[Search] [txt|pdf|bibtex] [Tracker] [WG] [Email] [Diff1] [Diff2] [Nits]

Versions: 00 01 02 03                                                   
SIMPLE WG                                                   H. Khartabil
Internet-Draft                                               E. Leppanen
Expires: February 12, 2004                                         Nokia
                                                                T. Moran
                                                         August 14, 2003


    Requirements for Presence Specific Event Notification Filtering
                 draft-ietf-simple-pres-filter-reqs-02

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
   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 February 12, 2004.

Copyright Notice

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

Abstract

   This document defines a set of structured requirements whereby a
   presence information subscriber may select specific information to be
   received in the presence information notification sent by the
   notifier. The purpose is to limit the content and frequency of
   notifications so that only essential information on a need basis is
   delivered by the server.








Khartabil, et al.      Expires February 12, 2004                [Page 1]


Internet-Draft      Presence Filtering Requirements          August 2003


Table of Contents

   1.    Introduction . . . . . . . . . . . . . . . . . . . . . . . .  3
   2.    Conventions  . . . . . . . . . . . . . . . . . . . . . . . .  3
   3.    Requirements for Specification of Filters  . . . . . . . . .  4
   3.1   Package Identification . . . . . . . . . . . . . . . . . . .  4
   3.2   Target URI . . . . . . . . . . . . . . . . . . . . . . . . .  4
   3.3   Notification Triggering  . . . . . . . . . . . . . . . . . .  4
   3.4   Notification Content . . . . . . . . . . . . . . . . . . . .  5
   4.    Requirements for Uploading Filter Criteria (Operational
         Rules) . . . . . . . . . . . . . . . . . . . . . . . . . . .  5
   4.1   Subscription . . . . . . . . . . . . . . . . . . . . . . . .  5
   4.1.1 Maintaining a Filter . . . . . . . . . . . . . . . . . . . .  5
   4.1.2 Changing a Filter  . . . . . . . . . . . . . . . . . . . . .  6
   4.2   Server Support For Filters . . . . . . . . . . . . . . . . .  6
   5.    Interaction with Other Features  . . . . . . . . . . . . . .  6
   5.1   Resource Lists . . . . . . . . . . . . . . . . . . . . . . .  6
   5.2   Partial Notifications  . . . . . . . . . . . . . . . . . . .  7
   5.3   Authorization  . . . . . . . . . . . . . . . . . . . . . . .  7
   6.    Security Considerations  . . . . . . . . . . . . . . . . . .  7
   7.    Example Applications for Notification Filtering  . . . . . .  8
   8.    Acknowledgements . . . . . . . . . . . . . . . . . . . . . .  8
   9.    Main changes from version 01 . . . . . . . . . . . . . . . .  8
   10.   Main changes from version 00 . . . . . . . . . . . . . . . .  9
         References . . . . . . . . . . . . . . . . . . . . . . . . .  9
         Authors' Addresses . . . . . . . . . . . . . . . . . . . . . 10
         Intellectual Property and Copyright Statements . . . . . . . 11
























Khartabil, et al.      Expires February 12, 2004                [Page 2]


Internet-Draft      Presence Filtering Requirements          August 2003


1. Introduction

   SIP event notification is described in [6]. It defines a general
   framework for subscriptions and notifications for SIP event packages.
   Concrete applications of the general event framework to a specific
   group of events are described in [5] (user presence) and [7] (watcher
   information).

   The presence information refers to a set of presence attributes
   describing the availability and willingness of the user (presentity)
   for communication. The user makes his presence information available
   for other users (watchers).

   As the inherent usage of event packages grows, the client needs some
   mechanisms for controlling the event notifications at the source.
   Evidence of this need is found in [4].

   The document describing the Presence event package [5] mentions the
   possibility for filtering. Accordingly, the SUBSCRIBE request may
   contain a body for filtering the presence information subscription.
   However, the definition of filtering was considered out of scope was
   left as future work.

   These mechanisms are expected to be particularly valuable to users of
   wireless devices. The characteristics of these devices typically
   include low bandwidth, low data processing capabilities, small
   display and limited battery power. Such devices can benefit from the
   ability to filter the amount of information generated at the source
   of the event notifications.

   However, it is expected that the control mechanisms for event
   notifications add value for all users irrespectively of their device
   or network access characteristics.

   Section 3 and Section 4 of this draft propose a set of requirements
   whereby a client may specify which notifications it is interested in.
   That is, a means to specify filtering rules to be executed by the
   server. Section 7 provides a few example applications of notification
   filtering.

2. Conventions

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





Khartabil, et al.      Expires February 12, 2004                [Page 3]


Internet-Draft      Presence Filtering Requirements          August 2003


3. Requirements for Specification of Filters

   The following requirements relate to the creation of filter criteria.

3.1 Package Identification

   REQ xx: It MUST be possible for the creator of the filter to specify
   the package the filter applies to.

3.2 Target URI

   REQ xx: It MUST be possible for the watcher to indicate, in the
   filter, the target presentity whose presence information a certain
   filter is applied to.

   REQ xx: It MUST be possible for the watcher to indicate, in the
   filter criteria, the target presentity list whose presence
   information a certain filter is applied to.

   REQ xx: It MUST be possible for the watcher to indicate, in the
   filter criteria, the target presentity sub-list whose presence
   information a certain filter is applied to.

   REQ xx: It MUST be possible for the watcher to indicate, in the
   filter criteria, the target domain that contains presentities whose
   presence information a certain filter is applied to.

3.3 Notification Triggering

   This chapter presents requirements for specifying the triggering
   conditions that result in notifications to be sent to the client.

   REQ xx: It MUST NOT be possible to break any server side policy
   constraints when applying the triggering conditions. For example, it
   must not be possible for a watcher to request a notification when the
   <status> element value of a certain presentity has changed from OPEN
   to CLOSED when there is a local server policy constraining the
   delivery of any tuple with a <status> element value of CLOSED.

   REQ xx: The triggering conditions MUST be based on the presence
   information. For example, the change of value of the <status>
   element.

   REQ xx: It MUST be possible to specify logical expressions based on
   the value of elements defined in the package for the purpose of
   triggering. This covers expressions (tests) related to the change of
   an element's value, and reaching a certain value of an element.




Khartabil, et al.      Expires February 12, 2004                [Page 4]


Internet-Draft      Presence Filtering Requirements          August 2003


   REQ xx: It MUST be possible to construct one filter that combine
   multiple triggering conditions.

3.4 Notification Content

   This chapter presents requirements for specifying the filter for
   choosing content to be sent in the notifications.

   REQ xx: It MUST NOT be possible to break any server side policy
   constraints when applying the content filter. For example, it must
   not be possible for a watcher to request a notification to contain
   the <contact> element of a certain presentity when there is a local
   server policy constraining the delivery of the <contact> element.

   REQ xx: It MUST be possible for the watcher to specify the presence
   information elements (XML elements and/or attributes) in [2] to be
   delivered in the notification.

   REQ xx: It MUST be possible for the watcher to specify presence
   information in any extension to PIDF to be delivered in the
   notifications, based on  XML elements and/or attributes. See for
   example [3].

   REQ xx: It MUST be possible for the watcher to specify presence
   information in any extension to be delivered in the notifications,
   based on  namespaces.

   REQ xx: It MUST be possible to construct one filter that combine
   multiple elements and attributes to be included the notifications.


4. Requirements for Uploading Filter Criteria (Operational Rules)

   REQ xx: It MUST be possible for the watcher to upload filter criteria
   to the server (notifier) and know the status - accepted or rejected.

4.1 Subscription

   REQ xx: It MUST be possible to place a filter in the body of the
   SUBSCRIBE request.

   REQ xx: It MAY be possible to deliver a filter to a server using
   other means. For example, it may be possible for the filter to be
   (permanently) stored in the server.

4.1.1 Maintaining a Filter

   REQ xx: The watcher MUST NOT be required to re-set a filter at any



Khartabil, et al.      Expires February 12, 2004                [Page 5]


Internet-Draft      Presence Filtering Requirements          August 2003


   time during the subscription, once the filter has been set.

   REQ xx: The watcher SHOULD NOT be required to re-set a filter when
   refreshing a subscription, once the filter has been set.

   REQ xx: Maintaining a filter across subscription refreshes SHOULD be
   bandwidth efficient.

4.1.2 Changing a Filter

   REQ xx: It MUST be possible to change the filter during a
   subscription.

   REQ xx: It MUST be possible for the watcher to remove a set filter,
   reverting back to a server defined default.

4.2 Server Support For Filters

   REQ xx: It MUST be possible for a server not supporting filtering  to
   inform the watcher of the failure.

   REQ xx:  It MUST be possible for a server not understanding a
   filtering  to inform the watcher of the failure.

   REQ xx: It MUST be possible for a server not accepting a filter to
   inform the watcher of the reasons for not accepting the filter.

   REQ xx: It MUST be possible for a server to terminate a subscription
   based on a filter becoming invalid due to sever local policy change.
   (How do I word this in a requirement text?)

5. Interaction with Other Features

5.1 Resource Lists

   REQ xx: It MUST be possible to support filtering for subscriptions to
   resource lists [8].

   REQ xx: It MUST be possible for a watcher to specify filter criteria
   for a resource list and/or any nested sub list of the resource list.

   REQ xx: It MUST be possible for a watcher to specify different filter
   for any individual member of a resource list in a resource list
   subscription.

   REQ xx: It MUST be possible for a watcher to specify different filter
   criteria for individual members of any of nested sub lists of a
   resource list in a resource list subscription. Any of the nested sub



Khartabil, et al.      Expires February 12, 2004                [Page 6]


Internet-Draft      Presence Filtering Requirements          August 2003


   lists may be located in a different domain from the parent list.

   REQ xx: It MUST be possible for each watcher to define own filter
   criteria within resource list subscription if there are several
   simultaneous watchers using the same list.

5.2 Partial Notifications

   REQ xx: It MUST be possible to use filtering along with the partial
   notification [9] within the same subscription.

5.3 Authorization

   REQ xx: Authorization SHOULD occur irrespective of the filtering.

6. Security Considerations

   Security requirements specified for [5] also applies to the presence
   filtering. Additional security considerations related to the presence
   filtering are described as follows.

   REQ xx: It SHOULD be possible for the server to hide the fact that a
   filter was not acceptable.

   REQ xx: The presence of filter criteria in the body in a SIP message
   has a significant effect on the way in which the request is handled
   at a server. As a result, it is especially important that messages
   containing filter criteria are authenticated and authorized.

   REQ xx: Modification to the Filter Criteria by an intermediary could
   also result in the watcher either not receiving notifications of
   presence information they are interested in or receiving a very large
   presence document. Therefore the filter criteria SHOULD be integrity
   protected between those nodes that are authorised to modify it (e.g.,
   the resource list servers).

   REQ xx: Processing of requests and looking up filter criteria
   requires some amount of computation. This enables a DoS attack
   whereby a user can send requests with substantial numbers messages
   with large contents, in the hopes of overloading the server. To
   prevent this the number of filter criteria allowed in a request
   should be limited.

   REQ xx: Requests containing filter criteria can reveal sensitive
   information about a UA's capabilities. If this information is
   sensitive, it SHOULD be encrypted using methods that allow it to be
   read by those nodes that need to do so (e.g., the resource list
   servers).



Khartabil, et al.      Expires February 12, 2004                [Page 7]


   REQ xx: The resource list servers SHOULD convey only those parts of
   filter information targeted to the same destination as the fanned out
   individual subscriptions, if the filter information is conveyed
   further within the subscription.

7. Example Applications for Notification Filtering

   1.  A watcher wishes to get to know presentity's availability and
       willingness for messaging (e.g. IM and MMS).

   2.  A watcher is interested in getting information about the
       communication means and contact addresses the presentity is
       currently available for communication.

   3.  A watcher requires a notification if the state of a buddy has
       changed to 'open'.

   4.  A watcher only wants to be notified when the presentity's
       location is Dallas or Fort Worth. The notification should include
       the vehicle license, driver name, and city.

   5.  A Basic location tracking service requires notification when the
       presentity's cell id changes. The notification should include the
       cell id.

   6.  A watcher is interested in being notified when a presentity gains
       a new communication capability such as a new networked
       multi-player game.


8. Acknowledgements

   The authors would like to thank Andrew Allen, Sreenivas Addagatla,
   Mikko Lonnfors, Juha Kalliokulju, Aki Niemi, Jose Costa-Requena and
   Markus Isomaki for their valuable input.

9. Main changes from version 01

   o  "Overview of Operation" section removed .

   o  "Common Syntax" section removed.

   o  "Discovery of Items" section removed as agreed in IETF 57

   o  Added requirement about filtering using namespaces.

   o  Added requirement about filtering using domain name.

   o  Clarified and split larger requirements into smaller more concrete
      requirements.



Khartabil, et al.      Expires February 12, 2004                [Page 8]


Internet-Draft      Presence Filtering Requirements          August 2003


   o  Updated the Authors of this ID


10. Main changes from version 00

   o  Overview of functionality chapter added.

   o  More specific requirements for supporting filtering with the
      resource lists, and nested lists.

   o  Interaction with other features chapter added.

   o  More specific requirements to support getting information about
      the structure of presence document, and changes in it.

   o  Several filter specific additions to security considerations.

   o  Several editorial changes, e.g., reference and terminology
      updates.

References

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

   [2]  Sugano, H., "CPIM Presence Information Data Format",
        draft-ietf-impp-cpim-pidf-08.txt, May 2003.

   [3]  Schulzrinne, H., "RPIDS -- Rich Presence Information Data Format
        for Presence Based on the Session Initiation Protocol (SIP)",
        draft-schulzrinne-simple-rpids-01.txt, February 2003.

   [4]  Kiss, K., "Requirements for Presence Service based on 3GPP
        specifications and wireless environment characteristics",
        draft-kiss-simple-presence-wireless-reqs-02, February 2003.

   [5]  Rosenberg, J., "Session Initiation Protocol (SIP) Extensions for
        Presence",  draft-ietf-simple-presence-10.txt, January 2003.

   [6]  Roach, A., "Session Initiation Protocol (SIP)-Specific Event
        Notification", RFC 3265, June 2002.

   [7]  Rosenberg, J., "A Watcher Information Event Template-Package for
        the Session Initiation Protocol (SIP)",
        draft-ietf-simple-winfo-package-05.txt, January 2003.

   [8]  Rosenberg, J., "A Session Initiation Protocol (SIP) Event
        Notification Extension for Resource Lists",



Khartabil, et al.      Expires February 12, 2004                [Page 9]


Internet-Draft      Presence Filtering Requirements          August 2003


        draft-ietf-simple-event-list-03.txt, May 2003.

   [9]  Lonnfors, M., "Partial Notification of Presence Information",
        draft-lonnfors-simple-partial-notify-01.txt, May 2003.


Authors' Addresses

   Hisham Khartabil
   Nokia
   P.O BOX 321
   Helsinki
   Finland

   Phone: +358 7180 76161
   EMail: hisham.khartabil@nokia.com


   Eva Leppanen
   Nokia
   P.O BOX 785
   Tampere
   Finland

   Phone: +358 7180 77066
   EMail: eva-maria.leppanen@nokia.com


   Tim Moran
   2800 Britt Drive
   Argyle, Texas 76226
   USA

   Phone: +1 972 849 8821
   EMail: tl_moran@att.net
















Khartabil, et al.      Expires February 12, 2004               [Page 10]


Internet-Draft      Presence Filtering Requirements          August 2003


Intellectual Property Statement

   The IETF takes no position regarding the validity or scope of any
   intellectual property 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; neither does it represent that it
   has made any effort to identify any such rights. Information on the
   IETF's procedures with respect to rights in standards-track and
   standards-related documentation can be found in BCP-11. Copies of
   claims of rights made available for publication 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 implementors or users of this specification can
   be obtained from the IETF Secretariat.

   The IETF invites any interested party to bring to its attention any
   copyrights, patents or patent applications, or other proprietary
   rights which may cover technology that may be required to practice
   this standard. Please address the information to the IETF Executive
   Director.


Full Copyright Statement

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

   This document and translations of it may be copied and furnished to
   others, and derivative works that comment on or otherwise explain it
   or assist in its implementation may be prepared, copied, published
   and distributed, in whole or in part, without restriction of any
   kind, provided that the above copyright notice and this paragraph are
   included on all such copies and derivative works. However, this
   document itself may not be modified in any way, such as by removing
   the copyright notice or references to the Internet Society or other
   Internet organizations, except as needed for the purpose of
   developing Internet standards in which case the procedures for
   copyrights defined in the Internet Standards process must be
   followed, or as required to translate it into languages other than
   English.

   The limited permissions granted above are perpetual and will not be
   revoked by the Internet Society or its successors or assignees.

   This document and the information contained herein is provided on an
   "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
   TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
   BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION



Khartabil, et al.      Expires February 12, 2004               [Page 11]


Internet-Draft      Presence Filtering Requirements          August 2003


   HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.


Acknowledgement

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











































Khartabil, et al.      Expires February 12, 2004               [Page 12]