User`s guide

3-11
Spooler Overview
In all versions of AIX prior to Version 4, the qdaemon assigns the job a job number when it
accesses the JDF and reads its contents into the aforementioned internal data structure. In
Version 4, the job number is assigned by enq. This change was made so lp would be
compliant with industry standards (lp is supposed to return a job number when the job is
submitted, regardless of whether or not the qdaemon accepts the job). This means two
things. The first is that the job number of NEW should no longer be seen in Version 4, as
the job number NEW only appeared after enq had created the JDF but before the
qdaemon had accessed the JDF and assigned a job number. The second is that the
existence or absence of a job number can no longer be used to determine if the job has
been accepted by the qdaemon.
When the qdaemon determines that the device upon which the job is queued is available,
the qdaemon invokes the backend for the queue, passing it arguments specified by the
JDF. The backend processes the job.