Real-Time Communications with ASP.NET Core SignalR

Real-Time Communications with ASP.NET Core SignalR

Building Real-Time Apps with ASP.NET Core SignalR

Real-time and interactive experiences are becoming the norm for modern web and mobile applications. Users increasingly expect apps to provide dynamic, up-to-date information without refreshing pages. Features like push notifications, live chat, collaborative editing, and streaming updates help create seamless, engaging apps. Implementing real-time functionality from scratch can be challenging, though. This is where SignalR comes in – it’s a library from Microsoft that makes adding bi-directional communication simple and consistent across platforms.

With SignalR, you can add real-time messaging, notifications, and other features to your ASP.NET Core web apps with minimal code. In this post, we’ll cover the basics of SignalR and see how to build a real-time chat application using it in ASP.NET Core. Whether you’re looking to create a multiplayer game, shared whiteboard, live support chat, or add dynamic flair to your app, SignalR is a powerful tool for enabling real-time communications. If you need help implementing SignalR, consider hiring a .NET development company with expertise in real-time web development. A qualified .NET dev shop can work with you to integrate SignalR and build engaging interactive experiences.

Overview of SignalR:

SignalR is the latest iteration of real-time web functionality libraries from Microsoft for ASP.NET. It builds on earlier versions like SignalR for ASP.NET and ASP.NET Core. Under the hood, SignalR handles connection management automatically and lets you focus on coding app logic. It provides a simple API for creating server-to-client RPCs (remote procedure calls) that can call JavaScript functions on clients from server-side .NET code. SignalR offers a variety of valuable capabilities:

  • Bi-directional communication between server and client – Clients can call server methods and receive data pushes from the server.
  • Persistent connections – Connections are kept alive indefinitely instead of making new HTTP requests for each data exchange.
  • Broadcasting messages – The server can push updates to all connected clients simultaneously. Valid for notifications, alerts, etc.
  • Groups – Logical groupings of connections for targeted messaging.
  • Multiple protocols – SignalR handles WebSockets, Server-Sent Events, and Long Polling under the hood.
  • Broad platform support – .NET, JavaScript, Java, Swift, Android, and more. Common APIs across platforms.

With its robust set of features, SignalR makes it simple to add powerful real-time functionality to your ASP.NET Core web apps. It handles all the complex aspects of real-time communication behind its easy-to-use APIs.

SignalR enables bi-directional communication between client and server so that both ends can send messages freely. The connections are persistent, meaning they stay open indefinitely instead of closing after each request-response cycle. This allows for true real-time sending and receiving of data.

Another excellent capability is the ability to broadcast messages from the server to all connected clients simultaneously. This is perfect for notifications and alerts that need to be pushed to all users. SignalR also supports grouping connections into channels for more targeted broadcasting.

Under the hood, SignalR automatically chooses the best transport method, like WebSockets or Server-Sent Events, based on the browser’s capabilities. This ensures reliable real-time transport without you having to worry about cross-browser differences.

Getting Started in SignalR

Let’s build a simple chat application in ASP.NET Core using SignalR.

  • First, create an ASP.NET Core web app project and install Microsoft.AspNetCore.SignalR.Core NuGet package.
  • Next, create a SignalR hub class, ChatHub, that will handle sending and receiving messages:

public class ChatHub : Hub


  public async Task SendMessage(string user, string message)


    await Clients.All.SendAsync(“ReceiveMessage”, user, message);



  • In Startup.cs, enable SignalR and map routes to the hub:

public void ConfigureServices(IServiceCollection services)




public void Configure(IApplicationBuilder app) 


  app.UseSignalR(routes =>





  • On the client side, install @aspnet/signalr npm package and establish a connection to the hub:

const connection = new signalR.HubConnectionBuilder()




  • We can now send messages by calling the hub methods from the client:

async function sendMessage(user, message) {

  await connection.invoke(“SendMessage”, user, message);


  • And receive messages by registering a handler:

connection.on(“ReceiveMessage”, (user, message) => {

  console.log(`${user}: ${message}`);


This covers setting up a real-time app with SignalR in ASP.NET Core! Next, we’ll look at some more advanced features.

Advanced Topics

SignalR has a number of advanced capabilities:

  • Authentication – Integrate auth systems like OAuth or JWT tokens to identify and authorize users.
  • Message types – Send different message payloads like strings, JSON, or bytes.
  • Multiple hubs – Organize related connections into different hub classes.
  • Frontend integration – Reuse hub connections across components in React, Angular, Blazor, etc.
  • Scaling – Horizontally scale using Redis, SQL Server, or Azure SignalR service.
  • Streaming – Push real-time data updates from the server.

These features allow for building more complex real-time behaviors in production apps.


SignalR makes it incredibly simple to build real-time web functionality with ASP.NET Core. With its simple APIs, cross-platform support, and advanced features, SignalR is the go-to library for adding push notifications, live updates, and messaging to .NET web applications. If you need help implementing real-time features in your ASP.NET Core app, hire dedicated .NET developers skilled in using SignalR. The right .NET developers can quickly leverage SignalR to add advanced real-time capabilities to your application.

About author

Carl Herman is an editor at DataFileHost enjoys writing about the latest Tech trends around the globe.