I am already considering to return to support of the usblp kernel module in the CUPS USB backend in Ubuntu. The deprecation of the module seems to be pre-mature as there is no libusb-based CUPS backend with bi-directional support. Another possibility would be to have a look into HPLIP's "hp" CUPS backend whether one could transfer bi-di libusb code into standard USB backend of CUPS.
I am already considering to return to support of the usblp kernel module in the CUPS USB backend in Ubuntu. The deprecation of the module seems to be pre-mature as there is no libusb-based CUPS backend with bi-directional support. Another possibility would be to have a look into HPLIP's "hp" CUPS backend whether one could transfer bi-di libusb code into standard USB backend of CUPS.