My question is, how can I generate Pentaho Report Designer's saved .prpt file programmatically, without Report Designer itself? Is there any API for that?
I need to generate those files programmatically, then later open using Report Designer and fix some values.

I've found informations about how to use Pentaho Reporting SDK. This sdk uses already available prpt file and produces excel file on its base. But I need to generate this prpt file programmatically, without GUI interface.