SIPPING                                                     G. Camarillo
Internet-Draft                                                  Ericsson
Expires: August 29, 2006                               February 25, 2006


     The Session Initiation Protocol (SIP) List State Event Package
               draft-camarillo-sipping-list-state-00.txt

Status of this Memo

   By submitting this Internet-Draft, each author represents that any
   applicable patent or other IPR claims of which he or she is aware
   have been or will be disclosed, and any of which he or she becomes
   aware will be disclosed, in accordance with Section 6 of BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF), its areas, and its working groups.  Note that
   other groups may also distribute working documents as Internet-
   Drafts.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   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 29, 2006.

Copyright Notice

   Copyright (C) The Internet Society (2006).

Abstract

   This document defines the SIP List State event package.  This event
   package is used by Resource List Servers to inform user agents about
   the consent-related status of the entries in one or several resource
   lists.








Camarillo                Expires August 29, 2006                [Page 1]


Internet-Draft          List State Event Package           February 2006


Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Terminology  . . . . . . . . . . . . . . . . . . . . . . . . .  3
   3.  Overview of Operation  . . . . . . . . . . . . . . . . . . . .  3
   4.  List State Event Package Definition  . . . . . . . . . . . . .  3
     4.1.  Event Package Name . . . . . . . . . . . . . . . . . . . .  4
       4.1.1.  Event Package Parameters . . . . . . . . . . . . . . .  4
       4.1.2.  SUBSCRIBE Bodies . . . . . . . . . . . . . . . . . . .  4
       4.1.3.  Subscription Duration  . . . . . . . . . . . . . . . .  4
       4.1.4.  NOTIFY Bodies  . . . . . . . . . . . . . . . . . . . .  4
       4.1.5.  Notifier Processing of SUBSCRIBE Requests  . . . . . .  5
       4.1.6.  Notifier Generation of NOTIFY Requests . . . . . . . .  5
       4.1.7.  Subscriber Processing of NOTIFY Requests . . . . . . .  5
       4.1.8.  Handling of Forked Requests  . . . . . . . . . . . . .  5
       4.1.9.  Rate of Notifications  . . . . . . . . . . . . . . . .  5
       4.1.10. State Agents . . . . . . . . . . . . . . . . . . . . .  5
       4.1.11. Example  . . . . . . . . . . . . . . . . . . . . . . .  6
   5.  Usage of the 'list-state' Event Package with the XCAP Diff
       Format . . . . . . . . . . . . . . . . . . . . . . . . . . . .  6
   6.  List State RLS Service . . . . . . . . . . . . . . . . . . . .  7
   7.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . .  7
   8.  Security Considerations  . . . . . . . . . . . . . . . . . . .  7
   9.  Acknowledgements . . . . . . . . . . . . . . . . . . . . . . .  8
   10. References . . . . . . . . . . . . . . . . . . . . . . . . . .  8
     10.1. Normative References . . . . . . . . . . . . . . . . . . .  8
     10.2. Informative References . . . . . . . . . . . . . . . . . .  8
   Author's Address . . . . . . . . . . . . . . . . . . . . . . . . .  9
   Intellectual Property and Copyright Statements . . . . . . . . . . 10






















Camarillo                Expires August 29, 2006                [Page 2]


Internet-Draft          List State Event Package           February 2006


1.  Introduction

   The framework for consent-based communications in SIP [4] identifies
   the need for users manipulating the translation logic at a relay
   (e.g., adding a new recipient) to be informed about the consent-
   related status of the recipients of a given translation.  That is,
   the user manipulating the translation logic needs to know which
   recipients have given the relay permission to send them SIP requests.

   This document defines a SIP event package whereby user agents can
   subscribe to the state of a resource list that defines a translation.
   This state includes the consent related-status of the resources of
   the resource list.


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.  Overview of Operation

   A user agent subscribes to a resource list server using the 'list-
   state' event package.  NOTIFY requests within this event package can
   carry an XML document in the "application/resource-lists+xml" format
   [5] or in the "application/xcap-diff+xml" format [6].

   A document in the "application/resource-lists+xml" format provides
   the user agent with the whole resource list, including consent-
   related state information.

   A document in the "application/xcap-diff+xml" format informs the user
   agent that the document that described the resource list has changed.
   The user agent then downloads the document in the "application/
   resource-lists+xml" format from the permission server using XCAP.


4.  List State Event Package Definition

   This section provides the details for defining a SIP [2] event
   notification package, as specified by RFC 3265 [3].






Camarillo                Expires August 29, 2006                [Page 3]


Internet-Draft          List State Event Package           February 2006


4.1.  Event Package Name

   The name of this event package is "list-state".  This package name is
   carried in the Event and Allow-Events header, as defined in RFC 3265
   [3].

4.1.1.  Event Package Parameters

   This package does not define any event package parameters.

4.1.2.  SUBSCRIBE Bodies

   A SUBSCRIBE for 'list-state' events MAY contain a body.  This body
   would serve the purpose of filtering the subscription.  The
   definition of such a body is outside the scope of this specification.

   A SUBSCRIBE for the 'list-state' package MAY be sent without a body.
   This implies that the default session policy filtering policy has
   been requested.  The default policy is that notifications are
   generated every time there is any change in the state of a resource
   in the list.

4.1.3.  Subscription Duration

   The default expiration time for a subscription is one hour (3600
   seconds).

4.1.4.  NOTIFY Bodies

   In this event package, the body of the notifications contains a
   resource list document.  This document describes a resource list and
   the consent-related state of its resources.  All subscribers and
   notifiers MUST support the "application/resource-lists+xml" data
   format [5] and its extension to carry consent-related state
   information [7].  The subscribe request MAY contain an Accept header
   field.  If no such header field is present, it has a default value of
   "application/resource-lists+xml".  If the header field is present, it
   MUST include "application/resource-lists+xml", and MAY include any
   other types capable of representing translation state.

   OPEN ISSUE: do we need to discuss how to use content indirection
   here?

   Additionally, all subscribers and notifiers SHOULD support the
   "application/xcap-diff+xml" format [6].  Section 5 discusses the
   usage of the 'list-state' event package with this format.





Camarillo                Expires August 29, 2006                [Page 4]


Internet-Draft          List State Event Package           February 2006


4.1.5.  Notifier Processing of SUBSCRIBE Requests

   The state of a resource list defining a translation can reveal
   sensitive information.  Therefore, all subscriptions SHOULD be
   authenticated and then authorized before approval.  Authorization
   policy is at the discretion of the administrator.

4.1.6.  Notifier Generation of NOTIFY Requests

   A notifier for the List State event package SHOULD include the
   <consent-status> element [7] when the framework for consent-based
   communications in SIP is used.  When present, the <consent-status>
   element MUST be positioned as an instance of the <any> element within
   the <entry> element.

   Notifications SHOULD be generated for the List State package whenever
   there is a change in the resource-list state.

4.1.7.  Subscriber Processing of NOTIFY Requests

   NOTIFY requests contain the full resource-list state.  The subscriber
   does not need to perform any type of information aggregation.

4.1.8.  Handling of Forked Requests

   The state of a given resource list is normally handled by a server
   and stored in a repository.  Therefore, there is usually a single
   place where the resource-list state is resident.  This implies that a
   subscription for this information is readily handled by a single
   element with access to this repository.  There is, therefore, no
   compelling need for a subscription to session policy information to
   fork.  As a result, a subscriber MUST NOT create multiple dialogs as
   a result of a single subscription request.  The required processing
   to guarantee that only a single dialog is established is described in
   Section 4.4.9 of RFC 3265 [3].

4.1.9.  Rate of Notifications

   For reasons of congestion control, it is important that the rate of
   notifications not become excessive.  As a result, it is RECOMMENDED
   that the server doesn't generate notifications for a single
   subscriber at a rate faster than once every 5 seconds.

4.1.10.  State Agents

   State agents have no role in the handling of this package.





Camarillo                Expires August 29, 2006                [Page 5]


Internet-Draft          List State Event Package           February 2006


4.1.11.  Example

   The following is an example of an "application/xcap-diff+xml"
   document that carries consent-related state information using
   <consent-status> elements:


      <?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"
       xmlns:cs="urn:ietf:params:xml:ns:consent-status">
       <list name="friends">
        <entry uri="sip:bill@example.com">
         <display-name>Bill Doe</display-name>
         <cs:consent-status>pending</cs:consent-status>
        </entry>
        <entry uri="sip:joe@example.com">
         <display-name>Joe Smith</display-name>
         <cs:consent-status>pending</cs:consent-status>
        </entry>
        <entry uri="sip:nancy@example.com">
         <display-name>Nancy Gross</display-name>
         <cs:consent-status>granted</cs:consent-status>
         </entry>
       </list>
      </resource-lists>


5.  Usage of the 'list-state' Event Package with the XCAP Diff Format

   As discussed in Section 4.1.4, if a client subscribing to the 'list-
   state' event package an Accept header field including the MIME type
   "application/xcap-diff+xml", the permission server has the option of
   returning documents in this format (instead of in the 'application/
   list-state+xml' format).

   Upon initial subscription, the permission server does not know which
   instance of the resource list document for the user (where each
   instance is identified by an etag) the client currently posessses, if
   any.  Indeed, upon startup, the client will not have any documents.

   The initial NOTIFY request in this case MUST include a <document>
   element for the resource list.  The "previous-etag" attribute MUST be
   absent, and the "new-etag" attribute MUST be present and contain the
   entity tag for the current version of the document.  An XCAP diff
   document structured this way is called a "reference" XCAP diff
   document.  It establishes the baseline etag and document URI for the
   document covered by the subscription.



Camarillo                Expires August 29, 2006                [Page 6]


Internet-Draft          List State Event Package           February 2006


   Upon receipt of this document, the client can determine whether its
   local instance document, if any, matches the etag in the XCAP diff
   document.  If they do not match, the client SHOULD perform a
   conditional GET for each document.  The document URI is constructed
   by appending the XCAP root in the "xcap-root" attribute of the <xcap-
   diff> element to the escape coded "doc-selector" from the <document>
   element.  The request is made conditional by including an If-Match
   header field, with the value of the etag from the <document> element.
   So long as the documents haven't changed between the NOTIFY and the
   GET, the client will obtain the reference version that the server
   will use for subsequent notifications.

   If the conditional GET should fail, the client SHOULD generate a
   SUBSCRIBE refresh request to trigger a new NOTIFY.  The server will
   always generate a "reference" XML diff document on receipt of a
   SUBSCRIBE refresh.  This establishes a new baseline etag, and the
   client can then attempt to do another fetch.

   Once the client has obtained the version of the document identified
   in the reference XML diff, it can process NOTIFY requests on that
   subscription.  To process the NOTIFY requests, it makes sure that its
   current version matches the version in the "previous-etag" attribute
   of the <document> element.  If not, the client can then fetch the
   updated document from the server.  If they do match, the client has
   the most current version.


6.  List State RLS Service

   TBD: Define the 'List State' RLS service [5].  Example:

   <packages>
         <package>presence</package>
         <package>list state</package>
   </packages>


7.  IANA Considerations

   TBD.


8.  Security Considerations

   TBD.






Camarillo                Expires August 29, 2006                [Page 7]


Internet-Draft          List State Event Package           February 2006


9.  Acknowledgements

   TBD.


10.  References

10.1.  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., "Session Initiation Protocol (SIP)-Specific Event
        Notification", RFC 3265, June 2002.

   [4]  Rosenberg, J., "A Framework for Consent-Based Communications in
        the Session Initiation  Protocol (SIP)",
        draft-ietf-sipping-consent-framework-03 (work in progress),
        October 2005.

   [5]  Rosenberg, J., "Extensible Markup Language (XML) Formats for
        Representing Resource Lists",
        draft-ietf-simple-xcap-list-usage-05 (work in progress),
        February 2005.

   [6]  Rosenberg, J., "An Extensible Markup Language (XML) Document
        Format for Indicating A Change  in XML Configuration Access
        Protocol (XCAP) Resources", draft-ietf-simple-xcap-diff-02 (work
        in progress), October 2005.

   [7]  Camarillo, G., "Session Initiation Protocol (SIP) Registration
        Event Package Extension for Consent-Based Communications",
        draft-camarillo-sipping-consent-reg-event-00 (work in progress),
        February 2006.

10.2.  Informative References











Camarillo                Expires August 29, 2006                [Page 8]


Internet-Draft          List State Event Package           February 2006


Author's Address

   Gonzalo Camarillo
   Ericsson
   Hirsalantie 11
   Jorvas  02420
   Finland

   Email: Gonzalo.Camarillo@ericsson.com










































Camarillo                Expires August 29, 2006                [Page 9]


Internet-Draft          List State Event Package           February 2006


Intellectual Property Statement

   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 in BCP 78 and BCP 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 at
   http://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.


Disclaimer of Validity

   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 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.


Copyright Statement

   Copyright (C) The Internet Society (2006).  This document is subject
   to the rights, licenses and restrictions contained in BCP 78, and
   except as set forth therein, the authors retain all their rights.


Acknowledgment

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




Camarillo                Expires August 29, 2006               [Page 10]