Tutorials ADO.NET Core Tutorial
Legacy System Modernization — Complete Guide
Legacy System Modernization — Complete Guide: free step-by-step lesson with examples, common mistakes, and interview tips — part of ADO.NET Core Tutorial on Toolliyo Academy.
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ADO.NET Core Tutorial · Lesson 69 of 100
Legacy System Modernization
Foundations ✓ → SQL & safety ✓ → Production → Projects
Production · 3 — ASP.NET & enterprise · ~10 min · Module 7: Advanced Enterprise Topics
What is this?
Modernize by wrapping legacy procs with ADO.NET adapters and strangling routes gradually.
Why should you care?
ShopNest cannot rewrite decades of usp_ overnight.
See it live — copy this example
Use a .NET console or API project with SQL Server LocalDB. Run dotnet run after pasting.
public sealed class LegacyPaymentAdapter : IPaymentClient
{
public Task CaptureAsync(...) =>
exec.ProcAsync("usp_Legacy_Capture", ...); // ADO.NET
}What happened?
- Adapter pattern + ADO.NET.
- Feature flags route new vs old.
- Characterization tests first.
Practice next
- Wrap one legacy proc.
- Interface for domain.
- Strangle one endpoint.
- Compare old/new outputs.
- Metric traffic % on new path.
Remember
Adapter over usp_. Incremental strangler. Tests first.
ShopNest payment strangler
New API calls legacy capture via ADO.NET.
Outcome: Risk stays low while migrating.
Interview prep for this lesson
Practice these questions aloud after reading—each links to a full structured answer.
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