Pass Parameters by Reference into AJAX JSON callback

Not quite sure how I pass a parameter by ref to a AJAX JSON callback C#.NET, e.g. if I have a web method like this:

[WebMethod] 
public static string MyMethod(Int32 x, Int32 y, ref Int32 z) 
{ 
  z =  x + y;
  return "Finished!";
} 

How do I set up the call below to get the CHANGED value of z without returning it?

    var jsonText = JSON.stringify({ x:1, y:1, z:0}); 
    $.ajax({ 
         type: "POST", 
         url: "myPage.aspx/MyMethod", 
         data: jsonText, 
         contentT开发者_Python百科ype: "application/json; charset=utf-8", 
         dataType: "json", 
         success: function () { alert("Success"); }, 
         failure: function () { alert("Failure"); } 
    }); 

You cannot get the value of Z without returning it. When posting to a WebMethod , you send a copy of your arguments. Similarly, when the web-method returns data, it returns a copy. Your WebMethod does not use the same memory as whatever entity is posting to it (most likely your web-browser). How would you expect a remote WebMethod to change the value, in memory, in your browser?