From owner-freebsd-hackers  Mon May 10 12:27:45 1999
Delivered-To: freebsd-hackers@freebsd.org
Received: from cygnus.rush.net (cygnus.rush.net [209.45.245.133])
	by hub.freebsd.org (Postfix) with ESMTP id ED19E14FB0
	for <freebsd-hackers@FreeBSD.ORG>; Mon, 10 May 1999 12:27:04 -0700 (PDT)
	(envelope-from bright@rush.net)
Received: from localhost (bright@localhost)
	by cygnus.rush.net (8.9.3/8.9.3) with SMTP id OAA00025;
	Mon, 10 May 1999 14:48:50 -0500 (EST)
Date: Mon, 10 May 1999 14:48:48 -0500 (EST)
From: Alfred Perlstein <bright@rush.net>
To: Zhihui Zhang <zzhang@cs.binghamton.edu>
Cc: Chuck Youse <cyouse@cybersites.com>, freebsd-hackers@FreeBSD.ORG
Subject: Re: Sockets and SYSTEM V message queue
In-Reply-To: <Pine.GSO.3.96.990510142747.29300B-100000@sol.cs.binghamton.edu>
Message-ID: <Pine.BSF.3.96.990510144409.24802K-100000@cygnus.rush.net>
MIME-Version: 1.0
Content-Type: TEXT/PLAIN; charset=US-ASCII
Sender: owner-freebsd-hackers@FreeBSD.ORG
Precedence: bulk
X-Loop: FreeBSD.ORG

On Mon, 10 May 1999, Zhihui Zhang wrote:

> 
> On Mon, 10 May 1999, Chuck Youse wrote:
> 
> > 
> > That's why you can create sockets in the UNIX domain (AF_UNIX, later
> > renamed AF_LOCAL).  When you bind a UNIX domain socket, it's bound to a
> > name in the filesystem.
> 
> Thanks for the reply. So a socket must be bound to something to be used. 
> You mention a name in the filesystem, does the file exist before binding
> or not? It seems to be a temporary file.

You would benifit greatly by purchaing "Unix Netowrk Programming Vol 1"
by Stevens.

several things:

you can communicate locally via a socket, the kernel detects this
and uses the loopback device, i'm quite sure that it will use a
fast impelementation of a local pipe

you can use named socket, yes they _do_ appear in the filesystem,
the entry should look like a directory, except that the 'd' is
an 's'

the only "problem" with sockets instead of SYSV messages is that
there are no "boundries", it's just a stream of binary gloop,
SYSV message queues allow you to specify the size of each message
sent.  Otherwise you have to sort of fake it and agree on a 
protocol for expressing message size...

does this make sense?

-Alfred




To Unsubscribe: send mail to majordomo@FreeBSD.org
with "unsubscribe freebsd-hackers" in the body of the message