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Get started with ASP.NET Core SignalR bradygaster In this tutorial, you create a chat app that uses ASP.NET Core SignalR. bradyg mvc 11/30/2018 tutorials/signalr

Tutorial: Get started with ASP.NET Core SignalR

This tutorial teaches the basics of building a real-time app using SignalR. You learn how to:

[!div class="checklist"]

  • Create a web project.
  • Add the SignalR client library.
  • Create a SignalR hub.
  • Configure the project to use SignalR.
  • Add code that sends messages from any client to all connected clients.

At the end, you'll have a working chat app:

SignalR sample app

View or download sample code (how to download).

[!INCLUDE |Prerequisites]

Create a web project

Visual Studio

  • From the menu, select File > New Project.

  • In the New Project dialog, select Installed > Visual C# > Web > ASP.NET Core Web Application. Name the project SignalRChat.

    New Project dialog in Visual Studio

  • Select Web Application to create a project that uses Razor Pages.

  • Select a target framework of .NET Core, select ASP.NET Core 2.2, and click OK.

    New Project dialog in Visual Studio

Visual Studio Code

  • Open the integrated terminal to the folder in which the new project folder will be created.

  • Run the following commands:

    dotnet new webapp -o SignalRChat
code -r SignalRChat

Visual Studio for Mac

  • From the menu, select File > New Solution.

  • Select .NET Core > App > ASP.NET Core Web App (Don't select ASP.NET Core Web App (MVC)).

  • Select Next.

  • Name the project SignalRChat, and then select Create.

Add the SignalR client library

The SignalR server library is included in the Microsoft.AspNetCore.App metapackage. The JavaScript client library isn't automatically included in the project. For this tutorial, you use Library Manager (LibMan) to get the client library from unpkg. unpkg is a content delivery network (CDN)) that can deliver anything found in npm, the Node.js package manager.

Visual Studio

  • In Solution Explorer, right-click the project, and select Add > Client-Side Library.

  • In the Add Client-Side Library dialog, for Provider select unpkg.

  • For Library, enter @aspnet/signalr@1, and select the latest version that isn't preview.

    Add Client-Side Library dialog - select library

  • Select Choose specific files, expand the dist/browser folder, and select signalr.js and signalr.min.js.

  • Set Target Location to wwwroot/lib/signalr/, and select Install.

    Add Client-Side Library dialog - select files and destination

    LibMan creates a wwwroot/lib/signalr folder and copies the selected files to it.

Visual Studio Code

  • In the integrated terminal, run the following command to install LibMan.

    dotnet tool install -g Microsoft.Web.LibraryManager.Cli

  • Run the following command to get the SignalR client library by using LibMan. You might have to wait a few seconds before seeing output.

    libman install @aspnet/signalr -p unpkg -d wwwroot/lib/signalr --files dist/browser/signalr.js --files dist/browser/signalr.min.js

    The parameters specify the following options:

    • Use the unpkg provider.
    • Copy files to the wwwroot/lib/signalr destination.
    • Copy only the specified files.

    The output looks like the following example:

    wwwroot/lib/signalr/dist/browser/signalr.js written to disk
wwwroot/lib/signalr/dist/browser/signalr.min.js written to disk
Installed library "@aspnet/signalr@1.0.3" to "wwwroot/lib/signalr"

Visual Studio for Mac

  • In the Terminal, run the following command to install LibMan.

    dotnet tool install -g Microsoft.Web.LibraryManager.Cli

  • Navigate to the project folder (the one that contains the SignalRChat.csproj file).

  • Run the following command to get the SignalR client library by using LibMan.

    libman install @aspnet/signalr -p unpkg -d wwwroot/lib/signalr --files dist/browser/signalr.js --files dist/browser/signalr.min.js

    The parameters specify the following options:

    • Use the unpkg provider.
    • Copy files to the wwwroot/lib/signalr destination.
    • Copy only the specified files.

    The output looks like the following example:

    wwwroot/lib/signalr/dist/browser/signalr.js written to disk
wwwroot/lib/signalr/dist/browser/signalr.min.js written to disk
Installed library "@aspnet/signalr@1.0.3" to "wwwroot/lib/signalr"

Create a SignalR hub

A hub is a class that serves as a high-level pipeline that handles client-server communication.

  • In the SignalRChat project folder, create a Hubs folder.

  • In the Hubs folder, create a ChatHub.cs file with the following code:

    [!code-csharpStartup]

    The ChatHub class inherits from the SignalR Hub class. The Hub class manages connections, groups, and messaging.

    The SendMessage method can be called by a connected client to send a message to all clients. JavaScript client code that calls the method is shown later in the tutorial. SignalR code is asynchronous to provide maximum scalability.

Configure SignalR

The SignalR server must be configured to pass SignalR requests to SignalR.

  • Add the following highlighted code to the Startup.cs file.

    [!code-csharpStartup]

    These changes add SignalR to the ASP.NET Core dependency injection system and the middleware pipeline.

Add SignalR client code

  • Replace the content in Pages\Index.cshtml with the following code:

    [!code-cshtmlIndex]

    The preceding code:

    • Creates text boxes for name and message text, and a submit button.
    • Creates a list with id="messagesList" for displaying messages that are received from the SignalR hub.
    • Includes script references to SignalR and the chat.js application code that you create in the next step.

  • In the wwwroot/js folder, create a chat.js file with the following code:

    [!code-javascriptIndex]

    The preceding code:

    • Creates and starts a connection.
    • Adds to the submit button a handler that sends messages to the hub.
    • Adds to the connection object a handler that receives messages from the hub and adds them to the list.

Run the app

Visual Studio

  • Press CTRL+F5 to run the app without debugging.

Visual Studio Code

  • In the integrated terminal, run the following command:

    dotnet run -p SignalRChat.csproj

Visual Studio for Mac

  • From the menu, select Run > Start Without Debugging.

  • Copy the URL from the address bar, open another browser instance or tab, and paste the URL in the address bar.

  • Choose either browser, enter a name and message, and select the Send Message button.

    The name and message are displayed on both pages instantly.

    SignalR sample app

[!TIP] If the app doesn't work, open your browser developer tools (F12) and go to the console. You might see errors related to your HTML and JavaScript code. For example, suppose you put signalr.js in a different folder than directed. In that case the reference to that file won't work and you'll see a 404 error in the console. signalr.js not found error

Next steps

In this tutorial, you learned how to:

[!div class="checklist"]

  • Create a web app project.
  • Add the SignalR client library.
  • Create a SignalR hub.
  • Configure the project to use SignalR.
  • Add code that uses the hub to send messages from any client to all connected clients.

To learn more about SignalR, see the introduction:

[!div class="nextstepaction"] Introduction to ASP.NET Core SignalR