Article
11/18/2011

ServiceContractAttribute.CallbackContract Property

Microsoft Silverlight will reach end of support after October 2021. Learn more.

Gets or sets the type of callback contract when the contract is a duplex contract.

Namespace: System.ServiceModel
Assembly: System.ServiceModel (in System.ServiceModel.dll)

Syntax

'Declaration
Public Property CallbackContract As Type

public Type CallbackContract { get; set; }

Property Value

Type: System.Type
A Type that indicates the callback contract. The default is nulla null reference (Nothing in Visual Basic).

Remarks

Specify an interface in the 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.

Examples

    'The following code contains an example of a duplex contract that contains a callback contract.
    <ServiceContract(Name := "SampleContract", Namespace := "Silverlight", CallbackContract := GetType(IDuplexClient))> _
    Public Interface IDuplexService
        <OperationContract(IsOneWay := True)> _
        Sub Order(ByVal name As String, ByVal quantity As Integer)
    End Interface

    <ServiceContract> _
    Public Interface IDuplexClient
        <OperationContract(IsOneWay := True)> _
        Sub Receive(ByVal order As Order)
    End Interface

//The following code contains an example of a duplex contract that contains a callback contract.
[ServiceContract(
    Name = "SampleContract", 
    Namespace = "Silverlight", 
    CallbackContract = typeof(IDuplexClient))]
public interface IDuplexService
{
    [OperationContract(IsOneWay = true)]
    void Order(string name, int quantity);
}

[ServiceContract]
public interface IDuplexClient
{
    [OperationContract(IsOneWay = true)]
    void Receive(Order order);
}

Version Information

Silverlight

Supported in: 5, 4, 3

Silverlight for Windows Phone

Supported in: Windows Phone OS 7.1, Windows Phone OS 7.0

XNA Framework

Supported in: Windows Phone OS 7.0

Platforms

For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.

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