read asp .net core source code from here

[JHinW]

https://github.com/aspnet/HttpAbstractions/blob/dev/src/Microsoft.AspNetCore.Http/Internal/ApplicationBuilder.cs

[JHinW]

asp .net core run middleWare in functional way, see this.

use lamda to show above logic: context => action(context).

we still need a next delegate to call, so lamda should look like this: next => {action(context); next.invoke();}

        private static IApplicationBuilder UseMiddlewareInterface(IApplicationBuilder app, Type middlewareType)
        {
            return app.Use(next /*this is next delegate*/=>
            {
                return async context =>
                {         
                    try
                    {
                        await middleware.InvokeAsync(context, next);
                    }
                };
            });
        }

[JHinW]

read code snippet

// this method will compose all middlewares which will make all delegate run in a single method.

        public RequestDelegate Build()
        {
            RequestDelegate app = context =>
            {
                context.Response.StatusCode = 404;
                return Task.CompletedTask;
            };

            foreach (var component in _components.Reverse())
            {
                app = component(app);
            }

            return app;
        }

[JHinW]

read code snippet

how [Ctrl+C] works when web console app is running

[JHinW]

ManualResetEventSlim

public static async Task RunAsync(this IWebHost host, CancellationToken token = default(CancellationToken))
        {
            // Wait for token shutdown if it can be canceled
            if (token.CanBeCanceled)
            {
                await host.RunAsync(token, shutdownMessage: null);
                return;
            }

            // If token cannot be canceled, attach Ctrl+C and SIGTERM shutdown

            // add by me:
            // ManualResetEventSlim only be setted when host.RunAsync is called
            var done = new ManualResetEventSlim(false);
            using (var cts = new CancellationTokenSource())
            {
                AttachCtrlcSigtermShutdown(cts, done, shutdownMessage: "Application is shutting down...");

                await host.RunAsync(cts.Token, "Application started. Press Ctrl+C to shut down.");
                done.Set();
            }
        }

[JHinW]

when you need to debug above open source

{
    // See https://go.microsoft.com/fwlink/?LinkId=733558
    // for the documentation about the tasks.json format
    "version": "0.1.0",
    "command": "dotnet",
    "isShellCommand": true,
    "args": [],
    "tasks": [
        {
            "taskName": "build",
            "args": [ 
               "./samples/SampleStartups/SampleStartups.csproj"
            ],
            "isBuildCommand": true,
            "showOutput": "silent",
            "problemMatcher": "$msCompile"
        }
    ]
}

{
    "version": "0.2.0",
    "configurations": [

        {
            "name": ".NET Core Launch (web)",
            "type": "coreclr",
            "request": "launch",
            "preLaunchTask": "build",
            "program": "${workspaceRoot}/samples/SampleStartups/bin/Debug/netcoreapp2.0/SampleStartups.dll",
            "args": [],
            "cwd": "${workspaceRoot}",
            "stopAtEntry": false,
            "launchBrowser": {
                "enabled": true,
                "args": "${auto-detect-url}",
                "windows": {
                    "command": "cmd.exe",
                    "args": "/C start ${auto-detect-url}"
                },
                "osx": {
                    "command": "open"
                },
                "linux": {
                    "command": "xdg-open"
                }
            },
            "env": {
                "ASPNETCORE_ENVIRONMENT": "Development"
            },
            "sourceFileMap": {
                "/Views": "${workspaceRoot}/Views"
            }
        },
        {
            "name": ".NET Core Attach",
            "type": "coreclr",
            "request": "attach",
            "processId": "${command:pickProcess}"
        }
    ]
}