Dotnet Framework 4.8 Expert

# .NET Framework 4.8 Expert - Code Examples & Patterns

This document contains real-world examples, use cases, and implementation patterns for .NET Framework 4.8 development.

## Example 1: Legacy ERP System Modernization

**Scenario:** A manufacturing company needs to add real-time inventory tracking to their 10-year-old ERP system built on .NET Framework 4.5.

**Approach:**
1. **Codebase Analysis**: Mapped dependencies and identified refactoring boundaries
2. **Feature Addition**: Implemented Web API 2 endpoints alongside existing WCF services
3. **Database Integration**: Used Entity Framework 6 with existing SQL Server
4. **Testing Strategy**: Created integration tests for new functionality

**Key Deliverables:**
- Real-time inventory API serving 1000 requests/minute
- Backward compatibility maintained for desktop clients
- Migration path documented for future .NET Core upgrade

### Implementation

```csharp
// Adding Web API 2 alongside existing WCF
// WebApiConfig.cs
public static class WebApiConfig
{
    public static void Register(HttpConfiguration config)
    {
        config.MapHttpAttributeRoutes();
        
        config.Routes.MapHttpRoute(
            name: "DefaultApi",
            routeTemplate: "api/{controller}/{id}",
            defaults: new { id = RouteParameter.Optional }
        );
        
        config.Formatters.JsonFormatter.SerializerSettings.ContractResolver = 
            new CamelCasePropertyNamesContractResolver();
    }
}

// InventoryController.cs
[RoutePrefix("api/inventory")]
public class InventoryController : ApiController
{
    private readonly IInventoryService _inventoryService;
    
    public InventoryController(IInventoryService inventoryService)
    {
        _inventoryService = inventoryService;
    }
    
    [HttpGet]
    [Route("")]
    public async Task<IHttpActionResult> GetAll()
    {
        var items = await _inventoryService.GetAllAsync();
        return Ok(items);
    }
    
    [HttpGet]
    [Route("{id:int}")]
    public async Task<IHttpActionResult> GetById(int id)
    {
        var item = await _inventoryService.GetByIdAsync(id);
        if (item == null)
            return NotFound();
        return Ok(item);
    }
    
    [HttpPost]
    [Route("")]
    public async Task<IHttpActionResult> Create(InventoryItem item)
    {
        if (!ModelState.IsValid)
            return BadRequest(ModelState);
            
        var created = await _inventoryService.CreateAsync(item);
        return CreatedAtRoute("DefaultApi", new { id = created.Id }, created);
    }
}
```

---

## Example 2: WCF to Modern Integration Bridge

**Scenario:** A healthcare provider needs to integrate a legacy WCF service with a modern cloud application.

**Solution Architecture:**
1. **WCF Service**: Enhanced existing SOAP service with additional endpoints
2. **REST API Layer**: Created OWIN-hosted Web API 2 for modern clients
3. **Authentication**: Implemented token-based auth bridging to existing Windows Auth
4. **Message Queue**: Added Azure Service Bus integration for async processing

**Results:**
- Modern clients can access legacy data through REST API
- Zero downtime during deployment
- HIPAA compliance maintained throughout

### Implementation

```csharp
// OWIN Startup for self-hosted Web API
public class Startup
{
    public void Configuration(IAppBuilder app)
    {
        var config = new HttpConfiguration();
        
        // Configure OAuth token validation
        app.UseJwtBearerAuthentication(new JwtBearerAuthenticationOptions
        {
            AuthenticationMode = AuthenticationMode.Active,
            TokenValidationParameters = new TokenValidationParameters
            {
                ValidAudience = ConfigurationManager.AppSettings["jwt:Audience"],
                ValidIssuer = ConfigurationManager.AppSettings["jwt:Issuer"],
                IssuerSigningKey = new SymmetricSecurityKey(
                    Encoding.UTF8.GetBytes(ConfigurationManager.AppSettings["jwt:Secr