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Versions: 00 01 02                                                      
SIPPING Working Group                                       G. Camarillo
Internet-Draft                                                  Ericsson
Expires: August 6, 2004                                         A. Roach
                                                             dynamicsoft
                                                        February 6, 2004


 Providing a Session Initiation Protocol (SIP) Application Server with
                             a List of URIs
                 draft-camarillo-sipping-uri-list-01.txt

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
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   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
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   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 August 6, 2004.

Copyright Notice

   Copyright (C) The Internet Society (2004). All Rights Reserved.

Abstract

   This document describes how a user agent can provide an application
   server with a list of URIs. The way the application server uses the
   URIs in the list is service specific.










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Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Terminology  . . . . . . . . . . . . . . . . . . . . . . . . .  3
   3.  URI Parameter vs. Header Field . . . . . . . . . . . . . . . .  3
   4.  The SIP and SIPS URI List Parameter  . . . . . . . . . . . . .  4
   5.  Ad-Hoc List' Life Time . . . . . . . . . . . . . . . . . . . .  4
   6.  The Content-ID SIP Header Field  . . . . . . . . . . . . . . .  4
   7.  Examples . . . . . . . . . . . . . . . . . . . . . . . . . . .  5
   7.1 Ad-Hoc Conference  . . . . . . . . . . . . . . . . . . . . . .  5
   7.2 Presence List  . . . . . . . . . . . . . . . . . . . . . . . .  7
   8.  Security Considerations  . . . . . . . . . . . . . . . . . . .  7
   9.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . .  8
       Normative References . . . . . . . . . . . . . . . . . . . . .  8
       Informational References . . . . . . . . . . . . . . . . . . .  8
       Authors' Addresses . . . . . . . . . . . . . . . . . . . . . .  9
       Intellectual Property and Copyright Statements . . . . . . . . 10


































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1. Introduction

   The need for exploders in SIP is described in [7]. Mechanisms to
   invoke exploders in SIP need to meet the requirements listed there.

   UAs need to have a means to provide application servers with a set of
   URIs for certain services. For example, a UA creating a conference
   needs to provide the conference server with the participants. The
   same way, a UA requesting presence information from a set of users
   needs to provide the resource list server with the URIs of the users
   that belong to the list.

   These lists are typically configured using out-of-band methods. For
   instance, a UA can use XCAP [6] to create a list of URIs and to
   associate this list with a SIP URI. It can, then, send a SIP request
   (an INVITE or a SUBSCRIBE in our previous examples) to that SIP URI.

   Still, there is a need to create lists of URIs in an ad-hoc way and
   send them directly in a SIP message. We define a SIP and SIPS URI
   paramerer called "list", which carries a URI. This URI is a pointer
   to a URI list.

   A UA creating a SIP request that needs to carry a URI list proceeds
   this way. It places the URI list (e.g., an XCAP resource list [4]) in
   a body part, and then, it adds a "list" parameter to the Request-URI.
   This "list" parameter contains a Content-ID URL [2] that points to
   the body part that carries the URI list.

   Alternatively, the URI in the "list" parameter can point to an
   external URI list (e.g., an http URI). In this case, the URI list
   would not be carried in the SIP request.

   The way the application server interprets the URI list received in
   the request is service specific.

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. URI Parameter vs. Header Field

   We have chosen to transport the pointer to the URI list in a URI
   parameter rather than in a header field because, this way, the
   Request-URI fully indentifies the service being invoked and all the



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   recipients of the service. Using a header field instead would imply
   that the Request-URI did not carry the list of the reciptiens.

   Network administrators should note that they need to configure
   proxies to route correctly Request-URIs that contain a "list"
   parameter and are addressed to their domain.

4. The SIP and SIPS URI List Parameter

   We define the "list" parameter for SIP and SIPS URIs. It MUST contain
   a URI that points to a URI list. The XCAP resource list format [4]
   MUST be supported; any other URI list formats MAY be supported. The
   ABNF of the "list" parameter is:

      list-param = "list=" absoluteURI

   The following is an example of a SIP URI with a list parameter
   pointing to a body part using a Content-ID URL [2]:

   sip:group@example.com;list=cid:cn35t8jf02@example.com

   The following is an example of a SIP URI with a list parameter
   pointing to an external URI:

   sip:group@example.com;list=http://xcap.example.com/lists/mylist.xml

5. Ad-Hoc List' Life Time

   An application server that receives a request with a URI list (or a
   pointer to it) creates a so called ad-hoc list, whose lifetime
   depends on the service provided by the server.

   Ad-Hoc lists created by requests that do not establish a dialog
   usually expire immediately. Ad-Hoc lists created by requests that
   establish a dialog usually expire when the dialog terminates.

6. The Content-ID SIP Header Field

   The Content-ID MIME header field is defined in RFC 2045 [5]. We
   define here the same header field to be used in SIP messages. Its
   ABNF is:

      Content-ID = "Content-ID" HCOLON msg-id

   RFC 2822 [3] defines msg-id in Section 3.6.4.

   The Content-ID value is used to uniquely identify a body or a body
   part. The Content-ID header field MAY appear in any SIP request or



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   response that contains a body.

7. Examples

   This section shows how to use the list parameter to create an ad-hoc
   conference and to subscribe to the presence information to a set of
   users. These examples illustrate the usage of the "list" parameter.
   They do not mandate how the previously mentioned services have to be
   implemented.

7.1 Ad-Hoc Conference

   Carol creates an ad-hoc conference by sending the INVITE request
   shown in Figure 1. The list parameter in the Request-URI points to a
   MIME body that carries the list of participants.


   INVITE sip:ad-hoc@example.com;list=cid:cn35t8jf02@example.com SIP/2.0
   Via: SIP/2.0/TCP client.chicago.example.com
       ;branch=z9hG4bKhjhs8ass83
   Max-Forwards: 70
   To: "Ad-Hoc Conferences" <sip:ad-hoc@example.com>
   From: Carol <sip:carol@chicago.example.com>;tag=32331
   Call-ID: d432fa84b4c76e66710
   CSeq: 1 INVITE
   Contact: <sip:carol@client.chicago.example.com>
   Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, REFER,
        SUBSCRIBE, NOTIFY
   Allow-Events: dialog
   Accept: application/sdp, message/sipfrag,
        application/resource-lists+xml
   Conten-Type: multipart/mixed;boundary="boundary1"
   Content-Length: 731

   --boundary1
   Content-Type: application/sdp
   Content-Length: 160

   v=0
   o=carol 2890844526 2890842807 IN IP4 chicago.example.com
   s=Example Subject
   c=IN IP4 192.0.0.1
   t=0 0
   m=audio 20000 RTP/AVP 0
   m=video 20002 RTP/AVP 31

   --boundary1
   Content-Type: application/resource-lists+xml



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   Content-Length: 367
   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--

                        Figure 1: INVITE request


   SIP/2.0 200 OK
   Via: SIP/2.0/TCP client.chicago.example.com
        ;branch=z9hG4bKhjhs8ass83;received=192.0.2.4
   To: "Ad-Hoc Conferences" <sip:ad-hoc@example.com>;tag=733413
   From: Carol <sip:carol@chicago.example.com>;tag=32331
   Call-ID: d432fa84b4c76e66710
   CSeq: 1 INVITE
   Contact: <sip:3402934234@example.com>;isfocus
   Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, REFER,
         SUBSCRIBE, NOTIFY
   Allow-Events: dialog, conference
   Accept: application/sdp, application/conference-info+xml,
         application/resource-lists+xml, message/sipfrag
   Supported: replaces, join
   Content-Type: application/sdp
   Content-Length: 312

   v=0
   o=focus431 2890844526 2890842807 IN IP4 ms5.conf.example.com
   s=Example Subject
   i=Example Conference Hosted by Example.com
   u=http://conf.example.com/3402934234
   e=3402934234@conf-help.example.com
   p=+1-888-555-1212
   c=IN IP4 ms5.conf.example.com
   t=0 0
   m=audio 49170 RTP/AVP 0
   m=video 51372 RTP/AVP 31

                      Figure 2: 200 (OK) response




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   The conference server responds with a 200 (OK) that carries the URI
   for the conference in its Contact header field. If the UA wants to
   obtain information about the status of the conference, for instance,
   it will SUBSCRIBE to the conference package using this URI.

7.2 Presence List

   Carol subscribes to the presence information of four of her friends
   using the list parameter.


   SUBSCRIBE sip:ad-hoc@example.com;list=cid:cn35t8jf02@example.com SIP/2.0
   Via: SIP/2.0/TCP client.chicago.example.com
       ;branch=z9hG4bKhjhs8ass83
   Max-Forwards: 70
   To: "Ad-Hoc Presence List" <sip:ad-hoc@example.com>
   From: Carol <sip:carol@chicago.example.com>;tag=32331
   Call-ID: d432fa84b4c76e66710
   CSeq: 1 INVITE
   Contact: <sip:carol@client.chicago.example.com>
   Require: eventlist
   Event: presence
   Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, REFER,
        SUBSCRIBE, NOTIFY
   Allow-Events: presence
   Accept: application/sdp, message/sipfrag,
        application/resource-lists+xml, application/rlmi+xml
   Content-Type: application/resource-lists+xml
   Content-Length: 367
   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>

                      Figure 3: SUBSCRIBE request


8. Security Considerations

   TBD.




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9. IANA Considerations

   This document registers the "list" SIP and SIPS URI parameter, which
   is described in Section 4. This parameter is to be added to the SIP
   and SIPS URI parameter registry under http://www.iana.org/ TBD.

   This document registers the Content-ID SIP header field, which is
   described in Section 6. This header field is to be added to the
   header field registry under http://www.iana.org/assignments/
   sip-parameters.

      Header Name: Content-ID

      Compact Form: (none)

Normative References

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

   [2]  Levinson, E., "Content-ID and Message-ID Uniform Resource
        Locators", RFC 2392, August 1998.

   [3]  Resnick, P., "Internet Message Format", RFC 2822, April 2001.

   [4]  Rosenberg, J., "An Extensible Markup Language (XML)
        Configuration Access Protocol (XCAP)  Usage for Presence Lists",
        draft-ietf-simple-xcap-list-usage-01 (work in progress), October
        2003.

Informational References

   [5]  Freed, N. and N. Borenstein, "Multipurpose Internet Mail
        Extensions (MIME) Part One: Format of Internet Message Bodies",
        RFC 2045, November 1996.

   [6]  Rosenberg, J., "The Extensible Markup Language (XML)
        Configuration Access Protocol (XCAP)", draft-ietf-simple-xcap-01
        (work in progress), October 2003.

   [7]  Camarillo, G., "Requirements for Session Initiation Protocol
        (SIP) Exploder Invocation", draft-camarillo-sipping-exploders-01
        (work in progress), November 2003.








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Authors' Addresses

   Gonzalo Camarillo
   Ericsson
   Hirsalantie 11
   Jorvas  02420
   Finland

   EMail: Gonzalo.Camarillo@ericsson.com


   Adam Roach
   dynamicsoft
   5100 Tennyson Pkwy
   Suite 1200
   Plano, TX  75024
   US

   EMail: adam@dynamicsoft.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

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











































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