dotnet-framework-4.8-expert

SKILL.md

.NET Framework 4.8 Expert

Purpose

Provides legacy .NET Framework development expertise specializing in WCF services, ASP.NET MVC, and enterprise application maintenance. Supports extending and integrating legacy .NET 4.8 applications with modern patterns while managing technical debt and migration strategies.

When to Use

Maintaining or extending .NET Framework 4.8 applications

Developing WCF services for enterprise integrations

Working with ASP.NET MVC 5 web applications

Managing Entity Framework 6 database access

Integrating legacy COM components

Planning migration strategies to modern .NET

Quick Start
Invoke When

Maintaining .NET Framework 4.x applications

Building or extending WCF SOAP/REST services

ASP.NET MVC 5 development

Entity Framework 6 database operations

Windows Service development

COM interop requirements

Don't Invoke When

New projects (use .NET 8+ with dotnet-core-expert)

Modern web APIs (use ASP.NET Core)

Cross-platform needs (use .NET 8)

Containerized deployments (prefer .NET 8)

Core Competencies

.NET Framework 4.8 Features

.NET Framework 4.8 security and compatibility features

Windows Forms and WPF application development

Entity Framework 6 for database access

Windows Communication Foundation (WCF) services

ASP.NET MVC 5 web application development

Windows Services and background processing

WCF Services Architecture

Service contracts and data contracts

Binding configurations (WSHttpBinding, BasicHttpBinding)

Service hosting and deployment

Security configurations (Transport, Message, Mixed)

RESTful services with WebHttpBinding

Duplex communication patterns

ASP.NET MVC 5 Development

MVC pattern implementation

Razor view engine and HTML helpers

Model binding and validation

Authentication and authorization

Route configuration and attribute routing

Integration with JavaScript frameworks

Legacy System Integration

COM Interop for legacy component integration

Third-party library management

Database connectivity with ADO.NET

XML and SOAP web service consumption

Performance optimization for legacy code

Migration strategies to modern frameworks

Decision Framework

When to Modernize vs. Maintain

Evaluating legacy .NET Framework application?
│
├─ Is it actively developed (>1 feature/month)?
│  │
│  ├─ YES → Does it need cross-platform or containers?
│  │        │
│  │        ├─ YES → **Plan migration to .NET 8** ✓
│  │        │        (use Upgrade Assistant)
│  │        │
│  │        └─ NO → Business-critical?
│  │                 │
│  │                 ├─ YES → **Incremental modernization** ✓
│  │                 │        (strangler fig pattern)
│  │                 │
│  │                 └─ NO → **Maintain in place** ✓
│  │
│  └─ NO → End-of-life planned?
│           │
│           ├─ YES → **Minimal maintenance** ✓
│           │        (security patches only)
│           │
│           └─ NO → **Maintain in place** ✓
│                    (with documentation focus)

WCF vs. Modern Alternatives

Aspect
WCF
ASP.NET Web API 2
gRPC

Protocol
SOAP, REST
REST
HTTP/2

Best for
Enterprise SOAP
REST APIs
High-perf services

Interop
Excellent (.NET, Java)
Universal
Limited

Complexity
High
Medium
Medium

Maintenance
Legacy
Legacy
Modern

Entity Framework 6 vs. Alternatives

Aspect
EF6
Dapper
ADO.NET

Complexity
Low
Medium
High

Performance
Good
Excellent
Best

Flexibility
Good
Excellent
Full control

Best for
CRUD apps
Performance-critical
Complex queries

Best Practices

.NET Framework Development

Dependency Management: Use NuGet Package Manager, pin versions

Configuration: Use web.config/app.config transforms for environments

Logging: Implement comprehensive logging (log4net, Serilog)

Error Handling: Global exception handlers, proper error pages

Testing: MSTest or NUnit for unit tests, integration tests

WCF Services

Security: Use wsHttpBinding with message security

Binding Selection: Match bindings to requirements

Throttling: Configure throttling, instancing, concurrency

Error Handling: Use fault contracts, implement IErrorHandler

Testing: Use WCF Test Client or Postman

ASP.NET MVC

Controller Patterns: Use dependency injection, avoid business logic

View Models: Separate view models from domain models

Validation: Use data annotations and IValidatableObject

Security: Anti-forgery tokens, output encoding, authorization

Database Access (EF6)

Context Management: Context per request, repository pattern

Query Optimization: Use Include() for eager loading, avoid N+1

Migrations: Use Code First Migrations, version control

Performance: Compiled queries, caching strategies

Legacy Application Management

Technical Debt: Document and prioritize, address critical issues

Testing: Add unit tests around new features

Security: Keep .NET Framework patched

Documentation: Maintain architecture diagrams, data flows

Migration: Evaluate .NET Upgrade Assistant

Common Use Cases

Enterprise Legacy Applications

Maintaining existing line-of-business applications

Adding new features to established systems

Performance optimization of legacy code

Integration with modern services and APIs

Database migration and schema updates

WCF Service Applications

Enterprise service bus implementations

Integration with third-party systems

SOAP web service development

RESTful API creation with WCF

Service orchestration and choreography

Windows Desktop Applications

Line-of-business desktop applications

Database-driven client applications

Integration with Office automation

File processing and reporting tools

When to Use This Expert

Ideal Scenarios:

Maintaining existing .NET Framework 4.8 applications

Extending legacy enterprise systems

Integrating new features with existing WCF services

ASP.NET MVC application enhancement

Windows service development and maintenance

Alternative Solutions:

For new applications: Consider .NET Core/.NET 6+

For web APIs: Consider ASP.NET Core

For modern desktop apps: Consider WPF with .NET 6+ or MAUI

Additional Resources

Detailed Technical Reference: See REFERENCE.md

Code Examples & Patterns: See EXAMPLES.md