Azure Service Bus trigger for Azure Functions

Article
06/27/2024

Use the Service Bus trigger to respond to messages from a Service Bus queue or topic. Starting with extension version 3.1.0, you can trigger on a session-enabled queue or topic.

For information on setup and configuration details, see the overview.

Service Bus scaling decisions for the Consumption and Premium plans are made based on target-based scaling. For more information, see Target-based scaling.

Important

This article uses tabs to support multiple versions of the Node.js programming model. The v4 model is currently in preview and is designed to have a more flexible and intuitive experience for JavaScript and TypeScript developers. Learn more about the differences between v3 and v4 in the upgrade guide.

Azure Functions supports two programming models for Python. The way that you define your bindings depends on your chosen programming model.

The Python v2 programming model lets you define bindings using decorators directly in your Python function code. For more information, see the Python developer guide.

This article supports both programming models.

Example

A C# function can be created using one of the following C# modes:

In-process class library: compiled C# function that runs in the same process as the Functions runtime.
Isolated process class library: compiled C# function that runs in a process isolated from the runtime. Isolated process is required to support C# functions running on .NET 5.0.
C# script: used primarily when creating C# functions in the Azure portal.

Important

Support will end for the in-process model on November 10, 2026. We highly recommend that you migrate your apps to the isolated worker model for full support.

Isolated worker model
In-process model

This code defines and initializes the ILogger:

// Copyright (c) .NET Foundation. All rights reserved.
// Licensed under the MIT License. See License.txt in the project root for license information.

using System;
using System.Threading.Tasks;
using Azure.Messaging.ServiceBus;
using Microsoft.Azure.Functions.Worker;
using Microsoft.Extensions.Logging;

namespace SampleApp
{
    /// <summary>
    /// Samples demonstrating binding to the <see cref="ServiceBusReceivedMessage"/> type.
    /// </summary>
    public class ServiceBusReceivedMessageFunctions
    {
        //<docsnippet_servicebusmessage_createlogger>
        private readonly ILogger<ServiceBusReceivedMessageFunctions> _logger;

        public ServiceBusReceivedMessageFunctions(ILogger<ServiceBusReceivedMessageFunctions> logger)
        {
            _logger = logger;
        }
        //</docsnippet_servicebusmessage_createlogger>
        /// <summary>
        /// This function demonstrates binding to a single <see cref="ServiceBusReceivedMessage"/>.
        /// </summary>
        //<docsnippet_servicebus_readmessage>
        [Function(nameof(ServiceBusReceivedMessageFunction))]
        [ServiceBusOutput("outputQueue", Connection = "ServiceBusConnection")]
        public string ServiceBusReceivedMessageFunction(
            [ServiceBusTrigger("queue", Connection = "ServiceBusConnection")] ServiceBusReceivedMessage message)
        {
            _logger.LogInformation("Message ID: {id}", message.MessageId);
            _logger.LogInformation("Message Body: {body}", message.Body);
            _logger.LogInformation("Message Content-Type: {contentType}", message.ContentType);

            var outputMessage = $"Output message created at {DateTime.Now}";
            return outputMessage;
        }
        //</docsnippet_servicebus_readmessage>
        /// <summary>
        /// This function demonstrates binding to an array of <see cref="ServiceBusReceivedMessage"/>.
        /// Note that when doing so, you must also set the <see cref="ServiceBusTriggerAttribute.IsBatched"/> property
        /// to <value>true</value>.
        /// </summary>
        //<docsnippet_servicebus_readbatch>
        [Function(nameof(ServiceBusReceivedMessageBatchFunction))]
        public void ServiceBusReceivedMessageBatchFunction(
            [ServiceBusTrigger("queue", Connection = "ServiceBusConnection", IsBatched = true)] ServiceBusReceivedMessage[] messages)
        {
            foreach (ServiceBusReceivedMessage message in messages)
            {
                _logger.LogInformation("Message ID: {id}", message.MessageId);
                _logger.LogInformation("Message Body: {body}", message.Body);
                _logger.LogInformation("Message Content-Type: {contentType}", message.ContentType);
            }
        }
        //</docsnippet_servicebus_readbatch>
        /// <summary>
        /// This functions demonstrates that it is possible to bind to both the ServiceBusReceivedMessage and any of the supported binding contract
        /// properties at the same time. If attempting this, the ServiceBusReceivedMessage must be the first parameter. There is not
        /// much benefit to doing this as all of the binding contract properties are available as properties on the ServiceBusReceivedMessage.
        /// </summary>
        [Function(nameof(ServiceBusReceivedMessageWithStringProperties))]
        public void ServiceBusReceivedMessageWithStringProperties(
            [ServiceBusTrigger("queue", Connection = "ServiceBusConnection")]
            ServiceBusReceivedMessage message, string messageId, int deliveryCount)
        {
            // The MessageId property and the messageId parameter are the same.
            _logger.LogInformation("Message ID: {id}", message.MessageId);
            _logger.LogInformation("Message ID: {id}", messageId);

            // Similarly the DeliveryCount property and the deliveryCount parameter are the same.
            _logger.LogInformation("Delivery Count: {count}", message.DeliveryCount);
            _logger.LogInformation("Delivery Count: {count}", deliveryCount);
        }
        //<docsnippet_servicebus_message_actions>
        [Function(nameof(ServiceBusMessageActionsFunction))]
        public async Task ServiceBusMessageActionsFunction(
            [ServiceBusTrigger("queue", Connection = "ServiceBusConnection", AutoCompleteMessages = false)]
            ServiceBusReceivedMessage message,
            ServiceBusMessageActions messageActions)
        {
            _logger.LogInformation("Message ID: {id}", message.MessageId);
            _logger.LogInformation("Message Body: {body}", message.Body);
            _logger.LogInformation("Message Content-Type: {contentType}", message.ContentType);

            // Complete the message
            await messageActions.CompleteMessageAsync(message);
        }
        //</docsnippet_servicebus_message_actions>
    }
}

This example shows a C# function that receives a single Service Bus queue message and writes it to the logs:

// Copyright (c) .NET Foundation. All rights reserved.
// Licensed under the MIT License. See License.txt in the project root for license information.

using System;
using System.Threading.Tasks;
using Azure.Messaging.ServiceBus;
using Microsoft.Azure.Functions.Worker;
using Microsoft.Extensions.Logging;

namespace SampleApp
{
    /// <summary>
    /// Samples demonstrating binding to the <see cref="ServiceBusReceivedMessage"/> type.
    /// </summary>
    public class ServiceBusReceivedMessageFunctions
    {
        //<docsnippet_servicebusmessage_createlogger>
        private readonly ILogger<ServiceBusReceivedMessageFunctions> _logger;

        public ServiceBusReceivedMessageFunctions(ILogger<ServiceBusReceivedMessageFunctions> logger)
        {
            _logger = logger;
        }
        //</docsnippet_servicebusmessage_createlogger>
        /// <summary>
        /// This function demonstrates binding to a single <see cref="ServiceBusReceivedMessage"/>.
        /// </summary>
        //<docsnippet_servicebus_readmessage>
        [Function(nameof(ServiceBusReceivedMessageFunction))]
        [ServiceBusOutput("outputQueue", Connection = "ServiceBusConnection")]
        public string ServiceBusReceivedMessageFunction(
            [ServiceBusTrigger("queue", Connection = "ServiceBusConnection")] ServiceBusReceivedMessage message)
        {
            _logger.LogInformation("Message ID: {id}", message.MessageId);
            _logger.LogInformation("Message Body: {body}", message.Body);
            _logger.LogInformation("Message Content-Type: {contentType}", message.ContentType);

            var outputMessage = $"Output message created at {DateTime.Now}";
            return outputMessage;
        }
        //</docsnippet_servicebus_readmessage>
        /// <summary>
        /// This function demonstrates binding to an array of <see cref="ServiceBusReceivedMessage"/>.
        /// Note that when doing so, you must also set the <see cref="ServiceBusTriggerAttribute.IsBatched"/> property
        /// to <value>true</value>.
        /// </summary>
        //<docsnippet_servicebus_readbatch>
        [Function(nameof(ServiceBusReceivedMessageBatchFunction))]
        public void ServiceBusReceivedMessageBatchFunction(
            [ServiceBusTrigger("queue", Connection = "ServiceBusConnection", IsBatched = true)] ServiceBusReceivedMessage[] messages)
        {
            foreach (ServiceBusReceivedMessage message in messages)
            {
                _logger.LogInformation("Message ID: {id}", message.MessageId);
                _logger.LogInformation("Message Body: {body}", message.Body);
                _logger.LogInformation("Message Content-Type: {contentType}", message.ContentType);
            }
        }
        //</docsnippet_servicebus_readbatch>
        /// <summary>
        /// This functions demonstrates that it is possible to bind to both the ServiceBusReceivedMessage and any of the supported binding contract
        /// properties at the same time. If attempting this, the ServiceBusReceivedMessage must be the first parameter. There is not
        /// much benefit to doing this as all of the binding contract properties are available as properties on the ServiceBusReceivedMessage.
        /// </summary>
        [Function(nameof(ServiceBusReceivedMessageWithStringProperties))]
        public void ServiceBusReceivedMessageWithStringProperties(
            [ServiceBusTrigger("queue", Connection = "ServiceBusConnection")]
            ServiceBusReceivedMessage message, string messageId, int deliveryCount)
        {
            // The MessageId property and the messageId parameter are the same.
            _logger.LogInformation("Message ID: {id}", message.MessageId);
            _logger.LogInformation("Message ID: {id}", messageId);

            // Similarly the DeliveryCount property and the deliveryCount parameter are the same.
            _logger.LogInformation("Delivery Count: {count}", message.DeliveryCount);
            _logger.LogInformation("Delivery Count: {count}", deliveryCount);
        }
        //<docsnippet_servicebus_message_actions>
        [Function(nameof(ServiceBusMessageActionsFunction))]
        public async Task ServiceBusMessageActionsFunction(
            [ServiceBusTrigger("queue", Connection = "ServiceBusConnection", AutoCompleteMessages = false)]
            ServiceBusReceivedMessage message,
            ServiceBusMessageActions messageActions)
        {
            _logger.LogInformation("Message ID: {id}", message.MessageId);
            _logger.LogInformation("Message Body: {body}", message.Body);
            _logger.LogInformation("Message Content-Type: {contentType}", message.ContentType);

            // Complete the message
            await messageActions.CompleteMessageAsync(message);
        }
        //</docsnippet_servicebus_message_actions>
    }
}

This example shows a C# function that receives multiple Service Bus queue messages in a single batch and writes each to the logs:

// Copyright (c) .NET Foundation. All rights reserved.
// Licensed under the MIT License. See License.txt in the project root for license information.

using System;
using System.Threading.Tasks;
using Azure.Messaging.ServiceBus;
using Microsoft.Azure.Functions.Worker;
using Microsoft.Extensions.Logging;

namespace SampleApp
{
    /// <summary>
    /// Samples demonstrating binding to the <see cref="ServiceBusReceivedMessage"/> type.
    /// </summary>
    public class ServiceBusReceivedMessageFunctions
    {
        //<docsnippet_servicebusmessage_createlogger>
        private readonly ILogger<ServiceBusReceivedMessageFunctions> _logger;

        public ServiceBusReceivedMessageFunctions(ILogger<ServiceBusReceivedMessageFunctions> logger)
        {
            _logger = logger;
        }
        //</docsnippet_servicebusmessage_createlogger>
        /// <summary>
        /// This function demonstrates binding to a single <see cref="ServiceBusReceivedMessage"/>.
        /// </summary>
        //<docsnippet_servicebus_readmessage>
        [Function(nameof(ServiceBusReceivedMessageFunction))]
        [ServiceBusOutput("outputQueue", Connection = "ServiceBusConnection")]
        public string ServiceBusReceivedMessageFunction(
            [ServiceBusTrigger("queue", Connection = "ServiceBusConnection")] ServiceBusReceivedMessage message)
        {
            _logger.LogInformation("Message ID: {id}", message.MessageId);
            _logger.LogInformation("Message Body: {body}", message.Body);
            _logger.LogInformation("Message Content-Type: {contentType}", message.ContentType);

            var outputMessage = $"Output message created at {DateTime.Now}";
            return outputMessage;
        }
        //</docsnippet_servicebus_readmessage>
        /// <summary>
        /// This function demonstrates binding to an array of <see cref="ServiceBusReceivedMessage"/>.
        /// Note that when doing so, you must also set the <see cref="ServiceBusTriggerAttribute.IsBatched"/> property
        /// to <value>true</value>.
        /// </summary>
        //<docsnippet_servicebus_readbatch>
        [Function(nameof(ServiceBusReceivedMessageBatchFunction))]
        public void ServiceBusReceivedMessageBatchFunction(
            [ServiceBusTrigger("queue", Connection = "ServiceBusConnection", IsBatched = true)] ServiceBusReceivedMessage[] messages)
        {
            foreach (ServiceBusReceivedMessage message in messages)
            {
                _logger.LogInformation("Message ID: {id}", message.MessageId);
                _logger.LogInformation("Message Body: {body}", message.Body);
                _logger.LogInformation("Message Content-Type: {contentType}", message.ContentType);
            }
        }
        //</docsnippet_servicebus_readbatch>
        /// <summary>
        /// This functions demonstrates that it is possible to bind to both the ServiceBusReceivedMessage and any of the supported binding contract
        /// properties at the same time. If attempting this, the ServiceBusReceivedMessage must be the first parameter. There is not
        /// much benefit to doing this as all of the binding contract properties are available as properties on the ServiceBusReceivedMessage.
        /// </summary>
        [Function(nameof(ServiceBusReceivedMessageWithStringProperties))]
        public void ServiceBusReceivedMessageWithStringProperties(
            [ServiceBusTrigger("queue", Connection = "ServiceBusConnection")]
            ServiceBusReceivedMessage message, string messageId, int deliveryCount)
        {
            // The MessageId property and the messageId parameter are the same.
            _logger.LogInformation("Message ID: {id}", message.MessageId);
            _logger.LogInformation("Message ID: {id}", messageId);

            // Similarly the DeliveryCount property and the deliveryCount parameter are the same.
            _logger.LogInformation("Delivery Count: {count}", message.DeliveryCount);
            _logger.LogInformation("Delivery Count: {count}", deliveryCount);
        }
        //<docsnippet_servicebus_message_actions>
        [Function(nameof(ServiceBusMessageActionsFunction))]
        public async Task ServiceBusMessageActionsFunction(
            [ServiceBusTrigger("queue", Connection = "ServiceBusConnection", AutoCompleteMessages = false)]
            ServiceBusReceivedMessage message,
            ServiceBusMessageActions messageActions)
        {
            _logger.LogInformation("Message ID: {id}", message.MessageId);
            _logger.LogInformation("Message Body: {body}", message.Body);
            _logger.LogInformation("Message Content-Type: {contentType}", message.ContentType);

            // Complete the message
            await messageActions.CompleteMessageAsync(message);
        }
        //</docsnippet_servicebus_message_actions>
    }
}

This example shows a C# function that receives multiple Service Bus queue messages, writes it to the logs, and then settles the message as completed:

// Copyright (c) .NET Foundation. All rights reserved.
// Licensed under the MIT License. See License.txt in the project root for license information.

using System;
using System.Threading.Tasks;
using Azure.Messaging.ServiceBus;
using Microsoft.Azure.Functions.Worker;
using Microsoft.Extensions.Logging;

namespace SampleApp
{
    /// <summary>
    /// Samples demonstrating binding to the <see cref="ServiceBusReceivedMessage"/> type.
    /// </summary>
    public class ServiceBusReceivedMessageFunctions
    {
        //<docsnippet_servicebusmessage_createlogger>
        private readonly ILogger<ServiceBusReceivedMessageFunctions> _logger;

        public ServiceBusReceivedMessageFunctions(ILogger<ServiceBusReceivedMessageFunctions> logger)
        {
            _logger = logger;
        }
        //</docsnippet_servicebusmessage_createlogger>
        /// <summary>
        /// This function demonstrates binding to a single <see cref="ServiceBusReceivedMessage"/>.
        /// </summary>
        //<docsnippet_servicebus_readmessage>
        [Function(nameof(ServiceBusReceivedMessageFunction))]
        [ServiceBusOutput("outputQueue", Connection = "ServiceBusConnection")]
        public string ServiceBusReceivedMessageFunction(
            [ServiceBusTrigger("queue", Connection = "ServiceBusConnection")] ServiceBusReceivedMessage message)
        {
            _logger.LogInformation("Message ID: {id}", message.MessageId);
            _logger.LogInformation("Message Body: {body}", message.Body);
            _logger.LogInformation("Message Content-Type: {contentType}", message.ContentType);

            var outputMessage = $"Output message created at {DateTime.Now}";
            return outputMessage;
        }
        //</docsnippet_servicebus_readmessage>
        /// <summary>
        /// This function demonstrates binding to an array of <see cref="ServiceBusReceivedMessage"/>.
        /// Note that when doing so, you must also set the <see cref="ServiceBusTriggerAttribute.IsBatched"/> property
        /// to <value>true</value>.
        /// </summary>
        //<docsnippet_servicebus_readbatch>
        [Function(nameof(ServiceBusReceivedMessageBatchFunction))]
        public void ServiceBusReceivedMessageBatchFunction(
            [ServiceBusTrigger("queue", Connection = "ServiceBusConnection", IsBatched = true)] ServiceBusReceivedMessage[] messages)
        {
            foreach (ServiceBusReceivedMessage message in messages)
            {
                _logger.LogInformation("Message ID: {id}", message.MessageId);
                _logger.LogInformation("Message Body: {body}", message.Body);
                _logger.LogInformation("Message Content-Type: {contentType}", message.ContentType);
            }
        }
        //</docsnippet_servicebus_readbatch>
        /// <summary>
        /// This functions demonstrates that it is possible to bind to both the ServiceBusReceivedMessage and any of the supported binding contract
        /// properties at the same time. If attempting this, the ServiceBusReceivedMessage must be the first parameter. There is not
        /// much benefit to doing this as all of the binding contract properties are available as properties on the ServiceBusReceivedMessage.
        /// </summary>
        [Function(nameof(ServiceBusReceivedMessageWithStringProperties))]
        public void ServiceBusReceivedMessageWithStringProperties(
            [ServiceBusTrigger("queue", Connection = "ServiceBusConnection")]
            ServiceBusReceivedMessage message, string messageId, int deliveryCount)
        {
            // The MessageId property and the messageId parameter are the same.
            _logger.LogInformation("Message ID: {id}", message.MessageId);
            _logger.LogInformation("Message ID: {id}", messageId);

            // Similarly the DeliveryCount property and the deliveryCount parameter are the same.
            _logger.LogInformation("Delivery Count: {count}", message.DeliveryCount);
            _logger.LogInformation("Delivery Count: {count}", deliveryCount);
        }
        //<docsnippet_servicebus_message_actions>
        [Function(nameof(ServiceBusMessageActionsFunction))]
        public async Task ServiceBusMessageActionsFunction(
            [ServiceBusTrigger("queue", Connection = "ServiceBusConnection", AutoCompleteMessages = false)]
            ServiceBusReceivedMessage message,
            ServiceBusMessageActions messageActions)
        {
            _logger.LogInformation("Message ID: {id}", message.MessageId);
            _logger.LogInformation("Message Body: {body}", message.Body);
            _logger.LogInformation("Message Content-Type: {contentType}", message.ContentType);

            // Complete the message
            await messageActions.CompleteMessageAsync(message);
        }
        //</docsnippet_servicebus_message_actions>
    }
}

The following example shows a C# function that reads message metadata and logs a Service Bus queue message:

[FunctionName("ServiceBusQueueTriggerCSharp")]                    
public static void Run(
    [ServiceBusTrigger("myqueue", Connection = "ServiceBusConnection")] 
    string myQueueItem,
    Int32 deliveryCount,
    DateTime enqueuedTimeUtc,
    string messageId,
    ILogger log)
{
    log.LogInformation($"C# ServiceBus queue trigger function processed message: {myQueueItem}");
    log.LogInformation($"EnqueuedTimeUtc={enqueuedTimeUtc}");
    log.LogInformation($"DeliveryCount={deliveryCount}");
    log.LogInformation($"MessageId={messageId}");
}

The following Java function uses the @ServiceBusQueueTrigger annotation from the Java functions runtime library to describe the configuration for a Service Bus queue trigger. The function grabs the message placed on the queue and adds it to the logs.

@FunctionName("sbprocessor")
 public void serviceBusProcess(
    @ServiceBusQueueTrigger(name = "msg",
                             queueName = "myqueuename",
                             connection = "myconnvarname") String message,
   final ExecutionContext context
 ) {
     context.getLogger().info(message);
 }

Java functions can also be triggered when a message is added to a Service Bus topic. The following example uses the @ServiceBusTopicTrigger annotation to describe the trigger configuration.

@FunctionName("sbtopicprocessor")
    public void run(
        @ServiceBusTopicTrigger(
            name = "message",
            topicName = "mytopicname",
            subscriptionName = "mysubscription",
            connection = "ServiceBusConnection"
        ) String message,
        final ExecutionContext context
    ) {
        context.getLogger().info(message);
    }

Model v4
Model v3

The following example shows a Service Bus trigger TypeScript function. The function reads message metadata and logs a Service Bus queue message.

import { app, InvocationContext } from '@azure/functions';

export async function serviceBusQueueTrigger1(message: unknown, context: InvocationContext): Promise<void> {
    context.log('Service bus queue function processed message:', message);
    context.log('EnqueuedTimeUtc =', context.triggerMetadata.enqueuedTimeUtc);
    context.log('DeliveryCount =', context.triggerMetadata.deliveryCount);
    context.log('MessageId =', context.triggerMetadata.messageId);
}

app.serviceBusQueue('serviceBusQueueTrigger1', {
    connection: 'MyServiceBusConnection',
    queueName: 'testqueue',
    handler: serviceBusQueueTrigger1,
});

Model v4
Model v3

The following example shows a Service Bus trigger JavaScript function. The function reads message metadata and logs a Service Bus queue message.

const { app } = require('@azure/functions');

app.serviceBusQueue('serviceBusQueueTrigger1', {
    connection: 'MyServiceBusConnection',
    queueName: 'testqueue',
    handler: (message, context) => {
        context.log('Service bus queue function processed message:', message);
        context.log('EnqueuedTimeUtc =', context.triggerMetadata.enqueuedTimeUtc);
        context.log('DeliveryCount =', context.triggerMetadata.deliveryCount);
        context.log('MessageId =', context.triggerMetadata.messageId);
    },
});

The following example shows a Service Bus trigger binding in a function.json file and a JavaScript function that uses the binding. The function reads message metadata and logs a Service Bus queue message.

Here's the binding data in the function.json file:

{
"bindings": [
    {
    "queueName": "testqueue",
    "connection": "MyServiceBusConnection",
    "name": "myQueueItem",
    "type": "serviceBusTrigger",
    "direction": "in"
    }
],
"disabled": false
}

Here's the JavaScript script code:

module.exports = async function(context, myQueueItem) {
    context.log('Node.js ServiceBus queue trigger function processed message', myQueueItem);
    context.log('EnqueuedTimeUtc =', context.bindingData.enqueuedTimeUtc);
    context.log('DeliveryCount =', context.bindingData.deliveryCount);
    context.log('MessageId =', context.bindingData.messageId);
};

The following example shows a Service Bus trigger binding in a function.json file and a PowerShell function that uses the binding.

Here's the binding data in the function.json file:

{
  "bindings": [
    {
      "name": "mySbMsg",
      "type": "serviceBusTrigger",
      "direction": "in",
      "topicName": "mytopic",
      "subscriptionName": "mysubscription",
      "connection": "AzureServiceBusConnectionString"
    }
  ]
}

Here's the function that runs when a Service Bus message is sent.

param([string] $mySbMsg, $TriggerMetadata)

Write-Host "PowerShell ServiceBus queue trigger function processed message: $mySbMsg"

The following example demonstrates how to read a Service Bus queue message via a trigger. The example depends on whether you use the v1 or v2 Python programming model.

import logging
import azure.functions as func

app = func.FunctionApp()

@app.function_name(name="ServiceBusQueueTrigger1")
@app.service_bus_queue_trigger(arg_name="msg", 
                               queue_name="<QUEUE_NAME>", 
                               connection="<CONNECTION_SETTING>")
def test_function(msg: func.ServiceBusMessage):
    logging.info('Python ServiceBus queue trigger processed message: %s',
                 msg.get_body().decode('utf-8'))

A Service Bus binding is defined in function.json where type is set to serviceBusTrigger and the queue is set by queueName.

{
  "scriptFile": "__init__.py",
  "bindings": [
    {
      "name": "msg",
      "type": "serviceBusTrigger",
      "direction": "in",
      "queueName": "inputqueue",
      "connection": "AzureServiceBusConnectionString"
    }
  ]
}

The code in _init_.py declares a parameter as func.ServiceBusMessage, which allows you to read the queue message in your function.

import azure.functions as func

import logging
import json

def main(msg: func.ServiceBusMessage):
    logging.info('Python ServiceBus queue trigger processed message.')

    result = json.dumps({
        'message_id': msg.message_id,
        'body': msg.get_body().decode('utf-8'),
        'content_type': msg.content_type,
        'expiration_time': msg.expiration_time,
        'label': msg.label,
        'partition_key': msg.partition_key,
        'reply_to': msg.reply_to,
        'reply_to_session_id': msg.reply_to_session_id,
        'scheduled_enqueue_time': msg.scheduled_enqueue_time,
        'session_id': msg.session_id,
        'time_to_live': msg.time_to_live,
        'to': msg.to,
        'user_properties': msg.user_properties,
        'metadata' : msg.metadata
    }, default=str)

    logging.info(result)

The following example demonstrates how to read a Service Bus queue topic via a trigger.

import logging
import azure.functions as func

app = func.FunctionApp()

@app.function_name(name="ServiceBusTopicTrigger1")
@app.service_bus_topic_trigger(arg_name="message", 
                               topic_name="TOPIC_NAME", 
                               connection="CONNECTION_SETTING", 
                               subscription_name="SUBSCRIPTION_NAME")
def test_function(message: func.ServiceBusMessage):
    message_body = message.get_body().decode("utf-8")
    logging.info("Python ServiceBus topic trigger processed message.")
    logging.info("Message Body: " + message_body)

A Service Bus binding is defined in function.json where type is set to serviceBusTrigger and the topic is set by topicName.

{
  "scriptFile": "__init__.py",
  "bindings": [
   {
     "type": "serviceBusTrigger",
     "direction": "in",
     "name": "msg",
     "topicName": "inputtopic",
     "connection": "AzureServiceBusConnectionString"
   }
  ]
}

The code in _init_.py declares a parameter as func.ServiceBusMessage, which allows you to read the topic in your function.

import json

import azure.functions as azf


def main(msg: azf.ServiceBusMessage) -> str:
    result = json.dumps({
        'message_id': msg.message_id,
        'body': msg.get_body().decode('utf-8'),
        'content_type': msg.content_type,
        'delivery_count': msg.delivery_count,
        'expiration_time': (msg.expiration_time.isoformat() if
                            msg.expiration_time else None),
        'label': msg.label,
        'partition_key': msg.partition_key,
        'reply_to': msg.reply_to,
        'reply_to_session_id': msg.reply_to_session_id,
        'scheduled_enqueue_time': (msg.scheduled_enqueue_time.isoformat() if
                                   msg.scheduled_enqueue_time else None),
        'session_id': msg.session_id,
        'time_to_live': msg.time_to_live,
        'to': msg.to,
        'user_properties': msg.user_properties,
    })

    logging.info(result)

Attributes

Both in-process and isolated worker process C# libraries use the ServiceBusTriggerAttribute attribute to define the function trigger. C# script instead uses a function.json configuration file as described in the C# scripting guide.

Isolated worker model
In-process model

The following table explains the properties you can set using this trigger attribute:

Property	Description
QueueName	Name of the queue to monitor. Set only if monitoring a queue, not for a topic.
TopicName	Name of the topic to monitor. Set only if monitoring a topic, not for a queue.
SubscriptionName	Name of the subscription to monitor. Set only if monitoring a topic, not for a queue.
Connection	The name of an app setting or setting collection that specifies how to connect to Service Bus. See Connections.
IsBatched	Messages are delivered in batches. Requires an array or collection type.
IsSessionsEnabled	`true` if connecting to a session-aware queue or subscription. `false` otherwise, which is the default value.
AutoCompleteMessages	`true` if the trigger should automatically complete the message after a successful invocation. `false` if it should not, such as when you are handling message settlement in code. If not explicitly set, the behavior will be based on the `autoCompleteMessages` configuration in `host.json`.

The following table explains the properties you can set using this trigger attribute:

Property	Description
QueueName	Name of the queue to monitor. Set only if monitoring a queue, not for a topic.
TopicName	Name of the topic to monitor. Set only if monitoring a topic, not for a queue.
SubscriptionName	Name of the subscription to monitor. Set only if monitoring a topic, not for a queue.
Connection	The name of an app setting or setting collection that specifies how to connect to Service Bus. See Connections.
Access	Access rights for the connection string. Available values are `manage` and `listen`. The default is `manage`, which indicates that the `connection` has the Manage permission. If you use a connection string that does not have the Manage permission, set `accessRights` to "listen". Otherwise, the Functions runtime might fail trying to do operations that require manage rights. In Azure Functions version 2.x and higher, this property is not available because the latest version of the Service Bus SDK doesn't support manage operations.
IsBatched	Messages are delivered in batches. Requires an array or collection type.
IsSessionsEnabled	`true` if connecting to a session-aware queue or subscription. `false` otherwise, which is the default value.
AutoComplete	`true` Whether the trigger should automatically call complete after processing, or if the function code will manually call complete. If set to `true`, the trigger completes the message automatically if the function execution completes successfully, and abandons the message otherwise. When set to `false`, you are responsible for calling ServiceBusReceiver methods to complete, abandon, or deadletter the message, session, or batch. When an exception is thrown (and none of the `ServiceBusReceiver` methods are called), then the lock remains. Once the lock expires, the message is re-queued with the `DeliveryCount` incremented and the lock is automatically renewed.

When you're developing locally, add your application settings in the local.settings.json file in the Values collection.

Decorators

Applies only to the Python v2 programming model.

For Python v2 functions defined using a decorator, the following properties on the service_bus_queue_trigger:

Property	Description
`arg_name`	The name of the variable that represents the queue or topic message in function code.
`queue_name`	Name of the queue to monitor. Set only if monitoring a queue, not for a topic.
`connection`	The name of an app setting or setting collection that specifies how to connect to Service Bus. See Connections.

For Python functions defined by using function.json, see the Configuration section.

Annotations

The ServiceBusQueueTrigger annotation allows you to create a function that runs when a Service Bus queue message is created. Configuration options available include the following properties:

Property	Description
name	The name of the variable that represents the queue or topic message in function code.
queueName	Name of the queue to monitor. Set only if monitoring a queue, not for a topic.
topicName	Name of the topic to monitor. Set only if monitoring a topic, not for a queue.
subscriptionName	Name of the subscription to monitor. Set only if monitoring a topic, not for a queue.
connection	The name of an app setting or setting collection that specifies how to connect to Service Bus. See Connections.

The ServiceBusTopicTrigger annotation allows you to designate a topic and subscription to target what data triggers the function.

When you're developing locally, add your application settings in the local.settings.json file in the Values collection.

See the trigger example for more detail.

Configuration

Applies only to the Python v1 programming model.

Model v4
Model v3

The following table explains the properties that you can set on the options object passed to the app.serviceBusQueue() or app.serviceBusTopic() methods.

Property	Description
queueName	Name of the queue to monitor. Set only if monitoring a queue, not for a topic.
topicName	Name of the topic to monitor. Set only if monitoring a topic, not for a queue.
subscriptionName	Name of the subscription to monitor. Set only if monitoring a topic, not for a queue.
connection	The name of an app setting or setting collection that specifies how to connect to Service Bus. See Connections.
accessRights	Access rights for the connection string. Available values are `manage` and `listen`. The default is `manage`, which indicates that the `connection` has the Manage permission. If you use a connection string that does not have the Manage permission, set `accessRights` to "listen". Otherwise, the Functions runtime might fail trying to do operations that require manage rights. In Azure Functions version 2.x and higher, this property is not available because the latest version of the Service Bus SDK doesn't support manage operations.
isSessionsEnabled	`true` if connecting to a session-aware queue or subscription. `false` otherwise, which is the default value.
autoComplete	Must be `true` for non-C# functions, which means that the trigger should either automatically call complete after processing, or the function code manually calls complete. When set to `true`, the trigger completes the message automatically if the function execution completes successfully, and abandons the message otherwise. Exceptions in the function results in the runtime calls `abandonAsync` in the background. If no exception occurs, then `completeAsync` is called in the background. This property is available only in Azure Functions 2.x and higher.

The following table explains the binding configuration properties that you set in the function.json file.

Property	Description
type	Must be set to `serviceBusTrigger`. This property is set automatically when you create the trigger in the Azure portal.
direction	Must be set to "in". This property is set automatically when you create the trigger in the Azure portal.
name	The name of the variable that represents the queue or topic message in function code.
queueName	Name of the queue to monitor. Set only if monitoring a queue, not for a topic.
topicName	Name of the topic to monitor. Set only if monitoring a topic, not for a queue.
subscriptionName	Name of the subscription to monitor. Set only if monitoring a topic, not for a queue.
connection	The name of an app setting or setting collection that specifies how to connect to Service Bus. See Connections.
accessRights	Access rights for the connection string. Available values are `manage` and `listen`. The default is `manage`, which indicates that the `connection` has the Manage permission. If you use a connection string that does not have the Manage permission, set `accessRights` to "listen". Otherwise, the Functions runtime might fail trying to do operations that require manage rights. In Azure Functions version 2.x and higher, this property is not available because the latest version of the Service Bus SDK doesn't support manage operations.
isSessionsEnabled	`true` if connecting to a session-aware queue or subscription. `false` otherwise, which is the default value.
autoComplete	Must be `true` for non-C# functions, which means that the trigger should either automatically call complete after processing, or the function code manually calls complete. When set to `true`, the trigger completes the message automatically if the function execution completes successfully, and abandons the message otherwise. Exceptions in the function results in the runtime calls `abandonAsync` in the background. If no exception occurs, then `completeAsync` is called in the background. This property is available only in Azure Functions 2.x and higher.

When you're developing locally, add your application settings in the local.settings.json file in the Values collection.

The following table explains the binding configuration properties that you set in the function.json file.

function.json property	Description
type	Must be set to `serviceBusTrigger`. This property is set automatically when you create the trigger in the Azure portal.
direction	Must be set to "in". This property is set automatically when you create the trigger in the Azure portal.
name	The name of the variable that represents the queue or topic message in function code.
queueName	Name of the queue to monitor. Set only if monitoring a queue, not for a topic.
topicName	Name of the topic to monitor. Set only if monitoring a topic, not for a queue.
subscriptionName	Name of the subscription to monitor. Set only if monitoring a topic, not for a queue.
connection	The name of an app setting or setting collection that specifies how to connect to Service Bus. See Connections.
accessRights	Access rights for the connection string. Available values are `manage` and `listen`. The default is `manage`, which indicates that the `connection` has the Manage permission. If you use a connection string that does not have the Manage permission, set `accessRights` to "listen". Otherwise, the Functions runtime might fail trying to do operations that require manage rights. In Azure Functions version 2.x and higher, this property is not available because the latest version of the Service Bus SDK doesn't support manage operations.
isSessionsEnabled	`true` if connecting to a session-aware queue or subscription. `false` otherwise, which is the default value.
autoComplete	Must be `true` for non-C# functions, which means that the trigger should either automatically call complete after processing, or the function code manually calls complete. When set to `true`, the trigger completes the message automatically if the function execution completes successfully, and abandons the message otherwise. Exceptions in the function results in the runtime calls `abandonAsync` in the background. If no exception occurs, then `completeAsync` is called in the background. This property is available only in Azure Functions 2.x and higher.

When you're developing locally, add your application settings in the local.settings.json file in the Values collection.

See the Example section for complete examples.

Usage

The following parameter types are supported by all C# modalities and extension versions:

Type	Description
System.String	Use when the message is simple text.
byte[]	Use for binary data messages.
Object	When a message contains JSON, Functions tries to deserialize the JSON data into known plain-old CLR object type.

Messaging-specific parameter types contain additional message metadata. The specific types supported by the Service Bus trigger depend on the Functions runtime version, the extension package version, and the C# modality used.

Use the ServiceBusReceivedMessage type to receive message metadata from Service Bus Queues and Subscriptions. To learn more, see Messages, payloads, and serialization.

In C# class libraries, the attribute's constructor takes the name of the queue or the topic and subscription.

You can also use the ServiceBusAccountAttribute to specify the Service Bus account to use. The constructor takes the name of an app setting that contains a Service Bus connection string. The attribute can be applied at the parameter, method, or class level. The following example shows class level and method level:

[ServiceBusAccount("ClassLevelServiceBusAppSetting")]
public static class AzureFunctions
{
    [ServiceBusAccount("MethodLevelServiceBusAppSetting")]
    [FunctionName("ServiceBusQueueTriggerCSharp")]
    public static void Run(
        [ServiceBusTrigger("myqueue", AccessRights.Manage)] 
        string myQueueItem, ILogger log)
{
    ...
}

The Service Bus account to use is determined in the following order:

The ServiceBusTrigger attribute's Connection property.
The ServiceBusAccount attribute applied to the same parameter as the ServiceBusTrigger attribute.
The ServiceBusAccount attribute applied to the function.
The ServiceBusAccount attribute applied to the class.
The AzureWebJobsServiceBus app setting.

Use the Message type to receive messages with metadata. To learn more, see Messages, payloads, and serialization.

Note

On 30 September 2026, we'll retire the Azure Service Bus SDK libraries WindowsAzure.ServiceBus, Microsoft.Azure.ServiceBus, and com.microsoft.azure.servicebus, which don't conform to Azure SDK guidelines. We'll also end support of the SBMP protocol, so you'll no longer be able to use this protocol after 30 September 2026. Migrate to the latest Azure SDK libraries, which offer critical security updates and improved capabilities, before that date.

Although the older libraries can still be used beyond 30 September 2026, they'll no longer receive official support and updates from Azure. For more information, see the support retirement announcement.

In C# class libraries, the attribute's constructor takes the name of the queue or the topic and subscription.

[ServiceBusAccount("ClassLevelServiceBusAppSetting")]
public static class AzureFunctions
{
    [ServiceBusAccount("MethodLevelServiceBusAppSetting")]
    [FunctionName("ServiceBusQueueTriggerCSharp")]
    public static void Run(
        [ServiceBusTrigger("myqueue", AccessRights.Manage)] 
        string myQueueItem, ILogger log)
{
    ...
}

The Service Bus account to use is determined in the following order:

The ServiceBusTrigger attribute's Connection property.
The ServiceBusAccount attribute applied to the same parameter as the ServiceBusTrigger attribute.
The ServiceBusAccount attribute applied to the function.
The ServiceBusAccount attribute applied to the class.
The AzureWebJobsServiceBus app setting.

The following parameter types are available for the queue or topic message:

BrokeredMessage - Gives you the deserialized message with the BrokeredMessage.GetBody<T>() method.
MessageReceiver - Used to receive and acknowledge messages from the message container, which is required when autoComplete is set to false.

Note

In C# class libraries, the attribute's constructor takes the name of the queue or the topic and subscription. In Azure Functions version 1.x, you can also specify the connection's access rights. If you don't specify access rights, the default is Manage.

[ServiceBusAccount("ClassLevelServiceBusAppSetting")]
public static class AzureFunctions
{
    [ServiceBusAccount("MethodLevelServiceBusAppSetting")]
    [FunctionName("ServiceBusQueueTriggerCSharp")]
    public static void Run(
        [ServiceBusTrigger("myqueue", AccessRights.Manage)] 
        string myQueueItem, ILogger log)
{
    ...
}

The Service Bus account to use is determined in the following order:

The ServiceBusTrigger attribute's Connection property.
The ServiceBusAccount attribute applied to the same parameter as the ServiceBusTrigger attribute.
The ServiceBusAccount attribute applied to the function.
The ServiceBusAccount attribute applied to the class.
The AzureWebJobsServiceBus app setting.

When you want the function to process a single message, the Service Bus trigger can bind to the following types:

Type	Description
`string`	The message as a string. Use when the message is simple text.
`byte[]`	The bytes of the message.
JSON serializable types	When a event contains JSON data, Functions tries to deserialize the JSON data into a plain-old CLR object (POCO) type.
ServiceBusReceivedMessage	(Preview¹) The message object.

When you want the function to process a batch of messages, the Service Bus trigger can bind to the following types:

Type	Description
`T[]` where `T` is one of the single message types	An array of events from the batch. Each entry represents one event.

The isolated process model does not yet support message settlement scenarios for Service Bus triggers.

¹ To use these types, you need to reference Microsoft.Azure.Functions.Worker.Extensions.ServiceBus 5.10.0-preview2 or later and the common dependencies for SDK type bindings.

When the Connection property isn't defined, Functions looks for an app setting named AzureWebJobsServiceBus, which is the default name for the Service Bus connection string. You can also set the Connection property to specify the name of an application setting that contains the Service Bus connection string to use.

The incoming Service Bus message is available via a ServiceBusQueueMessage or ServiceBusTopicMessage parameter.

Model v4
Model v3

Access the queue or topic message as the first argument to your function. The Service Bus message is passed into the function as either a string or JSON object.

The Service Bus instance is available via the parameter configured in the function.json file's name property.

The queue message is available to the function via a parameter typed as func.ServiceBusMessage. The Service Bus message is passed into the function as either a string or JSON object.

For a complete example, see the examples section.

Connections

The connection property is a reference to environment configuration which specifies how the app should connect to Service Bus. It may specify:

The name of an application setting containing a connection string
The name of a shared prefix for multiple application settings, together defining an identity-based connection.

If the configured value is both an exact match for a single setting and a prefix match for other settings, the exact match is used.

Connection string

To obtain a connection string, follow the steps shown at Get the management credentials. The connection string must be for a Service Bus namespace, not limited to a specific queue or topic.

This connection string should be stored in an application setting with a name matching the value specified by the connection property of the binding configuration.

If the app setting name begins with "AzureWebJobs", you can specify only the remainder of the name. For example, if you set connection to "MyServiceBus", the Functions runtime looks for an app setting that is named "AzureWebJobsMyServiceBus". If you leave connection empty, the Functions runtime uses the default Service Bus connection string in the app setting that is named "AzureWebJobsServiceBus".

Identity-based connections

If you are using version 5.x or higher of the extension, instead of using a connection string with a secret, you can have the app use an Azure Active Directory identity. To do this, you would define settings under a common prefix which maps to the connection property in the trigger and binding configuration.

In this mode, the extension requires the following properties:

Property	Environment variable template	Description	Example value
Fully Qualified Namespace	`<CONNECTION_NAME_PREFIX>__fullyQualifiedNamespace`	The fully qualified Service Bus namespace.	<service_bus_namespace>.servicebus.chinacloudapi.cn

Additional properties may be set to customize the connection. See Common properties for identity-based connections.

Note

When using Azure App Configuration or Key Vault to provide settings for Managed Identity connections, setting names should use a valid key separator such as : or / in place of the __ to ensure names are resolved correctly.

For example, <CONNECTION_NAME_PREFIX>:fullyQualifiedNamespace.

When hosted in the Azure Functions service, identity-based connections use a managed identity. The system-assigned identity is used by default, although a user-assigned identity can be specified with the credential and clientID properties. Note that configuring a user-assigned identity with a resource ID is not supported. When run in other contexts, such as local development, your developer identity is used instead, although this can be customized. See Local development with identity-based connections.

Grant permission to the identity

Whatever identity is being used must have permissions to perform the intended actions. You will need to assign a role in Azure RBAC, using either built-in or custom roles which provide those permissions.

Important

Some permissions might be exposed by the target service that are not necessary for all contexts. Where possible, adhere to the principle of least privilege, granting the identity only required privileges. For example, if the app only needs to be able to read from a data source, use a role that only has permission to read. It would be inappropriate to assign a role that also allows writing to that service, as this would be excessive permission for a read operation. Similarly, you would want to ensure the role assignment is scoped only over the resources that need to be read.

You'll need to create a role assignment that provides access to your topics and queues at runtime. Management roles like Owner aren't sufficient. The following table shows built-in roles that are recommended when using the Service Bus extension in normal operation. Your application may require additional permissions based on the code you write.

Binding type	Example built-in roles
Trigger¹	Azure Service Bus Data Receiver, Azure Service Bus Data Owner
Output binding	Azure Service Bus Data Sender

¹ For triggering from Service Bus topics, the role assignment needs to have effective scope over the Service Bus subscription resource. If only the topic is included, an error will occur. Some clients, such as the Azure portal, don't expose the Service Bus subscription resource as a scope for role assignment. In such cases, the Azure CLI may be used instead. To learn more, see Azure built-in roles for Azure Service Bus.

Poison messages

Poison message handling can't be controlled or configured in Azure Functions. Service Bus handles poison messages itself.

PeekLock behavior

The Functions runtime receives a message in PeekLock mode.

By default, the runtime calls Complete on the message if the function finishes successfully, or calls Abandon if the function fails. You can disable automatic completion through with the autoCompleteMessages property in host.json or through a property on the trigger attribute. You should disable automatic completion if your function code handles message settlement.

If the function runs longer than the PeekLock timeout, the lock is automatically renewed as long as the function is running. The maxAutoRenewDuration is configurable in host.json, which maps to ServiceBusProcessor.MaxAutoLockRenewalDuration. The default value of this setting is 5 minutes.

Message metadata

Messaging-specific types let you easily retrieve metadata as properties of the object. These properties depend on the Functions runtime version, the extension package version, and the C# modality used.

These properties are members of the ServiceBusReceivedMessage class.

Property	Type	Description
`ApplicationProperties`	`ApplicationProperties`	Properties set by the sender.
`ContentType`	`string`	A content type identifier utilized by the sender and receiver for application-specific logic.
`CorrelationId`	`string`	The correlation ID.
`DeliveryCount`	`Int32`	The number of deliveries.
`EnqueuedTime`	`DateTime`	The enqueued time in UTC.
`ScheduledEnqueueTimeUtc`	`DateTime`	The scheduled enqueued time in UTC.
`ExpiresAt`	`DateTime`	The expiration time in UTC.
`MessageId`	`string`	A user-defined value that Service Bus can use to identify duplicate messages, if enabled.
`ReplyTo`	`string`	The reply to queue address.
`Subject`	`string`	The application-specific label which can be used in place of the `Label` metadata property.
`To`	`string`	The send to address.

These properties are members of the Message class.

Note

Property	Type	Description
`ContentType`	`string`	A content type identifier utilized by the sender and receiver for application-specific logic.
`CorrelationId`	`string`	The correlation ID.
`DeliveryCount`	`Int32`	The number of deliveries.
`ScheduledEnqueueTimeUtc`	`DateTime`	The scheduled enqueued time in UTC.
`ExpiresAtUtc`	`DateTime`	The expiration time in UTC.
`Label`	`string`	The application-specific label.
`MessageId`	`string`	A user-defined value that Service Bus can use to identify duplicate messages, if enabled.
`ReplyTo`	`string`	The reply to queue address.
`To`	`string`	The send to address.
`UserProperties`	`IDictionary<string, object>`	Properties set by the sender.

These properties are members of the BrokeredMessage and MessageReceiver classes.

Note

Property	Type	Description
`ContentType`	`string`	A content type identifier utilized by the sender and receiver for application-specific logic.
`CorrelationId`	`string`	The correlation ID.
`DeadLetterSource`	`string`	The dead letter source.
`DeliveryCount`	`Int32`	The number of deliveries.
`EnqueuedTimeUtc`	`DateTime`	The enqueued time in UTC.
`ExpiresAtUtc`	`DateTime`	The expiration time in UTC.
`Label`	`string`	The application-specific label.
`MessageId`	`string`	A user-defined value that Service Bus can use to identify duplicate messages, if enabled.
`MessageReceiver`	`MessageReceiver`	Service Bus message receiver. Can be used to abandon, complete, or deadletter the message.
`MessageSession`	`MessageSession`	A message receiver specifically for session-enabled queues and topics.
`ReplyTo`	`string`	The reply to queue address.
`SequenceNumber`	`long`	The unique number assigned to a message by the Service Bus.
`To`	`string`	The send to address.
`UserProperties`	`IDictionary<string, object>`	Properties set by the sender.

These properties are members of the ServiceBusReceivedMessage class.

Property	Type	Description
`ApplicationProperties`	`ApplicationProperties`	Properties set by the sender.
`ContentType`	`string`	A content type identifier utilized by the sender and receiver for application-specific logic.
`CorrelationId`	`string`	The correlation ID.
`DeliveryCount`	`Int32`	The number of deliveries.
`EnqueuedTime`	`DateTime`	The enqueued time in UTC.
`ScheduledEnqueueTimeUtc`	`DateTime`	The scheduled enqueued time in UTC.
`ExpiresAt`	`DateTime`	The expiration time in UTC.
`MessageId`	`string`	A user-defined value that Service Bus can use to identify duplicate messages, if enabled.
`ReplyTo`	`string`	The reply to queue address.
`Subject`	`string`	The application-specific label which can be used in place of the `Label` metadata property.
`To`	`string`	The send to address.

Next steps

Send Azure Service Bus messages from Azure Functions (Output binding)

Azure Service Bus trigger for Azure Functions

Example

Attributes

Decorators

Annotations

Configuration

Usage

Connections

Connection string

Identity-based connections

Grant permission to the identity

Poison messages

PeekLock behavior

Message metadata

Next steps

Additional resources