dotnet-legacy-analysis

name	dotnet-legacy-analysis
description	Analyzes legacy .NET Framework applications (WinForms, WebForms, MVC, WCF) for migration readiness. Use when analyzing C# code structure, identifying framework-specific patterns, extracting business logic, or understanding legacy .NET architectures.

Purpose

Provide specialized knowledge for analyzing legacy .NET Framework applications across all UI technologies (WinForms, WebForms, MVC, WCF) to support migration planning and business logic extraction.

Application Type Detection

Identify the application type by looking for these markers:

Type	Key Indicators
WinForms	InitializeComponent(), *.Designer.cs, System.Windows.Forms, Form base class
WebForms	*.aspx, *.aspx.cs, Page_Load, System.Web.UI, ViewState, IsPostBack
MVC	Controller base class, *.cshtml, RouteConfig, ActionResult, [HttpGet]
WCF	[ServiceContract], [OperationContract], *.svc, ServiceHost, BasicHttpBinding
Web API	ApiController, [Route], IHttpActionResult, WebApiConfig
Console/Service	static void Main, ServiceBase, no UI references

WinForms Analysis Patterns

Event Handler Mapping

Button click → btnSave_Click() → Validate() → SaveToDatabase() → SP call
Form load → Form_Load() → LoadDropdowns() → BindGrids()
Grid selection → dgv_SelectionChanged() → LoadDetails() → UpdateUI()

Data Binding Discovery

• Check Designer.cs for DataBindings.Add() calls
• Look for BindingSource components and their DataSource assignments
• Identify DataGridView column mappings and their bound properties
• Check for DataSet/DataTable typed datasets (*.xsd files)

Form Navigation

• Search for new FormName().Show() or .ShowDialog() patterns
• Map MDI parent/child relationships
• Track DialogResult handling for modal flows

WebForms Analysis Patterns

Page Lifecycle

Page_Init → Page_Load → Control events → Page_PreRender → Render

Key Patterns to Extract

• Page_Load with !IsPostBack — initialization vs postback logic
• GridView/Repeater data binding in OnRowDataBound
• ViewState usage for state management
• User controls (*.ascx) reuse across pages
• Session object usage for cross-page state
• Response.Redirect / Server.Transfer for navigation

MVC Analysis Patterns

Controller → Action → View Flow

• Map each controller's actions to their views
• Identify [Authorize] attributes for role-based access
• Check ModelState.IsValid patterns for validation
• Look for TempData/ViewBag/ViewData usage
• Identify ActionFilter attributes for cross-cutting concerns

WCF Analysis Patterns

Service Contract Discovery

• Map [ServiceContract] interfaces to implementations
• Document [OperationContract] signatures with parameters/returns
• Check [DataContract] / [DataMember] for DTO shapes
• Analyze web.config / app.config for bindings, endpoints, behaviors
• Identify [FaultContract] for error handling patterns

Common .NET Framework Patterns

Configuration Extraction

• web.config → appSettings, connectionStrings, system.web
• app.config → same structure for desktop apps
• Custom configuration sections
• ConfigurationManager.AppSettings["key"] references in code

Data Access Identification

• ADO.NET: SqlConnection, SqlCommand, SqlDataReader, DataAdapter
• Entity Framework 6: DbContext, DbSet<T>, LINQ queries
• Typed DataSets: *.xsd files, TableAdapter, Fill() methods
• Stored procedure calls: CommandType.StoredProcedure, @parameter patterns

Authentication Detection

• Windows Authentication: WindowsIdentity, Thread.CurrentPrincipal
• Forms Authentication: FormsAuthentication.SetAuthCookie, [Authorize]
• Custom auth: role checks, token validation patterns