如何取消异步WCF调用？ [英] How to cancel an async WCF call?

问题描述

我一直在尝试一些时间，以了解如何基于新的.NET 4.5 CancellationToken机制实现WCF呼叫取消。我发现的所有样本都不基于WCF，并且没有跨越服务边界。

I have been trying some time to find out how to implement WCF call cancellation based on the new .NET 4.5 CancellationToken mechanism. All the samples I found are not WCF based, and do not cross the service boundary.

[ServiceBehavior(InstanceContextMode = InstanceContextMode.PerCall)]
public class MyService : IMyService
{   
    public void LongOperation()
    {
        // do stuff that takes ages...
        // please cancel me!
    }
}

我的客户（桌面应用程序）：

使用自动生成的代理：

My Client (Desktop App):

Using an auto generated proxy :

private async void DoLongRunningTaskAsync()
{
    var asyncTask = _myService.LongOperationAsync();
    await asyncTask;
}

如何取消此任务？请提供适用于.NET 4.5+上WCF的具体示例。

How do I cancel this task? Please provide a concrete example applicable to WCF on .NET 4.5+

下面的答案似乎表示出于技术原因是不可能的。因此，想象一下，我将服务设置为 ContextMode = Session ，然后设置一个名为 cancellationPending = true ，此阶段我的原始调用仍在运行，它会定期检查该变量。我仍然无法取消吗？还是不可能吗？如果是，为什么？

The answers below seem to indicate that its impossible for technical reasons. So, imagine, I make my service ContextMode=Session, then set a static variable (in a separate service call) called cancellationPending=true, my original call is still running at this stage, and it periodically checks that variable. Would I still not be able to cancel? would it still be impossible? if so, why?

推荐答案

如前所述。

如果要在客户端取消任务，可以使用扩展方法 Microsoft.VisualStudio.Threading.ThreadingTools> WithCancellation a>

If you want to cancel the Task on client side you can can use the extension method WithCancellation from Microsoft.VisualStudio.Threading.ThreadingTools

它是 Visual Studio SDK ，或者您也可以从 Nuget 。

It is part of Visual Studio SDK or you can also get it from Nuget.

 CancellationTokenSource ct = new CancellationTokenSource();
 ct.CancelAfter(20000);
 var asyncTask = _myService.LongOperationAsync();
 await asyncTask.WithCancellation(ct.Token);

这篇关于如何取消异步WCF调用？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！