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ServiceContractAttribute.CallbackContract propriété

 

Date de publication : novembre 2016

Obtient ou définit le type de contrat de rappel lorsque le contrat est un contrat duplex.

Espace de noms:   System.ServiceModel
Assembly:  System.ServiceModel (dans System.ServiceModel.dll)

public Type CallbackContract { get; set; }

Valeur de propriété

Type: System.Type

Type qui indique le contrat de rappel. La valeur par défaut est null.

Specify an interface in the P:System.ServiceModel.ServiceContractAttribute.CallbackContract property that represents the required opposite contract in a two-way (or duplex) message exchange. This enables client applications to listen for inbound operation calls that the server-side service application can send independently of client activity. Callback contracts that have one-way operations represent calls from the service that the client can handle.

System_CAPS_noteRemarque

The T:System.ServiceModel.ServiceContractAttribute attribute is ignored on callback contracts. To configure runtime behavior of callback objects, use the T:System.ServiceModel.CallbackBehaviorAttribute.

The following code example shows a service that specifies a callback contract, which indicates that a service of type IDuplexHello must have a correspondent that implements a service of type IHelloCallbackContract. In addition, IHelloCallbackContract implements a one-way callback method, enabling the service to call the client without waiting for a reply to support a distributed, event-driven client.

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);
    }
  }
}

Plateforme Windows universelle
Disponible depuis 8
.NET Framework
Disponible depuis 3.0
Bibliothèque de classes portable
Pris en charge dans : plateformes .NET portables
Silverlight
Disponible depuis 3.0
Silverlight pour Windows Phone
Disponible depuis 7.0
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