JOB is a software conceived for Java programmers. They know how to run a Java application . However, problems may arise with non-standard configurations.

Windows 95/98/NT
Simply double click on the file JOB.jar (the open command of jar files should be associated to the javaw program)

Otherwise
Write in the command line javaw -cp JOB.jar it.uno.job.Main
or simply javaw -jar JOB.jar.