OperationContext Class

Definition

public ref class OperationContext sealed : System::ServiceModel::IExtensibleObject<System::ServiceModel::OperationContext ^>

public sealed class OperationContext : System.ServiceModel.IExtensibleObject<System.ServiceModel.OperationContext>

type OperationContext = class
 interface IExtensibleObject<OperationContext>

Public NotInheritable Class OperationContext
Implements IExtensibleObject(Of OperationContext)

Inheritance

Object

OperationContext

Implements

IExtensibleObject<OperationContext>

Examples

The following code example uses the Current property and GetCallbackChannel method to obtain the channel back to the caller from within a method. All methods in this example are one-way methods, enabling the service and the client to communicate in both directions independently. In this case, the example client application expects only one return call before it exits, but another client, for example a Windows Forms client, can receive any number of calls from the service.

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);
 }
 }
}

Imports System.Collections.Generic
Imports System.ServiceModel
Imports System.Threading

Namespace Microsoft.WCF.Documentation
 <ServiceContract(Name:="SampleDuplexHello", Namespace:="http://microsoft.wcf.documentation", _
 CallbackContract:=GetType(IHelloCallbackContract), SessionMode:=SessionMode.Required)> _
 Public Interface IDuplexHello
 <OperationContract(IsOneWay:=True)> _
 Sub Hello(ByVal greeting As String)
 End Interface

 Public Interface IHelloCallbackContract
 <OperationContract(IsOneWay := True)> _
 Sub Reply(ByVal responseToGreeting As String)
 End Interface

 Public Class DuplexHello
 Implements IDuplexHello
 Public Sub New()
 Console.WriteLine("Service object created: " & Me.GetHashCode().ToString())
 End Sub

 Protected Overrides Sub Finalize()
 Console.WriteLine("Service object destroyed: " & Me.GetHashCode().ToString())
 End Sub

 Public Sub Hello(ByVal greeting As String) Implements IDuplexHello.Hello
 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)
 Dim callerProxy = OperationContext.Current.GetCallbackChannel(Of IHelloCallbackContract)()
 Dim response = "Service object " & Me.GetHashCode().ToString() & " received: " & greeting
 Console.WriteLine("Sending back: " & response)
 callerProxy.Reply(response)
 End Sub
 End Class
End Namespace

The following client implements the SampleDuplexHelloCallback to receive the callback message. The imported callback contract is not the same name as the one in the service, due to the use of the Name property in the preceding example. Note that the client makes no assumptions about whether or when it might receive a callback; the server callback is entirely independent of the client's outbound call.

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

namespace Microsoft.WCF.Documentation
{
 public class Client : SampleDuplexHelloCallback
 {
 AutoResetEvent waitHandle;

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

 public void Run()
 {
 // Picks up configuration from the config file.
 SampleDuplexHelloClient wcfClient
 = new SampleDuplexHelloClient(new InstanceContext(this));
 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();
 wcfClient.Close();
 }
 catch (TimeoutException timeProblem)
 {
 Console.WriteLine("The service operation timed out. " + timeProblem.Message);
 Console.ReadLine();
 wcfClient.Abort();
 }
 catch (CommunicationException commProblem)
 {
 Console.WriteLine("There was a communication problem. " + commProblem.Message);
 Console.ReadLine();
 wcfClient.Abort();
 }
 }

 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 System.ServiceModel
Imports System.ServiceModel.Channels
Imports System.Threading

Namespace Microsoft.WCF.Documentation
 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 config file.
 Dim wcfClient As New SampleDuplexHelloClient(New InstanceContext(Me))
 Try
 Console.ForegroundColor = ConsoleColor.White
 Console.WriteLine("Enter a greeting to send and press ENTER: ")
 Console.Write(">>> ")
 Console.ForegroundColor = ConsoleColor.Green
 Dim greeting = 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()
 wcfClient.Close()
 Catch timeProblem As TimeoutException
 Console.WriteLine("The service operation timed out. " & timeProblem.Message)
 Console.ReadLine()
 wcfClient.Abort()
 Catch commProblem As CommunicationException
 Console.WriteLine("There was a communication problem. " & commProblem.Message)
 Console.ReadLine()
 wcfClient.Abort()
 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 the OperationContext from within a service operation to access the current operation execution environment. In particular, the operation context is used to access callback channels in duplex services, to store extra state data across portions of the operations, and to access incoming message headers and properties as well as add outgoing message headers and properties.

For more information about using extensions to store state data, see Extensible Objects.

The OperationContext has the following properties and methods.

• The Current property returns the OperationContext object representing the current execution context.

• The ServiceSecurityContext property returns the security environment under which the method executes.

• The EndpointDispatcher property gets the operation's System.ServiceModel.Dispatcher.EndpointDispatcher.

• The Extensions property returns an extension collection for the current OperationContext.

• The Host property returns the ServiceHostBase object that manages the service.

• The HasSupportingTokens property returns a value that indicates whether the method has supporting tokens, if so, the SupportingTokens property gets them.

• The IncomingMessageHeaders, IncomingMessageProperties, and IncomingMessageVersion properties get these items from the incoming message.

• The OperationCompleted event is fired when the operation has completed.

• The OutgoingMessageHeaders and OutgoingMessageProperties properties get these items for the outbound message.

• The RequestContext property returns the RequestContext implementation for the method.

• The InstanceContext property returns the InstanceContext associated with the operation.

• The SessionId property returns the session identifier for the current channel and object.

• The GetCallbackChannel method returns a callback channel to the caller in the case of duplex communication.

• The SetTransactionComplete method commits the current transaction.