Asynchronous Web Method

[Simple Simon]

Hi, I'm having a little trouble with the architecture of my Web App.
Bascially, I need to import some MLS data into a SQL Db from (3)
comma-delimited files, as well as, upload and extract the images for
the MLS listings from a zip file. These things I can do, but am
worried about server time-outs.

I've read some MSDN articles about using Server-Side Asynchronous Web
Methods to perform lengthy back-end operations:
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dnservice/html/service10012002.asp

http://msdn.microsoft.com/library/d...onCreatingAsynchronousXMLWebServiceMethod.asp

I'm trying to figure out how to lay this out in my project. If I need
to have something like these ansynchronous web mehtods?

[WebMethod]
public string GetResidentialListings()

[WebMethod]
public string GetLandAndLotListings()

[WebMethod]
public string GetCommercialListings()

Then, I want to make Asynchronous Methods for each?

[WebMethod]
public IasyncResult BeginGetResidentialListings(AsyncCallback......)
[WebMethod]
public string EndGetResidentialListings(IAsyncResult......)

[WebMethod]
public IasyncResult BeginGetLandAndLotListings(AsyncCallback......)
public string EndGetLandAndLotListings(IAsyncResult......)
[WebMethod]

[WebMethod]
public IasyncResult BeginGetCommercialListings(AsyncCallback......)
[WebMethod]
public string EndGetCommercialListings(IAsyncResult......)

Then, should I have one "Master" WebMethod that calls all three?

TIA,
~Gordon