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Network Working Group                                          R. Sparks
Internet-Draft                                               dynamicsoft
Expires: April 27, 2003                                 October 27, 2002


   Establishing jabber Messaging Sessions with the Session Initiation
                                Protocol
                 draft-sparks-simple-jabber-sessions-00

Status of this Memo

   This document is an Internet-Draft and is in full conformance with
   all provisions of Section 10 of RFC2026.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF), its areas, and its working groups.  Note that
   other groups may also distribute working documents as Internet-
   Drafts.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   The list of current Internet-Drafts can be accessed at http://
   www.ietf.org/ietf/1id-abstracts.txt.

   The list of Internet-Draft Shadow Directories can be accessed at
   http://www.ietf.org/shadow.html.

   This Internet-Draft will expire on April 27, 2003.

Copyright Notice

   Copyright (C) The Internet Society (2002).  All Rights Reserved.

Abstract

   This document explores modeling jabber message streams as media
   sessions, and how they  can be initiated with the Session Initiation
   Protocol.  It also explores how these sessions can be integrated into
   existing session-based multimedia communication applications.










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Table of Contents

   1. An overview of session management using SIP  . . . . . . . . .   3
   2. Jabber messaging as a media session  . . . . . . . . . . . . .   3
   3. A example jabber chat session  . . . . . . . . . . . . . . . .   4
   4. Acknowledgments  . . . . . . . . . . . . . . . . . . . . . . .   8
      References . . . . . . . . . . . . . . . . . . . . . . . . . .   8
      Author's Address . . . . . . . . . . . . . . . . . . . . . . .   9
      Full Copyright Statement . . . . . . . . . . . . . . . . . . .  10










































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1. An overview of session management using SIP

   The Session Initiation Protocol [1] (SIP) is designed to manage media
   "sessions" between communicating parties.  The types of media these
   sessions can use is unbounded and can range from simple audio to
   synchronized audio, video, and text.  To establish such session, SIP
   first provides a rendezvous mechanism.  Parties wishing to enter into
   a communication session do not need to know beforehand how to reach
   their intended peers' endpoints.  Rather, they can send an invite to
   a session to the peer's address of record.  SIP services will route
   that invitation to the appropriate endpoint(s) based on information
   the peer has provided and the characteristics of the invitation.  In
   most cases, the invitation will contain an "offer" of a session
   (maybe several), describing the potential transports and encoding
   characteristics for the media streams within the session.  The peer
   provides an "answer" accepting or declining each stream in the offer,
   and includes its contribution to the necessary transport information
   and characteristic tuning for those streams it accepts.  ([2]
   discusses this offer/answer model in detail).  At this point, the
   session is established and the parties begin communication over those
   streams.  When one of the parties is finished with the session, they
   tell their peer "bye" using SIP, terminating the session.

2. Jabber messaging as a media session

   A series of jabber "chat" or "groupchat" messages can be viewed as a
   session.  This allows a communication user agent to offer a jabber
   messaging session as one of the possible media types in a session.
   For instance, Alice may want to communicate with Bob.  Alice doesn't
   know at the moment whether Bob has his phone or his jabber client
   handy, but she's willing to use either.  She sends an invitation to a
   session to the address of record she has for Bob, sip:bob@biloxi.com.
   Her invitation offers both voice and a jabber chat session.  The SIP
   services at biloxi.com forward the invitation to Bob at his currently
   registered clients.  Bob accepts the invitation at his jabber client
   and they begin a threaded chat conversation.

   This session model allows jabber message sessions to be integrated
   into advanced communications applications with little to no
   additional protocol development.  For example, during the above chat
   session, Bob decides Alice really needs to be talking to Carol.  Bob
   can transfer Alice to Carol, introducing them into their own jabber
   messaging session.  Jabber messaging sessions could be integrated
   into call-center and dispatch environments utilizing third-party call
   control and conferencing applications.

   The rendezvous and characteristics negotiation features of SIP can
   also be used to introduce peers to jabber networks that have



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   restricted server-to-server policies.  A SIP invitation can contain
   an address and port of a jabber server for the peer to connect to.
   It can also securely provide credentials or other data to be consumed
   by that jabber server.  Further, the invitation could provide
   material to be used to encrypt the bodies of the messages transported
   in the chat session being established.  In the extreme, an endpoint
   could create an ephemeral stand-alone jabber server co-located with
   its client and use SIP to invite a peer to enter into a chat session
   at that server.

   In other cases, the invitation would allow an endpoint's jabber
   client to use its usual "home" jabber server, establishing chat or
   groupchat sessions over an existing connection, if present.  The
   session management capabilities of SIP can be used to add concrete
   start and stop times to those sessions and, as above, provide
   material that the endpoints can use to secure the session.  For
   example, Alice might be in a phone conference with Bob and decides
   she needs a text sub-channel.  She is currently connected to the
   public jabber cloud through atlanta.com and Bob is currently
   connected to the public cloud through biloxi.com.  Alice and Bob
   don't know each other's jabber id.  Alice can use SIP to invite Bob
   into a chat session, providing her jabber id, a thread to use, and
   maybe even a key to encrypt the messages with.  Bob will provide his
   jabber id in the SIP answer.  Armed with this information, each of
   their endpoints can associate the resulting chat session with the
   phone call.

   Similarly, SIP can be used to invite peers to join ad-hoc or
   permanent jabber groupchat sessions.

3. A example jabber chat session

   Figure 1 shows Romeo attempting to establish a session with Juliet.
   Romeo offers both voice and a jabber chat session.  Juliet declines
   the voice session in favor of jabber chat, leading to the messaging
   dialog from section 4.5 of [3].  Caveat: This is a very rough first
   cut at what the session description (the SDP in the body of the
   messages) might look like, and must not be taken as a normative
   suggestion.  As this problem is studied, a different form will almost
   certainly be decided on.  The point of this example is to show,
   roughly, how the important information needed to set up such a
   session can be carried.

   ---------------------------------------------------------------------


   SIP Message 1:




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     INVITE sip:juliet@capulet.com SIP/2.0
     Via: SIP/2.0/TCP orchard.montague.net;branch=z9hG4bK2a9323
     To: Juliet <sip:juliet@capulet.com>
     From: Romeo <sip:romeo@montague.net>;tag=29923923
     Call-ID: 2349098234@orchard.montague.net
     CSeq: 13992 INVITE
     Max-Forwards: 70
     Contact: <sip:romeo@orchard.montague.net>
     Content-Type: application/sdp
     Content-Length: (appropriate value)

     v=0
     o=romeo 28908764872 28908764872 IN IP4 orchard.montague.net
     s=-
     c=IN IP4 orchard.montague.net
     t=0 0
     m=audio 39923 RTP/AVP 0
     a=rtpmap:0 PCMU/8000
     c=IN IP4 xmpp.montague.net
     t=0 0
     m=message 5222 xmpp/tcp chat
     a=jid:romeo@mantague.net/orchard
     a=thread:283461923759234

   SIP Message 2 :

     SIP/2.0 200 OK
     Via: SIP/2.0/TCP orchard.montague.net;branch=z9hG4bK2a9323
     To: Juliet <sip:juliet@capulet.com>;tag=9392312353
     From: Romeo <sip:romeo@montague.net>;tag=29923923
     Call-ID: 2349098234@orchard.montague.net
     CSeq: 13992 INVITE
     Max-Forwards: 70
     Contact: <sip:juliet@balconey.capulet.com>
     Content-Type: application/sdp
     Content-Length: (appropriate value)

     v=0
     o=juliet 28908765142 28908765142 IN IP4 balcony.capulet.com
     s=-
     c=IN IP4 balcony.capulet.com
     t=0 0
     m=audio 0 RTP/AVP 0
     a=rtpmap:0 PCMU/8000
     c=IN IP4 xmpp.montague.net
     t=0 0
     m=message 5222 xmpp/tcp chat
     a=jid:juliet@capulet.com/balcony



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   SIP Message 3 :

     ACK sip:juliet@balconey.capulet.com SIP/2.0
     Via: SIP/2.0/TCP orchard.montague.net;branch=z9hG4bK239s934
     To: Juliet <sip:juliet@capulet.com>;tag=9392312353
     From: Romeo <sip:romeo@montague.net>;tag=29923923
     Call-ID: 2349098234@orchard.montague.net
     CSeq: 13992 ACK
     Max-Forwards: 70
     Content-Length:0

                 Figure 1: Establishing a chat session

   ---------------------------------------------------------------------

   If they aren't already connected to the public jabber network, Romeo
   and Juliet now establish jabber sessions with xmpp.montague.net at
   port 5222 and register with the service.  They can then enter into
   the jabber chat session from section 4.5 of [3] also shown here in
   Figure 2.































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   ---------------------------------------------------------------------



      <message
          to="romeo@montague.net/orchard"
          from="juliet@capulet.com/balcony"
          type="chat">
        <body>Art thou not Romeo, and a Montague?</body>
        <thread>283461923759234</thread>
      </message>

      <message
          to="juliet@capulet.com/balcony"
          from="romeo@montague.net/orchard"
          type="chat">
        <body>Neither, fair saint, if either thee dislike.</body>
        <thread>283461923759234</thread>
      </message>

      <message
          to="romeo@montague.net/orchard"
          from="juliet@capulet.com/balcony"
          type="chat">
        <body>How cam'st thou hither, tell me, and wherefore?</body>
        <thread>283461923759234</thread>
      </message>


                    Figure 2: A jabber chat session

   ---------------------------------------------------------------------

   When they are done, Juliet terminates the session as shown in Figure
   3.
















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   ---------------------------------------------------------------------



   SIP Message 4:

     BYE sip:romeo@orchard.montague.net SIP/2.0
     Via: SIP/2.0/TCP balconey.capulet.com;branch=z9hG4bK993231
     From: Juliet <sip:juliet@capulet.com>;tag=9392312353
     To: Romeo <sip:romeo@montague.net>;tag=29923923
     Call-ID: 2349098234@orchard.montague.net
     CSeq: 33903 BYE
     Max-Forwards: 70
     Content-Length:0

   SIP Message 5:

     SIP/2.0 200 OK
     Via: SIP/2.0/TCP balconey.capulet.com;branch=z9hG4bK993231
     From: Juliet <sip:juliet@capulet.com>;tag=9392312353
     To: Romeo <sip:romeo@montague.net>;tag=29923923
     Call-ID: 2349098234@orchard.montague.net
     CSeq: 33903 BYE
     Max-Forwards: 70
     Content-Length:0


              Figure 3: Terminating a jabber chat session

   ---------------------------------------------------------------------


4. Acknowledgments

   The following have provided significant support to the creation of
   this document through detailed discussions and review:

      Jonathan Rosenberg
      Adam Roach
      Ben Campbell

References

   [1]  Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston, A.,
        Peterson, J., Sparks, R., Handley, M. and E. Schooler, "SIP:
        Session Initiation Protocol", RFC 3261, June 2002.

   [2]  Rosenberg, J. and H. Schulzrinne, "An Offer/Answer Model with



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        Session Description Protocol (SDP)", RFC 3264, June 2002.

   [3]  Miller, J. and P. Saint-Andre, "XMPP Instant Messaging",
        Internet-Draft <draft-miller-xmpp-im-00, June 2002.


Author's Address

   Robert J. Sparks
   dynamicsoft
   5100 Tennyson Parkway
   Suite 1200
   Plano, TX  75024

   EMail: rsparks@dynamicsoft.com




































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Full Copyright Statement

   Copyright (C) The Internet Society (2002).  All Rights Reserved.

   This document and translations of it may be copied and furnished to
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Acknowledgement

   Funding for the RFC Editor function is currently provided by the
   Internet Society.



















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