ISendMessageCallback Interface  
Definition
Important
Some information relates to prerelease product that may be substantially modified before it’s released. Microsoft makes no warranties, express or implied, with respect to the information provided here.
An interface that implements a callback that is called just before a message is sent on the wire by the Send or SendParametersContent activities.
public interface class ISendMessageCallbackpublic interface ISendMessageCallbacktype ISendMessageCallback = interfacePublic Interface ISendMessageCallbackExamples
The following example shows how to implement the ISendMessageCallback interface to a new header to a message before it is sent out on the wire.
class SendInstanceIdCallback : ISendMessageCallback
{
    public const string HeaderName = "InstanceIdHeader";
    public const string HeaderNS = "http://Microsoft.Samples.AccessingOperationContext";
    public Guid InstanceId { get; set; }
    public void OnSendMessage(System.ServiceModel.OperationContext operationContext)
    {
        operationContext.OutgoingMessageHeaders.Add(MessageHeader.CreateHeader(HeaderName, HeaderNS, this.InstanceId));
    }
}
Methods
| OnSendMessage(OperationContext) | Executed when a service message is sent. |