2

我正在使用一个 Windows 服务,我也想在其中添加一个 GUI。我通过我的服务创建了一个 ServiceHost 对象并托管 WCF 命名管道服务,然后我使用控制台应用程序来使用 WCF 服务并从服务获取回调响应(从服务器发送到连接的客户端的消息),进行了概念验证。这很好用,我的控制台应用程序运行并从服务中获得响应,没有中断或延迟。

但是,当在我的 WPF GUI 应用程序中做同样的事情时,当单击一个按钮然后调用 WCF 服务时,它会冻结整个 UI 线程,然后在几分钟后引发异常,然后使用消息回调更新 UI(服务器发送消息到连接的客户端),但由于抛出异常,服务的任何返回值都将丢失。

我得到的两个异常消息是论文(最常见的是第一个):

1:发送到net.pipe://localhost/PipeGUI的请求动作在指定的超时时间(00:00:59.9989999)内没有收到响应。分配给此操作的时间可能是较长超时的一部分。这可能是因为服务仍在处理操作,或者因为服务无法发送回复消息。提高操作的截止日期(通过输入通道/代理到图标文本通道并设置属性操作超时)并验证服务可以连接到客户端。

2:通讯对象System.ServiceModel.Channels.ServiceChannel,因为已经取消,不能用于通讯。

有人知道为什么会这样吗?如有必要,我可以发布更多代码。

更新,添加代码供参考

public interface IClientCallback
{
    [OperationContract(IsOneWay = true)]
    void MessageRecived(string message);
}

[ServiceContract(SessionMode = SessionMode.Required, CallbackContract = typeof(IClientCallback))]
public interface IPipeServiceContract
{
    [OperationContract]
    string Hello();

    [OperationContract]
    void Message(string msg);

    [OperationContract(IsInitiating = true)]
    void Connect();

    [OperationContract(IsTerminating = true)]
    void Disconnect();
}

[ServiceBehavior(InstanceContextMode = InstanceContextMode.Single, IncludeExceptionDetailInFaults = true, UseSynchronizationContext = false)]
public class PipeService : IPipeServiceContract
{
    List<IClientCallback> _clients = new List<IClientCallback>();

    public string Hello()
    {
        PublishMessage("Hello World.");
        return "Return from method!";
    }

    public void Connect()
    {
        _clients.Add(OperationContext.Current.GetCallbackChannel<IClientCallback>());
    }

    public void Disconnect()
    {
        IClientCallback callback = OperationContext.Current.GetCallbackChannel<IClientCallback>();
        _clients.Remove(callback);
    }

    void PublishMessage(string message)
    {
        for (int i = _clients.Count - 1; i > 0; i--)
        {
            try
            {
                _clients[i].MessageRecived(message);
            }
            catch (CommunicationObjectAbortedException coae)
            {
                _clients.RemoveAt(i);
            }
            catch(CommunicationObjectFaultedException cofe)
            {
                _clients.RemoveAt(i);
            }
        }
    }


    public void Message(string msg)
    {
        PublishMessage(msg);
    }
}


/// <summary>
/// Interaction logic for MainWindow.xaml
/// </summary>
public partial class MainWindow : Window, INotifyPropertyChanged, IClientCallback
{
    public ServiceController Service { get; set; }

    protected IPipeServiceContract Proxy { get; set; }
    protected DuplexChannelFactory<IPipeServiceContract> PipeFactory { get; set; }

    public ObservableCollection<ServerActivityNotification> Activity { get; set; }

    public override void BeginInit()
    {
        base.BeginInit();
        PipeFactory = new DuplexChannelFactory<IPipeServiceContract>(this, new NetNamedPipeBinding(), new EndpointAddress("net.pipe://localhost/PipeGUI"));
    }

    public MainWindow()
    {
        InitializeComponent();
        Activity = new ObservableCollection<ServerActivityNotification>();
        Service = ServiceController.GetServices().First(x => x.ServiceName == "Server Service");
        NotifyPropertyChanged("Service");
        var timer = new DispatcherTimer();
        timer.Tick += new EventHandler(OnUpdate);
        timer.Interval = new TimeSpan(0, 0, 0, 0, 850);
        timer.Start();

        if (Service.Status == ServiceControllerStatus.Running)
        {
            Proxy = PipeFactory.CreateChannel();
            Proxy.Connect();
        }
    }

    void OnUpdate(object sender, EventArgs e)
    {
        Service.Refresh();
        NotifyPropertyChanged("Service");

        StartButton.IsEnabled = Service.Status != ServiceControllerStatus.Running ? true : false;
        StopButton.IsEnabled = Service.Status != ServiceControllerStatus.Stopped ? true : false;

        if (PipeFactory != null && Service.Status == ServiceControllerStatus.Running)
        {
            Proxy = PipeFactory.CreateChannel();
            Proxy.Connect();
        }
    }

    public event PropertyChangedEventHandler PropertyChanged;

    public void NotifyPropertyChanged(string name)
    {
        if (PropertyChanged != null)
            PropertyChanged(this, new PropertyChangedEventArgs(name));
    }

    private void OnStart(object sender, RoutedEventArgs e)
    {
        try
        {
            Service.Start();
        }
        catch
        {
            Service.Refresh();
        }
    }

    private void OnStop(object sender, RoutedEventArgs e)
    {
        try
        {
            if (Proxy != null)
            {
                Proxy.Disconnect();
                PipeFactory.Close();
            }
            Service.Stop();
        }
        catch
        {
            Service.Refresh();
        }
    }

    public void MessageRecived(string message)
    {
        Dispatcher.BeginInvoke(DispatcherPriority.Background, new Action(() =>
        {
            ServerActivityNotification log = new ServerActivityNotification { Activity = message, Occured = DateTime.Now };
            Activity.Add(log);
            ListBoxLog.ScrollIntoView(log);
            NotifyPropertyChanged("Activity");
        }));
    }

    private void OnHello(object sender, RoutedEventArgs e)
    {
        try
        {
            Proxy.Message(txtSendMessage.Text);
        }
        catch (Exception ex)
        {
            Debug.WriteLine(ex.Message);
        }
    }
}

}

4

1 回答 1

1

尝试将UseSynchronizationContext服务行为的属性设置为false

[ServiceBehavior(UseSynchronizationContext = false)]
class MyService
{

}

[ServiceContract]
public interface IMyService
{

}

我相信默认情况下它设置为true,因此您当前正尝试在同一线程上使用和运行 WCF 服务,从而导致死锁。

无论如何,听起来您正试图在 WPF 应用程序的 UI 线程上使用 WCF 服务。通常,建议您在后台线程上执行可能长时间运行的任务,因为即使您的服务调用需要几秒钟/几分钟,这也会使界面保持响应。

编辑:

我尝试并成功复制了您的问题。尝试在 UI 线程上调用服务会导致 UI 冻结。但是,当我更改代码以在后台任务上调用服务时(见下文),我能够调用服务并接收回调:

    private void Button_Click(object sender, RoutedEventArgs e)
    {
        Task.Factory.StartNew(() =>
            {
                var myService = DuplexChannelFactory<IMyService>.CreateChannel(new CallbackImplementation(),
                                                                               new WSDualHttpBinding(),
                                                                               new EndpointAddress(
                                                                                   @"http://localhost:4653/myservice"));
                myService.CallService();
                string s = "";
            });
    }

我不得不承认,我不完全确定为什么会这样,并且任何关于 WCF 究竟如何管理托管服务实例的线程的澄清都将有助于弄清楚为什么会这样。

于 2013-09-18T13:01:28.487 回答