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Network Working Group                                       G. CamarilloRequest for Comments: 5367                                      EricssonUpdates:3265                                                 A.B. RoachCategory: Standards Track                                        Tekelec                                                                O. Levin                                                   Microsoft Corporation                                                            October 2008Subscriptions to Request-Contained Resource Listsin the Session Initiation Protocol (SIP)Status of This Memo   This document specifies an Internet standards track protocol for the   Internet community, and requests discussion and suggestions for   improvements.  Please refer to the current edition of the "Internet   Official Protocol Standards" (STD 1) for the standardization state   and status of this protocol.  Distribution of this memo is unlimited.Abstract   This document specifies a way to create subscription to a list of   resources in SIP.  This is achieved by including the list of   resources in the body of a SUBSCRIBE request.  Instead of having a   subscriber send a SUBSCRIBE request for each resource individually,   the subscriber defines the resource list, subscribes to it, and gets   notifications about changes in the resources' states using a single   SUBSCRIBE dialog.Table of Contents1. Introduction ....................................................22. Terminology .....................................................23. User Agent Client Procedures ....................................23.1. Response Handling ..........................................23.2. Subsequent SUBSCRIBE Requests ..............................34. URI-List Document Format ........................................35. Resource List Server Behavior ...................................45.1. Subsequent SUBSCRIBE Requests ..............................46. Providing a URI to Manipulate a Resource List ...................47. Example .........................................................58. Security Considerations .........................................69. IANA Considerations .............................................69.1. List-Management Purpose Parameter Value ....................69.2. recipient-list-subscribe Option-Tag ........................710. Acknowledgments ................................................711. Normative References ...........................................7Camarillo                   Standards Track                     [Page 1]

RFC 5367               SUBSCRIBE-Contained Lists            October 20081.  Introduction   [RFC4662] specifies how to establish subscriptions to a homogeneous   resource list in SIP (which is specified in [RFC3261]) and defines   the procedures for getting notifications about changes in the state   of the associated resources.  Yet, list creation is outside the scope   of [RFC4662].   This document specifies a way to create a list with a set of   resources and subscribe to it using a single SIP request.  This is   achieved by including the list of resources (as defined in [RFC5363])   in the body of the SUBSCRIBE request.2.  Terminology   The 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 inRFC 2119 [RFC2119].3.  User Agent Client Procedures   A UAC (User Agent Client) that wants to create a resource list and   subscribe to it using the mechanism described in this document   constructs a SUBSCRIBE request with at least one body, whose   disposition is type "recipient-list" as defined in [RFC5363], that   contains the URI list.  Additionally, the UAC MUST include the   'recipient-list-subscribe' option-tag (which is registered with the   IANA inSection 9) in a Require header field.  The UAC MUST build the   rest of the SUBSCRIBE request following the rules in [RFC3265].   The UAC MUST support the "rlmi+xml" format defined in [RFC4662] and   signal this by including "rlmi+xml" in the Accept header.  The UAC   MAY support additional formats and include them in the Accept header   field of the SUBSCRIBE request.3.1.  Response Handling   The status code in the response to the SUBSCRIBE request does not   provide any information about whether or not the resource list server   was able to successfully subscribe to the URIs in the URI list.  The   UAC obtains this information in the notifications sent by the server.Camarillo                   Standards Track                     [Page 2]

RFC 5367               SUBSCRIBE-Contained Lists            October 20083.2.  Subsequent SUBSCRIBE Requests   The previous sections have specified how to include a URI list in an   initial SUBSCRIBE request to a resource list server in order to   subscribe to the state of a set of resources.  Once the subscription   has been created and a dialog between the UAC and the resource list   server has been established, the UAC can send subsequent SUBSCRIBE   requests to, for example, extend the duration of the subscription.   At this point, there are no semantics associated with resource-list   bodies in subsequent SUBSCRIBE requests (although future extensions   can define them).  Therefore, UACs SHOULD NOT include resource-list   bodies in subsequent SUBSCRIBE requests to a resource list server.      Note that a difference between an initial SUBSCRIBE request and      subsequent ones is that while the initial request is sent to the      public URI of the resource list, subsequent ones are sent to the      URI provided by the server when the dialog is established.      Therefore, from the UAC's point of view, the resource identified      by the former URI supports recipient-list bodies, while the      resource identified by the latter does not support them.4.  URI-List Document Format   [RFC5363] mandates that each URI-list services specification, such as   the subscription service defined here, specifies the default format   for the recipient-list bodies used within the particular service.   The default format for the recipient-list bodies for the subscription   service defined in this document is the resource list format defined   in [RFC4826].  UAs (User Agents) generating recipient-list bodies   MUST support this format and MAY support other formats.  Resource   list servers able to handle recipient-list bodies MUST support this   format and MAY support other formats.   The Extensible Markup Language (XML) Configuration Access Protocol   (XCAP) resource list document provides features, such as hierarchical   lists and the ability to include entries by reference relative to the   XCAP root URI, that are not needed by the subscription service   defined here, which only needs to transfer a flat list of URIs   between a UA and the resource list server.  Therefore, when using the   default resource list document, UAs SHOULD use flat lists (i.e., no   hierarchical lists) and SHOULD NOT use <entry-ref> elements.  A   resource list server receiving a URI list with more information than   what has just been described MAY discard all the extra information.Camarillo                   Standards Track                     [Page 3]

RFC 5367               SUBSCRIBE-Contained Lists            October 2008   Figure 1 shows an example of a flat list that follows the resource   list document.   <?xml version="1.0" encoding="UTF-8"?>   <resource-lists xmlns="urn:ietf:params:xml:ns: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: URI list5.  Resource List Server Behavior   Resource list servers that are able to receive and process SUBSCRIBE   requests with a recipient-list body SHOULD include a 'recipient-list-   subscribe' option-tag in a Supported header field when responding to   OPTIONS requests.   On reception of a SUBSCRIBE request with a URI list, a resource list   server that chooses to accept the "rlmi+xml" format MUST comply with   [RFC4662] for creating the subscription and reporting the changes in   the resources within the created dialog.5.1.  Subsequent SUBSCRIBE Requests   At this point, there are no semantics associated with resource-list   bodies in subsequent SUBSCRIBE requests (although future extensions   may define them).  Therefore, a resource list server receiving a   subsequent SUBSCRIBE request with a resource-list body, following   standard SIP procedures, rejects it with a 415 (Unsupported Media   Type) response.6.  Providing a URI to Manipulate a Resource List   A UAC can 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 request 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 inSection 9.   The following is an example of such a header field.   Call-Info: <http://xcap.example.com/your-list.xml>              ;purpose=list-managementCamarillo                   Standards Track                     [Page 4]

RFC 5367               SUBSCRIBE-Contained Lists            October 2008   The lifetime of a resource list to be manipulated by the URI provided   by the server is bundled to the lifetime of the subscription.  That   is, the resource list SHOULD be destroyed when the subscription   expires or is otherwise terminated.Section 7.1 of [RFC3265] does not list the Call-Info header field in   the table of header fields that NOTIFY requests can carry.  This   document updates that table so that the Call-Info header field can be   optionally included in NOTIFY requests.7.  Example   The following is an example of a SUBSCRIBE request, which carries a   URI list in its body, sent by a UAC 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   Require: recipient-list-subscribe   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: recipient-list   Content-Length: 337   <?xml version="1.0" encoding="UTF-8"?>   <resource-lists xmlns="urn:ietf:params:xml:ns: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 2: SUBSCRIBE requestCamarillo                   Standards Track                     [Page 5]

RFC 5367               SUBSCRIBE-Contained Lists            October 20088.  Security Considerations   The Security Considerations section of [RFC4662] discusses security   issues related to resource list servers.  Resource list servers   accepting request-contained URI lists MUST also follow the security   guidelines given in [RFC4662].   "Framework and Security Considerations for Session Initiation   Protocol (SIP) URI-List Services" [RFC5363] discusses issues related   to SIP URI-list services.  Given that a resource list server sending   SUBSCRIBE requests 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   [RFC5363].  These rules include opt-in lists and mandatory   authentication and authorization of clients.9.  IANA Considerations   The following sections describe the IANA registration of the 'list-   management' value for the "purpose" parameter of the Call-Info header   field and the 'recipient-list-subscribe' SIP option-tag.9.1.  List-Management Purpose Parameter Value   This document defines the 'list-management' value for the "purpose"   parameter of the Call-Info header field.  A reference to this RFC (in   double brackets) has been added to the existing "purpose" Call-Info   parameter entry in the SIP Parameters registry, which currently looks   as follows:                                                  Predefined   Header Field                  Parameter Name     Values     Reference   ----------------------------  ---------------   ---------   ---------   Call-Info                     purpose             Yes       [RFC3261]Camarillo                   Standards Track                     [Page 6]

RFC 5367               SUBSCRIBE-Contained Lists            October 20089.2.  recipient-list-subscribe Option-Tag   This document defines the SIP option tag "recipient-list-subscribe".   The following row has been added to the "Option Tags" section of the   SIP Parameter Registry:   +--------------------------+----------------------------+-----------+   | Name                     | Description                | Reference |   +--------------------------+----------------------------+-----------+   | recipient-list-subscribe | This option tag is used to | [RFC5367] |   |                          | ensure that a server can   |           |   |                          | process the recipient-list |           |   |                          | body used in a SUBSCRIBE   |           |   |                          | request.                   |           |   +-------------------------------------------------------+-----------+10.  Acknowledgments   Cullen Jennings and Jonathan Rosenberg provided useful comments on   this document.11.  Normative References   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate              Requirement Levels",BCP 14,RFC 2119, March 1997.   [RFC3261]  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.   [RFC3265]  Roach, A.B., "Session Initiation Protocol (SIP)-Specific              Event Notification",RFC 3265, June 2002.   [RFC4662]  Roach, A.B., Campbell, B., and J. Rosenberg, "A Session              Initiation Protocol (SIP) Event Notification Extension for              Resource Lists",RFC 4662, August 2006.   [RFC4826]  Rosenberg, J., "Extensible Markup Language (XML) Formats              for Representing Resource Lists",RFC 4826, May 2007.   [RFC5363]  Camarillo, G. and A.B. Roach, "Framework and Security              Considerations for Session Initiation Protocol (SIP) URI-              List Services",RFC 5363, October 2008.Camarillo                   Standards Track                     [Page 7]

RFC 5367               SUBSCRIBE-Contained Lists            October 2008Authors' Addresses   Gonzalo Camarillo   Ericsson   Hirsalantie 11   Jorvas  02420   Finland   EMail: Gonzalo.Camarillo@ericsson.com   Adam Roach   Tekelec   17210 Campbell Rd Ste 250   Dallas, TX  75252   USA   EMail: Adam.Roach@tekelec.com   Orit Levin   Microsoft Corporation   One Microsoft Way   Redmond, WA  98052   EMail: oritl@microsoft.comCamarillo                   Standards Track                     [Page 8]

RFC 5367               SUBSCRIBE-Contained Lists            October 2008Full Copyright Statement   Copyright (C) The IETF Trust (2008).   This document is subject to the rights, licenses and restrictions   contained inBCP 78, and except as set forth therein, the authors   retain all their rights.   This document and the information contained herein are provided on an   "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS   OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND   THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS   OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF   THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED   WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.Intellectual Property   The IETF takes no position regarding the validity or scope of any   Intellectual Property Rights or other rights that might be claimed to   pertain to the implementation or use of the technology described in   this document or the extent to which any license under such rights   might or might not be available; nor does it represent that it has   made any independent effort to identify any such rights.  Information   on the procedures with respect to rights in RFC documents can be   found inBCP 78 andBCP 79.   Copies of IPR disclosures made to the IETF Secretariat and any   assurances of licenses to be made available, or the result of an   attempt made to obtain a general license or permission for the use of   such proprietary rights by implementers or users of this   specification can be obtained from the IETF on-line IPR repository athttp://www.ietf.org/ipr.   The IETF invites any interested party to bring to its attention any   copyrights, patents or patent applications, or other proprietary   rights that may cover technology that may be required to implement   this standard.  Please address the information to the IETF at   ietf-ipr@ietf.org.Camarillo                   Standards Track                     [Page 9]