using System;
using System.Collections.Generic;
using System.Text;
using System.ServiceModel;
namespace Artech.SessionfulCalculator.Contract
{
[ServiceContract]
public interface ICalculator
{
[OperationContract(IsOneWay = true)]
void  Adds(double x);
[OperationContract]
double GetResult();
}
}

using System;
using System.Collections.Generic;
using System.Text;
using System.ServiceModel;
using Artech.SessionfulCalculator.Contract;
namespace Artech.SessionfulCalculator.Service
{
public class CalculatorService:ICalculator
{
private double _result;
ICalculator Members#region ICalculator Members
public void Adds(double x)
{
Console.WriteLine("The Add method is invoked and the current session ID is: {0}", OperationContext.Current.SessionId);
this._result += x;
}
public double GetResult()
{
Console.WriteLine("The GetResult method is invoked and the current session ID is: {0}", OperationContext.Current.SessionId);
return this._result;
}
#endregion
public CalculatorService()
{
Console.WriteLine("Calculator object has been created");
}
~CalculatorService()
{
Console.WriteLine("Calculator object has been destoried");
}
}
}