OliverLeitner/AspNetCoreChatRoom.csproj

## _Layout.cshtml
<!DOCTYPE html>
<html>
<head>
    <meta charset="utf-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>@ViewData["Title"] - AspNetCoreChatRoom</title>
    <environment include="Development">
        <link rel="stylesheet" href="~/css/site.css" />
    </environment>
    <environment exclude="Development">
        <link rel="stylesheet" href="~/css/site.min.css" asp-append-version="true" />
    </environment>
</head>
<body>
    <div class="container body-content">
        @RenderBody()
    </div>
</body>
</html>

## AspNetCoreChatRoom.csproj
<Project Sdk="Microsoft.NET.Sdk.Web">

  <PropertyGroup>
    <TargetFramework>netcoreapp2.1</TargetFramework>
  </PropertyGroup>

  <ItemGroup>
    <PackageReference Include="Microsoft.AspNetCore.App" />
    <PackageReference Include="Microsoft.AspNetCore.WebSockets" Version="2.1.1" />
  </ItemGroup>

</Project>

## ChatWebSocketMiddleware.cs
using System;
using System.Collections.Concurrent;
using System.IO;
using System.Net.WebSockets;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Http;

namespace AspNetCoreChatRoom {
    public class ChatWebSocketMiddleware {
        private static ConcurrentDictionary<string, WebSocket> _sockets = new ConcurrentDictionary<string, WebSocket> ();

        private readonly RequestDelegate _next;

        public ChatWebSocketMiddleware (RequestDelegate next) {
            _next = next;
        }

        public async Task Invoke (HttpContext context) {
            if (!context.WebSockets.IsWebSocketRequest) {
                await _next.Invoke (context);
                return;
            }

            CancellationToken ct = context.RequestAborted;
            WebSocket currentSocket;
            //trying to build a connection
            try {
                currentSocket = await context.WebSockets.AcceptWebSocketAsync ();
            } catch (Exception ex) {
                Console.WriteLine(ex.Message);
                return;
            }
            var socketId = Guid.NewGuid ().ToString ();

            _sockets.TryAdd (socketId, currentSocket);

            while (true) {
                if (ct.IsCancellationRequested) {
                    break;
                }

                var response = await ReceiveStringAsync (currentSocket, ct);
                if (string.IsNullOrEmpty (response)) {
                    if (currentSocket.State != WebSocketState.Open) {
                        break;
                    }

                    continue;
                }

                foreach (var socket in _sockets) {
                    if (socket.Value.State != WebSocketState.Open) {
                        continue;
                    }

                    await SendStringAsync (socket.Value, response, ct, socketId);
                }
            }

            WebSocket dummy;
            _sockets.TryRemove (socketId, out dummy);

            //trying to normally close the connection
            try {
                await currentSocket.CloseAsync (WebSocketCloseStatus.NormalClosure, "Closing", ct);
                currentSocket.Dispose ();
            } catch (Exception ex) {
                //if anything goes wrong...
                //output error
                Console.WriteLine (ex.Message);
                currentSocket.Abort ();
            }
        }

        private static Task SendStringAsync (WebSocket socket, string data, CancellationToken ct = default (CancellationToken), string socketId = "deadbeef") {
            //append the socketid to the message for debugging purposes
            //couldve taken it globally, this is just a poc
            var buffer = Encoding.UTF8.GetBytes (data + ' ' + socketId);
            var segment = new ArraySegment<byte> (buffer);
            return socket.SendAsync (segment, WebSocketMessageType.Text, true, ct);
        }

        private static async Task<string> ReceiveStringAsync (WebSocket socket, CancellationToken ct = default (CancellationToken)) {
            var buffer = new ArraySegment<byte> (new byte[8192]);
            using (var ms = new MemoryStream ()) {
                WebSocketReceiveResult result;
                do {
                    ct.ThrowIfCancellationRequested ();

                    result = await socket.ReceiveAsync (buffer, ct);
                    ms.Write (buffer.Array, buffer.Offset, result.Count);
                }
                while (!result.EndOfMessage);

                ms.Seek (0, SeekOrigin.Begin);
                if (result.MessageType != WebSocketMessageType.Text) {
                    return null;
                }

                // Encoding UTF8: https://tools.ietf.org/html/rfc6455#section-5.6
                using (var reader = new StreamReader (ms, Encoding.UTF8)) {
                    return await reader.ReadToEndAsync ();
                }
            }
        }
    }
}

## HomeController.cs
using Microsoft.AspNetCore.Mvc;

namespace AspNetCoreChatRoom.Controllers {
    public class HomeController : Controller {
        [HttpGet]
        public IActionResult Index () {
            return View ("InsertUserName");
        }

        [HttpPost]
        public IActionResult Index (string username) {
            return View ("Index", username);
        }

        public IActionResult Error () {
            return View ();
        }
    }
}

## index.cshtml
@model string
@{
    ViewData["Title"] = "Home Page";
}
<div class="msg">
    <div id="msgs"></div>
</div>
<div>
    <input type="text" id="MessageField" placeholder="type message and press enter" />
</div>
<script>
    const userName = '@Model';
</script>
<environment include="Development">
    <script src="~/js/site.js"></script>
</environment>
<environment exclude="Development">
    <script src="~/js/site.min.js"></script>
</environment>

## InsertUserName.cshtml
<form action="@Url.Action("Index")" method="post">
    <input type="text" placeholder="Insert user name" name="userName" />
    <input type="submit" value="Eńter" />
</form>

## site.css
body {
    margin: 0;
    padding: 0;
    float:left;
    width: 100%;
}

.msg {
    display:block;
    white-space:nowrap;
    padding-left: 30px;
    padding-top: 10px;
}

input#MessageField {
    position: absolute;
    bottom: 0;
    min-width: 320px;
    width: calc(100% - 23px);
    height: 30px;
    padding-left: 20px;
}

## site.js
const protocol = location.protocol === "https:" ? "wss:" : "ws:";
const wsUri = protocol + "//" + window.location.host;
const socket = new WebSocket(wsUri);
socket.onopen = e => {
    console.log("socket opened", e);
};

socket.onclose = ((e) => {
    console.log("socket closed", e);
});

socket.onmessage = ((e) => {
    console.log(e);
    document.getElementById('msgs').innerHTML += e.data + '<br/>';
});

socket.onerror = ((e) => {
    console.error(e.data);
});

window.addEventListener('keydown', ((e) => {
    //13 == enter key
    //and if nothing is in the input field -> no reason to submit it
    if (e.keyCode != 13 || e.target.value === undefined || e.target.value === '') {
        return;
    }
    e.preventDefault();
    let message = userName + ": " + e.target.value;
    socket.send(message);
    e.target.value = '';
}));

## Startup.cs
//needed for timespan function
using System;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Logging;
//enable useresponsecompression
using Microsoft.AspNetCore.ResponseCompression;
//for proxying
using Microsoft.AspNetCore.HttpOverrides;

namespace AspNetCoreChatRoom {
    public class Startup {
        public Startup (IHostingEnvironment env) {
            var builder = new ConfigurationBuilder ()
                .SetBasePath (env.ContentRootPath)
                .AddJsonFile ("appsettings.json", optional : false, reloadOnChange : true)
                .AddJsonFile ($"appsettings.{env.EnvironmentName}.json", optional : true)
                .AddEnvironmentVariables ();
            Configuration = builder.Build ();
        }

        public IConfigurationRoot Configuration { get; }

        // This method gets called by the runtime. Use this method to add services to the container.
        public void ConfigureServices (IServiceCollection services) {
            // Add framework services.
            services.AddMvc ();
            //deflate as a service
            services.AddResponseCompression ();
        }

        // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
        public void Configure (IApplicationBuilder app, IHostingEnvironment env, ILoggerFactory loggerFactory) {
            loggerFactory.AddConsole (Configuration.GetSection ("Logging"));
            loggerFactory.AddDebug ();

            if (env.IsDevelopment ()) {
                app.UseDeveloperExceptionPage ();
            } else {
                app.UseExceptionHandler ("/Shared/Error");
            }
            app.UseStaticFiles ();
            //use deflate
            app.UseResponseCompression ();
            var wsOptions = new WebSocketOptions () {
                KeepAliveInterval = TimeSpan.FromSeconds (120),
                ReceiveBufferSize = 4 * 1024
            };
            app.UseWebSockets (wsOptions);
            app.UseMiddleware<ChatWebSocketMiddleware> ();
            app.UseForwardedHeaders (new ForwardedHeadersOptions {
                ForwardedHeaders = ForwardedHeaders.XForwardedFor | ForwardedHeaders.XForwardedProto
            });
            app.UseMvc (routes => {
                routes.MapRoute (
                    name: "default",
                    template: "{controller=Home}/{action=Index}/{id?}");
            });
        }
    }
}
	<!DOCTYPE html>
	<html>
	<head>
	<meta charset="utf-8" />
	<meta name="viewport" content="width=device-width, initial-scale=1.0" />
	<title>@ViewData["Title"] - AspNetCoreChatRoom</title>
	<environment include="Development">
	<link rel="stylesheet" href="~/css/site.css" />
	</environment>
	<environment exclude="Development">
	<link rel="stylesheet" href="~/css/site.min.css" asp-append-version="true" />
	</environment>
	</head>
	<body>
	<div class="container body-content">
	@RenderBody()
	</div>
	</body>
	</html>
	<Project Sdk="Microsoft.NET.Sdk.Web">

	<PropertyGroup>
	<TargetFramework>netcoreapp2.1</TargetFramework>
	</PropertyGroup>

	<ItemGroup>
	<PackageReference Include="Microsoft.AspNetCore.App" />
	<PackageReference Include="Microsoft.AspNetCore.WebSockets" Version="2.1.1" />
	</ItemGroup>

	</Project>
	using System;
	using System.Collections.Concurrent;
	using System.IO;
	using System.Net.WebSockets;
	using System.Text;
	using System.Threading;
	using System.Threading.Tasks;
	using Microsoft.AspNetCore.Http;

	namespace AspNetCoreChatRoom {
	public class ChatWebSocketMiddleware {
	private static ConcurrentDictionary<string, WebSocket> _sockets = new ConcurrentDictionary<string, WebSocket> ();

	private readonly RequestDelegate _next;

	public ChatWebSocketMiddleware (RequestDelegate next) {
	_next = next;
	}

	public async Task Invoke (HttpContext context) {
	if (!context.WebSockets.IsWebSocketRequest) {
	await _next.Invoke (context);
	return;
	}

	CancellationToken ct = context.RequestAborted;
	WebSocket currentSocket;
	//trying to build a connection
	try {
	currentSocket = await context.WebSockets.AcceptWebSocketAsync ();
	} catch (Exception ex) {
	Console.WriteLine(ex.Message);
	return;
	}
	var socketId = Guid.NewGuid ().ToString ();

	_sockets.TryAdd (socketId, currentSocket);

	while (true) {
	if (ct.IsCancellationRequested) {
	break;
	}

	var response = await ReceiveStringAsync (currentSocket, ct);
	if (string.IsNullOrEmpty (response)) {
	if (currentSocket.State != WebSocketState.Open) {
	break;
	}

	continue;
	}

	foreach (var socket in _sockets) {
	if (socket.Value.State != WebSocketState.Open) {
	continue;
	}

	await SendStringAsync (socket.Value, response, ct, socketId);
	}
	}

	WebSocket dummy;
	_sockets.TryRemove (socketId, out dummy);

	//trying to normally close the connection
	try {
	await currentSocket.CloseAsync (WebSocketCloseStatus.NormalClosure, "Closing", ct);
	currentSocket.Dispose ();
	} catch (Exception ex) {
	//if anything goes wrong...
	//output error
	Console.WriteLine (ex.Message);
	currentSocket.Abort ();
	}
	}

	private static Task SendStringAsync (WebSocket socket, string data, CancellationToken ct = default (CancellationToken), string socketId = "deadbeef") {
	//append the socketid to the message for debugging purposes
	//couldve taken it globally, this is just a poc
	var buffer = Encoding.UTF8.GetBytes (data + ' ' + socketId);
	var segment = new ArraySegment<byte> (buffer);
	return socket.SendAsync (segment, WebSocketMessageType.Text, true, ct);
	}

	private static async Task<string> ReceiveStringAsync (WebSocket socket, CancellationToken ct = default (CancellationToken)) {
	var buffer = new ArraySegment<byte> (new byte[8192]);
	using (var ms = new MemoryStream ()) {
	WebSocketReceiveResult result;
	do {
	ct.ThrowIfCancellationRequested ();

	result = await socket.ReceiveAsync (buffer, ct);
	ms.Write (buffer.Array, buffer.Offset, result.Count);
	}
	while (!result.EndOfMessage);

	ms.Seek (0, SeekOrigin.Begin);
	if (result.MessageType != WebSocketMessageType.Text) {
	return null;
	}

	// Encoding UTF8: https://tools.ietf.org/html/rfc6455#section-5.6
	using (var reader = new StreamReader (ms, Encoding.UTF8)) {
	return await reader.ReadToEndAsync ();
	}
	}
	}
	}
	}
	using Microsoft.AspNetCore.Mvc;

	namespace AspNetCoreChatRoom.Controllers {
	public class HomeController : Controller {
	[HttpGet]
	public IActionResult Index () {
	return View ("InsertUserName");
	}

	[HttpPost]
	public IActionResult Index (string username) {
	return View ("Index", username);
	}

	public IActionResult Error () {
	return View ();
	}
	}
	}
	@model string
	@{
	ViewData["Title"] = "Home Page";
	}
	<div class="msg">
	<div id="msgs"></div>
	</div>
	<div>
	<input type="text" id="MessageField" placeholder="type message and press enter" />
	</div>
	<script>
	const userName = '@Model';
	</script>
	<environment include="Development">
	<script src="~/js/site.js"></script>
	</environment>
	<environment exclude="Development">
	<script src="~/js/site.min.js"></script>
	</environment>
	<form action="@Url.Action("Index")" method="post">
	<input type="text" placeholder="Insert user name" name="userName" />
	<input type="submit" value="Eńter" />
	</form>
	body {
	margin: 0;
	padding: 0;
	float:left;
	width: 100%;
	}

	.msg {
	display:block;
	white-space:nowrap;
	padding-left: 30px;
	padding-top: 10px;
	}

	input#MessageField {
	position: absolute;
	bottom: 0;
	min-width: 320px;
	width: calc(100% - 23px);
	height: 30px;
	padding-left: 20px;
	}
	const protocol = location.protocol === "https:" ? "wss:" : "ws:";
	const wsUri = protocol + "//" + window.location.host;
	const socket = new WebSocket(wsUri);
	socket.onopen = e => {
	console.log("socket opened", e);
	};

	socket.onclose = ((e) => {
	console.log("socket closed", e);
	});

	socket.onmessage = ((e) => {
	console.log(e);
	document.getElementById('msgs').innerHTML += e.data + '<br/>';
	});

	socket.onerror = ((e) => {
	console.error(e.data);
	});

	window.addEventListener('keydown', ((e) => {
	//13 == enter key
	//and if nothing is in the input field -> no reason to submit it
	if (e.keyCode != 13 \|\| e.target.value === undefined \|\| e.target.value === '') {
	return;
	}
	e.preventDefault();
	let message = userName + ": " + e.target.value;
	socket.send(message);
	e.target.value = '';
	}));
	//needed for timespan function
	using System;
	using Microsoft.AspNetCore.Builder;
	using Microsoft.AspNetCore.Hosting;
	using Microsoft.Extensions.Configuration;
	using Microsoft.Extensions.DependencyInjection;
	using Microsoft.Extensions.Logging;
	//enable useresponsecompression
	using Microsoft.AspNetCore.ResponseCompression;
	//for proxying
	using Microsoft.AspNetCore.HttpOverrides;

	namespace AspNetCoreChatRoom {
	public class Startup {
	public Startup (IHostingEnvironment env) {
	var builder = new ConfigurationBuilder ()
	.SetBasePath (env.ContentRootPath)
	.AddJsonFile ("appsettings.json", optional : false, reloadOnChange : true)
	.AddJsonFile ($"appsettings.{env.EnvironmentName}.json", optional : true)
	.AddEnvironmentVariables ();
	Configuration = builder.Build ();
	}

	public IConfigurationRoot Configuration { get; }

	// This method gets called by the runtime. Use this method to add services to the container.
	public void ConfigureServices (IServiceCollection services) {
	// Add framework services.
	services.AddMvc ();
	//deflate as a service
	services.AddResponseCompression ();
	}

	// This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
	public void Configure (IApplicationBuilder app, IHostingEnvironment env, ILoggerFactory loggerFactory) {
	loggerFactory.AddConsole (Configuration.GetSection ("Logging"));
	loggerFactory.AddDebug ();

	if (env.IsDevelopment ()) {
	app.UseDeveloperExceptionPage ();
	} else {
	app.UseExceptionHandler ("/Shared/Error");
	}
	app.UseStaticFiles ();
	//use deflate
	app.UseResponseCompression ();
	var wsOptions = new WebSocketOptions () {
	KeepAliveInterval = TimeSpan.FromSeconds (120),
	ReceiveBufferSize = 4 * 1024
	};
	app.UseWebSockets (wsOptions);
	app.UseMiddleware<ChatWebSocketMiddleware> ();
	app.UseForwardedHeaders (new ForwardedHeadersOptions {
	ForwardedHeaders = ForwardedHeaders.XForwardedFor \| ForwardedHeaders.XForwardedProto
	});
	app.UseMvc (routes => {
	routes.MapRoute (
	name: "default",
	template: "{controller=Home}/{action=Index}/{id?}");
	});
	}
	}
	}