SIPPING Working Group                                       G. Camarillo
Internet-Draft                                                  Ericsson
Expires: November 30, 2004                                      A. Roach
                                                             dynamicsoft
                                                               June 2004


    Subscriptions to Request-Contained Resource Lists in the Session
                       Initiation Protocol (SIP)
              draft-ietf-sipping-uri-list-subscribe-00.txt

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Copyright Notice

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

Abstract

   This document describes how to create subscriptions to
   request-contained resource lists in SIP. This is done by having the
   SUBSCRIBE request that requests the creation of the subscription
   carry a URI list.







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Table of Contents

   1.   Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
   2.   Terminology  . . . . . . . . . . . . . . . . . . . . . . . . . 3
   3.   Providing a Resource List Server with a URI List . . . . . . . 3
   4.   URI List Format  . . . . . . . . . . . . . . . . . . . . . . . 3
   5.   Resource List Server Behavior  . . . . . . . . . . . . . . . . 4
   6.   Resource List Life-Time  . . . . . . . . . . . . . . . . . . . 4
   7.   Providing a URI to Manipulate a Resource List  . . . . . . . . 4
   8.   Example  . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
   9.   Security Considerations  . . . . . . . . . . . . . . . . . . . 5
   10.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 6
   11.  Acknowledges . . . . . . . . . . . . . . . . . . . . . . . . . 6
   12.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 6
   12.1   Normative References . . . . . . . . . . . . . . . . . . . . 6
   12.2   Informational References . . . . . . . . . . . . . . . . . . 6
        Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 7
        Intellectual Property and Copyright Statements . . . . . . . . 8

































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1.  Introduction

   Subscriptions to homogeneous resource lists in SIP [2] are described
   in [3], which assumes that a resource list (i.e., a list of URIs) is
   represented by a URI (generally a SIP URI). Once a UA obtains the URI
   that represents a resource list, it can use the mechanisms described
   in [3] to subscribe to it.

   For example, let us assume that the resource list identified by the
   SIP URI sip:my-friends@example.com contains the following URIs:


   sip:bill@example.com
   sip:joe@example.org
   sip:ted@example.net

   If a UA subscribes to the presece information of
   sip:my-friends@example.com, it will obtain the presence information
   of all the resources in the list.

   List creation is outside the scope of [3]. This document describes a
   way to create a list with a set of resources, and subscribe to it,
   using a single SIP request. We use the mechanism to carry URI lists
   in SIP messages described in [4].

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.  Providing a Resource List Server with a URI List

   A client that wants to create a resource list and subscribe to it
   using the mechanism described in this document generates a SUBSCRIBE
   with a body whose disposition type is uri-list as defined in [4].
   This body contains the URIs that belong to the resource list. The
   client MUST build the remaining of the SUBSCRIBE request following
   the rules in [3].

4.  URI List Format

   As described in [4], the default format for URI lists in SIP is the
   XCAP resource list format [6]. Still, specific services need to
   describe which information clients should include in their URI lists,
   as described in [4].



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   UAs subscribing to a request-contained resource list SHOULD use flat
   lists (i.e., no hierarchical lists), SHOULD NOT use any entry's
   attributes but "uri", and SHOULD NOT include any elements inside
   entries but "display-name" elements.

   Resource list servers receiving a URI list with more information than
   what we have just described SHOULD discard all the extra information.

5.  Resource List Server Behavior

   On reception of a SUBSCRIBE with a URI list as described in Section
   3, a resource list server MUST follow the rules described in  [3] to
   create the subscription, using the URI list just received as the
   resource list for the subscription.

   Once the resource list server has created the subscription, it
   behaves as a regular resource list server and MUST follow the rules
   in [3].

   Note that the status code in the response to the SUBSCRIBE does not
   provide any information about whether or not the resource list server
   was able to succesfully subscribe to the URIs in the URI list. The
   client obtains this information in the NOTIFIES sent by the server.

6.  Resource List Life-Time

   The life-time of a resource list created as described in Section 5 is
   blundled to the life-time of the subscription. That is, the resource
   list SHOULD be destroyed when the subscription expires or is
   otherwise terminated.

7.  Providing a URI to Manipulate a Resource List

   A client may need to manipulate a resource list at a resource list
   server. The resource list server MAY provide a URI to manipulate the
   resource list associated with a subscription using the Call-Info
   header field in the NOTIFY that establishes the subscription. The
   "purpose" parameter of the Call-Info header field MUST have a value
   of "list-management", which we register with the IANA in Section 10.
   The following is an example of such a header field.


   Call-Info: <http://xcap.example.com/your-list.xml>
              ;purpose=list-management







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8.  Example

   The following is an example of a SUBSCRIBE request, which carries a
   URI list in its body, sent by a UA to a resource list server.


   SUBSCRIBE  sip:rls@example.com SIP/2.0
   Via: SIP/2.0/TCP terminal.example.com;branch=z9hG4bKwYb6QREiCL
   Max-Forwards: 70
   To: RLS <sip:rls@example.com>
   From: <sip:adam@example.com>;tag=ie4hbb8t
   Call-ID: cdB34qLToC@terminal.example.com
   CSeq: 1 SUBSCRIBE
   Contact: <sip:terminal.example.com>
   Event: presence
   Expires: 7200
   Supported: eventlist
   Accept: application/cpim-pidf+xml
   Accept: application/rlmi+xml
   Accept: multipart/related
   Accept: multipart/signed
   Accept: multipart/encrypted
   Content-Type: application/resource-lists+xml
   Content-Disposition: uri-list
   Content-Length: 274

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

                      Figure 1: SUBSCRIBE request


9.  Security Considerations

   The Security Considerations Section of [3] discusses security issues
   related to resource list servers. Resource list servers accepting
   request-contained URI-lists MUST also follow the security guidelines
   given in [3].

   The Security Considerations Section of the Requirements and Framework
   for SIP URI-List Services [5] discusses issues related to SIP
   URI-list services. Given that a resource list server sending



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   SUBSCRIBEs to a set of users acts as a URI-list service,
   implementations of resource list servers that handle
   request-contained URI-lists MUST follow the security-related rules in
   [5]. These rules include mandatory authentication and authorization
   of clients, and opt-in lists.

10.  IANA Considerations

   The document defines the "list-management" value for the purpose
   parameter of the Call-Info header field. A reference to this RFC
   should be added to the purpose Call-Info parameter entry in the SIP
   header field parameter registry on:

   http://www.iana.org/assignments/sip-parameters

11.  Acknowledges

   Cullen Jennings provided useful comments on this document.

12.  References

12.1  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.

   [3]  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.

   [4]  Camarillo, G., "Providing a Session Initiation Protocol (SIP)
        Application Server with a  List of URIs",
        draft-camarillo-sipping-uri-list-01 (work in progress), February
        2004.

   [5]  Camarillo, G., "Requirements for Session Initiation Protocol
        (SIP) Exploder Invocation", draft-camarillo-sipping-exploders-02
        (work in progress), February 2004.

12.2  Informational References

   [6]  Rosenberg, J., "An Extensible Markup Language (XML)
        Configuration Access Protocol (XCAP)  Usage for Presence Lists",



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        draft-ietf-simple-xcap-list-usage-02 (work in progress),
        February 2004.


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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