SIPPING Working Group                                       G. Camarillo
Internet-Draft                                                  Ericsson
Expires: May 22, 2004                                           A. Niemi
                                                            H. Khartabil
                                                              M. Isomaki
                                                                   Nokia
                                                       November 22, 2003


         Session Initiation Protocol (SIP) Exploder Invocation
           draft-camarillo-sipping-exploders-solution-00.txt

Status of this Memo

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

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Copyright Notice

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

Abstract

   This document defined the SIP EXPLODE method, which is used to
   instruct user agents to send a request to a set of destinations.










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Table of Contents

   1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . 3
   2. Terminology  . . . . . . . . . . . . . . . . . . . . . . . . . . 3
   3. The EXPLODE Method . . . . . . . . . . . . . . . . . . . . . . . 3
   4. The Template Disposition-Type  . . . . . . . . . . . . . . . . . 3
   5. Example  . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
      Normative References . . . . . . . . . . . . . . . . . . . . . . 5
      Informational References . . . . . . . . . . . . . . . . . . . . 6
      Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6
      Intellectual Property and Copyright Statements . . . . . . . . . 8








































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1. Introduction

   The need for exploders in SIP is described in [6]. Mechanisms to
   invoke exploders in SIP need to meet the requirements listed there.

   The SIP REFER method [4] allows a user agent to request another user
   agent to send a request to a third party. Still, we need to define a
   new method due to the following two reasons:

   1.  REFER allows only a single destination (i.e., a single Refer-To
       URI.)

   2.  REFER's implicit subscriptions are problematic in certain
       scenarios.

   We introduce a new method called EXPLODE that carries a set of
   destinations in a URI list. The Request-URI of an EXPLODE method
   carries a URI in a list parameter that points to the URI list. The
   URI may be carried in the EXPLODE request itself or may be fetched
   from somewhere (e.g., using XCAP.)

   EXPLODE methods do not establish any type of subscription. If a user
   agent sending a EXPLODE request is interested in some aspect of the
   explosion, it can send a SUBSCRIBE request to the URI received in the
   response to the EXPLODE.

2. Terminology

   In this document, the key words "MUST", "MUST NOT", "REQUIRED",
   "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT
   RECOMMENDED", "MAY", and "OPTIONAL" are to be interpreted as
   described in BCP 14, RFC 2119 [1] and indicate requirement levels for
   compliant implementations.

3. The EXPLODE Method

   EXPLODE is a SIP method as defined by RFC 3261 [2]. The EXPLODE
   method indicates that the recipient (identified by the Request-URI)
   should contact a set of third parties using the contact information
   provided in the URI list that the list parameter of the Request-URI
   points to.

   The protocol for emitting and responding to an EXPLODE request is
   identical to that for a BYE request in RFC 3261 [2].

4. The Template Disposition-Type

   When using REFER, the new request to be sent is described using URI



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   parameters. For example, the following Refer-To header field contains
   the values of the Accept-Contact and Call-ID header fields of the new
   request.


   Refer-To: <sip:bob@biloxi.example.net?Accept-Contact=sip:bobsdesk.
          biloxi.example.net&Call-ID%3D55432%40alicepc.atlanta.example.com>

   Exploders typically generate several similar requests towards
   different destinations. So, although it is possible to add the same
   URI parameters to all the URIs in the definition of the URI list, it
   is not an efficient way to encode that information.

   We define a new disposition-type: template. Bodies of this
   disposition-type (typically sipfrag bodies as defined in RFC 3420
   [3]) provide the exploder with a template for the messages to be
   sent.

   The following example shows a body whose disposition-type is
   template. It indicates that the requests to be sent should be
   MESSAGEs carrying the text "Hello world."


   Content-Disposition: template
   Content-type: message/sipfrag
   Content-Length: xxx

   MESSAGE sip:whoever.invalid SIP/2.0
   Content-Type: text/plain
   Content-Length: 12

   Hello World.

   If any of the URIs in a Explode-To header field has a URI parameter
   indicating a different value for a header field than the one
   indicated in the template, the exploder MUST use the value in the URI
   parameter.

   Note that in order to include the method in a sipfrag body, it is
   necessary to include the Request-URI as well (the whole Request-line
   needs to be included as specified in RFC 3420 [3]. If the Explode-To
   header field only contains one URI, this URI SHOULD be placed in the
   Request-URI of the template body. Otherwise, it is RECOMMENDED that
   the Request-URI in the template body is an invalid URI.

5. Example

   We need to add the whole call flow.



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   EXPLODE sip:exploder@example.com;list=cid:cn35t8jf02@example.com SIP/2.0
   Via: SIP/2.0/TCP client.example.com:5060;branch=z9hG4bK74bf9
   Max-Forwards: 70
   From: Alice <sip:alice@example.com>;tag=9fxced76sl
   To: Exploder <sip:exploder@example.com>
   Call-ID: 3848276298220188511@client.example.com
   CSeq: 1 EXPLODE
   Contact: <sip:alice@client.example.com;transport=tcp>
   Conten-Type: multipart/mixed;boundary="boundary1"
   Content-Length: xxx

   --boundary1
   Content-Disposition: template
   Content-type: message/sipfrag
   Content-Length: xxx

   MESSAGE sip:whoever.invalid SIP/2.0
   Content-Type: text/plain
   Content-Length: 12

   Hello World.

   --boundary1
   Content-Type: application/resource-lists+xml
   Content-Length: xxx
   Content-ID: <cn35t8jf02@example.com>

   <?xml version="1.0" encoding="UTF-8"?>
   <resource-lists xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
     <list name="ad-hoc-1">
       <entry name="1" uri="sip:bill@example.com" />
       <entry name="2" uri="sip:joe@example.com" />
       <entry name="3" uri="sip:ted@example.com" />
       <entry name="4" uri="sip:bob@example.com" />
     </list>
   </resource-lists>

   --boundary1--

Normative References

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

   [2]  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.




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   [3]  Sparks, R., "Internet Media Type message/sipfrag", RFC 3420,
        November 2002.

Informational References

   [4]  Sparks, R., "The Session Initiation Protocol (SIP) Refer
        Method", RFC 3515, April 2003.

   [5]  Roach, A., Rosenberg, J. and B. Campbell, "A Session Initiation
        Protocol (SIP) Event Notification Extension for  Resource
        Lists", draft-ietf-simple-event-list-04 (work in progress), June
        2003.

   [6]  Camarillo, G., "Requirements for Session Initiation Protocol
        (SIP) Exploder Invocation", draft-camarillo-sipping-exploders-00
        (work in progress), September 2003.


Authors' Addresses

   Gonzalo Camarillo
   Ericsson
   Hirsalantie 11
   Jorvas  02420
   Finland

   EMail: Gonzalo.Camarillo@ericsson.com


   Aki Niemi
   Nokia
   P.O. Box 321
   NOKIA GROUP, FIN 00045
   Finland

   EMail: Aki.Niemi@nokia.com


   Hisham Khartabil
   Nokia
   P.O. Box 321
   NOKIA GROUP, FIN 00045
   Finland

   EMail: Hisham.Khartabil@nokia.com






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   Markus Isomaki
   Nokia
   Itamerenkatu 11-13
   Helsinki  00180
   Finland

   EMail: Markus.Isomaki@nokia.com












































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Intellectual Property Statement

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   HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
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Acknowledgment

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   Internet Society.











































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