Tutorials Design Patterns in C#
Middleware Pattern in ASP.NET Core — Complete Guide
Middleware Pattern in ASP.NET Core — Complete Guide: free step-by-step lesson with examples, common mistakes, and interview tips — part of Design Patterns in C# on Toolliyo Academy.
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Design Patterns in C# · Lesson 56 of 69
Middleware Pattern in ASP.NET Core
GoF Core ✓ → Enterprise ✓ → Cloud & Craft
Cloud & Craft · 3 — Microservices & interviews · ~10 min · Module 7: ASP.NET Core Architecture Patterns
What is this?
ASP.NET Core middleware is a chain of delegates that process HTTP requests/responses — logging, auth, correlation ids.
Why should you care?
ShopNest needs request ids and exception handling on every endpoint without repeating code.
See it live — copy this example
Paste into a C# console or class library project and run dotnet run.
// Program.cs style
// app.Use(async (ctx, next) => {
// ctx.Response.Headers["X-Request-Id"] = Guid.NewGuid().ToString("N");
// await next();
// });
Console.WriteLine("middleware: request-id -> auth -> endpoints");Run Example »
Edit the code below and click Run to see the result in Toolliyo’s live editor.
What happened?
- Order matters.
- Short-circuit when needed.
- Prefer built-in middleware when it fits; write custom for ShopNest-specific cross-cutting.
Practice next
- Add request-id middleware.
- Place exception handler early.
- Keep business rules out of middleware.
- Log elapsed ms per request.
- Reject missing API version header.
Remember
HTTP pipeline chain. Order is critical. Cross-cutting only.
ShopNest request-id middleware
Every response carries X-Request-Id.
Outcome: Support correlates logs instantly.
Interview prep for this lesson
Practice these questions aloud after reading—each links to a full structured answer.
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