Return render Twig

[fyher]

Hi, i want to return the render of the twig or the string like this:

<?xml version="1.0" encoding="UTF-8"?> <SOAP-ENV:Envelope xmlns:SOAP-ENV = "http://schemas.xmlsoap.org/soap/envelope/" xmlns:ns1 = "http://schemas.xmlsoap.org/ws/2004/08/addressing" xmlns:ns2 = "http://www.opentravel.org/OTA/2003/05"> <SOAP-ENV:Body> <ns2:OTA_HotelAvailRS Version = "1.001" Timestamp = "2011-09-12T15:19:21+02:00"> <ns2:Success/> <ns2:RoomStays> <ns2:RoomStay> <ns2:BasicPropertyInfo HotelCode = "5092"/> <ns2:RoomTypes> <ns2:RoomType RoomTypeCode = "SNG"> <ns2:RoomDescription Name = "Single room"/> </ns2:RoomType> <ns2:RoomType RoomTypeCode = "DBL"> <ns2:RoomDescription Name = "Double room"/> </ns2:RoomType> </ns2:RoomTypes> </ns2:RoomStay> </ns2:RoomStays> </ns2:OTA_HotelAvailRS> </SOAP-ENV:Body> </SOAP-ENV:Envelope>

but i havre this error :
Format 'soap' not supported, handler must be implemented

or You must return an instance of BeSimple\SoapBundle\Soap\SoapResponse

thanks for your help :)