Re: [Sip] Difference between dialog and session in SIP?

Jonathan Rosenberg <jdrosen@dynamicsoft.com> Thu, 03 April 2003 09:45 UTC

Received: from www1.ietf.org (ietf.org [132.151.1.19] (may be forged)) by ietf.org (8.9.1a/8.9.1a) with ESMTP id EAA11624 for <sip-archive@odin.ietf.org>; Thu, 3 Apr 2003 04:45:15 -0500 (EST)
Received: (from mailnull@localhost) by www1.ietf.org (8.11.6/8.11.6) id h339lRp27228 for sip-archive@odin.ietf.org; Thu, 3 Apr 2003 04:47:27 -0500
Received: from www1.ietf.org (localhost.localdomain [127.0.0.1]) by www1.ietf.org (8.11.6/8.11.6) with ESMTP id h339j3K27064; Thu, 3 Apr 2003 04:45:03 -0500
Received: from ietf.org (odin.ietf.org [132.151.1.176]) by www1.ietf.org (8.11.6/8.11.6) with ESMTP id h339fqK26877 for <sip@optimus.ietf.org>; Thu, 3 Apr 2003 04:41:52 -0500
Received: from mail3.dynamicsoft.com (ietf-mx.ietf.org [132.151.6.1]) by ietf.org (8.9.1a/8.9.1a) with ESMTP id EAA11515 for <sip@ietf.org>; Thu, 3 Apr 2003 04:39:09 -0500 (EST)
Received: from dynamicsoft.com (dyn-tx-app-004.dfw.dynamicsoft.com [63.110.3.2]) by mail3.dynamicsoft.com (8.12.8/8.12.1) with ESMTP id h339fXBd010444; Thu, 3 Apr 2003 04:41:36 -0500 (EST)
Message-ID: <3E8C01C4.6060707@dynamicsoft.com>
Date: Thu, 03 Apr 2003 04:41:24 -0500
From: Jonathan Rosenberg <jdrosen@dynamicsoft.com>
Organization: dynamicsoft
User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.0; en-US; rv:1.1) Gecko/20020826
X-Accept-Language: en-us, en
MIME-Version: 1.0
To: Patrick Lam <patrickl@astri.org>
CC: sip@ietf.org
Subject: Re: [Sip] Difference between dialog and session in SIP?
References: <008a01c2f76c$a8ac0690$2306050a@patrickXP>
Content-Type: text/plain; charset="us-ascii"; format="flowed"
Content-Transfer-Encoding: 7bit
Content-Transfer-Encoding: 7bit
Sender: sip-admin@ietf.org
Errors-To: sip-admin@ietf.org
X-BeenThere: sip@ietf.org
X-Mailman-Version: 2.0.12
Precedence: bulk
List-Unsubscribe: <https://www1.ietf.org/mailman/listinfo/sip>, <mailto:sip-request@ietf.org?subject=unsubscribe>
List-Id: Session Initiation Protocol <sip.ietf.org>
List-Post: <mailto:sip@ietf.org>
List-Help: <mailto:sip-request@ietf.org?subject=help>
List-Subscribe: <https://www1.ietf.org/mailman/listinfo/sip>, <mailto:sip-request@ietf.org?subject=subscribe>
Content-Transfer-Encoding: 7bit


Patrick Lam wrote:
> Dear all:
> 
> I am a little confused about the concept of a dialog.  What exactly is
> the difference between a dialog and a session? 

A dialog is a sip relationship. A session is a media relationship.

> Does dialog mean a "call
> has already been setup" in the signaling sense, while a session mean the
> "media has already been setup" in the media sense?

Thats pretty much right.

> 
> Also, what does "part of a dialog" mean?  Are "INVITE", "ACK" and the
> responses considered "part of a dialog"?

Dialog represents state, which includes sequence numbers, route sets, 
and URIs. A request sent as part of a dialog means that it includes 
route headers from the route set of the dialog, and uses the next 
highest sequence number in the dialog.'

> 
> What does "outside the dialog" mean then?  Is a request is outside the
> dialog, does it still affect or change anything "inside the dialog"
> then?

Outside the dialog means that it is not within the context of a dialog. 
It doesnt use the callid, cseq, or route sets of any existing dialogs, 
and when such a reuqest is set, it has no impact on the state of an 
existing dialog.

-Jonathan R.

-- 
Jonathan D. Rosenberg, Ph.D.                600 Lanidex Plaza
Chief Scientist                             Parsippany, NJ 07054-2711
dynamicsoft
jdrosen@dynamicsoft.com                     FAX:   (973) 952-5050
http://www.jdrosen.net                      PHONE: (973) 952-5000
http://www.dynamicsoft.com

_______________________________________________
Sip mailing list  https://www1.ietf.org/mailman/listinfo/sip
This list is for NEW development of the core SIP Protocol
Use sip-implementors@cs.columbia.edu for questions on current sip
Use sipping@ietf.org for new developments on the application of sip