Batch Task API - Progress and Warning

Hi,

I am working on a custom batch task, which adds additional files to a project. I found out that  if i want to sign that an error occoured during the task on final report screen, then i should throw an Exception during the BtachTask process. However in a few cases i only want to show a "Warning". How can i add a "Warning" to this screen?

Also one more question: currently i am using "AbstractFileContentProcessingAutomaticTask", in which you can select multiple files and the progress of the task is set automatically after a file is processed (as far as i experienced). However i want to run the BatchTask on a project. My question is that, is there any Task-class, which run on project (so there is no need for selecting files) and in which i can set the progress bar manually (at the batch task running window).

Thanks in advance,

Balazs