Replacing Jetform - Open Source Barcode Printing Alternatives?

diabolus_in_america asks: "I work for a mid-size manufacturer. Currently we use Jetform running on HP/UX to print the majority of our barcode labels to Zebra thermal printers. However, Jetform is a dead technology, and we are would like to look at open source alternatives. Is there an open source alternative to Jetform? What we need is a system that lets us mark up and design a barcode label which can then be populated from data files at print time. In its day, the Jetform system was an excellent and quick solution to barcode printing. But those days are over, at least for us, and we'd like to move to an open source alternative, if one exists."