Vb.net asynchrous function

Hi Nick,
It's not a problem in this case if my application it's locked.
So yes, I want to wait for the response.

Thank's

Pablo

If blocking is ok, you will need some synchronization.

You haven't posted enough details for me to give you code, but here is a start:

In getX(), start the asynchronous operation by calling askX(). Then wait on an EventWaitHandle ( ManualResetEvent or AutoResetEvent ). In communication_X_RCVD(), store the result in a visible field and then signal the EventWaitHandle. When getX() resumes, the result will be available.

If you post the signature of askX() and communication_X_RCVD(), I could be more specific.

Nick

Hi
My signatures method are

getX() as MyCustomObject<br />
<br />
askX(){<br />
server.AskX()<br />
}<br />
<br />
communication_X_RCVD(eventhandler) handles server.Event<br />
{<br />
}<br />

So to be a little more clear.
I request the server via server.askX() to create a file with some content.
the server event notify me that the file has been created.
I parse the file and build MyCustomObject.

I never worked with EventWaitHandle ( ManualResetEvent or AutoResetEvent ).

Thank's for helping Nick

Regards
Pablo

Hi Pablo,

This code will work as long as you only call getX from your UI thread:

Imports System.Threading

Public Class MyCustomObject
    Public Property I As Integer
End Class

Public Class Server
    Public Sub AskX()
    End Sub
    Public Event ReceivedX As EventHandler
End Class

Public Class TestAsyncEvent
    Private WithEvents server As New Server
    Private mre As New ManualResetEvent(False)
    Private tmpX As MyCustomObject

    Public Function getX() As MyCustomObject

        tmpX = Nothing
        mre.Reset()

        askX()

        mre.WaitOne(TimeSpan.FromSeconds(30)) 'Specify some reasonable timeout

        Return tmpX

    End Function

    Private Sub askX()
        server.AskX()
    End Sub

    Private Sub communication_X_RCVD(ByVal sender As Object, ByVal args As EventArgs) Handles server.ReceivedX
        Dim x As New MyCustomObject
        x.I = 42
        tmpX = x
        mre.Set()
    End Sub
End Class

I suggest you read up on concurrent software. There is an excellent free primer here:

http://www.albahari.com/threading/[^]

Nick