Differences between ASP.NET SignalR and ASP.NET Core SignalR

ASP.NET Core SignalR isn't compatible with clients or servers for ASP.NET SignalR. This article details features which have been removed or changed in ASP.NET Core SignalR.

How to identify the SignalR version

	ASP.NET SignalR	ASP.NET Core SignalR
Server NuGet package	Microsoft.AspNet.SignalR	None. Included in the Microsoft.AspNetCore.App shared framework.
Client NuGet packages	Microsoft.AspNet.SignalR.Client Microsoft.AspNet.SignalR.JS	Microsoft.AspNetCore.SignalR.Client
JavaScript client npm package	signalr	@microsoft/signalr
Java client	GitHub Repository (deprecated)	Maven package com.microsoft.signalr
Server app type	ASP.NET (System.Web) or OWIN Self-Host	ASP.NET Core
Supported server platforms	.NET Framework 4.5 or later	.NET Core 3.0 or later

Feature differences

Automatic reconnects

In ASP.NET SignalR:

• By default, SignalR attempts to reconnect to the server if the connection is dropped.

In ASP.NET Core SignalR:

• Automatic reconnects are opt-in with both the .NET client and the JavaScript client:

HubConnection connection = new HubConnectionBuilder()
    .WithUrl(new Uri("http://127.0.0.1:5000/chathub"))
    .WithAutomaticReconnect()
    .Build();

const connection = new signalR.HubConnectionBuilder()
    .withUrl("/chathub")
    .withAutomaticReconnect()
    .build();

Protocol support

ASP.NET Core SignalR supports JSON, as well as a new binary protocol based on MessagePack. Additionally, custom protocols can be created.

Transports

The Forever Frame transport isn't supported in ASP.NET Core SignalR.

Differences on the server

The ASP.NET Core SignalR server-side libraries are included in Microsoft.AspNetCore.App, which is used in the ASP.NET Core Web Application template for both Razor and MVC projects.

ASP.NET Core SignalR is an ASP.NET Core middleware. It must be configured by calling AddSignalR in Startup.ConfigureServices.

services.AddSignalR()

To configure routing, map routes to hubs inside the UseEndpoints method call in the Startup.Configure method.

app.UseRouting();

app.UseEndpoints(endpoints =>
{
    endpoints.MapHub<ChatHub>("/hub");
});

Sticky sessions

The scaleout model for ASP.NET SignalR allows clients to reconnect and send messages to any server in the farm. In ASP.NET Core SignalR, the client must interact with the same server for the duration of the connection. For scaleout using Redis, that means sticky sessions are required. For scaleout using Azure SignalR Service, sticky sessions aren't required because the service handles connections to clients.

Single hub per connection

In ASP.NET Core SignalR, the connection model has been simplified. Connections are made directly to a single hub, rather than a single connection being used to share access to multiple hubs.

Streaming

ASP.NET Core SignalR now supports streaming data from the hub to the client.

State

The ability to pass arbitrary state between clients and the hub (often called HubState) has been removed, as well as support for progress messages. There is no counterpart of hub proxies at the moment.

PersistentConnection removal

In ASP.NET Core SignalR, the PersistentConnection class has been removed.

GlobalHost

ASP.NET Core has dependency injection (DI) built into the framework. Services can use DI to access the HubContext. The GlobalHost object that is used in ASP.NET SignalR to get a HubContext doesn't exist in ASP.NET Core SignalR.

HubPipeline

ASP.NET Core SignalR doesn't have support for HubPipeline modules.

Differences on the client

TypeScript

The ASP.NET Core SignalR client is written in TypeScript. You can write in JavaScript or TypeScript when using the JavaScript client.

The JavaScript client is hosted at npm

In ASP.NET versions, the JavaScript client was obtained through a NuGet package in Visual Studio. In the ASP.NET Core versions, the @microsoft/signalr npm package contains the JavaScript libraries. This package isn't included in the ASP.NET Core Web Application template. Use npm to obtain and install the @microsoft/signalr npm package.

npm init -y
npm install @microsoft/signalr

jQuery

The dependency on jQuery has been removed, however projects can still use jQuery.

Internet Explorer support

ASP.NET Core SignalR doesn't support Microsoft Internet Explorer, whereas ASP.NET SignalR supports Microsoft Internet Explorer 8 or later. For more information, see ASP.NET Core SignalR supported platforms.

JavaScript client method syntax

The JavaScript syntax has changed from the ASP.NET version of SignalR. Rather than using the $connection object, create a connection using the HubConnectionBuilder API.

const connection = new signalR.HubConnectionBuilder()
    .withUrl("/hub")
    .build();

Use the on method to specify client methods that the hub can call.

connection.on("ReceiveMessage", (user, message) => {
    const msg = message.replace(/&/g, "&amp;").replace(/</g, "&lt;").replace(/>/g, "&gt;");
    const encodedMsg = `${user} says ${msg}`;
    console.log(encodedMsg);
});

After creating the client method, start the hub connection. Chain a catch method to log or handle errors.

connection.start().catch(err => console.error(err));

Hub proxies

Hub proxies are no longer automatically generated. Instead, the method name is passed into the invoke API as a string.

.NET and other clients

The Microsoft.AspNetCore.SignalR.Client NuGet package contains the .NET client libraries for ASP.NET Core SignalR.

Use the HubConnectionBuilder to create and build an instance of a connection to a hub.

connection = new HubConnectionBuilder()
    .WithUrl("url")
    .Build();

Scaleout differences

ASP.NET SignalR supports SQL Server and Redis. ASP.NET Core SignalR supports Azure SignalR Service and Redis.

ASP.NET

• SignalR scaleout with Azure Service Bus
• SignalR scaleout with Redis
• SignalR scaleout with SQL Server

ASP.NET Core

• Azure SignalR Service
• Redis Backplane

Additional resources

• Hubs
• JavaScript client
• .NET client
• Supported platforms