worker = new BackgroundWorker();
            worker.WorkerReportsProgress = true;
            worker.WorkerSupportsCancellation = true;
            worker.DoWork += new DoWorkEventHandler(worker_DoWork);
            worker.ProgressChanged += new ProgressChangedEventHandler(worker_ProgressChanged);
            worker.RunWorkerCompleted += new RunWorkerCompletedEventHandler(worker_RunWorkerCompleted);
//////////////////////////////////////////////////
private void worker_DoWork(object sender, DoWorkEventArgs e)
        {
            if (worker.CancellationPending) return;           
            
            foreach (XmlFormat xf in xmlList)
            {
                if (worker.CancellationPending) return;
                switch (xf.method.ToLower())
                {
                    case "upload": upload(xf); break;
                    case "download": download(xf); break;
                    default: return;
                }
            }
           
        }
//////////////////