Open XFDF file in Browser using Abobe Reader

I was facing with one simple problem. I had XFDF file on our web suite. Users open that XFDF file as URL (http://database/view/doc/$File/fileName) but it did not open in Adobe Reader, but in Browser as XML. I looked around and found solution. Add these line before XFDF output and it will start to work.

Print {Content-Type:application/vnd.adobe.xfdf}
Print {Cache-Control: public, must-revalidate}
Print {Expires: Sat, 26 Jul 1997 05:00:00 GMT}
Print xml_output