Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!uc!wd!wade
From: wade@wd.msc.umn.edu (Wade Stebbings)
Newsgroups: comp.unix.wizards
Subject: Re: programmatic devices
Keywords: Sprite
Message-ID: <999@uc.msc.umn.edu>
Date: 30 Dec 89 01:28:45 GMT
References: <10641@ucsd.Edu>
Sender: news@uc.msc.umn.edu
Reply-To: wade@wd.UUCP (Wade Stebbings)
Organization: Minnesota Supercomputer Center, Minneapolis, MN
Lines: 18

In article <10641@ucsd.Edu> brian@ucsd.Edu (Brian Kantor) writes:
>A programmatic device (pdev) is a program (an executable binary) living
>in the /dev directory.  When a user program tries to open it for
>reading or writing, a process is started that runs the program, and
>ties its stdin and stdout to the user program open.  All I/O to and
>from the pdev appears to the user as though it is simply reading and
>writing a device; the pdev can open real or pseudo-devices and do real
>I/O as appropriate.  Ordinarily, the last close will cause the pdev to
>stop running and exit.  . . .

    SPRITE pseudo-devices are very similar to this idea; one main
difference is the way open/close are handled.  SPRITE is a Berkeley
research project.  I believe the paper "Pseudo Devices: User-Level
Extensions to the Sprite File System" is in the USENIX proceedings
from a couple years back (in San Francisco).  This stuff also runs
on BSD, if I remember the paper correctly.

wade