Printing, Technical Summary
Below you will find information about the PALS server and other aspects about how printing is controlled and billed. New users should review the information before proceeding to check your status.
Summary
What it is
PALS (Page Accounting and Login Server) is a server that collects records of who is using which machine (IP address), provides this information to printing servers when a print job is received, and maintains information for each user as to how many pages have been printed and how many are allowed.
What it does
When a person logs onto one of our managed computers he/she is authenticated with their Access Account userid and password (methods vary by platform); the userid and IP address are sent to PALS which updates a record in a database which says "user xxx123 is logged into the machine at this IP address". Later, when a print job is sent to the lab's print server, the server asks PALS "is user xxx123 really logged into this IP address, and how many pages are they allowed to print?" If PALS says you can print, the job is accepted. However, since there may be several jobs in queue, when the job comes up next to be printed, the print server asks PALS again how many pages the user is allowed to print (some jobs may have used up allowed pages since the last time it asked). This time the user does not have to be logged on. When the job is finally sent to a printer, PALS sends the workstation a message about which printer the job will come out on and how many pages the user has left.
How it works
In terms of PALS, a "login" is a userid that is assigned to a particular address. You may be "logged into" more than one computer, or you might be left "logged in" if you turn off the computer without logging out, or if there is some network problem when you logout and the computer cannot send a logout record to PALS. If somehow the logout message was not sent, and someone else logs into that computer, a logout record is generated for you, but it is identified as an automatic logout because someone else logged in. Communication between the printer server and PALS is via Uniprint exits. User messages are sent to a custom program on the workstation to be displayed to the user.
Uniprint
We use the commercial product Pharos Uniprint to mange print queues and process print jobs. The important thing it does for us is interpret the postscript code in a print job to count the pages, before the job is sent to the printer. It has "exits" that we use to make it communicate with PALS.
Status Changes
Changes in user status such as becoming staff instead of a student or, for students, signing on a signature station to agree for billing for pages printed over the 110 subsidized pages, causes a change in the person's printing limits. The changes are made nightly, and hourly from the hours of 8am to 12 midnight.
Billing
Every few weeks (the timing is variable depending on where we are in the current semester), print record are grouped and billing records are sent to the Bursar to be added to students' accounts. Actual bills are sent only when the balance reaches a certain amount.
Credits
Students can request credits for print jobs that don't come out or are spoiled when they do print. A detailed form has to be filled out for the accouting staff to match up the credit request with a print job record. Often a print job that doesn't print at all will not result in a print charge, so no credit needs to be made.
Technical Details
We have some technical notes on Pals that may be of interest to a few.
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This page was last modified: 11/20/2006 9:09:38 AM.