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Network Working Group                                      J. Hildebrand
Internet-Draft                                              Jabber, Inc.
Expires: August 22, 2003                               February 21, 2003


 TINS: A Transport for Initiating and Negotiating Sessions using SDPng
                               over XMPP
                     draft-hildebrand-xmpp-sdpng-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
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   Drafts.

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

   This Internet-Draft will expire on August 22, 2003.

Copyright Notice

   Copyright (C) The Internet Society (2003).  All Rights Reserved.

Abstract

   This document describes a method of initiating and negotiating media
   sessions by using SDPng on top of the eXtensible Messaging and
   Presence Protocol (XMPP) as the signalling protocol.











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Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
   1.1 Terminology  . . . . . . . . . . . . . . . . . . . . . . . . .  3
   1.2 Discussion Venue . . . . . . . . . . . . . . . . . . . . . . .  3
   1.3 Intellectual Property Notice . . . . . . . . . . . . . . . . .  3
   2.  Stanza Flow Overview . . . . . . . . . . . . . . . . . . . . .  4
   3.  Transactions . . . . . . . . . . . . . . . . . . . . . . . . .  8
   4.  TINS Methods . . . . . . . . . . . . . . . . . . . . . . . . .  9
   4.1 INVITE . . . . . . . . . . . . . . . . . . . . . . . . . . . .  9
   4.2 ACK  . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  9
   4.3 BYE  . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  9
   5.  Results  . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
   6.  Security Considerations  . . . . . . . . . . . . . . . . . . . 11
   7.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 12
       References . . . . . . . . . . . . . . . . . . . . . . . . . . 13
       Author's Address . . . . . . . . . . . . . . . . . . . . . . . 13
       Full Copyright Statement . . . . . . . . . . . . . . . . . . . 14

































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1. Introduction

   The MMUSIC WG has defined an XML format for Session Description and
   Capability Negotiation (SDPng [1]).  Given the availability of a
   native XML transport in the form of the Extensible Messaging and
   Presence Protocol (XMPP [2]), it may be valuable to explore how to
   build a framework for media stream/session initiation and negotiation
   over XMPP.  This document explores such a framework, with SDPng over
   XMPP providing a semantics for signalling call setup that is similar
   to the semantics alternatively provided by the Session Initiation
   Protocol (SIP [3]).

1.1 Terminology

   This document inherits terminology defined in SDPng [1] and in XMPP
   Core [2].

   The capitalized key words "MUST", "MUST NOT", "REQUIRED", "SHALL",
   "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in RFC
   2119 [4].

1.2 Discussion Venue

   The author welcomes discussion and comments related to the topics
   presented in this document.  The preferred forum is the
   <xmppwg@jabber.org> mailing list, for which archives and subscription
   information are available at <http://www.jabber.org/cgi-bin/mailman/
   listinfo/xmppwg/>.

1.3 Intellectual Property Notice

   This document is in full compliance with all provisions of Section 10
   of RFC 2026.

















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2. Stanza Flow Overview

   The following is an example flow of XMPP stanzas to initiate a call.
   The from addresses will usually be added by the XMPP server, but are
   shown for clarity.

   Step 1: A sends an invite to B:

   <message from='A@example.com/work' to='B@example.com'>
     <thread>1234@hostA.example.com</thread>
     <body>This message contains a TINS invite,
           but your client does not support TINS.</body>
     <tins method='INVITE'
       xmlns='http://www.jabber.org/protocol/tins'>

       <def xmlns='http://www.iana.org/sdpng'>
         <codec name="audio-basic" encoding="PCMU"
           sampling="8000" channels="1"
           xmlns='http://www.iana.org/sdpng/audio'/>
         <pt name="rtp-avp-0" pt="0" format="audio-basic"
           xmlns='http://www.iana.org/sdpng/rtp'/>
       </def>

       <cfg xmlns='http://www.iana.org/sdpng'>
         <component name="interactive-audio" media="audio">
           <alt name="AVP-audio-0">
             <session format="rtp-avp-0"
                    xmlns='http://www.iana.org/sdpng/rtp'>
               <udp role="receive" endpoint="A" addr="192.168.1.1"
                    rtp-port="7800"/>
             </session>
           </alt>
         </component>
       </cfg>

       <conf xmlns='http://www.iana.org/sdpng'>
         <owner user="A@example.com" id="98765432" version="1" nettype="IN"
                addrtype="IP4" addr="192.168.1.1"/>
         <session name="SDPng questions"/>

         <info name="interactive-audio" function="voice">
           Telephony media stream
         <info>
       </conf>
     </tins>
   </message>





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   Step 2: B tells A that it is trying:

   <message from='B@example.com/laptop' to='A@example.com/work'>
     <thread>1234@hostA.example.com</thread>
     <tins method='result' code='100' reason='Trying'
       xmlns='http://www.jabber.org/protocol/tins'/>
   </message>

   Step 3: B tells A that it is ringing:

   <message from='B@example.com/laptop' to='A@example.com/work'>
     <thread>1234@hostA.example.com</thread>
     <tins method='result' code='180' reason='Ringing'
       xmlns='http://www.jabber.org/protocol/tins'/>
   </message>




































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   Step 4: B sends A updated description:

   <message from='B@example.com/laptop' to='A@example.com/work'>
     <thread>1234@hostA.example.com</thread>
     <tins method='result' code='200' reason='OK'
       xmlns='http://www.jabber.org/protocol/tins'>

       <def xmlns='http://www.iana.org/sdpng'>
         <codec name="audio-basic" encoding="PCMU"
           sampling="8000" channels="1"
            xmlns='http://www.iana.org/sdpng/audio'/>
         <pt name="rtp-avp-0" pt="0" format="audio-basic"
           xmlns='http://www.iana.org/sdpng/rtp'/>
       </def>

       <cfg xmlns='http://www.iana.org/sdpng'>
         <component name="interactive-audio" media="audio">
           <alt name="AVP-audio-0">
             <session format="rtp-avp-0"
               xmlns='http://www.iana.org/sdpng/rtp'>
               <udp role="receive" endpoint="A" addr="192.168.1.1"
                  rtp-port="7800"/>
               <udp role="receive" endpoint="B" addr="192.168.1.2"
                  rtp-port="9410"/>
             </session>
           </alt>
         </component>
       </cfg>
     </t:tins>
   </message>

   Step 5: A sends an ACKnowldgement:

   <message to='B@example.com/laptop' from='A@example.com/work'>
     <thread>1234@hostA.example.com</thread>
     <tins method='ACK'
       xmlns='http://www.jabber.org/protocol/tins'/>
   </message>













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   Step 6: B hangs up:

   <message from='B@example.com/laptop' to='A@example.com/work'>
     <thread>1234@hostA.example.com</thread>
     <tins method='BYE'
       xmlns='http://www.jabber.org/protocol/tins'/>
   </message>

   Step 7: A acknowledges the hang up:

   <message to='B@example.com/laptop' from='A@example.com/work'>
     <thread>1234@hostA.example.com</thread>
     <tins method='result' code='200' reason='OK'
       xmlns='http://www.jabber.org/protocol/tins'/>
   </message>




































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3. Transactions

   The <thread/> element from XMPP is used to group TINS messages
   together into a shared context.  A unique thread value MUST be used
   for each transaction.  An example of a transaction might be a single
   voice call.













































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4. TINS Methods

   The following methods can be used in a TINS message.

4.1 INVITE

   Invite the target user to an out-of-band session.  The content inside
   the <tins/> element MAY be SDPng descriptions of the connection types
   offered.  If a session is already established for this transaction,
   the new INVITE serves as a renegotiation of session parameters.

4.2 ACK

   The initiator tells the invitee that an out-of-band session has been
   established.

4.3 BYE

   Either side of the conversation decides to terminate the transaction.
   This message SHOULD cause all resources associated with this
   transaction to be freed, and any associated network connections to be
   terminated.





























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5. Results

   In reply to each of the method messages, the receiver sends 0 or more
   replies, with the method set to 'result'.  Result codes are as
   specified in RFC 3261, section 21.














































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6. Security Considerations

   TINS is subject to the same security considerations as XMPP,
   particularly with regard to authentication and channel encryption.

   This document does not describe how the media protocols (e.g.  RTP)
   traverse firewalls and NATs.

   There is no general-purpose way to ensure that media protocol
   connections are associated with the in-band TINS conversation.









































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7. IANA Considerations

   None
















































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References

   [1]  Ott, J., Bormann, C. and D. Kutscher, "Session Description and
        Capability Negotiation", draft-ietf-mmusic-sdpng-05 (work in
        progress), July 2002.

   [2]  Saint-Andre, P. and J. Miller, "XMPP Core (draft-ietf-xmpp-core-
        03, work in progress)", February 2003.

   [3]  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.

   [4]  Bradner, S., "Key words for use in RFCs to Indicate Requirement
        Levels", BCP 14, RFC 2119, March 1997.

   [5]  Internet Assigned Numbers Authority, "Internet Assigned Numbers
        Authority", January 1998, <http://www.iana.org/>.


Author's Address

   Joe Hildebrand
   Jabber, Inc.

   EMail: jhildebrand@jabber.com
   URI:   http://www.jabber.com/
























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Full Copyright Statement

   Copyright (C) The Internet Society (2003).  All Rights Reserved.

   This document and translations of it may be copied and furnished to
   others, and derivative works that comment on or otherwise explain it
   or assist in its implementation may be prepared, copied, published
   and distributed, in whole or in part, without restriction of any
   kind, provided that the above copyright notice and this paragraph are
   included on all such copies and derivative works.  However, this
   document itself may not be modified in any way, such as by removing
   the copyright notice or references to the Internet Society or other
   Internet organizations, except as needed for the purpose of
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   followed, or as required to translate it into languages other than
   English.

   The limited permissions granted above are perpetual and will not be
   revoked by the Internet Society or its successors or assigns.

   This document and the information contained herein is provided on an
   "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
   TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
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Acknowledgement

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



















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