ASP.NET Core SignalR in a nutshell

Enabling two-way real-time communication between the client and the server in ASP.NET Core

Created byFiodar Sazanavets

Last updated 7/2020

English

What you'll learn

SignalR on .NET Core

Course content

7 sections • 47 lectures • 1h 25m total length

Introduction3:38
Discover how SignalR enables two-way client-server communication in ASP.NET Core, handles JSON serialization, and auto-selects transports such as WebSockets or server-sent events for easy scaling across instances.
Transport mechanisms3:46
Discover how ASP.NET Core SignalR enables persistent two-way communication via transport mechanisms like WebSockets, server-sent events, and long polling, with automatic or explicit transport selection.
Setting up your environment0:31
Setting up your solution4:33
Open Visual Studio 2017, create an ASP.NET Core web application, add SignalR dependencies, implement a LearningHub that broadcasts messages, and register the hub with services.AddSignalR and app.UseSignalR at /learningHub.
Test yourself

Introduction to SignalR Hub2:03
Explore how the LearningHub class models a SignalR Hub, inheriting from the abstract Hub class to enable remote method calls and manage connections via the Context, Clients, and Groups properties.
Example of SignalR Hub0:33
SignalR Hub explained2:24
Explore how a SignalR hub broadcasts messages, handles calls to the caller or others, and manages groups, with connection events and strongly typed, json-serialized client calls.
An example of a strongly typed Hub0:38
Strongly typed Hub explained0:57
Define a strongly typed hub by using a client interface, replacing SendAsync with ReceiveMessage for compiler-checked calls. Update the interface when client methods change, but benefits outweigh drawbacks.
SignalR Hub documentation0:05
Test yourself

Introduction to SignalR clients0:30
Connect to the service side of SignalR by exploring JavaScript, Java, and .NET clients, tailored for .NET developers, with links to additional Java client resources.
Setting up JavaScript client3:10
Install the SignalR JavaScript client with npm in Visual Studio 2017, then copy signalr and signalr.min to wwwroot/lib/signalr. Update the layout to reference SignalR before site.js for proper client loading.
Example of JavaScript client1:22
JavaScript client explained3:24
Show how the JavaScript SignalR client initializes the hub, wires events to hub methods, and demonstrates broadcast, send to self, send to others, and group messaging with automatic reconnection.
Setting up .NET Client1:10
Set up a .NET SignalR client in a console app by adding a new console app project named SignalRClient to the solution and installing the SignalR client NuGet package.
Example of .NET client1:02
.NET client explained3:24
Explain configuring a .NET SignalR client with the hub url and transport, bind a C# method to hub messages, and connect to learningHub to send to self or others.
Additional resources0:14
Test yourself

Why WebSockets client1:11
Create a console app named WebSocketsClient to connect a plain WebSockets client to a SignalR hub for legacy systems. Configure it as a startup project and set SignalRClient to None.
Example of .NET WebSockets client0:38
.NET WebSockets client explained4:03
Explain building a .NET WebSockets client for a SignalR hub, including WS/WSS URL setup, handshake, and message listening. Describe decoding buffers, filtering heartbeats, and interpreting JSON messages.
Other types of WebSockets clients0:25

Introduction0:47
Explore SignalR security in a nutshell, learn how to restrict origins and authenticate and authorize users, building on hub, server, and client fundamentals.
Example of CORS configuration0:15
CORS configuration explained2:44
Explain CORS in ASP.NET Core, two policies: allow any get and a policy from example.com, and the middleware order before SignalR to support websockets.
Setting up authentication3:24
Set up authentication in an ASP.NET Core app by registering in middleware, scaffolding Identity, generating the database schema, and updating the layout to enable user login.
Example of Identity authentication0:32
Identity authentication explained4:18
Demonstrate ASP.NET Identity's authentication and authorization via the Authorize attribute, roles, and policies, with examples on registering users and restricting actions like broadcast messages.
User authentication example0:44
User authentication explained1:51
ConfigureServices adds IdentityOptions and cookie authentication to enable authentication, and UseAuthentication must precede UseSignalR and UseMvc in the pipeline, as shown by registering and logging in to authorize hub methods.
Enabling messaging individual users1:43
Messaging individual users3:49
Implement per-user groups in ASP.NET Core SignalR to send messages to individual authenticated users, update hub methods, and prepend usernames to messages.
Further reading on web application security0:47
Test yourself

Why would you need to scale out1:54
scale out the SignalR hub by running multiple hub instances behind a load balancer, with a backplane enabled by Redis to synchronize client and group state.
Introducing Redis cache1:40
Redis acts as an in-memory database, cache, and message broker for SignalR backplane scaling. Hubs publish and subscribe via Redis, routing messages to clients across multiple hubs.
Setting up Redis1:26
Connecting SignalR Hub to Redis1:46
Connect a SignalR hub to Redis by installing the NuGet package, configuring AddRedis with your Redis connection string, and enabling a backplane to scale out across multiple hub instances.
Multiple Hub instances6:57
Move the SignalR hub to a class library and reference it from a second web app, then share the same Redis backplane to treat both apps as one hub.
Example of Hub Context0:13
Hub Context explained2:55
Explain how IHubContext lets external code access a hub's Clients, Context, and Groups to broadcast messages via a Redis backplane, enabling scalable, simplified cross-app messaging.
Setting up Azure SignalR Service0:45
Azure SignalR dependencies1:05
Configure a distributed asp.net core app to use an Azure SignalR resource by adding the Microsoft.Azure.SignalR NuGet package to one project, allowing the dependency to implicitly propagate to both projects.
Connecting application to the SignalR Service0:39
Azure SignalR code explained4:05
Replace addredis with Azure SignalR Service configuration and use rest api calls to post to the learningHub, sending a payload with target and arguments and checking the response code.
More on scaling-out SignalR0:26
Test yourself

Requirements

Be able to build basic web applications on ASP .NET Core

Description

Are you a web developer? If so, you would know that many web development projects these days require the ability to establish a persistent connection between a client and a server without having to keep sending repeated requests from the client. As you may also know, such functionality may be hard to implement.

However, if you can build your web application in ASP.NET Core, there is a way to make this whole process easy. There is a library called SignalR. This is what I'm going to talk about in this course. As well as doing all the heavy lifting for you, the library abstracts away all complex implementation details, so your code can be made extremely simple.

However, as you would already know, nothing in programming is simple in absolute terms. Programming is a complex activity, so even those concepts that are relatively simple require some practice and studying.

This is why I've created this course. By the end of it, you should be able to build a web application that clients will be able to establish a persistent connection with and exchange the data with in real time.

Who this course is for:

Web developers who want to enable a persistent real-time communication between the client and the server
ASP .NET Core developers
Any other web developers using Microsoft programming stack

ASP.NET Core SignalR in a nutshell

What you'll learn

Explore related topics

Course content

Introduction4 lectures • 12min

Setting up SignalR Hub6 lectures • 7min

Setting up SignalR clients8 lectures • 14min

Connecting a standard WebSocket client4 lectures • 6min

SignalR security11 lectures • 21min

Scaling out SignalR hub12 lectures • 24min

Wrapping up2 lectures • 2min

Requirements

Description

Who this course is for: