Spooler Plus Programmer's Guide

Using the Spooler Print Procedures, Print Processes, and
Perusal Processes
Spooler Plus Programmer’s Guide—522293-003
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Writing a Print Process
Writing a Print Process
The following pages discuss the considerations associated with writing your own print
process. Appendix A, Sample Print Process, contains an example of a user-written
print process.
A print process must perform three tasks:
1. Read the Startup message.
2. Retrieve and print spooled data (using PRINTSTART and PRINTREAD).
3. Communicate with the spooler supervisor (using PRINTCOMPLETE,
PRINTSTATUS, and PRINTREADCOMMAND).
Print Process Startup Message
A print process not currently running is started by the spooler supervisor for one of two
reasons:

A job is ready to be printed on a device controlled by the print process.

A device controlled by the print process has been declared exclusive.
Immediately after starting a print process, the supervisor sends the print process a
Startup message, passing it the process name of the supervisor.
The format of the Startup message from the supervisor is shown in Table 3-2.
The first action taken by a print process should be to read its Startup message to
obtain the name of the supervisor, its backup processor, and its print process device
parameter.
Table 3-2. Startup Message From the Spooler Supervisor
Word Byte Contents
[0] [0:1] -1 (all bits on)
[1:20] [2:41] ASCII blanks
[21:32] [42:65] Process name of supervisor, blank-filled. This can be passed
by the print process directly to the OPEN procedure
[33] [66:67] Backup processor number, in ASCII, specified in the Spoolcom
command PRINT BACKUP. If no backup was specified, this
word contains -1 in ASCII (that is, %026461).
[34 left byte] [68] ASCII comma (,)
[34 right byte:
37 left byte]
[69:74] Print process parameter; field contains six ASCII characters
from the Spoolcom command PRINT PARM
[37 right byte] [75] ASCII null (0)