User`s guide

3-7
Spooler Overview
Spooler Parts
The AIX spooler can be viewed as a process or a subsystem with a beginning,
points–in–between, and an ending. To accomplish its tasks, the AIX spooler has four basic
parts:
1. The enq command is the true entry point to the spooler, and as such is the beginning of
any spooler activity. This command accepts requests for job processing.
2. The qdaemon is responsible for accepting and tracking all jobs submitted to the spooler
by the enq command. It is also responsible, once all the necessary resources are
available, for allowing a queue backend to process a job. The qdaemon is one of the
points–in–between in the spooler process.
3. The spooler backend is a collection of programs invoked by the spooler’s qdaemon
command to process a job in some queue. The backend sends output to a specific
device, such as a printer. When the backend is piobe, it involves a formatter filter, which
in turn involves a printer colon file. The backend is one of the points–in–between as well
as the ending, since the backend contains the specific process that will deliver the
processed job to its final destination.
4. The configuration file, /etc/qconfig, describes the configuration of available queues and
devices. Both the enq command and the qdaemon command refer to the configuration
file. This configuration file is considered as conceptually important as the other three
spooler parts due to its critical value to the correct operation of the AIX spooler as a
whole.