How to wait and send the return response in anther web service return

Hello Team,

 

I'm new in web service, Suggest the idea of below implementation:

 

I write two WebMethod in the web service. For example, the WebMethod is A and B.

 

A is check continuously, desktop to the server if any request is received in the B.

 

I'm mobile to send the 'file path' in B web service method, now I need to pass the file path in A WebMethod to return response in desktop then check the file path is exist or not in the desktop and if exist I need to send B return response as "the file path exists in the desktop".

 

Thanks