[ServiceContract(SessionMode=SessionMode.Required)] public interface IContract {   [OperationContract]   void Test(); } [ServiceBehavior(InstanceContextMode=InstanceContextMode.PerSession)] public class MyService : IContract, IDisposable {   public MyService()   {     Console.WriteLine("Constructor:{0}", OperationContext.Current.SessionId);   }   public void Dispose()   {     Console.WriteLine("Dispose...");     Console.WriteLine("Is ThreadPool Thread? {0}", Thread.CurrentThread.IsThreadPoolThread);     Console.WriteLine("OperationContext = Null? {0}", OperationContext.Current == null);   }   public void Test()   {     Console.WriteLine("Test...");   } } public class WcfTest {   public static void Test()   {     AppDomain.CreateDomain("Server1").DoCallBack(delegate     {       ServiceHost host = new ServiceHost(typeof(MyService), new Uri("http://localhost:8080/MyService"));       host.AddServiceEndpoint(typeof(IContract), new WSHttpBinding(), "");       ServiceThrottlingBehavior throttling = new ServiceThrottlingBehavior();       throttling.MaxConcurrentInstances = 10;       host.Description.Behaviors.Add(throttling);       host.Open();     });     IContract channel = ChannelFactory<IContract>.CreateChannel(new WSHttpBinding();,       new EndpointAddress("http://localhost:8080/MyService"));     using (channel as IDisposable)     {       channel.Test();     }   } }