How to receive the xml file from client-side(javascript,i usejQuery)?

[JUN]

Sends an xml document as data to the server. By setting the
processData option to false, the automatic conversion of data to
strings is prevented.

code from jQuery documentation

var xmlDocument = [create xml document];
$.ajax({
url: "save.aspx",
processData: false,
data: xmlDocument,
success: handleResponse
});

Now,in server script, how do i read the xmlDocument and save a file.my
code like this,but it can't work.

private void Page_Load(object sender, System.EventArgs e){
Stream stream = Request.InputStream;
XmlDocument doc = new XmlDocument();
try
{
doc.Load(stream); // it will goto catch
doc.Save(Server.MapPath("bbbbbbbbbbbbbbbbbbbbb.xml "));
}
catch
{
}

}

Thanks a lot. it's very urgent.