public AssignmentRetreiver()
{
if (instance != null)
return;
instance = this;
backgroundWorker = new BackgroundWorker();
backgroundWorker.DoWork += backgroundWorker_DoWork;
backgroundWorker.RunWorkerCompleted += backgroundWorker_RunWorkerCompleted;
timer = new Timer();
timer.Tick += TimerMethod;
timer.Interval = 100;
timer.Start();
}