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From: BRACKENRIDGE@C.ISI.EDU (Billy)
Newsgroups: comp.protocols.tcp-ip.ibmpc
Subject: Redirector Wanted and Dos Tasking
Message-ID: <8711231334.aa19994@Louie.UDEL.EDU>
Date: Mon, 23-Nov-87 13:32:38 EST
Article-I.D.: Louie.8711231334.aa19994
Posted: Mon Nov 23 13:32:38 1987
Date-Received: Thu, 26-Nov-87 21:30:40 EST
Sender: usenet@ucbvax.BERKELEY.EDU
Organization: The ARPA Internet
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Does anybody have any idea how to get a redirector? or a redirector
specification?

A redirector is part of MS-DOS (or perhaps MS-NET) that sits between
the file system and the network. It looks at DOS file calls at the file
handle level and calls either the disk driver or net driver as
appropriate.

Redirectors are sold by Microsoft and Locus. Neither company acknowledges
that they sell such a beast. As far as I can tell Locus doesn't acknowledge
that they sell anything!

I have used the redirector with 3Comm 3+, Apollo token net card (a really
nice but expensive system), and Sun's PC-NFS. The first two products
(and I believe Novell) use the Microsoft redirector. The Sun product uses
the Locus redirector.

The tricky part of the redirector is that it handles the DOS 3.x access
privilege bits and advisory file locking system calls over a distributed
file system. Of course I am a clever programmer and could reverse engineer
the functionality (probably without disassembling the code) if necessary.

This doesn't do me a lot of good. The object of the game is to be compatible
with everyone else.

Currently I am using the Sun PC-NFS developers toolkit (sockets Yuch!!!)
to talk appletalk protocols encapsulated in UDP datagrams. Currently I
interface at the virtual disk level because I know how to do it. I'd like
to be able to interface at the redirector level, so I can mount Apple
File System (AFS) volumes concurrently with NFS volumes and provide 
all the good stuff like file access control and file locking.

Nobody at Locus or Microsoft seems willing to sell a redirector or 
let loose specifications? Anybody know what the story is here?

Note in response to Phil Karn's comment about DOS tasking:

Your package is really neat and is a mind warper to people who believe
IP/TCP protocols are too complicated to do on a PC or that MS-DOS
can't do two things at once, but it isn't the only way to do things.
Some of us have more limited goals that we have to supply to users
who are used to the DOS they know and loathe.

A resident package such as the FTP's 2.0 package with a non sockets truly
asynchronous buffered interface is real useful to the rest of us.
Try doing a compile over the Sun NFS system. It is a sockets blocking
interface and it sucks performance wise. Every net transaction is a 
complete block. I am running on a 10 Mhz AST premium with megabytes
of EEMS memory. I'd like to use some of it to buffer network disk I/O
and boost performance but can't with the demented sockets interface.
With the FTP interface I can do that and open up mail and other connections
as well. This is enough of a step in the right direction to provide
useful products people want in the existing DOS environment.

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