private static InterfaceImpl initInterface(PageContext pc,Page page,String callPath,boolean isRealPath, Map interfaceUDFs) throws PageException {
if(!(page instanceof InterfacePage))
throw new ApplicationException("invalid interface definition ["+callPath+"]");
InterfacePage ip=(InterfacePage)page;
InterfaceImpl i = ip.newInstance(callPath,isRealPath,interfaceUDFs);
return i;
}