Cross Threading error on Wesbervice Completed Event

[m.lancashire]

I have a dotnet 2.0 web service method that I execut asynchronously using the
auto generated method.
I catch the event using this
Private Sub Event_Completed (ByVal sender As Object _
, ByVal e As MyService.Event CompletedEventA rgs) Handles
m_MyService.Eve ntCompleted

me.text = e.Result.tostri ng

End Sub
I get a cross threading error when I update the text property of the form.

Where am I going wrong with this.

[Robert Wilczynski]

Hi,

This happens because you are not allowed to update the user interface from
a non UI thread. Here's a C# solution (shouldn't be too difficult to convert
to VB)

this.Invoke(new MethodInvoker(
delegate()
{
this.Text = e.Result.ToStri ng();
}
));

Also you may want to check out one of the episoder of DNR TV (http://dnrtv.com/default.aspx?showID=4).
I might be wrong but believe it has an example that should help you.

Best regards,
Robert Wilczynski

wi************* **@gmail.com

I have a dotnet 2.0 web service method that I execut asynchronously
using the
auto generated method.
I catch the event using this
Private Sub Event_Completed (ByVal sender As Object _
, ByVal e As MyService.Event CompletedEventA rgs) Handles
m_MyService.Eve ntCompleted
me.text = e.Result.tostri ng

End Sub
I get a cross threading error when I update the text property of the
form.
Where am I going wrong with this.

[Steven Cheng[MSFT]]

Thank for Robert's input.

As for async webservice method, the callback procedure is executed in a
background thread which is different from the winform's executing UI
thread. Also, for winform form/controls, they're forced to be manipulated
in their UI thread only(due the win32 message based model). Here are some
other msdn articles have discussed on this:

#Safe, Simple Multithreading in Windows Forms, Part 1
http://msdn.microsoft.com/library/en...6112002.asp?fr
ame=true

#Give Your .NET-based Application a Fast and Responsive UI with Multiple
Threads
http://msdn.microsoft.com/msdnmag/is...toc.asp?frame=
true

Hope this also helps.

Regards,

Steven Cheng
Microsoft Online Support

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