Question

当我使用以下内容时：

var deadLetterPath = SubscriptionClient.FormatDeadLetterPath(topicPath,subName);
var client = SubscriptionClient.CreateFromConnectionString(connectionString, deadLetterPath, subName);

我收到了InvalidOperationException

无法在子队列上直接创建客户端。在上创建一个客户端主队列并使用它来创建适当的接收器子队列

azure文档的某些部分说使用SubscriptionClient.CreateReceiver来访问子队列，但该方法不存在。

Answer 1

这种方法对你有用吗？

MessagingFactory factory = MessagingFactory.CreateFromConnectionString(cnxString);
var deadLetterPath = SubscriptionClient.FormatDeadLetterPath(topicPath,subName);
var dlqReceiver = factory.CreateMessageReceiver(deadLetterPath, ReceiveMode.ReceiveAndDelete);

我没有在这里测试（在会议中），但试一试

欢呼声

Answer 2

使用Azure Service Bus对死信队列进行常规命名：

对于Service Bus队列：queuePath / $ DeadLetterQueue
对于Service Bus订阅：topicPath / subscriptionName / $ DeadLetterQueue

因此，您可以像访问队列一样访问死信队列。

从@SamVanhoutte回答，您可以看到ServiceBus框架提供了格式化死信队列名称的方法：

对于服务总线队列：QueueClient.FormatDeadLetterPath(queuePath)
对于服务总线订阅：SubscriptionClient.FormatDeadLetterPath(topicPath, subscriptionName)

我编写了两个小方法来为队列和订阅创建一个消息接收器，您可以在其中设置是否需要交易信件队列：

/// <summary>
/// Create a new <see cref="MessageReceiver"/> object using the specified Service Bus Queue path.
/// </summary>
/// <param name="connectionString">The connection string to access the desired service namespace.</param>
/// <param name="queuePath">The Service Bus Queue path.</param>
/// <param name="isDeadLetter">True if the desired path is the deadletter queue.</param>
public static MessageReceiver CreateMessageReceiver(string connectionString, string queuePath,
    bool isDeadLetter = false)
{
    return MessagingFactory.CreateFromConnectionString(connectionString)
        .CreateMessageReceiver(isDeadLetter
            ? QueueClient.FormatDeadLetterPath(queuePath)
            : queuePath);
}

/// <summary>
/// Create a new <see cref="MessageReceiver"/> object using the specified Service Bus Topic Subscription path.
/// </summary>
/// <param name="connectionString">The connection string to access the desired service namespace.</param>
/// <param name="topicPath">The Service Bus Topic path.</param>
/// <param name="subscriptionName">The Service Bus Topic Subscription name.</param>
/// <param name="isDeadLetter">True if the desired path is the deadletter subqueue.</param>
public static MessageReceiver CreateMessageReceiver(string connectionString, string topicPath,
    string subscriptionName, bool isDeadLetter = false)
{
    return MessagingFactory.CreateFromConnectionString(connectionString)
        .CreateMessageReceiver(isDeadLetter
            ? SubscriptionClient.FormatDeadLetterPath(topicPath, subscriptionName)
            : SubscriptionClient.FormatSubscriptionPath(topicPath, subscriptionName));
}

Answer 3

如果您使用的是Microsoft.Azure.ServiceBus而不是Microsoft.ServiceBus，则略有不同。

var deadQueuePath = EntityNameHelper.FormatDeadLetterPath(your_queue_name);
var deadQueueReceiver = new MessageReceiver(connectionString, deadQueuePath);

根据EntityNameHelper命名空间中的Microsoft.Azure.ServiceBus类，对于主题，请使用订阅路径，而不要使用your_queue_name。

队列名称或订阅路径。

/// <summary>
/// Formats the dead letter path for either a queue, or a subscription.
/// </summary>
/// <param name="entityPath">The name of the queue, or path of the subscription.</param>
/// <returns>The path as a string of the dead letter entity.</returns>
public static string FormatDeadLetterPath(string entityPath)
{
    return EntityNameHelper.FormatSubQueuePath(entityPath, EntityNameHelper.DeadLetterQueueName);
}

Answer 4

使用最新的服务总线客户端库，您可以像这样访问死信队列。请注意在创建接收器时指定死信队列时跨语言的一致性：

JS

const { ServiceBusClient } = require("@azure/service-bus");

const client = new ServiceBusClient("<connectionstring>");
const deadletterReceiver = client.createReceiver("queueName", { subQueueType: "deadLetter" });
const messages = await deadletterReceiver.receiveMessages(1);

if (messages.length > 0) {
    console.log("Received the message from DLQ - ", messages[0].body);

    // Mark message as complete, i.e. remove from DLQ
    await deadletterReceiver.completeMessage(messages[0]);
} else {
    console.log("Error: No messages were received from the DLQ.");
}

await deadletterReceiver.close();

Java

import com.azure.messaging.servicebus.*;
import com.azure.messaging.servicebus.models.SubQueue;

ServiceBusReceiverClient deadletterReceiver = new ServiceBusClientBuilder()
    .connectionString("<connectionstring>")
    .receiver() // Use this for session or non-session enabled queue or topic/subscriptions
    .queueName("queuename")
    .subQueue(SubQueue.DEAD_LETTER_QUEUE)
    .buildClient();

IterableStream<ServiceBusReceivedMessage> messages = receiver.receiveMessages(10);
messages.forEach(message -> {
    System.out.printf("Id: %s. Contents: %s%n", message.getMessageId(),
        message.getBody().toString());

    //Remove message from DLQ
    deadletterReceiver.complete(message);
});

deadletterReceiver.close();

Python

import asyncio
from azure.servicebus import ServiceBusMessage, ServiceBusSubQueue
from azure.servicebus.aio import ServiceBusClient

servicebus_client = ServiceBusClient.from_connection_string(conn_str="<connectionstring>")
dlq_receiver = servicebus_client.get_queue_receiver(queue_name="queuename", 
               sub_queue=ServiceBusSubQueue.DEAD_LETTER)

async with dlq_receiver:
    received_msgs = await dlq_receiver.receive_messages(max_message_count=10, max_wait_time=5)
    for msg in received_msgs:
        print(msg)
        
        # remove the message from the DLQ
        await dlq_receiver.complete_message(msg)

.NET

using Azure.Messaging.ServiceBus;

await using var client = new ServiceBusClient("<connectionstring>");
ServiceBusReceiver deadletterReceiver = client.CreateReceiver(
    "queuename",
     new ServiceBusReceiverOptions { SubQueue = SubQueue.DeadLetter }
);

ServiceBusReceivedMessage message = await deadletterReceiver.ReceiveMessageAsync();
            
if (message != null)
{
    Console.WriteLine($"DeadLetter message = {message.Body}");
    
    // remove the message from the DLQ
    await deadletterReceiver.CompleteMessageAsync(message);
}
else
{
    // DLQ was empty on last receive attempt
    Console.WriteLine("Error: No messages were received from the DLQ."); 
}

await deadletterReceiver.CloseAsync();

Answer 5

那些想用python做的人。

从死信队列中接收消息：

from azure.servicebus import ServiceBusClient
import json
connectionString = "Your Connection String to Service Bus"
serviceBusClient = ServiceBusClient.from_connection_string(connectionString)
queueName = "Your Queue Name created in the Service Bus"
queueClient = serviceBusClient.get_queue(queueName)
with queueClient.get_deadletter_receiver(prefetch=5) as queueReceiver:
    messages = queueReceiver.fetch_next(timeout=100)
    for message in messages:
        # message.body is a generator object. Use next() to get the body.
        body = next(message.body)
        message.complete()

希望对某人有帮助。

如何访问Azure订阅上的死信子队列？

5 个答案: