azure-servicebus-dotnet

Author's original introduction

Azure Service Bus SDK for .NET. Enterprise messaging with queues, topics, subscriptions, and sessions. Use for reliable message delivery, pub/sub patterns, dead letter handling, and background processing. Triggers: "Service Bus", "ServiceBusClient", "ServiceBusSender", "ServiceBusReceiver", "ServiceBusProcessor", "message queue", "pub/sub .NET", "dead letter queue".

SkillPi interpretation

Tasks

azure-servicebus-dotnet

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Use the scope in the original author introduction.

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This azure-servicebus-dotnet package contains Microsoft Azure SDK documentation and examples, not a runtime-verified installer. Check SDK names/versions, tenant/subscription and actual endpoints; grant only task-specific least privilege. Never put administrator credentials or real secrets in samples, logs or commits. Connected cloud services may receive selected text, documents, audio, messages, logs or other input and incur charges; confirm scope, redaction and costs first. Ask the user to confirm each resource creation/update/deletion, key/access change or outbound message and test with disposable resources before production. Replace and verify placeholder endpoints and samples. SkillPi checked pinned source, complete attachments and static/antivirus evidence only; it did not run the SDK, verify service compatibility or authorize cloud access.

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Original author introduction preserved; Chinese is a corresponding translation. Examples were not run by SkillPi; versions, compatibility and outcomes are author claims.

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caution · Static evidence review; not a runtime safety guarantee.

This azure-servicebus-dotnet package contains Microsoft Azure SDK documentation and examples, not a runtime-verified installer. Check SDK names/versions, tenant/subscription and actual endpoints; grant only task-specific least privilege. Never put administrator credentials or real secrets in samples, logs or commits. Connected cloud services may receive selected text, documents, audio, messages, logs or other input and incur charges; confirm scope, redaction and costs first. Ask the user to confirm each resource creation/update/deletion, key/access change or outbound message and test with disposable resources before production. Replace and verify placeholder endpoints and samples. SkillPi checked pinned source, complete attachments and static/antivirus evidence only; it did not run the SDK, verify service compatibility or authorize cloud access.

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Original SKILL.md

---
name: azure-servicebus-dotnet
description: |
  Azure Service Bus SDK for .NET. Enterprise messaging with queues, topics, subscriptions, and sessions. Use for reliable message delivery, pub/sub patterns, dead letter handling, and background processing. Triggers: "Service Bus", "ServiceBusClient", "ServiceBusSender", "ServiceBusReceiver", "ServiceBusProcessor", "message queue", "pub/sub .NET", "dead letter queue".
license: MIT
metadata:
  author: Microsoft
  version: "1.0.0"
  package: Azure.Messaging.ServiceBus
---

# Azure.Messaging.ServiceBus (.NET)

Enterprise messaging SDK for reliable message delivery with queues, topics, subscriptions, and sessions.

## Installation

```bash
dotnet add package Azure.Messaging.ServiceBus
dotnet add package Azure.Identity
```

**Current Version**: v7.20.1 (stable)

## Environment Variables

```bash
AZURE_SERVICEBUS_FULLY_QUALIFIED_NAMESPACE=<namespace>.servicebus.windows.net  # Required: Service Bus fully qualified namespace
AZURE_TOKEN_CREDENTIALS=prod  # Required only if DefaultAzureCredential is used in production
AZURE_SERVICEBUS_CONNECTION_STRING=Endpoint=sb://...  # Alternative to Entra ID auth
```

## Authentication

### Microsoft Entra Token Credential

```csharp
using Azure.Identity;
using Azure.Messaging.ServiceBus;

string fullyQualifiedNamespace = "<namespace>.servicebus.windows.net";
// Local dev: DefaultAzureCredential. Production: set AZURE_TOKEN_CREDENTIALS=prod or AZURE_TOKEN_CREDENTIALS=<specific_credential>
var credential = new DefaultAzureCredential(
    DefaultAzureCredential.DefaultEnvironmentVariableName
);
// Or use a specific credential directly in production:
// See https://learn.microsoft.com/dotnet/api/overview/azure/identity-readme?view=azure-dotnet#credential-classes
// var credential = new ManagedIdentityCredential();
await using ServiceBusClient client = new(fullyQualifiedNamespace, credential);
```

### Connection String

```csharp
string connectionString = "<connection_string>";
await using ServiceBusClient client = new(connectionString);
```

### ASP.NET Core Dependency Injection

```csharp
services.AddAzureClients(builder =>
{
    builder.AddServiceBusClientWithNamespace("<namespace>.servicebus.windows.net");
    builder.UseCredential(new DefaultAzureCredential());
});
```

## Client Hierarchy

```
ServiceBusClient
├── CreateSender(queueOrTopicName)      → ServiceBusSender
├── CreateReceiver(queueName)           → ServiceBusReceiver
├── CreateReceiver(topicName, subName)  → ServiceBusReceiver
├── AcceptNextSessionAsync(queueName)   → ServiceBusSessionReceiver
├── CreateProcessor(queueName)          → ServiceBusProcessor
└── CreateSessionProcessor(queueName)   → ServiceBusSessionProcessor

ServiceBusAdministrationClient (separate client for CRUD)
```

## Core Workflows

### 1. Send Messages

```csharp
await using ServiceBusClient client = new(fullyQualifiedNamespace, new DefaultAzureCredential());
ServiceBusSender sender = client.CreateSender("my-queue");

// Single message
ServiceBusMessage message = new("Hello world!");
await sender.SendMessageAsync(message);

// Safe batching (recommended)
using ServiceBusMessageBatch batch = await sender.CreateMessageBatchAsync();
if (batch.TryAddMessage(new ServiceBusMessage("Message 1")))
{
    // Message added successfully
}
if (batch.TryAddMessage(new ServiceBusMessage("Message 2")))
{
    // Message added successfully
}
await sender.SendMessagesAsync(batch);
```

### 2. Receive Messages

```csharp
ServiceBusReceiver receiver = client.CreateReceiver("my-queue");

// Single message
ServiceBusReceivedMessage message = await receiver.ReceiveMessageAsync();
string body = message.Body.ToString();
Console.WriteLine(body);

// Complete the message (removes from queue)
await receiver.CompleteMessageAsync(message);

// Batch receive
IReadOnlyList<ServiceBusReceivedMessage> messages = await receiver.ReceiveMessagesAsync(maxMessages: 10);
foreach (var msg in messages)
{
    Console.WriteLine(msg.Body.ToString());
    await receiver.CompleteMessageAsync(msg);
}
```

### 3. Message Settlement

```csharp
// Complete - removes message from queue
await receiver.CompleteMessageAsync(message);

// Abandon - releases lock, message can be received again
await receiver.AbandonMessageAsync(message);

// Defer - prevents normal receive, use ReceiveDeferredMessageAsync
await receiver.DeferMessageAsync(message);

// Dead Letter - moves to dead letter subqueue
await receiver.DeadLetterMessageAsync(message, "InvalidFormat", "Message body was not valid JSON");
```

### 4. Background Processing with Processor

```csharp
ServiceBusProcessor processor = client.CreateProcessor("my-queue", new ServiceBusProcessorOptions
{
    AutoCompleteMessages = false,
    MaxConcurrentCalls = 2
});

processor.ProcessMessageAsync += async (args) =>
{
    try
    {
        string body = args.Message.Body.ToString();
        Console.WriteLine($"Received: {body}");
        await args.CompleteMessageAsync(args.Message);
    }
    catch (Exception ex)
    {
        Console.WriteLine($"Error processing: {ex.Message}");
        await args.AbandonMessageAsync(args.Message);
    }
};

processor.ProcessErrorAsync += (args) =>
{
    Console.WriteLine($"Error source: {args.ErrorSource}");
    Console.WriteLine($"Entity: {args.EntityPath}");
    Console.WriteLine($"Exception: {args.Exception}");
    return Task.CompletedTask;
};

await processor.StartProcessingAsync();
// ... application runs
await processor.StopProcessingAsync();
```

### 5. Sessions (Ordered Processing)

```csharp
// Send session message
ServiceBusMessage message = new("Hello")
{
    SessionId = "order-123"
};
await sender.SendMessageAsync(message);

// Receive from next available session
ServiceBusSessionReceiver receiver = await client.AcceptNextSessionAsync("my-queue");

// Or receive from specific session
ServiceBusSessionReceiver receiver = await client.AcceptSessionAsync("my-queue", "order-123");

// Session state management
await receiver.SetSessionStateAsync(new BinaryData("processing"));
BinaryData state = await receiver.GetSessionStateAsync();

// Renew session lock
await receiver.RenewSessionLockAsync();
```

### 6. Dead Letter Queue

```csharp
// Receive from dead letter queue
ServiceBusReceiver dlqReceiver = client.CreateReceiver("my-queue", new ServiceBusReceiverOptions
{
    SubQueue = SubQueue.DeadLetter
});

ServiceBusReceivedMessage dlqMessage = await dlqReceiver.ReceiveMessageAsync();

// Access dead letter metadata
string reason = dlqMessage.DeadLetterReason;
string description = dlqMessage.DeadLetterErrorDescription;
Console.WriteLine($"Dead letter reason: {reason} - {description}");
```

### 7. Topics and Subscriptions

```csharp
// Send to topic
ServiceBusSender topicSender = client.CreateSender("my-topic");
await topicSender.SendMessageAsync(new ServiceBusMessage("Broadcast message"));

// Receive from subscription
ServiceBusReceiver subReceiver = client.CreateReceiver("my-topic", "my-subscription");
var message = await subReceiver.ReceiveMessageAsync();
```

### 8. Administration (CRUD)

```csharp
var adminClient = new ServiceBusAdministrationClient(
    fullyQualifiedNamespace, 
    new DefaultAzureCredential());

// Create queue
var options = new CreateQueueOptions("my-queue")
{
    MaxDeliveryCount = 10,
    LockDuration = TimeSpan.FromSeconds(30),
    RequiresSession = true,
    DeadLetteringOnMessageExpiration = true
};
QueueProperties queue = await adminClient.CreateQueueAsync(options);

// Update queue
queue.LockDuration = TimeSpan.FromSeconds(60);
await adminClient.UpdateQueueAsync(queue);

// Create topic and subscription
await adminClient.CreateTopicAsync(new CreateTopicOptions("my-topic"));
await adminClient.CreateSubscriptionAsync(new CreateSubscriptionOptions("my-topic", "my-subscription"));

// Delete
await adminClient.DeleteQueueAsync("my-queue");
```

### 9. Cross-Entity Transactions

```csharp
var options = new ServiceBusClientOptions { EnableCrossEntityTransactions = true };
await using var client = new ServiceBusClient(connectionString, options);

ServiceBusReceiver receiverA = client.CreateReceiver("queueA");
ServiceBusSender senderB = client.CreateSender("queueB");

ServiceBusReceivedMessage receivedMessage = await receiverA.ReceiveMessageAsync();

using (var ts = new TransactionScope(TransactionScopeAsyncFlowOption.Enabled))
{
    await receiverA.CompleteMessageAsync(receivedMessage);
    await senderB.SendMessageAsync(new ServiceBusMessage("Forwarded"));
    ts.Complete();
}
```

## Key Types Reference

| Type | Purpose |
|------|---------|
| `ServiceBusClient` | Main entry point, manages connection |
| `ServiceBusSender` | Sends messages to queues/topics |
| `ServiceBusReceiver` | Receives messages from queues/subscriptions |
| `ServiceBusSessionReceiver` | Receives session messages |
| `ServiceBusProcessor` | Background message processing |
| `ServiceBusSessionProcessor` | Background session processing |
| `ServiceBusAdministrationClient` | CRUD for queues/topics/subscriptions |
| `ServiceBusMessage` | Message to send |
| `ServiceBusReceivedMessage` | Received message with metadata |
| `ServiceBusMessageBatch` | Batch of messages |

## Best Practices

1. **Use singletons** — Clients, senders, receivers, and processors are thread-safe
2. **Always dispose** — Use `await using` or call `DisposeAsync()`
3. **Dispose order** — Close senders/receivers/processors first, then client
4. **Use DefaultAzureCredential** — Prefer over connection strings for production
5. **Use processors for background work** — Handles lock renewal automatically
6. **Use safe batching** — `CreateMessageBatchAsync()` and `TryAddMessage()`
7. **Handle transient errors** — Use `ServiceBusException.Reason`
8. **Configure transport** — Use `AmqpWebSockets` if ports 5671/5672 are blocked
9. **Set appropriate lock duration** — Default is 30 seconds
10. **Use sessions for ordering** — FIFO within a session

## Error Handling

```csharp
try
{
    await sender.SendMessageAsync(message);
}
catch (ServiceBusException ex) when (ex.Reason == ServiceBusFailureReason.ServiceBusy)
{
    // Retry with backoff
}
catch (ServiceBusException ex)
{
    Console.WriteLine($"Service Bus Error: {ex.Reason} - {ex.Message}");
}
```

## Related SDKs

| SDK | Purpose | Install |
|-----|---------|---------|
| `Azure.Messaging.ServiceBus` | Service Bus (this SDK) | `dotnet add package Azure.Messaging.ServiceBus` |
| `Azure.Messaging.EventHubs` | Event streaming | `dotnet add package Azure.Messaging.EventHubs` |
| `Azure.Messaging.EventGrid` | Event routing | `dotnet add package Azure.Messaging.EventGrid` |

## Reference Links

| Resource | URL |
|----------|-----|
| NuGet Package | https://www.nuget.org/packages/Azure.Messaging.ServiceBus |
| API Reference | https://learn.microsoft.com/dotnet/api/azure.messaging.servicebus |
| GitHub Source | https://github.com/Azure/azure-sdk-for-net/tree/main/sdk/servicebus/Azure.Messaging.ServiceBus |
| Troubleshooting | https://github.com/Azure/azure-sdk-for-net/blob/main/sdk/servicebus/Azure.Messaging.ServiceBus/TROUBLESHOOTING.md |

Copyright and license notice

    MIT License

    Copyright (c) Microsoft Corporation.

    Permission is hereby granted, free of charge, to any person obtaining a copy
    of this software and associated documentation files (the "Software"), to deal
    in the Software without restriction, including without limitation the rights
    to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
    copies of the Software, and to permit persons to whom the Software is
    furnished to do so, subject to the following conditions:

    The above copyright notice and this permission notice shall be included in all
    copies or substantial portions of the Software.

    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
    IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
    FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
    AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
    LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
    OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
    SOFTWARE