ChatRoom

Build Your First Azure SignalR Service Application

In ChatRoomLocal sample you have learned how to use SignalR to build a chat room application. In that sample, the SignalR runtime (which manages the client connections and message routing) is running on your local machine. As the number of the clients increases, you'll eventually hit a limit on your machine and you'll need to scale up your machine to handle more clients. This is usually not an easy task. In this tutorial, you'll learn how to use Azure SignalR Service to offload the connection management part to the service so that you don't need to worry about the scaling problem.

Provision a SignalR Service

First let's provision a SignalR service on Azure.

1. Open Azure portal, click "Create a resource" and find "SignalR Service" in "Web + Mobile".

   

2. Click "Create", and then fill in basic information including resource name, resource group and location.

   

   Resource name will also be used as the DNS name of your service endpoint. So you'll get a <resource_name>.service.signalr.net that your application can connect to.

   Select a pricing tier. There're two pricing tiers:

   • Free: which can handle 100 connections at the same time and can send and receive one million messages in a month.
   • Basic: which has 1000 concurrent connections and 75 millions message per month limit for one unit. You can scale up to 10 units for a single service instance and you'll be charged by the number of units you use.

3. Click "Create", your SignalR service will be created in a few minutes.

   

After your service is ready, go to the Keys page of your service instance and you'll get two connection strings that your application can use to connect to the service.

The connection string is in the form of the following:

Endpoint=<service_endpoint>;AccessKey=<access_key>;

Update Chat Room to Use Azure SignalR Service

Then, let's update the chat room sample to use the new service you just created.

Let's look at the key changes:

1. In Startup.cs, instead of calling AddSignalR() and UseSignalR(), you need to call AddAzureSignalR() and UseAzureSignalR() and pass in connection string to make the application connect to the service instead of hosting SignalR by itself.

   public void ConfigureServices(IServiceCollection services)
   {
       ...
       services.AddSignalR()
               .AddAzureSignalR();
   }
   
   public void Configure(IApplicationBuilder app)
   {
       ...
       app.UseAzureSignalR(routes => 
       { 
           routes.MapHub<Chat>("/chat"); 
       });
   }

   You also need to reference the service SDK before using these APIs. This is how that would look in your ChatRoom.csproj file:

   <PackageReference Include="Microsoft.Azure.SignalR" Version="1.0.0-*" />

Other than these changes, everything else remains the same, you can still use the hub interface you're already familiar with to write business logic.

Under the hood, an endpoint /chat/negotiate is exposed for negotiation by Azure SignalR Service SDK. It will return a special negotiation response when clients try to connect and redirect clients to service endpoint from the connection string. Read more details about the redirection at SignalR's Negotitation Protocol.

Now set the connection string in the Secret Manager tool for .NET Core, and run this app.

dotnet restore
dotnet user-secrets set Azure:SignalR:ConnectionString "<your connection string>"
dotnet run

When you open http://localhost:5000, you can see the application runs as usual, just instead of hosting a SignalR runtime by itself, it connects to the SignalR service running on Azure.

In this sample, you have learned how to use Azure SignalR Service to replace your self-hosted SignalR runtime. But you still need a web server to host your hub logic. In the next tutorial you'll learn how to use other Azure services to host your hub logic so you can get everything running in the cloud.