults: HTTPS, HSTS, content security policy.
Protect secrets with Azure Key Vault or similar secret stores; avoid hardcoding credentials.
Keep dependencies up-to-date; use tools for vulnerability scanning (Dependabot, Snyk).
Implement proper authentication/authorization boundaries; use claims-based auth for flexibility.

Hands-on Workshop: Build a Small Service (Walkthrough)

Project goal: Create a small task management API with ASP.NET Core, EF Core, and Docker.

Setup
- dotnet new webapi -n TaskApi
- dotnet new sln; dotnet sln add TaskApi/TaskApi.csproj
Model & DbContext
- Create TaskItem model with Id, Title, Description, IsComplete, CreatedAt.
- Configure ApplicationDbContext with DbSet and add SQLite/SQL Server provider.
Repository & Services
- Add ITaskRepository, TaskRepository; register in DI as scoped.
- Implement basic CRUD and paging/filtering.
Controllers / Minimal API
- Use minimal APIs or Controllers with endpoints for Get, Post, Put, Delete.
- Add validation (DataAnnotations or FluentValidation).
Migrations & Local DB
- dotnet ef migrations add InitialCreate
- dotnet ef database update
Tests
- Add xUnit project; write unit tests for service logic and integration tests using WebApplicationFactory.
Dockerize
- Create Dockerfile with multi-stage build and publish; build/push image; run container.
CI/CD
- Add GitHub Actions workflow: build, test, scan, build image, push to registry, deploy to Azure App Service or AKS.

Advanced Topics

Microservices and Event-Driven Architectures

Use lightweight services with well-defined contracts.
Prefer asynchronous messaging via RabbitMQ, Kafka, or Azure Service Bus.
Keep services independently deployable and version APIs carefully.

gRPC and high-performance comms

gRPC works well for inter-service comms in .NET with C# codegen and HTTP/2 benefits.
Use protobuf contracts and support streaming for real-time use cases.

AOT, Native, and Trimming

Ahead-of-time compilation and trimming reduce startup time and binary size for certain workloads (Blazor, MAUI).

Sample Code Snippet: Minimal API (Task endpoint)

// Program.cs (minimal) var builder = WebApplication.CreateBuilder(args); builder.Services.AddDbContext<AppDbContext>(opt => opt.UseSqlite("Data Source=tasks.db")); builder.Services.AddScoped<ITaskRepository, TaskRepository>(); builder.Services.AddEndpointsApiExplorer(); builder.Services.AddSwaggerGen(); var app = builder.Build(); app.UseSwagger(); app.UseSwaggerUI(); app.MapGet("/tasks", async (ITaskRepository repo) => await repo.ListAsync()); app.MapGet("/tasks/{id}", async (ITaskRepository repo, int id) => await repo.GetAsync(id) is var t && t != null ? Results.Ok(t) : Results.NotFound()); app.MapPost("/tasks", async (ITaskRepository repo, TaskItemDto dto) => {     var task = new TaskItem { Title = dto.Title, Description = dto.Description, CreatedAt = DateTime.UtcNow };     await repo.AddAsync(task);     return Results.Created($"/tasks/{task.Id}", task); }); app.Run();

Learning Path and Resources

Start with C# fundamentals, async programming, and LINQ.
Build small web APIs using ASP.NET Core minimal APIs.
Learn EF Core and database migrations.
Practice Dockerizing apps and deploy to cloud.
Study architecture patterns (Clean Architecture, DDD) and apply in mid-size projects.
Follow change logs for .NET releases and use LTS versions for production.

Conclusion

Mastering modern .NET development means combining language fluency, sound architecture, robust tooling, and cloud-native practices. Build incrementally: small focused projects, consistent testing, and automation in CI/CD. With .NET’s growing ecosystem and Microsoft’s investments, the platform is a strong choice for scalable, maintainable applications across domains.