calling webservice asynchronously in vb.net - vb.net

Question

I am trying to call this webservice asynchrounously in vb.net. So on the aspx side i added this property async="true". Now on the vb.net code side i have this function inside my webservice that i am calling.
So -
dim as as webservice.webstring
as.functionasync(param1, param2)
Now when i run the page, i can see that it wont call the webservice after a timegap.
Should i add .thread.sleep()?
Do i require the beginAsyn function and the EndAsyn function.
I'm using asp.net 3.5 with IIS7

Answer 1

First, please read this MSDN article about how the asynchronous pages work in ASP.NET.
Second, you need to have an asynchronous method in your web-service. Please read this HOWTO article about how to create such methods.
This is how your implementation of the async page could look like:
private _as as WebService.WebString = Nothing
Public Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs) Handles MyBase.Load
AddOnPreRenderCompleteAsync(New BeginEventHandler(BeginCallingWebService),
New EndEventHandler(EndCallingWebService));
End Sub
Private Function BeginCallingWebService(Byval sender As Object, ByVal e As EventArgs, ByVal cb As AsyncCallback, ByVal state As Object)
_as = New WebService.WebString()
Return _as.BeginMyMethod(cb, state)
End Function
Private Sub EndCallingWebService(ByVal ar as IAsyncResult)
Dim result As MyWebServiceResult = _as.EndMyMethod(ar)
' Process the result of the web-service method
End Sub
Hope this will help you.