語言

OperationContext.GetCallbackChannel<T> 方法

定義

命名空間:
System.ServiceModel
組件:
System.ServiceModel.dll, System.ServiceModel.Primitives.dll
組件:
System.ServiceModel.dll
組件:
System.ServiceModel.Primitives.dll
套件:
System.ServiceModel.Primitives v10.1.0
來源:
OperationContext.cs
來源:
OperationContext.cs
來源:
OperationContext.cs

它會取得一個通道到呼叫當前操作的客戶端實例。

public:
generic <typename T>
 T GetCallbackChannel();
public T GetCallbackChannel<T>();
member this.GetCallbackChannel : unit -> 'T
Public Function GetCallbackChannel(Of T) () As T

類型參數

T

用來回撥客戶端的頻道類型。

傳回

T

一個通道連接到客戶端實例，呼叫屬性中 CallbackContract 指定的操作。

範例

以下程式碼範例使用屬性 Current 與 GetCallbackChannel 方法，從操作內建立回呼叫者的通道。 本例中的所有操作皆為單向操作，使服務與客戶端能獨立雙向通訊。 在這種情況下，範例客戶端應用程式預期只會回撥一次，然後退出，但另一個客戶端，例如Windows Forms客戶端，可以接收該服務任意數量的呼叫。

using System;
using System.Collections.Generic;
using System.ServiceModel;
using System.Threading;

namespace Microsoft.WCF.Documentation
{
  [ServiceContract(
    Name = "SampleDuplexHello",
    Namespace = "http://microsoft.wcf.documentation",
    CallbackContract = typeof(IHelloCallbackContract),
    SessionMode = SessionMode.Required
  )]
  public interface IDuplexHello
  {
    [OperationContract(IsOneWay = true)]
    void Hello(string greeting);
  }

  public interface IHelloCallbackContract
  {
    [OperationContract(IsOneWay = true)]
    void Reply(string responseToGreeting);
  }

  public class DuplexHello : IDuplexHello
  {
    public DuplexHello()
    {
      Console.WriteLine("Service object created: " + this.GetHashCode().ToString());
    }

    ~DuplexHello()
    {
      Console.WriteLine("Service object destroyed: " + this.GetHashCode().ToString());
    }

    public void Hello(string greeting)
    {
      Console.WriteLine("Caller sent: " + greeting);
      Console.WriteLine("Session ID: " + OperationContext.Current.SessionId);
      Console.WriteLine("Waiting two seconds before returning call.");
      // Put a slight delay to demonstrate asynchronous behavior on client.
      Thread.Sleep(2000);
      IHelloCallbackContract callerProxy
        = OperationContext.Current.GetCallbackChannel<IHelloCallbackContract>();
      string response = "Service object " + this.GetHashCode().ToString() + " received: " + greeting;
      Console.WriteLine("Sending back: " + response);
      callerProxy.Reply(response);
    }
  }
}

以下用戶端實 SampleDuplexHelloCallback 作了接收回撥訊息的 。 匯入的回撥合約名稱與服務中的合約不同，因為前述範例中使用了該 Name 屬性。 請注意，用戶端對於是否或何時會收到回撥不做任何假設;伺服器回撥完全獨立於用戶端的外撥通話。

Note

關於在客戶端情境中使用該 OperationContext 類別的範例，請參見 OperationContextScope。

using System;
using System.ServiceModel;
using System.ServiceModel.Channels;
using System.Threading;

namespace Microsoft.WCF.Documentation
{
  public class Client : SampleDuplexHelloCallback
  {
    AutoResetEvent waitHandle;

    public Client()
    {
      waitHandle = new AutoResetEvent(false);
    }

    public void Run()
    {
      // Picks up configuration from the config file.
      SampleDuplexHelloClient wcfClient
        = new SampleDuplexHelloClient(new InstanceContext(this));
      try
      {
        Console.ForegroundColor = ConsoleColor.White;
        Console.WriteLine("Enter a greeting to send and press ENTER: ");
        Console.Write(">>> ");
        Console.ForegroundColor = ConsoleColor.Green;
        string greeting = Console.ReadLine();
        Console.ForegroundColor = ConsoleColor.White;
        Console.WriteLine("Called service with: \r\n\t" + greeting);
        wcfClient.Hello(greeting);
        Console.WriteLine("Execution passes service call and moves to the WaitHandle.");
        this.waitHandle.WaitOne();
        Console.ForegroundColor = ConsoleColor.Blue;
        Console.WriteLine("Set was called.");
        Console.Write("Press ");
        Console.ForegroundColor = ConsoleColor.Red;
        Console.Write("ENTER");
        Console.ForegroundColor = ConsoleColor.Blue;
        Console.Write(" to exit...");
        Console.ReadLine();
        wcfClient.Close();
      }
      catch (TimeoutException timeProblem)
      {
        Console.WriteLine("The service operation timed out. " + timeProblem.Message);
        Console.ReadLine();
        wcfClient.Abort();
      }
      catch (CommunicationException commProblem)
      {
        Console.WriteLine("There was a communication problem. " + commProblem.Message);
        Console.ReadLine();
        wcfClient.Abort();
      }
    }

    public static void Main()
    {
      Client client = new Client();
      client.Run();
    }

    public void Reply(string response)
    {
      Console.WriteLine("Received output.");
      Console.WriteLine("\r\n\t" + response);
      this.waitHandle.Set();
    }
  }
}

備註

呼叫該 GetCallbackChannel<T>() 方法取得一個通道，可以用來呼叫呼叫該服務的客戶端實例的操作。

適用於