Azure 调度程序：将 JSON 消息添加到 Azure 存储队列

Question

我创建了一个在特定时间运行的调度程序，并将 JSON 消息插入存储队列。 JSON 消息是固定的，我在调度程序设置期间将其放在 BODY 字段中（表示 text/plain）。消息是：

{ "action": "SendReminderMessages" }

在接收端（WebJob），我轮询队列，然后尝试反序列化这些消息中的 JSON。我得到的 JSON 消息不是上面预期的 JSON，而是包裹在 XML 消息中的 JSON 消息：

<?xml version="1.0" encoding="utf-16"?>
<StorageQueueMessage xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
  <ExecutionTag>(Some Hex String)</ExecutionTag>
  <ClientRequestId>(Some GUID)</ClientRequestId>
  <ExpectedExecutionTime>2015-09-17T07:00:00</ExpectedExecutionTime>
  <SchedulerJobId>reminder-mails</SchedulerJobId>
  <SchedulerJobCollectionId>scheduler-jobs</SchedulerJobCollectionId>
  <Region>West Europe</Region>
  <Message>{ "action": "SendReminderMessages" }</Message>
</StorageQueueMessage>

如何按原样发送 JSON 消息，即没有信封？

Answer 1

这听起来很奇怪，我只对电子邮件做完全相同的事情，而且对我来说效果很好。我已经添加了我的代码，我希望它能帮助你发现你的错误。

/// <summary>
/// Create or update a queue
/// </summary>
/// <param name="queueName">Name of queue</param>
/// <param name="message">Message to post in the queue</param>
/// <returns>Return true on success, false if already exists, throw exception on error</returns>
public bool PutMessage(string queueName, CloudQueueMessage message)
{
    try
    {
        var queue = queueContext.QueueClient.GetQueueReference(queueName);
        queue.AddMessage(message);
        return true;
    }
    catch (StorageClientException ex)
    {
        if ((int)ex.StatusCode == 404) return false;
        throw;
    }
}

/// <summary>
/// Serializes a e-mail to Json
/// </summary>
/// <param name="from">Sender e-mail address</param>
/// <param name="to">Recipient e-mail address</param>
/// <param name="subject">E-mail subject text</param>
/// <param name="body">E-mail body text</param>
/// <returns>Json</returns>
string SerializeEmail(string from, string to, string subject, string body)
{
    var email = new EmailEntity()
                    {
                        From = from,
                        To = to,
                        Subject = subject,
                        Body = body
                    };

    var stream = new MemoryStream();
    var serializer = new DataContractJsonSerializer(typeof(EmailEntity));
    serializer.WriteObject(stream, email);
    var serializedEmail = Encoding.Default.GetString(stream.ToArray());
    stream.Close();
    return serializedEmail;
}

/// <summary>
/// Puts a e-mail on the Azure queue to be sent
/// </summary>
/// <param name="from">Sender e-mail address</param>
/// <param name="to">Recipient e-mail address</param>
/// <param name="subject">E-mail subject text</param>
/// <param name="body">E-mail body text</param>
/// <returns>Return true on success, false if already exists, throw exception on error</returns>
public bool SendEmail(string from, string to, string subject, string body)
{
    var serializedEmail = SerializeEmail(from, to, subject, body);
    var message = new CloudQueueMessage(serializedEmail);
    return PutMessage(AzureQueueContext.EmailQueueName, message);
}

/// <summary>
/// Retrieve the next message from a queue
/// </summary>
/// <param name="queueName">Name of queue</param>
/// <param name="message">Message</param>
/// <returns>Return true on success (message available), false if no message or no queue, throw exception on error</returns>
bool GetMessage(string queueName, out CloudQueueMessage message)
{
    message = null;

    try
    {
        var queue = GetCloudQueueClient().GetQueueReference(queueName);
        message = queue.GetMessage();
        return message != null;
    }
    catch (StorageClientException ex)
    {
        if ((int)ex.StatusCode == 404) return false;

        throw;
    }
}

/// <summary>
/// Deserializes a e-mail message
/// </summary>
/// <param name="message">Message serialized in the Json inerchange format</param>
/// <returns>Deserialized e-mail as a EmailEntity object</returns>
EmailEntity DeserializeEmail(CloudQueueMessage message)
{
    var stream = new MemoryStream(Encoding.Default.GetBytes(message.AsString));
    var ser = new DataContractJsonSerializer(typeof(EmailEntity));
    var email = (EmailEntity)ser.ReadObject(stream);
    stream.Close();
    return email;
}

/// <summary>
/// Retrieve the next message from a queue
/// </summary>
/// <param name="email">E-mail</param>
/// <returns>Return true on success (message available), false if no message or no queue, throw exception on error</returns>
public bool GetEmail(out EmailEntity email, out CloudQueueMessage message)
{
    var result = GetMessage(AzureQueueContext.EmailQueueName, out message);
    email = result ? DeserializeEmail(message) : null;
    return result;
}

Answer 2

调度程序当前向正文添加了一个 XML 包装器，作为传递作业元数据的一种方式。您可以使用 Scheduler SDK 中的 StorageQueueMessage class（在 Microsoft.WindowsAzure.Scheduler.Models 下）来正确反序列化消息。您可以投票支持 Azure 调度程序功能，以添加不在我们的 Azure Scheduler User Voice forum 上包含包装器的功能。

Answer 3

我之前通过创建一个完全独立的 WebJob 来解决这个问题，该 WebJob 读取 XML，将 JSON 拉出，并将 re-queues JSON 值放入存储队列（此处的解决方案：https://github.com/Stonefinch/AzureIntro/tree/master/src/AzureIntro.WebJobs.AzureScheduler）

不过，我最近发现使用 Azure Functions 对消息进行排队提供了一个不错的解决方法。更多信息在这里：http://aaron-hoffman.blogspot.com/2017/01/replace-azure-scheduler-with-azure.html

Azure 调度程序：将 JSON 消息添加到 Azure 存储队列

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