Connect to Azure SignalR Service

This page describes how consuming apps connect to an Azure SignalR Service resource that’s already modeled in your AppHost. For the AppHost API surface — adding a SignalR resource, service modes, emulator, and Bicep customization — see Azure SignalR Service hosting integration.

Azure SignalR Service acts as a proxy between hub servers (where Hub or Hub<T> types are hosted) and clients (browser or mobile apps using the SignalR client). The architecture differs from a direct database connection: the server never receives connections from clients directly — Azure SignalR Service routes all traffic.

Note

Aspire integrates at the hub server level, not the end-client level. The WithReference call injects the service endpoint into the server-side project so it can connect to Azure SignalR Service. End clients (browser apps, mobile apps) connect to hubs through normal SignalR client negotiation, not through Aspire.

Connection properties

When you reference an Azure SignalR Service resource from a consuming app, Aspire injects the following connection properties:

Property Name	Description
Uri	The endpoint URI for the SignalR service, with the format https://{host} in Azure (typically https://<resource-name>.service.signalr.net) or the emulator endpoint when running locally

Aspire exposes each property as an environment variable named [RESOURCE]_[PROPERTY]. For instance, the Uri property of a resource called signalr becomes SIGNALR_URI.

Additionally, Aspire sets ConnectionStrings__signalr (which maps to ConnectionStrings:signalr in .NET configuration) for use by the AddNamedAzureSignalR extension method in Default mode.

Example values:

SIGNALR_URI: https://my-signalr.service.signalr.net
ConnectionStrings__signalr: Endpoint=https://my-signalr.service.signalr.net;AuthType=azure.msitoken;...

When using the emulator locally, the connection string includes an AccessKey:

ConnectionStrings__signalr: Endpoint=http://localhost:8888;AccessKey=ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789;Version=1.0;

Connect from your app

Pick the language your consuming app is written in. Each example assumes your AppHost adds an Azure SignalR Service resource named signalr and references it from the consuming app.

C#

The recommended approach for C# hub server apps is the Microsoft.Azure.SignalR package. It integrates Azure SignalR Service directly into ASP.NET Core’s SignalR infrastructure and reads configuration injected by Aspire.

Default mode — hub server

In Default mode, your hub server project registers its hubs normally with Azure SignalR Service acting as the transport layer. Install the 📦 Microsoft.Azure.SignalR NuGet package:

.NET CLI

.NET CLI — Add Microsoft.Azure.SignalR package

dotnet add package Microsoft.Azure.SignalR

Program.cs (C# file-based app)

Program.cs

#:package Microsoft.Azure.SignalR@*

PackageReference (*.csproj)

XML — Add Microsoft.Azure.SignalR package reference

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

In Program.cs, chain AddNamedAzureSignalR onto AddSignalR:

C# — Program.cs

var builder = WebApplication.CreateBuilder(args);

builder.Services.AddSignalR()
    .AddNamedAzureSignalR("signalr");

var app = builder.Build();

app.MapHub<ChatHub>("/chat");

app.Run();

The AddNamedAzureSignalR method reads the connection string from ConnectionStrings:signalr, which Aspire injects as ConnectionStrings__signalr. The connection name must match the resource name used in your AppHost.

Note

If you’re using the Azure SignalR emulator, you cannot use AddNamedAzureSignalR. The emulator requires Serverless mode — see the Serverless mode section below.

Serverless mode

In Serverless mode, there is no hub server. Instead, apps communicate with Azure SignalR Service through the Management SDK. Install the 📦 Microsoft.Azure.SignalR.Management NuGet package:

.NET CLI

.NET CLI — Add Microsoft.Azure.SignalR.Management package

dotnet add package Microsoft.Azure.SignalR.Management

Program.cs (C# file-based app)

Program.cs

#:package Microsoft.Azure.SignalR.Management@*

PackageReference (*.csproj)

XML — Add Microsoft.Azure.SignalR.Management package reference

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

Register the ServiceManager using the Aspire-injected connection string and expose a /negotiate endpoint:

C# — Program.cs

var builder = WebApplication.CreateBuilder(args);

builder.Services.AddSingleton(sp =>
{
    return new ServiceManagerBuilder()
        .WithOptions(options =>
        {
            options.ConnectionString = builder.Configuration.GetConnectionString("signalr");
        })
        .BuildServiceManager();
});

var app = builder.Build();

app.MapPost("/negotiate", async (string? userId, ServiceManager sm, CancellationToken token) =>
{
    var context = await sm.CreateHubContextAsync("messages", token);

    var negotiateResponse = await context.NegotiateAsync(new NegotiationOptions
    {
        UserId = userId
    }, token);

    return Results.Json(negotiateResponse, new JsonSerializerOptions(JsonSerializerDefaults.Web)
    {
        DefaultIgnoreCondition = JsonIgnoreCondition.WhenWritingNull
    });
});

app.Run();

The /negotiate endpoint establishes a connection between the connecting client and the Azure SignalR Service. The ServiceHubContext is used to broadcast messages and manage connections to clients.

For more information, see Use Azure SignalR Management SDK.

Read environment variables in C#

To read the endpoint URI directly from the Aspire-injected environment variable:

C# — Program.cs

var endpoint = Environment.GetEnvironmentVariable("SIGNALR_URI");
// Use endpoint to configure the SignalR Service connection manually

Go

Azure SignalR Service doesn’t have a native Go server SDK, but you can communicate with it using the Azure SDK for Go and the SignalR REST API.

Note

Azure SignalR Service is primarily designed for server-side communication in .NET. Go servers typically interact with the service through the Management REST API to broadcast messages or manage connections.

Install the Azure Identity package for authentication:

Terminal

go get github.com/Azure/azure-sdk-for-go/sdk/azidentity

Read the Aspire-injected endpoint and send messages via REST API:

Go — main.go

package main

import (
    "bytes"
    "context"
    "encoding/json"
    "fmt"
    "net/http"
    "os"

    "github.com/Azure/azure-sdk-for-go/sdk/azidentity"
    "github.com/Azure/azure-sdk-for-go/sdk/azcore/policy"
)

func main() {
    // Read the Aspire-injected endpoint URI
    endpoint := os.Getenv("SIGNALR_URI")

    // Authenticate using managed identity (matches Aspire's default provisioning)
    cred, err := azidentity.NewDefaultAzureCredential(nil)
    if err != nil {
        panic(err)
    }

    ctx := context.Background()
    token, err := cred.GetToken(ctx, policy.TokenRequestOptions{
        Scopes: []string{"https://signalr.azure.com/.default"},
    })
    if err != nil {
        panic(err)
    }

    // Broadcast a message to all clients in a hub
    hubName := "messages"
    url := fmt.Sprintf("%s/api/v1/hubs/%s", endpoint, hubName)

    payload := map[string]interface{}{
        "target":    "newMessage",
        "arguments": []string{"Hello from Go"},
    }
    body, _ := json.Marshal(payload)

    req, _ := http.NewRequest("POST", url, bytes.NewBuffer(body))
    req.Header.Set("Authorization", "Bearer "+token.Token)
    req.Header.Set("Content-Type", "application/json")

    resp, err := http.DefaultClient.Do(req)
    if err != nil {
        panic(err)
    }
    defer resp.Body.Close()
}

For local development with the emulator, use the connection string format (SIGNALR_CONNECTIONSTRING) with an access key instead of managed identity. For more information, see Azure SignalR Service REST API.

Python

Azure SignalR Service doesn’t have a dedicated Python server SDK. Python apps interact with the service through the Management REST API or using the azure-messaging-webpubsubservice package for the Web PubSub protocol.

Note

The azure-messaging-webpubsubservice package targets Azure Web PubSub, which shares protocol concepts with Azure SignalR Service Serverless mode. For Azure SignalR Service specifically, use the REST API with managed identity.

Install the Azure Identity package:

Terminal

pip install azure-identity requests

Read the Aspire-injected endpoint and broadcast via REST API:

Python — app.py

import os
import requests
from azure.identity import DefaultAzureCredential

# Read the Aspire-injected endpoint URI
endpoint = os.getenv("SIGNALR_URI")

# Authenticate using managed identity (matches Aspire's default provisioning)
credential = DefaultAzureCredential()
token = credential.get_token("https://signalr.azure.com/.default")

hub_name = "messages"
url = f"{endpoint}/api/v1/hubs/{hub_name}"

headers = {
    "Authorization": f"Bearer {token.token}",
    "Content-Type": "application/json",
}
payload = {
    "target": "newMessage",
    "arguments": ["Hello from Python"],
}

response = requests.post(url, json=payload, headers=headers)
response.raise_for_status()

For local development with the emulator, construct the authorization header using the access key from the connection string instead of a bearer token. For more information, see Azure SignalR Service REST API.

TypeScript

The @microsoft/signalr package is the official TypeScript/JavaScript client for connecting to SignalR hubs from browsers or Node.js applications. This is a client-side library — it connects to the hub endpoint, not to the Azure SignalR Service endpoint directly.

Note

End clients (browsers, Node.js apps) connect to the hub server’s negotiate endpoint, which in turn connects to Azure SignalR Service. End clients don’t connect to Azure SignalR Service directly and don’t need the Aspire-injected endpoint. The Aspire-injected SIGNALR_URI is for the server that hosts the hub.

Install the package:

Terminal

npm install @microsoft/signalr

Connect to a hub using the negotiate endpoint of your hub server app:

TypeScript — index.ts

import * as signalR from '@microsoft/signalr';

// Connect to the hub server's negotiate endpoint (not Azure SignalR Service directly)
const connection = new signalR.HubConnectionBuilder()
    .withUrl("https://your-hub-server/chat")
    .withAutomaticReconnect()
    .build();

connection.on("newMessage", (user: string, message: string) => {
    console.log(`${user}: ${message}`);
});

await connection.start();
await connection.invoke("SendMessage", "user1", "Hello from TypeScript!");

For Node.js server-side scenarios where you need to broadcast messages using the Management REST API, read the Aspire-injected endpoint:

TypeScript — server.ts

import { DefaultAzureCredential } from '@azure/identity';

// Read the Aspire-injected endpoint URI
const endpoint = process.env.SIGNALR_URI;

const credential = new DefaultAzureCredential();
const tokenResponse = await credential.getToken("https://signalr.azure.com/.default");

const hubName = "messages";
const url = `${endpoint}/api/v1/hubs/${hubName}`;

const response = await fetch(url, {
    method: "POST",
    headers: {
        "Authorization": `Bearer ${tokenResponse.token}`,
        "Content-Type": "application/json",
    },
    body: JSON.stringify({
        target: "newMessage",
        arguments: ["Hello from TypeScript"],
    }),
});

Install the Azure Identity package:

Terminal

npm install @azure/identity

For more information, see Azure SignalR Service REST API and the @microsoft/signalr package.

Tip

If your app expects specific environment variable names different from the Aspire defaults, you can pass individual connection properties from the AppHost. See Customize provisioning infrastructure in the hosting integration reference.