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title Azure Service Bus Topics Quickstart With .NET
description This tutorial shows you how to send messages to Azure Service Bus topics and receive messages from topics subscriptions using the .NET programming language.
ms.topic quickstart
ms.tgt_pltfrm dotnet
ms.date 02/13/2026
ms.devlang csharp
ms.custom mode-api, passwordless-dotnet, devx-track-dotnet

Quickstart: Get started with Azure Service Bus topics and subscriptions (.NET)

This quickstart shows how to send messages to a Service Bus topic and receive messages from a subscription to that topic by using the Azure.Messaging.ServiceBus .NET library.

In this quickstart, you do the following steps:

  1. Create a Service Bus namespace, using the Azure portal.
  2. Create a Service Bus topic, using the Azure portal.
  3. Create a Service Bus subscription to that topic, using the Azure portal.
  4. Write a .NET console application to send a set of messages to the topic.
  5. Write a .NET console application to receive those messages from the subscription.

Note

This quickstart provides step-by-step instructions to implement a simple scenario of sending a batch of messages to a Service Bus topic and receiving those messages from a subscription of the topic. For more samples on other and advanced scenarios, see Service Bus .NET samples on GitHub.

  • This quickstart shows you two ways of connecting to Azure Service Bus: connection string and passwordless. The first option shows you how to use a connection string to connect to a Service Bus namespace. The second option shows you how to use your security principal in Microsoft Entra ID and the role-based access control (RBAC) to connect to a Service Bus namespace. You don't need to worry about having hard-coded connection string in your code or in a configuration file or in secure storage like Azure Key Vault. If you're new to Azure, you might find the connection string option easier to follow. We recommend using the passwordless option in real-world applications and production environments. For more information, see Authentication and authorization.

Prerequisites

If you're new to the service, see Service Bus overview before you do this quickstart.

  • Azure subscription. To use Azure services, including Azure Service Bus, you need a subscription. If you don't have an existing Azure account, you can sign up for a free trial.
  • Visual Studio 2022 or later. The sample application makes use of new features that were introduced in C# 10. You can still use the Service Bus client library with previous C# language versions, but the syntax might vary. To use the latest syntax, we recommend that you install .NET 6.0, or higher and set the language version to latest. If you're using Visual Studio, versions before Visual Studio 2022 aren't compatible with the tools needed to build C# 10 projects.

[!INCLUDE service-bus-create-namespace-portal]

[!INCLUDE service-bus-create-topic-subscription-portal]

[!INCLUDE service-bus-passwordless-template-tabbed]

Launch Visual Studio

Passwordless

You can authorize access to the service bus namespace using the following steps:

  1. Launch Visual Studio. If you see the Get started window, select the Continue without code link in the right pane.

  2. Select the Sign in button in the top right of Visual Studio.

    :::image type="content" source="./media/service-bus-dotnet-get-started-with-queues/azure-sign-button-visual-studio.png" alt-text="Screenshot of the button to sign in to Azure using Visual Studio.":::

  3. Sign-in using the Microsoft Entra account you assigned a role to previously.

    :::image type="content" source="..//storage/blobs/media/storage-quickstart-blobs-dotnet/sign-in-visual-studio-account-small.png" alt-text="Screenshot of the account selection dialog.":::

Connection String

Launch Visual Studio. If you see the Get started window, select the Continue without code link in the right pane.

Send messages to the topic

This section shows you how to create a .NET console application to send messages to a Service Bus topic.

Note

This quickstart provides step-by-step instructions to implement a simple scenario of sending a batch of messages to a Service Bus topic and receiving those messages from a subscription of the topic. For more samples on other and advanced scenarios, see Service Bus .NET samples on GitHub.

Create a console application

  1. In Visual Studio, select File -> New -> Project menu.
  2. On the Create a new project dialog box, do the following steps: If you don't see this dialog box, select File on the menu, select New, and then select Project.

    1. Select C# for the programming language.

    2. Select Console for the type of the application.

    3. Select Console App from the results list.

    4. Then, select Next.

      :::image type="content" source="./media/service-bus-dotnet-get-started-with-queues/new-send-project.png" alt-text="Screenshot of the Create a new project dialog box with C# and Console selected.":::

  3. Enter TopicSender for the project name, ServiceBusTopicQuickStart for the solution name, and then select Next.
  4. On the Additional information page, select Create to create the solution and the project.

Add the NuGet packages to the project

Passwordless

  1. Select Tools > NuGet Package Manager > Package Manager Console from the menu.

  2. Run the following command to install the Azure.Messaging.ServiceBus NuGet package.

    Install-Package Azure.Messaging.ServiceBus

  3. Run the following command to install the Azure.Identity NuGet package.

    Install-Package Azure.Identity

Connection String

  1. Select Tools > NuGet Package Manager > Package Manager Console from the menu.

  2. Run the following command to install the Azure.Messaging.ServiceBus NuGet package:

    Install-Package Azure.Messaging.ServiceBus

Add code to send messages to the topic

  1. Replace the contents of Program.cs with the following code. The important steps are outlined in this section, with additional information in the code comments.

    Passwordless

    1. Creates a ServiceBusClient object using the DefaultAzureCredential object. DefaultAzureCredential automatically discovers and uses the credentials of your Visual Studio sign-in to authenticate to Azure Service Bus.
    2. Invokes the CreateSender method on the ServiceBusClient object to create a ServiceBusSender object for the specific Service Bus topic.
    3. Creates a ServiceBusMessageBatch object by using the ServiceBusSender.CreateMessageBatchAsync.
    4. Add messages to the batch using the ServiceBusMessageBatch.TryAddMessage.
    5. Sends the batch of messages to the Service Bus topic using the ServiceBusSender.SendMessagesAsync method.

    [!IMPORTANT] Update placeholder values (<NAMESPACE-NAME> and <TOPIC-NAME>) in the code snippet with names of your Service Bus namespace and topic.

    using System.Threading.Tasks;
using Azure.Messaging.ServiceBus;
using Azure.Identity;

// the client that owns the connection and can be used to create senders and receivers
ServiceBusClient client;

// the sender used to publish messages to the topic
ServiceBusSender sender;

// number of messages to be sent to the topic
const int numOfMessages = 3;

// The Service Bus client types are safe to cache and use as a singleton for the lifetime
// of the application, which is best practice when messages are being published or read
// regularly.

//TODO: Replace the "<NAMESPACE-NAME>" and "<TOPIC-NAME>" placeholders.
client = new ServiceBusClient(
    "<NAMESPACE-NAME>.servicebus.windows.net",
    new DefaultAzureCredential());
sender = client.CreateSender("<TOPIC-NAME>");

// create a batch 
using ServiceBusMessageBatch messageBatch = await sender.CreateMessageBatchAsync();

for (int i = 1; i <= numOfMessages; i++)
{
    // try adding a message to the batch
    if (!messageBatch.TryAddMessage(new ServiceBusMessage($"Message {i}")))
    {
        // if it is too large for the batch
        throw new Exception($"The message {i} is too large to fit in the batch.");
    }
}

try
{
    // Use the producer client to send the batch of messages to the Service Bus topic
    await sender.SendMessagesAsync(messageBatch);
    Console.WriteLine($"A batch of {numOfMessages} messages has been published to the topic.");
}
finally
{
    // Calling DisposeAsync on client types is required to ensure that network
    // resources and other unmanaged objects are properly cleaned up.
    await sender.DisposeAsync();
    await client.DisposeAsync();
}

Console.WriteLine("Press any key to end the application");
Console.ReadKey();

    Connection String

    [!IMPORTANT] Update placeholder values (<NAMESPACE-CONNECTION-STRING> and <TOPIC-NAME>) in the code snippet with actual values you noted down earlier.

    1. Creates a ServiceBusClient object using the connection string to the namespace.
    2. Invokes the CreateSender method on the ServiceBusClient object to create a ServiceBusSender object for the specific Service Bus topic.
    3. Creates a ServiceBusMessageBatch object by using the ServiceBusSender.CreateMessageBatchAsync.
    4. Add messages to the batch using the ServiceBusMessageBatch.TryAddMessage.
    5. Sends the batch of messages to the Service Bus topic using the ServiceBusSender.SendMessagesAsync method.
    using System.Threading.Tasks;
using Azure.Messaging.ServiceBus;

// the client that owns the connection and can be used to create senders and receivers
ServiceBusClient client;

// the sender used to publish messages to the topic
ServiceBusSender sender;

// number of messages to be sent to the topic
const int numOfMessages = 3;

// The Service Bus client types are safe to cache and use as a singleton for the lifetime
// of the application, which is best practice when messages are being published or read
// regularly.
//TODO: Replace the "<NAMESPACE-CONNECTION-STRING>" and "<TOPIC-NAME>" placeholders.
client = new ServiceBusClient("<NAMESPACE-CONNECTION-STRING>");
sender = client.CreateSender("<TOPIC-NAME>");

// create a batch 
using ServiceBusMessageBatch messageBatch = await sender.CreateMessageBatchAsync();

for (int i = 1; i <= numOfMessages; i++)
{
    // try adding a message to the batch
    if (!messageBatch.TryAddMessage(new ServiceBusMessage($"Message {i}")))
    {
        // if it is too large for the batch
        throw new Exception($"The message {i} is too large to fit in the batch.");
    }
}

try
{
    // Use the producer client to send the batch of messages to the Service Bus topic
    await sender.SendMessagesAsync(messageBatch);
    Console.WriteLine($"A batch of {numOfMessages} messages has been published to the topic.");
}
finally
{
    // Calling DisposeAsync on client types is required to ensure that network
    // resources and other unmanaged objects are properly cleaned up.
    await sender.DisposeAsync();
    await client.DisposeAsync();
}

Console.WriteLine("Press any key to end the application");
Console.ReadKey();

  2. Build the project, and ensure that there are no errors.

  3. Run the program and wait for the confirmation message.

    A batch of 3 messages has been published to the topic

    [!IMPORTANT] In most cases, it takes a minute or two for the role assignment to propagate in Azure. In rare cases, it might take up to eight minutes. If you receive authentication errors when you first run your code, wait a few moments and try again.

  4. In the Azure portal, follow these steps:

    1. Navigate to your Service Bus namespace.

    2. On the Overview page, in the bottom-middle pane, switch to the Topics tab, and select the Service Bus topic. In the following example, it's mytopic.

      :::image type="content" source="./media/service-bus-dotnet-how-to-use-topics-subscriptions/select-topic.png" alt-text="Screenshot of selecting a topic.":::

    3. On the Service Bus Topic page, In the Messages chart in the bottom Metrics section, you can see that there are three incoming messages for the topic. If you don't see the value, wait for a few minutes, and refresh the page to see the updated chart.

      :::image type="content" source="./media/service-bus-dotnet-how-to-use-topics-subscriptions/sent-messages-essentials.png" alt-text="Screenshot of messages sent to the topic." lightbox="./media/service-bus-dotnet-how-to-use-topics-subscriptions/sent-messages-essentials.png":::

    4. Select the subscription in the bottom pane. In the following example, it's S1. On the Service Bus Subscription page, you see the Active message count as 3. The subscription has received the three messages that you sent to the topic, but no receiver has picked them yet.

      :::image type="content" source="./media/service-bus-dotnet-how-to-use-topics-subscriptions/subscription-page.png" alt-text="Screenshot of messages received at the subscription." lightbox="./media/service-bus-dotnet-how-to-use-topics-subscriptions/subscription-page.png":::

Receive messages from a subscription

In this section, you create a .NET console application that receives messages from the subscription to the Service Bus topic.

Note

This quickstart provides step-by-step instructions to implement a simple scenario of sending a batch of messages to a Service Bus topic and receiving those messages from a subscription of the topic. For more samples on other and advanced scenarios, see Service Bus .NET samples on GitHub.

Create a project for the receiver

  1. In the Solution Explorer window, right-click the ServiceBusTopicQuickStart solution, point to Add, and select New Project.
  2. Select Console application, and select Next.
  3. Enter SubscriptionReceiver for the Project name, and select Next.
  4. On the Additional information page, select Create.
  5. In the Solution Explorer window, right-click SubscriptionReceiver, and select Set as a Startup Project.

Add the NuGet packages to the project

Passwordless

  1. Select Tools > NuGet Package Manager > Package Manager Console from the menu.

  2. Select SubscriptionReceiver for Default project drop-down list.

  3. Run the following command to install the Azure.Messaging.ServiceBus NuGet package.

    Install-Package Azure.Messaging.ServiceBus

  4. Run the following command to install the Azure.Identity NuGet package.

    Install-Package Azure.Identity

Connection String

  1. Select Tools > NuGet Package Manager > Package Manager Console from the menu.

  2. Run the following command to install the Azure.Messaging.ServiceBus NuGet package:

    Install-Package Azure.Messaging.ServiceBus

Add code to receive messages from the subscription

In this section, you add code to retrieve messages from the subscription.

  1. Replace the existing contents of Program.cs with the following properties and methods:

    Passwordless

    using System.Threading.Tasks;
using Azure.Messaging.ServiceBus;
using Azure.Identity;

// the client that owns the connection and can be used to create senders and receivers
ServiceBusClient client;

// the processor that reads and processes messages from the subscription
ServiceBusProcessor processor;    

// handle received messages
async Task MessageHandler(ProcessMessageEventArgs args)
{
    string body = args.Message.Body.ToString();
    Console.WriteLine($"Received: {body} from subscription.");

    // complete the message. messages is deleted from the subscription. 
    await args.CompleteMessageAsync(args.Message);
}

// handle any errors when receiving messages
Task ErrorHandler(ProcessErrorEventArgs args)
{
    Console.WriteLine(args.Exception.ToString());
    return Task.CompletedTask;
}

    Connection String

    [!IMPORTANT] Update placeholder values (<TOPIC-SUBSCRIPTION-NAME>) in the code snippet with names of the topic and the subscription.

    using System.Threading.Tasks;
using Azure.Messaging.ServiceBus;

// the client that owns the connection and can be used to create senders and receivers
ServiceBusClient client;

// the processor that reads and processes messages from the subscription
ServiceBusProcessor processor;    

// handle received messages
async Task MessageHandler(ProcessMessageEventArgs args)
{
    // TODO: Replace the <TOPIC-SUBSCRIPTION-NAME> placeholder
    string body = args.Message.Body.ToString();
    Console.WriteLine($"Received: {body} from subscription: <TOPIC-SUBSCRIPTION-NAME>");

    // complete the message. messages is deleted from the subscription. 
    await args.CompleteMessageAsync(args.Message);
}

// handle any errors when receiving messages
Task ErrorHandler(ProcessErrorEventArgs args)
{
    Console.WriteLine(args.Exception.ToString());
    return Task.CompletedTask;
}

  2. Append the following code to the end of Program.cs.

    Passwordless

    • Creates a ServiceBusClient object using the DefaultAzureCredential object. DefaultAzureCredential automatically discovers and uses the credentials of your Visual Studio sign-in to authenticate to Azure Service Bus.
    • Invokes the CreateProcessor method on the ServiceBusClient object to create a ServiceBusProcessor object for the specified Service Bus topic.
    • Specifies handlers for the ProcessMessageAsync and ProcessErrorAsync events of the ServiceBusProcessor object.
    • Starts processing messages by invoking the StartProcessingAsync on the ServiceBusProcessor object.
    • When user presses a key to end the processing, invokes the StopProcessingAsync on the ServiceBusProcessor object.

    [!IMPORTANT] Update placeholder values (<NAMESPACE-NAME>, <TOPIC-NAME>, <SUBSCRIPTION-NAME>) in the code snippet with names of your Service Bus namespace, topic, and subscription.

    For more information, see code comments.

    // The Service Bus client types are safe to cache and use as a singleton for the lifetime
// of the application, which is best practice when messages are being published or read
// regularly.
//
// Create the clients that we'll use for sending and processing messages.
// TODO: Replace the <NAMESPACE-NAME> placeholder
client = new ServiceBusClient(
    "<NAMESPACE-NAME>.servicebus.windows.net",
    new DefaultAzureCredential());

// create a processor that we can use to process the messages
// TODO: Replace the <TOPIC-NAME> and <SUBSCRIPTION-NAME> placeholders
processor = client.CreateProcessor("<TOPIC-NAME>", "<SUBSCRIPTION-NAME>", new ServiceBusProcessorOptions());

try
{
    // add handler to process messages
    processor.ProcessMessageAsync += MessageHandler;

    // add handler to process any errors
    processor.ProcessErrorAsync += ErrorHandler;

    // start processing 
    await processor.StartProcessingAsync();

    Console.WriteLine("Wait for a minute and then press any key to end the processing");
    Console.ReadKey();

    // stop processing 
    Console.WriteLine("\nStopping the receiver...");
    await processor.StopProcessingAsync();
    Console.WriteLine("Stopped receiving messages");
}
finally
{
    // Calling DisposeAsync on client types is required to ensure that network
    // resources and other unmanaged objects are properly cleaned up.
    await processor.DisposeAsync();
    await client.DisposeAsync();
}

    Connection String

    [!IMPORTANT] Update placeholder values (<NAMESPACE-CONNECTION-STRING>, <TOPIC-NAME>, <SUBSCRIPTION-NAME>) in the code snippet with actual values you noted down earlier.

    For more information, see code comments.

    // The Service Bus client types are safe to cache and use as a singleton for the lifetime
// of the application, which is best practice when messages are being published or read
// regularly.
//
// Create the clients that we'll use for sending and processing messages.
// TODO: Replace the <NAMESPACE-CONNECTION-STRING> placeholder
client = new ServiceBusClient("<NAMESPACE-CONNECTION-STRING>");

// create a processor that we can use to process the messages
// TODO: Replace the <TOPIC-NAME> and <SUBSCRIPTION-NAME> placeholders
processor = client.CreateProcessor("<TOPIC-NAME>", "<SUBSCRIPTION-NAME>", new ServiceBusProcessorOptions());

try
{
    // add handler to process messages
    processor.ProcessMessageAsync += MessageHandler;

    // add handler to process any errors
    processor.ProcessErrorAsync += ErrorHandler;

    // start processing 
    await processor.StartProcessingAsync();

    Console.WriteLine("Wait for a minute and then press any key to end the processing");
    Console.ReadKey();

    // stop processing 
    Console.WriteLine("\nStopping the receiver...");
    await processor.StopProcessingAsync();
    Console.WriteLine("Stopped receiving messages");
}
finally
{
    // Calling DisposeAsync on client types is required to ensure that network
    // resources and other unmanaged objects are properly cleaned up.
    await processor.DisposeAsync();
    await client.DisposeAsync();
}

  3. Here's what your Program.cs should look like:

    Passwordless

    using System;
using System.Threading.Tasks;
using Azure.Messaging.ServiceBus;
using Azure.Identity;

// the client that owns the connection and can be used to create senders and receivers
ServiceBusClient client;

// the processor that reads and processes messages from the subscription
ServiceBusProcessor processor;

// handle received messages
async Task MessageHandler(ProcessMessageEventArgs args)
{
    string body = args.Message.Body.ToString();
    Console.WriteLine($"Received: {body} from subscription.");

    // complete the message. messages is deleted from the subscription. 
    await args.CompleteMessageAsync(args.Message);
}

// handle any errors when receiving messages
Task ErrorHandler(ProcessErrorEventArgs args)
{
    Console.WriteLine(args.Exception.ToString());
    return Task.CompletedTask;
}

// The Service Bus client types are safe to cache and use as a singleton for the lifetime
// of the application, which is best practice when messages are being published or read
// regularly.
//
// Create the clients that we'll use for sending and processing messages.
// TODO: Replace the <NAMESPACE-NAME> placeholder
client = new ServiceBusClient(
    "<NAMESPACE-NAME>.servicebus.windows.net",
    new DefaultAzureCredential());

// create a processor that we can use to process the messages
// TODO: Replace the <TOPIC-NAME> and <SUBSCRIPTION-NAME> placeholders
processor = client.CreateProcessor("<TOPIC-NAME>", "<SUBSCRIPTION-NAME>", new ServiceBusProcessorOptions());

try
{
    // add handler to process messages
    processor.ProcessMessageAsync += MessageHandler;

    // add handler to process any errors
    processor.ProcessErrorAsync += ErrorHandler;

    // start processing 
    await processor.StartProcessingAsync();

    Console.WriteLine("Wait for a minute and then press any key to end the processing");
    Console.ReadKey();

    // stop processing 
    Console.WriteLine("\nStopping the receiver...");
    await processor.StopProcessingAsync();
    Console.WriteLine("Stopped receiving messages");
}
finally
{
    // Calling DisposeAsync on client types is required to ensure that network
    // resources and other unmanaged objects are properly cleaned up.
    await processor.DisposeAsync();
    await client.DisposeAsync();
}

    Connection String

    using System;
using System.Threading.Tasks;
using Azure.Messaging.ServiceBus;

// the client that owns the connection and can be used to create senders and receivers
ServiceBusClient client;

// the processor that reads and processes messages from the subscription
ServiceBusProcessor processor;

// handle received messages
async Task MessageHandler(ProcessMessageEventArgs args)
{
    string body = args.Message.Body.ToString();
    Console.WriteLine($"Received: {body} from subscription.");

    // complete the message. messages is deleted from the subscription. 
    await args.CompleteMessageAsync(args.Message);
}

// handle any errors when receiving messages
Task ErrorHandler(ProcessErrorEventArgs args)
{
    Console.WriteLine(args.Exception.ToString());
    return Task.CompletedTask;
}

// The Service Bus client types are safe to cache and use as a singleton for the lifetime
// of the application, which is best practice when messages are being published or read
// regularly.
//
// Create the clients that we'll use for sending and processing messages.
// TODO: Replace the <NAMESPACE-CONNECTION-STRING> placeholder
client = new ServiceBusClient("<NAMESPACE-CONNECTION-STRING>");

// create a processor that we can use to process the messages
// TODO: Replace the <TOPIC-NAME> and <SUBSCRIPTION-NAME> placeholders
processor = client.CreateProcessor("<TOPIC-NAME>", "<SUBSCRIPTION-NAME>", new ServiceBusProcessorOptions());

try
{
    // add handler to process messages
    processor.ProcessMessageAsync += MessageHandler;

    // add handler to process any errors
    processor.ProcessErrorAsync += ErrorHandler;

    // start processing 
    await processor.StartProcessingAsync();

    Console.WriteLine("Wait for a minute and then press any key to end the processing");
    Console.ReadKey();

    // stop processing 
    Console.WriteLine("\nStopping the receiver...");
    await processor.StopProcessingAsync();
    Console.WriteLine("Stopped receiving messages");
}
finally
{
    // Calling DisposeAsync on client types is required to ensure that network
    // resources and other unmanaged objects are properly cleaned up.
    await processor.DisposeAsync();
    await client.DisposeAsync();
}

  4. Build the project, and ensure that there are no errors.

  5. Run the receiver application. You should see the received messages. Press any key to stop the receiver and the application.

    Wait for a minute and then press any key to end the processing
Received: Message 1 from subscription: S1
Received: Message 2 from subscription: S1
Received: Message 3 from subscription: S1

Stopping the receiver...
Stopped receiving messages

  6. Check the portal again.

    • On the Service Bus Topic page, in the Messages chart, you see three incoming messages and three outgoing messages. If you don't see these numbers, wait for a few minutes, and refresh the page to see the updated chart.

      :::image type="content" source="./media/service-bus-dotnet-how-to-use-topics-subscriptions/messages-size-final.png" alt-text="Screenshot of messages sent and received." lightbox="./media/service-bus-dotnet-how-to-use-topics-subscriptions/messages-size-final.png":::

    • On the Service Bus Subscription page, you see the Active message count as zero. It's because a receiver has received messages from this subscription and completed the messages.

      :::image type="content" source="./media/service-bus-dotnet-how-to-use-topics-subscriptions/subscription-page-final.png" alt-text="Screenshot of the active message count at the subscription at the end." lightbox="./media/service-bus-dotnet-how-to-use-topics-subscriptions/subscription-page-final.png":::

Related content

See the following documentation and samples: