Question

在下面的代码中，我想要做的是允许我的客户端在服务器上调用wcf方法，返回成功，然后给出当前进度的回调，即完成百分比。客户端可以在10％之后断开连接，并且该方法将继续。

在下面的代码中 - 返回“success”行会导致函数退出。我想要返回的原因是客户端阻塞，直到他知道服务有一些重要的处理完成。

这可能吗？

namespace WCFService
{
    [ServiceBehavior(InstanceContextMode = InstanceContextMode.PerCall)]
    public class WCFJobsLibrary : IWCFJobsLibrary
    {
        public String ChatToServer(string texttoServer) // send some text to the server
        {
            Logging.Write_To_Log_File("Entry", MethodBase.GetCurrentMethod().Name, "", "", "", 1);

            try
            {
                // Some extemely important prechecks .....
                //........
                return "success";

                // Dont care now if client disconnects but lets give them some updates as progress happens if they are still connected


                IMyContractCallBack callback = OperationContext.Current.GetCallbackChannel<IMyContractCallBack>();
                // Some processing .....
                callbackmethod("20% complete", callback);
                // Some processing .....
                callbackmethod("40% complete", callback);
                // Some processing .....
                callbackmethod("60% complete", callback);
                // Some processing .....
                callbackmethod("80% complete", callback);
                // Some processing .....
                callbackmethod("100% complete", callback);

            }
            catch (Exception ex)
            {
                return "error";
            }
        }

        public void callbackmethod(string text, IMyContractCallBack somecallback)
        {
            try
            {
                somecallback.callbacktoServer(text);
            }    
            catch (Exception)
            {

            }    
        }
    }
}

Answer 1

当你在一个函数中return时，它将停在该行。在返回之后你没有执行任何操作。事实上，您的编译器应该已经警告过您无法访问的代码。

编辑：

我建议在调用return之前启动一个线程，它将运行continue工作并发送更新调用。

public String ChatToServer(string texttoServer) // send some text to the server
        {

            try
            {
                Logging.Write_To_Log_File("Entry", MethodBase.GetCurrentMethod().Name, "", "", "", 1);
                // Some extemely important prechecks .....
                System.Threading.Thread thread = new System.Threading.Thread(DoWork);
                thread.Start();
                //........
                return "success";

                // Dont care now if client disconnects but lets give them some updates as progress happens if they are still connected

            }
            catch (Exception ex)
            {
                return "error";
            }
        }

        void DoWork()
        {
            IMyContractCallBack callback = OperationContext.Current.GetCallbackChannel<IMyContractCallBack>();
            // Some processing .....
            callbackmethod("20% complete", callback);
            // Some processing .....
            callbackmethod("40% complete", callback);
            // Some processing .....
            callbackmethod("60% complete", callback);
            // Some processing .....
            callbackmethod("80% complete", callback);
            // Some processing .....
            callbackmethod("100% complete", callback);

        }

Answer 2

您可以进行回调异步，它们将触发，方法将返回，但您必须在调用回调后放置return行。

如果出现错误，WCF内置了自动异常处理功能，因此您只需Throw异常，就不需要返回它......然后可以在客户端捕获它。并且将获得更多信息，而不仅仅是“错误”。

使用TPL的示例:(使用System.Threading.Tasks命名空间，.net 4 +）

    string yourMethod() 
    {
        // Logging

        try 
        {   
            // prechecks 
        } 
        catch (Exception ex)
        {
            return "failed" // ok as you have now if no more information is needed
            // throw; // Can also throw exception which WCF client on other end can catch
        }     

        Task.Factory.StartNew(() => {
            IMyContractCallBack callback = OperationContext.Current.GetCallbackChannel<IMyContractCallBack>();
            // Some processing .....
            callbackmethod("20% complete", callback);
            // Some processing .....
            callbackmethod("40% complete", callback);
            // Some processing .....
            callbackmethod("60% complete", callback);
            // Some processing .....
            callbackmethod("80% complete", callback);
            // Some processing .....
            callbackmethod("100% complete", callback);
        });
        return "success";
   }

返回客户端的值，然后返回一些回调

2 个答案: