🚀 go-pugleaf

I'm (now) one of the coordinators of the MMDF sources and am currently
working on this problem ... in the context of MMDF.

For this place where I am now we have a wide mix of machines.  Vaxen
of various shapes & sizes, a Sun server & some Sun workstations, a
Sequent Balance, and a student lab full of 3b2's & 3b1's.  It was
felt that it would be 'nice' if, ignoring the 3b[21]'s, all our machines
could have shared access to mailboxes, either through some POP like
protocol or with NFS.

The project to develop the POP-like protocol got abandoned.  So, later
I came up with a scheme to run under MMDF, which I am still testing
out.  I use NFS to access the mailbox directory.  For file locking I
have a directory (/usr/spool/mbxlckdir == MBXLCKDIR) into which I put
lock files.  (I made a little simplification here, the only files for
which I'm providing this locking is the system mailboxes, the other
mailboxes use the normal locking meaning that the locks only work
within one particular system).  There's some heuristics involved with
the lock files, in the lock file I put the system name and pid of the
owner, then later there are checks when someone else tries to acquire
the lock.

I went with this because 1) I was also wanting to support RFS with
the same type of thing and I didn't know if RFS did locks across
systems, 2) not all of our NFS's supported flock() anyway, and 3) for
some reason I don't 'trust' across-the-net flock()s.

Currently my heuristics don't work... I have to debug it, but I have
to get time to go back to it.  Also NFS errors (timeouts and the like)
cause the mail readers to get confused.  BUT, we are able to read
mail across NFS and have it usually work.  Possibly ALWAYS work with
a little bit of effort put into the code.  And it's really nice to
be able to read mail from anywhere.

It is possible that, for MMDF anyway, someone could fix up a copy
of libmmdf.a & mail reader such that someone on a PC running PC-NFS
(this could also be an Amiga with Ameristar TCP/IP/NFS) could send
& read mail from their PC.  Mailbox access would be across the net,
and mail sending could be with either code that does SMTP or does
the user-agent-to-submit protocol that MMDF uses internally.  Again,
across the network.  I would be interested in seeing that capability,
but don't have the time to develop it myself.
-- 
<-- David Herron; an MMDF guy                              <david@ms.uky.edu>
<-- ska: David le casse\*'      {rutgers,uunet}!ukma!david, david@UKMA.BITNET
<--
<--  "Smarter than the average pagan god ... "