Visual Studio 2005 has a WinForms control called
BackgroundWorker that let’s you fire off an asynchronous process on background
thread and supports cancellation, progress reporting, and other events. All you
have to do is drag and drop the control on your Web Form and you are ready to
rock after wiring up a few simple events…
private
void buttonRunBackgroundWorker_Click(object
sender, EventArgs e)
{
this.backgroundWorker1.WorkerReportsProgress =
true;
this.backgroundWorker1.RunWorkerCompleted +=
new
RunWorkerCompletedEventHandler(backgroundWorker1_RunWorkerCompleted);
this.backgroundWorker1.DoWork +=
new
DoWorkEventHandler(backgroundWorker1_DoWork);
this.backgroundWorker1.ProgressChanged +=
new
ProgressChangedEventHandler(backgroundWorker1_ProgressChanged);
int countTo = 100;
this.backgroundWorker1.RunWorkerAsync(countTo);
}
void
backgroundWorker1_DoWork(object sender,
DoWorkEventArgs e)
{
int countTo = (int)e.Argument;
for (int i = 1;
i < countTo; i++)
{
System.Threading.Thread.Sleep(100);
backgroundWorker1.ReportProgress(i);
}
}
void
backgroundWorker1_ProgressChanged(object sender,
ProgressChangedEventArgs e)
{
this.progressBar1.Value = e.ProgressPercentage;
}
void
backgroundWorker1_RunWorkerCompleted(object
sender, RunWorkerCompletedEventArgs e)
{
MessageBox.Show("Done!");
}
As you can see in this simple example, the button click
event wires up the DoWork, ProgressChanges, and RunWorkerCompleted events. The
DoWork event is where the background work takes place. As the loop fires, the
background worker reports “progress” to the UI thread via
backgroundWorker1_ProgressChanged and likewise fires the
backgroundWorker1_RunWorkerCompleted when the background task is
completed (or cancelled or if an Exception is thrown).
