Question

Following is the code snippet

Server Code :

   namespace WcfService3
{
    [ServiceContract]
    public interface ICalculator
    {     
        [OperationContract]
        string GetCount();
    }
}


[ServiceBehavior(InstanceContextMode = InstanceContextMode.Single)]
public class Calculator : ICalculator
{
    int count = 0;

    public string GetCount()
    {
        count++;
        return "Thread ID : " + Thread.CurrentThread.ManagedThreadId.ToString() + " Counter value : " + count.ToString();
    }
}

---

Client Code

class Program
    {
        static void Main(string[] args)
        {
            ICalculator calculator = new ServiceReference2.CalculatorClient();

            for (int index = 1; index <= 10; index++)
            {
                Console.WriteLine(calculator.GetCount());
            }

            Console.ReadLine();
        }
    }

---

If I set InstanceContextMode as InstanceContextMode.Persession or InstanceContextMode.PerCall I get the same result.

Thread ID : 34 Counter value : 1
Thread ID : 34 Counter value : 1
Thread ID : 34 Counter value : 1
Thread ID : 34 Counter value : 1
Thread ID : 34 Counter value : 1
Thread ID : 34 Counter value : 1
Thread ID : 34 Counter value : 1
Thread ID : 34 Counter value : 1
Thread ID : 34 Counter value : 1
Thread ID : 34 Counter value : 1

With InstanceContextMode.Single, Counter value increase, This is the expected behavior.
Thread ID : 34 Counter value : 1
Thread ID : 34 Counter value : 2
Thread ID : 34 Counter value : 3
Thread ID : 34 Counter value : 4
Thread ID : 34 Counter value : 5
Thread ID : 34 Counter value : 6
Thread ID : 34 Counter value : 7
Thread ID : 34 Counter value : 8
Thread ID : 34 Counter value : 9
Thread ID : 34 Counter value : 10

I am not able to understand why the value of counter is not increasing with PerCall. Can anybody please explain?

Atul

Answer 1

With PerCall you are taking a new instance of the Calculator service so the count variable is reset. With PerSession you are not, you will be using the same instance until the session expires.

Take a look at this and this