标签：#aspdotnet

ASP.NET Core: Building High-Performance Web Applications and APIs A practical guide to ASP.NET Core — the cross-platform framework for building REST APIs, MVC applications, and backend services on .NET, covering architecture, minimal APIs, middleware, performance, and modern patterns. Table of Contents Introduction Architecture Overview Minimal APIs MVC and Controllers Middleware Pipeline Dependency Injection Configuration and Options Authentication and Authorization Performance Features Testing and Observability Quick Reference Table Conclusion Introduction ASP.NET Core is a free, open-source, cross-platform framework for building web apps, APIs, and backend services. It's a ground-up rewrite of the original ASP.NET, designed around three priorities: Performance — it's consistently one of the fastest mainstream web frameworks in independent benchmarks (e.g., TechEmpower). Modularity — you opt into only the middleware and services your app actually needs, instead of a fixed, heavyweight pipeline. Cross-platform — runs identically on Windows, Linux, and macOS, and deploys to containers, serverless, or bare metal. This guide covers the core building blocks you'll use in almost any ASP.NET Core project, from a five-line minimal API to a full MVC application with authentication and background services. 1. Architecture Overview Every ASP.NET Core app starts from a unified entry point — Program.cs — using the minimal hosting model introduced in .NET 6. var builder = WebApplication . CreateBuilder ( args ); // Register services (dependency injection container) builder . Services . AddControllers (); builder . Services . AddEndpointsApiExplorer (); builder . Services . AddSwaggerGen (); var app = builder . Build (); // Configure the HTTP request pipeline (middleware) if ( app . Environment . IsDevelopment ()) { app . UseSwagger (); app . UseSwaggerUI (); } app . UseHttpsRedirection (); app . UseAuthorization (); app . MapControllers (); app . Run (); Two phases matter here:

It is straightforward to configure a minimal API to produce an OpenAPI document at build time . This runs the API during build, requests the OpenAPI document from it, and saves it to disk. The slightly trickier part is to put checks in Program.cs to exclude any startup code that cannot run at build time. This is typically done because configuration key/value pairs are not available at that time. For example: if (! isBuildTime ) { connString = builder . Configuration . GetConnectionString ( "AppDB" ) ?? throw new InvalidOperationException ( "Connection string 'AppDB' is not configured." ); builder . Services . AddDbContext < AppDbContext >( options => { options . UseNpgsql ( connString ); } ); } The question is how to deduce that the API has been launched at build time, i.e. isBuildTime should be true? The official way of doing this is to check that the assembly that invoked the API is "GetDocument.Insider" : var isBuildTime = Assembly . GetEntryAssembly ()?. GetName (). Name == "GetDocument.Insider" ; GetDocument.Insider.dll is the command line tool that automatically runs during build of the API if the .csproj includes the following reference: <PackageReference Include= "Microsoft.Extensions.ApiDescription.Server" Version= "10.0.7" > ... </PackageReference> This package is a shim. It only provides build targets and props and hooks into the build of the API to run the command-line tool dotnet-getdocument . This tool in turn runs the command line tool GetDocument.Insider that we check for. This is a pretty convoluted sequence: Microsoft.Extensions.ApiDescription.Server provides targets that run during build of the API. One of those targets runs the command line tool dotnet-getdocument That in turn runs the command line tool GetDocument.Insider That in turn runs the API and fetches the /openapi/v1/json (or other configured endpoint) to get the OpenAPI document and saves it to disk. Checking in Program.cs if the API was invoked by the assembly GetDocument.Insider.dll t