Re: [rtcweb] PRANSWER is unusable for serial forking

Iñaki Baz Castillo <ibc@aliax.net> Tue, 09 October 2012 09:25 UTC

Return-Path: <ibc@aliax.net>
X-Original-To: rtcweb@ietfa.amsl.com
Delivered-To: rtcweb@ietfa.amsl.com
Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id 8950E21F8843 for <rtcweb@ietfa.amsl.com>; Tue, 9 Oct 2012 02:25:06 -0700 (PDT)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -2.602
X-Spam-Level:
X-Spam-Status: No, score=-2.602 tagged_above=-999 required=5 tests=[AWL=0.075, BAYES_00=-2.599, FM_FORGED_GMAIL=0.622, MIME_8BIT_HEADER=0.3, RCVD_IN_DNSWL_LOW=-1]
Received: from mail.ietf.org ([64.170.98.30]) by localhost (ietfa.amsl.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id lOOMsWH9QR7m for <rtcweb@ietfa.amsl.com>; Tue, 9 Oct 2012 02:25:06 -0700 (PDT)
Received: from mail-lb0-f172.google.com (mail-lb0-f172.google.com [209.85.217.172]) by ietfa.amsl.com (Postfix) with ESMTP id D713D21F84B5 for <rtcweb@ietf.org>; Tue, 9 Oct 2012 02:24:59 -0700 (PDT)
Received: by mail-lb0-f172.google.com with SMTP id k13so3947080lbo.31 for <rtcweb@ietf.org>; Tue, 09 Oct 2012 02:24:58 -0700 (PDT)
X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20120113; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :cc:content-type:content-transfer-encoding:x-gm-message-state; bh=rOzxGZhWU+6iyoeGTKrYpgVvwlz5buZnVFzyUkR2ZN8=; b=PAceI0No916oqCu4ZVdfIX3Fv5XlRzyqa/iCgGOiNNxnJ5utfuOluC7BOaW1SDnz/u uBeg1XXmDtds51EhuY0ZV460CsfgwUyXA8xRnsJIXAlJR4W75Et8NAl9aPuur3eOZAUo Vq7xDRU4SeYS+t+wKc5XYr5NA9Ndrt5PmJNC5FK1Tj6rVVjtbBJELY/nSpmocb72jHHV w9XZGLvGW96o0TxfKarANaDvUBXCggB6ol5c1Xw5blib6ebcvDjbgx4Y+j2IOUPxaS9j Xjvwdx1GDBFVlWpNMQNtpFOnG/Oo4WzToWSV4mvEQnR2T5A0RxbCkXWVwlxS7hTcx7Ko lP6A==
Received: by 10.112.38.39 with SMTP id d7mr7771529lbk.112.1349774698730; Tue, 09 Oct 2012 02:24:58 -0700 (PDT)
MIME-Version: 1.0
Received: by 10.114.3.7 with HTTP; Tue, 9 Oct 2012 02:24:38 -0700 (PDT)
In-Reply-To: <CAD5OKxuOVgcKY_PBLXHeT_cyqJU9sExDWmP1M5u3-87cMQWtVA@mail.gmail.com>
References: <CAD5OKxuOVgcKY_PBLXHeT_cyqJU9sExDWmP1M5u3-87cMQWtVA@mail.gmail.com>
From: =?UTF-8?Q?I=C3=B1aki_Baz_Castillo?= <ibc@aliax.net>
Date: Tue, 9 Oct 2012 11:24:38 +0200
Message-ID: <CALiegfncwrOK3+3qsP8iP730FwjOrjtkins7SFaTABRMTZ6j5w@mail.gmail.com>
To: Roman Shpount <roman@telurix.com>
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: quoted-printable
X-Gm-Message-State: ALoCoQnC3mZMBccksXDLcjccKdO8vrIcPqqF6x8cUCpMjg0Ttig6AlmtU2c5+9yWZKAVsEi9QQth
Cc: rtcweb@ietf.org
Subject: Re: [rtcweb] PRANSWER is unusable for serial forking
X-BeenThere: rtcweb@ietf.org
X-Mailman-Version: 2.1.12
Precedence: list
List-Id: Real-Time Communication in WEB-browsers working group list <rtcweb.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/options/rtcweb>, <mailto:rtcweb-request@ietf.org?subject=unsubscribe>
List-Archive: <http://www.ietf.org/mail-archive/web/rtcweb>
List-Post: <mailto:rtcweb@ietf.org>
List-Help: <mailto:rtcweb-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/rtcweb>, <mailto:rtcweb-request@ietf.org?subject=subscribe>
X-List-Received-Date: Tue, 09 Oct 2012 09:25:06 -0000

2012/10/9 Roman Shpount <roman@telurix.com>om>:
> SIP does not have serial forking.

SIp has serial forking but just at signaling level, not at media level :)


> Offer/Answer does not describe something
> like this.

+1


> We either need to define it and make it something that describes
> some set of existing scenarios or add support for something that is defined.

IMHO the solution is described in other mail thread (maybe in rtcweb
WG): implement cloning. Example:

- My JS SIP app sends an INVITE with SDP and receives a 183 response
with To-tag "AAAA" and SDP A, so I already have a media stream.

- Later the voicemail system answers the call so replies a 200 with
To-tag "BBBB" and SDP B. Since To-tag is different I do know (as per
RFC 3261/3264) that I should create another media "session" sharing my
local SDP (but cloning it). And I also want to close the previous one.

Of course, for this we need some API method like
"cloneLocalDescription(new_remote_sdp_object)" or whatever.

AFAIR this has been recently discussed in rtcweb WG.



-- 
Iñaki Baz Castillo
<ibc@aliax.net>