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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Retrieving and Printing Spooled Data

The sequence of events involved in retrieving and printing a job is as follows:

1. Open the spooler supervisor with nowait I/O, call PRINTINIT to format a print

control buffer, and call AWAITIO[X] to wait for a message from the supervisor. Call

PRINTCOMPLETE to get the print-control-buffer from the supervisor.

2. Call PRINTREADCOMMAND to interpret the information contained in the

supervisor print-control-buffer. PRINTREADCOMMAND returns the name

of the data file, the job route and attributes, and the name of the device on which

the job is to be printed.

3. Open the data file and the device, then call PRINTSTART. This places control

information for the job into a job-control-buffer. The control information in

the job-control-buffer consists of pointers to the current page and line

number, the file numbers of the supervisor and data file, and so on.

4. Call PRINTREAD to get one line of spooled data. PRINTREAD also updates the

control information in the print process buffer to point to the next line.

5. You can now access the job with a succession of calls to PRINTREAD.

In theory, the print process can take any action whatsoever with the data; the usual

action, though, is to write the data to the device specified by

PRINTREADCOMMAND.

Communicating With the Spooler Supervisor

Communication with the supervisor falls into two categories: responding to messages

and sending errors.

Responding to Spooler Supervisor Messages

The print process must periodically check for a completion on the file to the supervisor.

When a completion is detected, PRINTCOMPLETE is called to obtain the message,

which is then passed to PRINTREADCOMMAND for interpretation.

PRINTREADCOMMAND returns a control number to indicate the nature of the

message.

It is up to the programmer to decide how often to check for a supervisor message.

However, the more often you check for a message, the more responsive your print

process will be to Spoolcom commands. For example, a print process that checks for

Note. You can write a print process that handles as many concurrent jobs as you like, subject to time

and memory limitations. A separate job-control-buffer must be maintained for each job, and there must

be some way of keeping track of which job control buffers go with which devices. The supervisor might

attempt to start a job on each device that has been associated with a print process (using Spoolcom).

Therefore, if a print process is associated with devices X, Y, and Z, it must be capable of handling three

jobs concurrently.