CallbackBehaviorAttribute.UseSynchronizationContext CallbackBehaviorAttribute.UseSynchronizationContext CallbackBehaviorAttribute.UseSynchronizationContext CallbackBehaviorAttribute.UseSynchronizationContext Property

Definition

Gets or sets a value that specifies whether to use the current synchronization context to choose the thread of execution.

public:
 property bool UseSynchronizationContext { bool get(); void set(bool value); };
public bool UseSynchronizationContext { get; set; }
member this.UseSynchronizationContext : bool with get, set
Public Property UseSynchronizationContext As Boolean

Property Value

true if all calls to the service must run on the thread specified by the SynchronizationContext; otherwise, false. The default value is true.

Examples

The following code example shows a CallbackBehaviorAttribute on a callback object that uses the SynchronizationContext object to determine which thread to marshal to, the ValidateMustUnderstand property to enforce message validation, and the IncludeExceptionDetailInFaults property to return exceptions as FaultException objects to the service for debugging purposes.

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

namespace Microsoft.WCF.Documentation
{
  [CallbackBehaviorAttribute(
   IncludeExceptionDetailInFaults= true, 
    UseSynchronizationContext=true,
    ValidateMustUnderstand=true
  )]
  public class Client : SampleDuplexHelloCallback
  {
    AutoResetEvent waitHandle;

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

    public void Run()
    {
      // Picks up configuration from the configuration file.
      SampleDuplexHelloClient wcfClient
        = new SampleDuplexHelloClient(new InstanceContext(this), "WSDualHttpBinding_SampleDuplexHello");
      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();
      }
      catch (TimeoutException timeProblem)
      {
        Console.WriteLine("The service operation timed out. " + timeProblem.Message);
        Console.ReadLine();
      }
      catch (CommunicationException commProblem)
      {
        Console.WriteLine("There was a communication problem. " + commProblem.Message);
        Console.ReadLine();
      }
    }
    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 Microsoft.VisualBasic
Imports System
Imports System.ServiceModel
Imports System.ServiceModel.Channels
Imports System.Threading

Namespace Microsoft.WCF.Documentation
  <CallbackBehaviorAttribute(IncludeExceptionDetailInFaults:= True, UseSynchronizationContext:=True, ValidateMustUnderstand:=True)> _
  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 configuration file.
	  Dim wcfClient As New SampleDuplexHelloClient(New InstanceContext(Me), "WSDualHttpBinding_SampleDuplexHello")
	  Try
		Console.ForegroundColor = ConsoleColor.White
		Console.WriteLine("Enter a greeting to send and press ENTER: ")
		Console.Write(">>> ")
		Console.ForegroundColor = ConsoleColor.Green
		Dim greeting As String = 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()
	  Catch timeProblem As TimeoutException
		Console.WriteLine("The service operation timed out. " & timeProblem.Message)
		Console.ReadLine()
	  Catch commProblem As CommunicationException
		Console.WriteLine("There was a communication problem. " & commProblem.Message)
		Console.ReadLine()
	  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

Remarks

Use this property to provide the user interface thread affinity that some applications require. For example, a Windows Forms application may be registered as a singleton service object. In this case, all calls into the service must run on the Windows Forms thread. The default case, in which UseSynchronizationContext is set to true, synchronizes all calls to the service to run on the user interface thread.

Note that the thread used is the current synchronization thread when DuplexChannelFactory<TChannel>.CreateChannel or DuplexClientBase<TChannel>.CreateChannel is called. In the case of an Windows Forms application, this means that these calls should occur after a call to the Application.Run method.

Applies to