Delimiting Print Jobs
Many print jobs can be sent over a single PC/3270 printer session. PC/3270 allows
multiple sessions and applications to share a single workstation printer
on a between-jobs basis. PC/3270 needs to know when each print job
starts and ends so that printers can be shared properly and begin
and end job strings can be sent at the appropriate times. The emulator
recognizes a number of different methods of delimiting print jobs:
- By Session
- PC/3270 printer support assumes, by default, that all print jobs are delimited by sessions. That is, in the absence of all other indicators, PC/3270 assumes that a print job begins when a printer session is started and ends when it is reset.
- Time-Out Interval
- On non-SNA DFT sessions, print jobs can be delimited by a user-specified timeout interval. A print job on a non-SNA DFT printer session begins when the first host-outbound data for that job is received, and ends when no host-outbound data is received for a period of time exceeding the user-specified non-SNA DFT timeout interval. For PC/3270, this interval is specified during configuration.
- By Brackets
- On a SNA session with an LU 1 or LU 3 host application, PC/3270 can
use bracket indicators to delimit print jobs. The emulator opens the
printer when it receives the begin bracket, then it processes and
prints data. The emulator closes the printer after it receives an
end bracket.
When the emulator receives another begin bracket, it again opens a printer and begins processing a print job.
- Structured Fields
- The host can use structured fields to indicate to the device that a new file is beginning or that the current file is completed. PC/3270 delimits print jobs with Begin of File and End of File structured fields (SF) to perform host-directed printing. Structured fields are described in Structured Fields.