OperationContext.GetCallbackChannel<T> Methode

public:
generic <typename T>
 T GetCallbackChannel();

public T GetCallbackChannel<T>();

member this.GetCallbackChannel : unit -> 'T

Public Function GetCallbackChannel(Of T) () As T

Type parameters

Retouren

Een kanaal naar het clientexemplaren dat de bewerking aangeroepen van het type dat is opgegeven in de CallbackContract eigenschap.

Voorbeelden

In het volgende codevoorbeeld wordt de Current eigenschap en GetCallbackChannel methode gebruikt om vanuit een bewerking een kanaal terug te maken naar de aanroeper. Alle bewerkingen in dit voorbeeld zijn bewerkingen in één richting, waardoor de service en de client onafhankelijk van elkaar kunnen communiceren. In dit geval verwacht de voorbeeldclienttoepassing slechts één retouroproep voordat deze wordt afgesloten, maar een andere client, bijvoorbeeld een Windows Forms client, kan een willekeurig aantal oproepen van de service ontvangen.

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);
    }
  }
}

Imports System.Collections.Generic
Imports System.ServiceModel
Imports System.Threading

Namespace Microsoft.WCF.Documentation
    <ServiceContract(Name:="SampleDuplexHello", Namespace:="http://microsoft.wcf.documentation", _
                     CallbackContract:=GetType(IHelloCallbackContract), SessionMode:=SessionMode.Required)> _
  Public Interface IDuplexHello
        <OperationContract(IsOneWay:=True)> _
        Sub Hello(ByVal greeting As String)
    End Interface

  Public Interface IHelloCallbackContract
    <OperationContract(IsOneWay := True)> _
    Sub Reply(ByVal responseToGreeting As String)
  End Interface

  Public Class DuplexHello
      Implements IDuplexHello
    Public Sub New()
      Console.WriteLine("Service object created: " & Me.GetHashCode().ToString())
    End Sub

    Protected Overrides Sub Finalize()
      Console.WriteLine("Service object destroyed: " & Me.GetHashCode().ToString())
    End Sub

    Public Sub Hello(ByVal greeting As String) Implements IDuplexHello.Hello
      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)
            Dim callerProxy = OperationContext.Current.GetCallbackChannel(Of IHelloCallbackContract)()
            Dim response = "Service object " & Me.GetHashCode().ToString() & " received: " & greeting
      Console.WriteLine("Sending back: " & response)
      callerProxy.Reply(response)
    End Sub
  End Class
End Namespace

De volgende client implementeert het SampleDuplexHelloCallback om het callback-bericht te ontvangen. Het geïmporteerde callback-contract is niet dezelfde naam als het contract in de service, vanwege het gebruik van de Name eigenschap in het vorige voorbeeld. Houd er rekening mee dat de client geen aannames doet over of of of het een callback kan ontvangen; de server callback is volledig onafhankelijk van de uitgaande aanroep van de client.

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();
    }
  }
}

Imports System.ServiceModel
Imports System.ServiceModel.Channels
Imports System.Threading

Namespace Microsoft.WCF.Documentation
  Public Class Client
      Implements SampleDuplexHelloCallback
    Private waitHandle As AutoResetEvent

    Public Sub New()
      waitHandle = New AutoResetEvent(False)
    End Sub

    Public Sub Run()
      ' Picks up configuration from the config file.
      Dim wcfClient As New SampleDuplexHelloClient(New InstanceContext(Me))
      Try
        Console.ForegroundColor = ConsoleColor.White
        Console.WriteLine("Enter a greeting to send and press ENTER: ")
        Console.Write(">>> ")
        Console.ForegroundColor = ConsoleColor.Green
                Dim greeting = Console.ReadLine()
        Console.ForegroundColor = ConsoleColor.White
        Console.WriteLine("Called service with: " & Constants.vbCrLf & Constants.vbTab & greeting)
        wcfClient.Hello(greeting)
        Console.WriteLine("Execution passes service call and moves to the WaitHandle.")
        Me.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 timeProblem As TimeoutException
        Console.WriteLine("The service operation timed out. " & timeProblem.Message)
        Console.ReadLine()
        wcfClient.Abort()
      Catch commProblem As CommunicationException
        Console.WriteLine("There was a communication problem. " & commProblem.Message)
        Console.ReadLine()
        wcfClient.Abort()
      End Try
    End Sub

    Public Shared Sub Main()
      Dim client As New Client()
      client.Run()
    End Sub

    Public Sub Reply(ByVal response As String) Implements SampleDuplexHelloCallback.Reply
      Console.WriteLine("Received output.")
      Console.WriteLine(Constants.vbCrLf & Constants.vbTab & response)
      Me.waitHandle.Set()
    End Sub
  End Class
End Namespace

Opmerkingen

Roep de GetCallbackChannel<T>() methode aan om een kanaal te verkrijgen dat u kunt gebruiken om bewerkingen aan te roepen op het clientexemplaren dat de service wordt genoemd.