Drupal render xml

[mait]

In Drupal6 i realized a XML document rendering in a function just withPHP XMLWriter and \[code\]drupal_set_header()\[/code\] function.In Drupal7 \[code\]drupal_set_header()\[/code\] changed to \[code\]drupal_add_http_header()\[/code\].Everthing works fine, but Drupal7 is rendering the whole template structure, and added it after the XML document structure. Does somebody have an idea, how to prevent the template rendering?Thanks a lot;-)