This is not your program. This is xml_split - split huge XML documents into smaller chunks, also in XML::Twig. It often helps to give credit where credit is due so that no untoward suspicions are raised as to whether you are trying to pass off code you didn't write as your own.

If you want to process data instead of writing it to a file, why don't you just rip out the part where the program is writing to a file and replace it by your processing code?