我有一个使用MSMQ进行异步处理的应用程序。
我使用WCF将消息放入队列并拥有一个WCF MSMQ监听器（Windows服务）来接收消息并处理它们。
我的问题是保持稳定。处理（例如）队列服务器（这是一个单独的盒子）的正确方法是什么？前几天发生这种情况并且服务只是坐在那里 - 没有抛出任何异常，它只是停止接收消息。 我希望它在队列服务器关闭时抛出异常，然后重新尝试连接到它，直到它能够。
我还注意到，在服务上执行“停止”通常会导致它在最终停止之前挂起一段时间。
任何代码建议或批评都是受欢迎的。显然我首先为谷歌做了这个，但是大多数例子都向我展示了我已经拥有的东西，并且我想让我的系统比那更强大。
目前我有这个：
（注意：IMyExampleServiceContract是我的WCF服务合同，而QueueHandler是实现它的东西）
namespace xyz.MyExample.MSMQListener
{
/// <summary>
/// The class that handles starting and stopping of the WCF MSMQ Listener windows service.
/// It will respond to start and stop commands from within the windows services administration snap-in
/// It creates a WCF NetMsmqBinding that watches a particular queue for messaages defined by a contract
/// in the ServiceContracts project.
/// </summary>
public partial class MsmqListenerService : ServiceBase
{
/// <summary>
/// The WCF service host
/// </summary>
private ServiceHost _serviceHost;
/// <summary>
/// Defines the maximum size for a WCF message
/// </summary>
private const long MaxMessageSize = 1024 * 1024 * 1024; // 1 gb
/// <summary>
/// Defines the maximum size for a WCF array
/// </summary>
private const int MaxArraySize = 1024 * 1024 * 1024; // 1 gb
/// <summary>
/// The queue name
/// </summary>
private readonly string _queueName;
/// <summary>
/// The queue server
/// </summary>
private readonly string _queueServer;
/// <summary>
/// Initializes a new instance of the <see cref="MsmqListenerService"/> class.
/// </summary>
public MsmqListenerService()
{
InitializeComponent();
using (ConfigManager config = new ConfigManager())
{
_queueName = config.GetAppSetting("QueueName");
_queueServer = config.GetAppSetting("QueueServer");
}
}
/// <summary>
/// When implemented in a derived class, executes when a Start command is sent to the service by the Service Control Manager (SCM) or when the operating system starts (for a service that starts automatically). Specifies actions to take when the service starts.
/// <para>
/// The logic in this method creates a WCF service host (i.e. something that listens for messages) using the <see cref="IMyExampleServiceContract"/> contract.
/// The WCF end point is a NetMSMQBinding to the MyExample MSMQ server/queue.
/// It sets up this end point and provides a class to handle the messages received on it.
/// The NetMSMQBinding is a Microsoft WCF binding that handles serialisation of data to MSMQ. It is a ms proprietary format and means that the message on the queue
/// can only be read by a WCF service with the correct contract information.
/// </para>
/// </summary>
/// <param name="args">Data passed by the start command.</param>
protected override void OnStart(string[] args)
{
try
{
Logger.Write("MyExample MSMQ listener service started.", StandardCategories.Information);
Uri serviceUri = new Uri("net.msmq://" + QueueServer + QueueName);
NetMsmqBinding serviceBinding = new NetMsmqBinding();
serviceBinding.Security.Transport.MsmqAuthenticationMode = MsmqAuthenticationMode.None;
serviceBinding.Security.Transport.MsmqProtectionLevel = System.Net.Security.ProtectionLevel.None;
serviceBinding.MaxReceivedMessageSize = MaxMessageSize;
serviceBinding.ReaderQuotas.MaxArrayLength = MaxArraySize;
//QueueHandler implements IMyExampleServiceContract
_serviceHost = new ServiceHost(typeof(QueueHandler));
_serviceHost.AddServiceEndpoint(typeof(IMyExampleServiceContract), serviceBinding, serviceUri);
_serviceHost.Open();
Logger.Write("MyExample MSMQ listener service completed OnStart method.", StandardCategories.Information);
}
catch (Exception ex)
{
ExceptionReporting.ReportException(ex, "DefaultExceptionPolicy");
throw;
}
}
/// <summary>
/// Gets the name of the queue to send to.
/// This is retrieved from the application settings under QueueName
/// </summary>
private string QueueName
{
get { return _queueName; }
}
/// <summary>
/// Gets the name of the queue server to send to.
/// This is retrieved from the application settings under QueueServer
/// </summary>
private string QueueServer
{
get { return _queueServer; }
}
/// <summary>
/// When implemented in a derived class, executes when a Stop command is sent to the service by the Service Control Manager (SCM). Specifies actions to take when a service stops running.
/// </summary>
protected override void OnStop()
{
if (_serviceHost != null)
{
_serviceHost.Close();
_serviceHost = null;
}
}
/// <summary>
/// The main entry point for the application.
/// </summary>
public static void Main()
{
//Code will have to be compiled in release mode to be installed as a windows service
#if (!DEBUG)
try
{
Logger.Write("Attempting to start queue listener service.", StandardCategories.Information);
ServiceBase[] ServicesToRun;
ServicesToRun = new ServiceBase[]
{
new MsmqListenerService()
};
ServiceBase.Run(ServicesToRun);
Logger.Write("Finished ServiceBase.Run of queue listener service.", StandardCategories.Information);
}
catch (Exception e)
{
ExceptionReporting.ReportException(e, "DefaultExceptionPolicy");
throw;
}
#else
//This allows us to run from within visual studio
MsmqListenerService service = new MsmqListenerService();
service.OnStart(null);
System.Threading.Thread.Sleep(System.Threading.Timeout.Infinite);
#endif
}
}
}
答案 0 :(得分：5)
我不确定为什么你的服务主机会挂起，但我绝对可以想到一些让它更可靠的事情：
a）它可以成功发送它们
b）正在侦听该队列的本地WCF运行状况服务正在拾取和处理这些消息。这可用于检测一些可能的错误情况。
答案 1 :(得分：3)
底层WCF MSMQ侦听器可能在它到达您的代码之前抛出异常。这是令人沮丧的情况，因为它看起来没有任何反应，最糟糕的是你的消息被丢弃。打开服务配置文件中的WCF service tracing。
现在，当您运行服务时，它将跟踪并提供更多详细信息。而不是通过XML使你的眼睛紧张，用MS服务跟踪查看器打开这个日志文件。
当我遇到这个问题时，我收到了“System.ServiceModel.ProtocolException”：
传入的MSMQ消息在其正文中包含无效或意外的.NET消息帧信息。无法接收消息。确保发件人使用与匹配的SessionMode *兼容的服务合同。我的服务合同已更改为具有SessionMode = SessionMode.Required属性，但客户端未发送带有事务的消息。
答案 2 :(得分：1)
尽管WCF为MSMQ添加了一些很酷的功能，但有时您可以轻松实现目标，并且如果手动编写MSMQ处理代码，则可以更好地控制。
如果您手动处理队列，您将能够准确地看到正在发生的事情＆amp;处理抛出的MessageQueueExceptions，例如你将能够捕获MessageQueueErrorCodes，例如QueueNotFound或MachineNotFound。
不幸的是，这意味着还要管理有害消息队列，向处理添加事务，向队列添加超时时间等等.WCF很好地为您处理所有这些事情。
使用WCF的主要好处是，您可以使用WAS实例化Web应用程序，而不是持续运行Windows服务。如果你没有利用这个好处，那么我并没有真正看到WCF带来任何好处 - 它只是抽象出你需要触摸和看到的很多东西。
就像旁注一样;也许您可以在将消息放入队列时检查服务器是否可用？如果服务器可以将消息放入队列，则侦听器将能够立即处理它们。