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CallbackBehaviorAttribute Class

Configures a callback service implementation in a client application.

Namespace:  System.ServiceModel
Assembly:  System.ServiceModel (in System.ServiceModel.dll)
'Declaration
<AttributeUsageAttribute(AttributeTargets.Class)> _
Public NotInheritable Class CallbackBehaviorAttribute _
	Inherits Attribute _
	Implements IEndpointBehavior
'Usage
Dim instance As CallbackBehaviorAttribute

Use the CallbackBehaviorAttribute attribute to configure or extend the execution behavior of a callback contract implementation in a client application. This attribute performs the same function for the callback class as the ServiceBehaviorAttribute attribute with the exception of instancing behavior and transaction settings.

The CallbackBehaviorAttribute must be applied to the class that implements the callback contract. If applied to a non-duplex contract implementation an InvalidOperationException exception is thrown at runtime.

NoteNote:

You can also use the OperationBehaviorAttribute attribute for the callback operation implementations. However, if OperationBehaviorAttribute is used on a callback operation, the ReleaseInstanceMode property must be None or an InvalidOperationException exception is thrown at runtime.

The following properties are available:

  • The AutomaticSessionShutdown property automatically closes the session when the channel is closed and the callback has finished processing any remaining messages.

  • The ConcurrencyMode property controls the internal threading model, enabling support for reentrant or multithreaded callback objects.

  • The IgnoreExtensionDataObject property enables the runtime to ignore extra serialization information that is not required to process the message.

  • The IncludeExceptionDetailInFaults property specifies whether unhandled exceptions in a service are returned to the service as SOAP faults for debugging purposes.

  • The MaxItemsInObjectGraph property limits on the number of items in an object graph that are serialized.

  • The TransactionIsolationLevel property specifies the transaction isolation level that the contract supports.

  • The TransactionTimeout property specifies the time period within which a transaction must complete or it aborts.

  • The UseSynchronizationContext property indicates whether to synchronize inbound method calls automatically using the current SynchronizationContext object.

  • The ValidateMustUnderstand property informs the system whether it should confirm that SOAP headers marked as MustUnderstand have, in fact, been understood.

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();
    }
  }
}
System.Object
  System.Attribute
    System.ServiceModel.CallbackBehaviorAttribute
Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

Windows 7, Windows Vista, Windows XP SP2, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003

The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

.NET Framework

Supported in: 3.5, 3.0
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