Subject: Re: LWIIf&g hang w/netatalk
From: wes.craig@umich.edu
Date: Mon Aug 24 1992 - 15:24:48 EDT
> From: aimla!ruby!jennine@uunet.UU.NET (Jennine Townsend)
> To: uunet!terminator.cc.umich.edu!wes@uunet.UU.NET
> My thanks for netatalk; we're using 1.2.1 currently on a network
> of Suns, Macs, and LaserWriters. I was curious about the ETA of phase II;
> I don't think I've seen an update lately!
Still working on it. I'm not giving estimates, these days: Saves me from
lying...
> But I'm actually writing to ask about an odd behavior of
> LaserWriter (just IIf and IIg) printers on LocalTalk when a printout
> from the Sun is over three pages long; pap gets stuck cycling like this:
> [deleted]
> and the LaserWriter stuck with its status light blinking, and the Sun
> print queue still shows the (completely printed) job pending.
> Have you seen this?
Yupyupyup. This is a known problem. We're pretty sure it's the
printer. The behavior seems to be that if the job is over a certain
length (or on some printers, any job), the printer never closes its
output stream. This is the stream on which errors are reported. The
PAP protocol allows several jobs/files to be sent over a given
connection/session. It reports errors on a coresponding output/error
file. According to the protocol, when the client (the pap program on
unix) sends EOF, the server (printer) is supposed to flush its output
and send eof as well. This allows errors to be reported reliably and
associated with the appropriate file.
Unfortunately, somewhere around System 7, the LaserWriter driver
stopped waiting for this EOF to close. I guess some programmer wanted
to give the user the impression of faster printing, so he just arranged
to send an immediate close, rather than waiting to see that the job
printed. Shortly after *that*, several implementations of PAP for
printers (and spoolers) came out that didn't bother to send the EOF,
e.g. the IIf and g.
We have a new version of pap which fixes a number of problems. It also
includes a temporary fix for the EOF problem, as well. At some point,
I'd like to investigate a fix for this problem that wouldn't just
prematurely drop the connection as is done in the System 7 laserwriter
drivers. If people are interested, I am willing to put this version of
pap up for anonymous ftp.
wes
This archive was generated by hypermail 2b28 : Sat Dec 18 1999 - 16:09:01 EST