C# Sample code: starts a worker thread, and a Timer

using System;
using System.Threading;


namespace CallBacks
{
   class Program
   {
       private string message;
       private static Timer timer;
       private static bool complete;


       static void Main(string[] args)
       {
           Program p = new Program();
           Thread workerThread = new Thread(p.DoSomeWork);
           workerThread.Start();

           //create timer with callback
           TimerCallback timerCallBack =
               new TimerCallback(p.GetState);
           timer = new Timer(timerCallBack, null,
               TimeSpan.Zero, TimeSpan.FromSeconds(2));

           //wait for worker to complete
           do
           {
               //simply wait, do nothing
           } while (!complete);

           Console.WriteLine("exiting main thread");
           Console.ReadLine();
       }


       public void GetState(Object state)
       {
           //not done so return
           if (message == string.Empty) return;
           Console.WriteLine("Worker is {0}", message);
           //is other thread completed yet, if so signal main
           //thread to stop waiting
           if (message == "Completed")
           {
               timer.Dispose();
               complete = true;
           }
       }

       public void DoSomeWork()
       {
           message = "processing";
           //simulate doing some work
           Thread.Sleep(3000);
           message = "Completed";
       }
   }
}