Question

In my WPF client, I have a loop that calls a WCF service to update some records. When the loop is done, I display a message, ‘Update complete’.

I’m changing my WCF calls to async calls now.

    ServiceClient client = new ServiceClient();     client.UpdateRecordsCompleted +=new System.EventHandler<System.ComponentModel.AsyncCompletedEventArgs>(client_UpdateRecordsCompleted);      foreach (MyItem item in someCollection)     {          client.UpdateRecordsAsync(item);     }       MessageBox.Show('Update complete'); 

I don’t need to do anything in the competed event of each operation. I need to just display a message at the end of the last one.

Any ideas?

EDIT: I may be porting this to Silverlight, so that’s why I need to call the service asyncronously. I don’t think I can use the background worker.

Answer 1

I would add a thread-safe field to your WPF window to track the number of client updates the user has queued:

private int recordsQueued = 0; 

Before dispatching the individual async operations, set recordsQueued to someCollection.Count.

recordsQueued = someCollection.Count; 

Finally, in client_UpdateRecordsCompleted, decrement recordsQueued; if it is zero, display the ‘Update Complete’ message:

private void client_UpdateRecordsCompleted(AsyncCompletedEventArgs args) {   if (Interlocked.Decrement(ref recordsQueued) == 0)     MessageBox.Show('Update complete.');       }