Docusign - Another ways to retrieve file

Is there another solutions rather than pass the returnUrl parameter. For example, retrieve the file directly in my server.

I have an iframe in a popup with the signature process. When I click on "Completed", the program launch my return url on iframe. But, I don't want that. I would prefer to close the popup and so to detect that the button "Completed" was clicked and the URL changed. I have this code for detecting location change but got this error : "Origin cross platform".

    window.FinishSignatureProcess = function (event, e) 
    {
      try {
        var source = e.contentWindow.location.hash; //Line problem
      }
      catch (e) {
        //Exception
      }
    }

I found a solution for my problem. I simply redirected to a page indicating that it's finished and it's up to the user to close the popin.