This is a little library for talking PJL to HP JetDirect printers.  It
may be used to talk PJL to other printers that understand PJL, but I
have never tested that, nor do I have a need to.

You may ask, why would anyone want to talk directly to a printer?

Being able to talk directly to the printer allows you to micromanage
job progress.  This is important in applications where each paper
printed is highly valuable and duplicates or lack of printing could be
problematic.  For example, I have used it for a (proprietary) check
printing system, and I am able to tell when each newly printed check
rolls out onto the top bin.  Being able to tell when this happens
allows me to mark it as printed in the system as it happens to prevent
it from being printed again.  I can also watch for out of paper
events, paper jams, or job cancellations and deal with them
gracefully.  In addition, Since I am talking to the printer, I can
store postscript dictionaries on the printer, and ask the printer what
it has in memory to find out what I may need to load before sending
the job, saving precious bandwidth on printers that live far across a
WAN.  All of these things are difficult to do with the extra layer of
abstraction of a print queue between the application and printer.

Please see test/ExampleJob for an example of using this library.
There is also a testng net.lump.print.TestPrinting which has more
examples.