如何在异步ASP上定义客户端超时.NET web服务调用

请检查你的app.config，它将有一些servicemodel的设置，并且它有各种可以配置的值。

当我添加新的服务引用时，我可以在app.config、中看到以下内容

<system.serviceModel>
    <bindings>
        <basicHttpBinding>
            <binding name="HeaderedServiceSoap" 
                     closeTimeout="00:01:00" 
                     openTimeout="00:01:00"
                     receiveTimeout="00:10:00" 
                     sendTimeout="00:01:00" 
                     allowCookies="false"
                     bypassProxyOnLocal="false" 
                     hostNameComparisonMode="StrongWildcard"
                     maxBufferSize="65536" 
                     maxBufferPoolSize="524288" 
                     maxReceivedMessageSize="65536"
                     messageEncoding="Text" 
                     textEncoding="utf-8" 
                     transferMode="Buffered"
                     useDefaultWebProxy="true">
                <readerQuotas maxDepth="32" 
                              maxStringContentLength="8192" 
                              maxArrayLength="16384"
                              maxBytesPerRead="4096" 
                              maxNameTableCharCount="16384" />
                <security mode="None">
                    <transport clientCredentialType="None" 
                               proxyCredentialType="None"
                               realm="" />
                    <message clientCredentialType="UserName" 
                             algorithmSuite="Default" />
                </security>
            </binding>
        </basicHttpBinding>
    </bindings>
    <client>
        <endpoint 
          address="http://localhost/MyService.asmx"
          binding="basicHttpBinding" 
          bindingConfiguration="HeaderedServiceSoap"
          contract="WSTest.HeaderedServiceSoap" 
          name="HeaderedServiceSoap" />
    </client>
</system.serviceModel>

请再次尝试删除和添加引用，确保您的应用程序的目标框架是4.0，并且您正在添加服务引用（而不是Web引用）。

实际上，您不能总是将WebRequest.TimeOut用于异步操作；至少不是针对抽象CCD_ 5类的所有实现者。例如，在msdn上有文档记载，当调用HttpWebRequest.BeginGetResponse来启动异步操作时，会忽略此属性。它明确指出，TimeOut属性被忽略，如果需要，实现超时行为是用户的责任。

在msdn上HttpWebRequest.BeginGetResponse文档附带的示例代码中，ManualResestEvent allDone与WaitOrTimerCallback的组合使用如下：

IAsyncResult result = (IAsyncResult) myHttpWebRequest.BeginGetResponse(
  new AsyncCallback(RespCallback), myRequestState);
// TimeoutCallback aborts the request if the timer fires.
ThreadPool.RegisterWaitForSingleObject (result.AsyncWaitHandle, 
                                        new WaitOrTimerCallback(TimeoutCallback),
                                        myHttpWebRequest, 
                                        DefaultTimeout, 
                                        true);
// The response came in the allowed time. The work processing will happen in the 
// callback function RespCallback.
allDone.WaitOne();

请参阅msdn上的完整示例。

最重要的是你必须自己实现这一点。

我做了一个小项目来演示如何做到这一点；这并不像我想象的那么简单，但是，那到底是什么呢？

这是整个项目，其中有一个Web服务，还有一个WPF中的客户端，它有一个按钮，可以在有和没有超时的情况下调用http://www.mediafire.com/file/3xj4o16hgzm139a/ASPWebserviceAsyncTimeouts.zip.我会在下面放一些相关的片段。我使用了代码中描述的DispatcherTimer类来进行超时；看起来这个对象显然是对WPF友好的，并且（如果不是全部的话）应该可以解决大多数可能遇到的同步问题。

注意：这可能可以通过WCF风格的"服务引用"来实现，然而，我无法找到方法，遇到了很多死胡同。我最终选择了一个老式的"Web参考"（您可以通过转到"添加服务参考…"，选择"高级"按钮，然后选择"添加Web参考"来获得它。

我之所以使用helper类，是为了演示在有很多调用的情况下可以做些什么；如果我们没有这些，记录每件事会很快变得一团糟。此外，可能会得到一个更通用的版本，其中几乎所有的处理都可以在代码中完成，但由于在服务引用代码中使用泛型的方式，我花了大部分时间的WCF代码不适合这种处理。我只是快速地查看了web服务代码，看起来更有可能完成，但不幸的是，我没有足够的时间来处理这部分内容。如果你想让我再看一眼，我会看看我能做些什么。

现在开始表演！）

回调助手：AsyncCallHelper.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
// contains base classes for webservice calls
using System.ServiceModel; 
// contains the DispatcherTimer class for callback timers
using System.Windows.Threading; 
namespace ASPSandcastleWPFClient
{
    /// <summary>
    /// DispatcherTimer usage info thanks to:
    /// 
    /// Wildermuth, Shawn, "Build More Responsive Apps With The Dispatcher", MSDN Magazine, October 2007
    /// Original URL: http://msdn.microsoft.com/en-us/magazine/cc163328.aspx
    /// Archived at http://www.webcitation.org/605qBiUEC on July 11, 2011.
    /// 
    /// this class is not set up to handle multiple outstanding calls on the same async call;
    /// if you wish to do that, there would need to be some sort of handling for multiple
    /// outstanding calls designed into the helper.
    /// </summary>
    public class AsyncCallHelper
    {
        #region Static Defaults
        private static TimeSpan myDefaultTimeout;
        /// <summary>
        /// default timeout for all instances of the helper; should different timeouts
        /// be required, a member should be created that can override this setting.
        /// 
        /// if this is set to null or a value less than zero, the timout will be set 
        /// to TimeSpan.Zero, and the helper will not provide timeout services to the 
        /// async call.
        /// </summary>
        public static TimeSpan DefaultTimeout
        {
            get
            {
                return myDefaultTimeout;
            }
            set
            {
                if ((value == null) || (value < TimeSpan.Zero))
                    myDefaultTimeout = TimeSpan.Zero;
                else
                    myDefaultTimeout = value;
            }
        }
        #endregion
        /// <summary>
        /// creates an instance of the helper to assist in timing out on an async call
        /// </summary>
        /// <param name="AsyncCall">the call which is represented by this instance. may not be null.</param>
        /// <param name="FailureAction">an action to take, if any, upon the failure of the call. may be null.</param>
        public AsyncCallHelper(Action AsyncCall, Action FailureAction)
        {
            myAsyncCall = AsyncCall;
            myFailureAction = FailureAction;
            myTimer = new DispatcherTimer();
            myTimer.Interval = DefaultTimeout;
            myTimer.Tick += new EventHandler(myTimer_Tick);
        }
        /// <summary>
        /// Make the call
        /// </summary>
        public void BeginAsyncCall()
        {
            myAsyncCall();
            if (DefaultTimeout > TimeSpan.Zero)
            {
                myTimer.Interval = DefaultTimeout;
                myTimer.Start();
            }
        }
        /// <summary>
        /// The client should call this upon receiving a response from the
        /// async call.  According to the reference given above, it seems that 
        /// the WPF will only be calling this on the same thread as the UI, 
        /// so there should be no real synchronization issues here.  
        /// 
        /// In a true multi-threading situation, it would be necessary to use
        /// some sort of thread synchronization, such as lock() statements
        /// or a Mutex in order to prevent the condition where the call completes
        /// successfully, but the timer fires prior to calling "CallComplete"
        /// thus firing the FailureAction after the success of the call.
        /// </summary>
        public void CallComplete()
        {
            if ((DefaultTimeout != TimeSpan.Zero) && myTimer.IsEnabled)
                myTimer.Stop();
        }
        private void myTimer_Tick(object sender, EventArgs e)
        {
            CallComplete();
            if (myFailureAction != null)
                myFailureAction();
        }
        /// <summary>
        /// WPF-friendly timer for use in aborting "Async" Webservice calls
        /// </summary>
        private DispatcherTimer myTimer;
        /// <summary>
        /// The call to be made
        /// </summary>
        private Action myAsyncCall;
        /// <summary>
        /// What action the helper should take upon a failure
        /// </summary>
        private Action myFailureAction;
    }
}

具有相关代码的MainWindow.xaml.cs文件：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;
using ASPSandcastleWPFClient.ASPSandcastleWebserviceClient;
namespace ASPSandcastleWPFClient
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {
        private ASPSandcastleWebservice myClient = null;
        private AsyncCallHelper myHelloWorldHelper = null;
        public MainWindow()
        {
            InitializeComponent();
        }
        private void InitializeClient()
        {
            myClient = new ASPSandcastleWebservice();
            myHelloWorldHelper = 
                new AsyncCallHelper
                    (
                        myClient.HelloWorldAsync,
                        HelloWorldTimeout
                    );
        }
        private void Window_Initialized(object sender, EventArgs e)
        {
            InitializeClient();
        }
        /// <summary>
        /// this is called prior to making a call so that we do not end up with multiple
        /// outstanding async calls
        /// </summary>
        private void DisableButtons()
        {
            btnStartAsyncCall.IsEnabled = false;
            btnStartAsyncCallWithTimeout.IsEnabled = false;
        }
        /// <summary>
        /// this is called after a result is received or the call is cancelled due to timeout
        /// so that we know it's safe to make another call.
        /// </summary>
        private void EnableButtons()
        {
            btnStartAsyncCall.IsEnabled = true;
            btnStartAsyncCallWithTimeout.IsEnabled = true;
        }
        private void btnStartAsyncCall_Click(object sender, RoutedEventArgs e)
        {
            DisableButtons();
            // disable the timeout handling
            AsyncCallHelper.DefaultTimeout = TimeSpan.Zero;
            myClient.HelloWorldCompleted += new HelloWorldCompletedEventHandler(myClient_HelloWorldCompleted);
            myHelloWorldHelper.BeginAsyncCall();
            lblResponse.Content = "waiting...";
        }
        private void btnStartAsyncCallWithTimeout_Click(object sender, RoutedEventArgs e)
        {
            DisableButtons();
            // enable the timeout handling
            AsyncCallHelper.DefaultTimeout = TimeSpan.FromSeconds(10);
            lblResponse.Content = "waiting for 10 seconds...";
            myHelloWorldHelper.BeginAsyncCall();
        }
        /// <summary>
        /// see note RE: possible multi-thread issues when not using WPF in AsyncCallHelper.cs
        /// </summary>
        private void HelloWorldTimeout()
        {
            myClient.CancelAsync(null);
            lblResponse.Content = "call timed out...";
            EnableButtons();
        }
        void myClient_HelloWorldCompleted(object sender, HelloWorldCompletedEventArgs e)
        {
            myHelloWorldHelper.CallComplete();
            if (!e.Cancelled)
                lblResponse.Content = e.Result;
            EnableButtons();
        }
    }
}

我不知道它是否惯用，但当通过WebClient.DownloadStringAsync(...)发出异步请求时，我也使用Silverlight中的计时器（DispatchTimer）。

web服务返回什么？XML、JSON或其他？你是在用这个网站吗？如果是这样，为什么不尝试使用jquery-ajax调用，然后异步加载它，然后使用.ajax（）指定超时。